EPAC08 - List of Keywords (simulation)

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simulation

Paper	Title	Other Keywords	Page
MOZAG01	Simulations of the Emittance Compensation in Photoinjectors and Comparison with SPARC Measurements	emittance, gun, linac, space-charge	21
	C. Ronsivalle, L. Giannessi, M. Quattromini ENEA C. R. Frascati, Frascati (Roma) A. Bacci, A. R. Rossi, L. Serafini INFN-Milano, Milano E. Chiadroni, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, B. Marchetti, M. Migliorati, A. Mostacci, L. Palumbo, C. Vaccarezza INFN/LNF, Frascati (Roma) A. Cianchi INFN-Roma II, Roma
	FEL photoinjectors are based on the emittance compensation process, by which a high brightness beam can be accelerated without degradation. The experimental results obtained in the SPARC facility for which the beam dynamics has been extensively simulated confirm the theoretical predictions. The paper illustrates the most relevant beam dynamics results as well as a comparison between simulations and measurements.
	Slides

MOPC002	Extension of the FERMI FEL1 to Shorter Wavelengths	electron, undulator, radiation, laser	64
	E. Allaria ELETTRA, Basovizza, Trieste G. De Ninno University of Nova Gorica, Nova Gorica
	We propose a modification of the first stage (FEL-1) of the FERMI@Elettra project in order to extend the wavelength from the original limit of 40 nm down to 20 nm. The modified setup takes advantage of a shorter radiator undulator period. We present the numerical studies that have been carried out to compare the expected performance of the new FEL-1 with that of the original FERMI setup. Results show that the modified configuration represents a good alternative to the second stage of the project (FEL-2) in the wavelength range between 40 nm and 20 nm. C. J. Bocchetta et al. 'FERMI@Elettra Conceptual Design Report' ST/F-TN-07/12 (2007)

MOPC003	Estimation of Undulator Requirements for Coherent Harmonic Generation on FERMI@Elettra	undulator, electron, bunching, laser	67
	E. Allaria, G. De Ninno, B. Diviacco ELETTRA, Basovizza, Trieste
	The FERMI project is devoted to the realization of a FEL user facility based on the principle of coherent harmonic generation (CHG). The advantages of such a method (with respect, e.g., to self amplified spontaneous emission) is that the output properties of the light are strongly determined by the interaction of the seed laser with the electron beam within the modulator undulator. In CHG FELs therefore, in addition to the requirements for the radiator where FEL radiation is produced, it is important to understand and satisfy the requirements for the modulator. In this work, we present a study focused on the first stage (FEL-1) of the FERMI@Elettra setup. The study aims at providing an estimation of the undulator requirements in terms of magnetic field accuracy for both the modulator and the radiator. The work is based on numerical simulations of the FEL-1 using the numerical code GINGERH [1]. The required undulator tolerances have been obtained by means of a large number of simulation runs taking into account different sets of undulator parameters. [1] W. Fawley, “A User Manual for GINGER-H and its Post-Processor XPLOTGINH” LCLS-TN-07-YY Technical note, Lawrence Berkeley National Laboratory (2007)

MOPC008	The Impact of PSK Timing on Energy Stability of e-Beam at FERMI@ELETTRA	linac, klystron, synchrotron, injection	82
	G. D'Auria, P. Delgiusto, M. M. Milloch, C. Serpico, D. Wang ELETTRA, Basovizza, Trieste
	The existing linac sections S1-S7 at ELETTRA will be upgraded for the FERMI@ELETTRA FEL project. These seven sections are 3/4 π-mode backward traveling wave (BTW) constant-impedance structures, powered by 45-MW klystrons (Thales TH 2132A) and with a SLED system to increase the RF peak power. Because of the strict requirement on the pulse-to-pulse beam energy stability (<0.1%) of the FERMI@ELETTRA project, the impact of phase shift keying (PSK), the timing of phase flipping, on beam energy needs to be revisited and evaluated. Here the results obtained with a simulation model built up by use of MATLAB simulink are present and discussed.

MOPC012	PSI XFEL Simulations with SIMPLEX and GENESIS	undulator, electron, emittance, radiation	91
	V. G. Khachatryan, V. M. Tsakanov CANDLE, Yerevan R. J. Bakker PSI, Villigen V. V. Sahakyan, A. Tarloyan YSU, Yerevan
	The numerical simulation results of the SASE FEL process for PSI XFEL project are presented. The main purpose of the investigations using FEL simulation codes SIMPLEX and GENESIS is the reliable definition of the undulators design parameters (K value, period, segment length, number of segments) that provide desirable radiation characteristics such as wavelength, bandwidth, saturation length, peak power and the brightness.

MOPC013	Effect of Jitter and Quadrupole Alignment Errors on SASE FEL Performance	radiation, quadrupole, undulator, electron	94
	V. G. Khachatryan, A. Tarloyan, V. M. Tsakanov CANDLE, Yerevan W. Decking DESY, Hamburg
	Numerical simulations of the radiation process at the European XFEL project are presented. The impact of quadrupole misalignments on the saturation length and saturation power is investigated using the simulation codes SIMPLEX and GENESIS. The influence of trajectory steering in the presence of BPM misalignments on the FEL performance is analyzed. The study is performed for the SASE 1 undulator designed for 0.1nm radiation wavelength.

MOPC014	Optimization of the Focusing Lattice for European XFEL	lattice, undulator, focusing, radiation	97
	V. G. Khachatryan, A. Tarloyan, V. M. Tsakanov CANDLE, Yerevan W. Decking DESY, Hamburg V. V. Sahakyan YSU, Yerevan
	Detailed knowledge of the impact of the undulator section focusing lattice on the FEL performance is an important issue to ensure the stable operation of the facility with reliable tolerances. In this paper the results of numerical simulation studies for the European XFEL project are presented. The saturation length, saturation power and the spectral brightness of the SASE FEL are calculated for various focusing lattice arrangements. A focusing optics option with reduced number of FODO cells is discussed to reach the design goals with relaxed quadrupole magnet tolerances. The numerical simulations are performed using the SIMPLEX and GENESIS codes.

MOPC015	Start-to-End Simulations of the PSI 250 MeV Injector Test Facility	gun, emittance, linac, booster	100
	Y. Kim, A. Adelmann, R. J. Bakker, M. Dehler, R. Ganter, T. Garvey, A. Oppelt, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, A. Streun, F. Stulle, A. F. Wrulich PSI, Villigen
	From 2003, PSI has been investigating the advanced Low Emittance Gun (LEG) based 6 GeV PSI XFEL facility to supply coherent, ultra-bright, and ultra-fast XFEL photon beams covering from 0.1 nm to 10 nm. To build whole facility within a 800 m space, required beam parameters in front of undulators are challenging. For the first two FEL beamlines (FEL 1 and FEL 2), the required normalized slice emittance, slice energy spread, and peak current are about 0.2 mm.mrd, 0.6 MeV, and 1.5 kA, respectively. However, the required beam parameters for the third FEL beamline (FEL 3) covering 1 nm to 10 nm are somewhat flexible. Therefore PSI has been developing two different gun technologies. The 1 MV high gradient pulsed diode and field emission based advanced LEG will be used for first two FEL beamlines, while the CTF3 gun type V based conventional RF photoinjector will be used for the third FEL beamline. To test those two injector technologies, a dedicated 250 MeV injector test facility will be constructed at PSI from 2008. In this paper, we describe beam dynamics in two accelerator optimizations of the CTF3 RF gun based 250 MeV injector test facility for the PSI XFEL project.

MOPC019	Velocity Bunching at FLASH	emittance, bunching, electron, gun	112
	T. Limberg, B. Beutner, W. Decking, M. Huening, M. Krasilnikov, M. Vogt DESY, Hamburg O. Grimm Uni HH, Hamburg
	The vacuum-ultra-violet free electron laser in Hamburg (FLASH) is a linac driven SASE-FEL. High peak currents are, in routine operation, produced using magnetic bunch compression chicanes. Longitudinal dispersion in these chicanes allow bunch length changes of relativistic electron beams. For low energy electron beams (~5 MeV), the velocity dependence on electron energy can be utilized for bunch compression. Since strong bunch compression at low beam energies gives rise to strong space charge interactions which has an impact on, for instance, beam emittance and is therefore not suitable for full compression to the kA peak currents needed for SASE operation. Moderate velocity bunching, however, might be used to optimize the total bunch compression system of FLASH or the European XFEL. Experiments on the velocity bunching process at FLASH are presented here. Results on bunch length and transverse emittance measurements are discussed and compared with numerical tracking calculations.

MOPC032	Progress of the Commissioning of the Test FEL at MAX-lab	laser, gun, electron, emittance	139
	S. Thorin, F. Curbis, N. Cutic, F. Lindau, S. Werin MAX-lab, Lund M. Abo-Bakr, J. Bahrdt, K. Holldack BESSY GmbH, Berlin
	In a collaboration between MAX-lab and BESSY a seeded Harmonic Generation Free Electron Laser is being constructed at MAX-lab. The setup uses the existing MAX-lab facility together with a Ti:Sa 266 nm lasersytem used for both the gun and seeding and an optical klystron consisting of a modulator, a chicane and a radiator. The different parts of the system has been installed and commissioning with electrons of the full setup started during the fall of 2007. In this paper the progress of the commissioning of the Test FEL and our initial results are presented.

MOPC036	Pancakes versus Beer-cans in Terms of 6D Phase-space Density	laser, emittance, electron, cathode	151
	S. B. van der Geer, O. J. Luiten, M. J. de Loos TUE, Eindhoven S. B. van der Geer Pulsar Physics, Eindhoven
	Uniformly filled ellipsoidal (waterbag) electron bunches can be created in practice by space charge blow out of transversely tailored ‘pancake’ bunches. Ellipsoidal bunches have linear self fields in all dimensions, and will not deteriorate in quality under linear transport and acceleration. There is a discussion if such a bunch is better than a conventional beer-can shape. This paper compares the two approaches in terms of usable phase-space density. Detailed GPT simulations of a simplified setup show that although the pancakes approach requires less charge, it is the application that is decisive. O. J. Luiten et al. Phys. Rev. Lett. Vol 93, 094802 (2004).

MOPC037	Single Spike Operation in SPARC SASE-FEL	radiation, emittance, undulator, injection	154
	V. Petrillo, I. Boscolo Universita' degli Studi di Milano, Milano A. Bacci, S. Cialdi, L. Serafini INFN-Milano, Milano R. Bonifacio, M. Boscolo, M. Ferrario, C. Vaccarezza INFN/LNF, Frascati (Roma) F. Castelli Università degli Studi di Milano, Milano L. Giannessi, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) L. Palumbo Rome University La Sapienza, Roma S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California M. Serluca INFN-Roma, Roma
	We describe in this paper a possible experiment with the existing SPARC photoinjector to test the generation of sub-picosecond high brightness electron bunches able to produce single spike radiation pulses at 500 nm in the SPARC self-amplified spontaneous emission free-electron laser (SASE-FEL). The main purpose of the experiment will be the production of short electron bunches as long as few SASE cooperation lengths and to validate scaling laws to foresee operation at shorter wavelength in the future operation with SPARX. The basic physics, the experimental parameters and 3-D simulations are discussed. Complete start-to-end simulations with realistic SPARC parameters are presented, in view of an experiment for tests on superradiant theory with the existing hardware.

MOPC060	Transverse Resistive-wall Wake of a Round Pipe with Finite Thickness and its Effect on the ERL Multi-bunch Beam	impedance, vacuum, injection, lattice	202
	N. Nakamura ISSP/SRL, Chiba
	We already started to study the effect of resistive-wall wake on the multi-bunch beam in an ERL (energy recovery linac)-based light source, because resistive-wall beam breakup(RWBBU) could be caused by the cumulative transverse wake generated by interaction between the resistive vacuum pipe and the intense multi-bunch beam. However the resistive-wall wake function of a round pipe used so far for studying the RWBBU was valid only in a limited time range and improper to the RWBBU simulation for a longer time period. Therefore we analytically derived an exact expression of resistive-wall impedance of a round pipe with finite thickness over all the frequency range and numerically calculated the resistive-wall wake functions of several different pipes from the exact impedance expression. The calculated wake functions enabled us to study and simulate the beam behavior in an ERL made of the pipes accurately. We will present the transverse resistive-wall wake of a round pipe with finite thickness and its effect on the ERL multi-bunch beam. N. Nakamura et al., Proceedings of PAC07, Albuquerque, June 2007, pp. 1010-1012.

MOPC063	Characterisation of Electron Bunches from ALICE (ERLP) DC Photoinjector Gun at Two Different Laser Pulse Lengths	laser, emittance, electron, gun	211
	Y. M. Saveliev, S. P. Jamison, L. B. Jones, B. D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	In high-voltage DC photoinjector guns, the laser pulse duration affects the electron bunch characteristics and therefore is an important subject for experimental investigation and in the optimisation of the operation of the gun. Initial experimental study of this effect has been conducted using the Energy Recovery Linac Prototype (ERLP) photoinjector. During the commissioning of its DC photoinjector gun, the electron bunch parameters were measured at two laser pulse durations, ~7ps and ~28ps FWHM. The shorter laser pulse is the intrinsic output of the laser, while the longer pulse was produced with the use of a pulse stacker. The electron bunch parameters that were measured included transverse emittance, correlated and uncorrelated energy spread and bunch length. The experimental results and their comparison with computer simulations are presented and discussed.

MOPC064	Beam Losses Due to Intra-Beam and Residual Gas Scattering for Cornell's Energy Recovery Linac	beam-losses, radiation, scattering, undulator	214
	A. Temnykh Cornell University, Department of Physics, Ithaca, New York M. P. Ehrlichman, G. Hoffstaetter CLASSE, Ithaca
	In this paper we analyze particle loss rates in Cornell's x-ray Energy Recovery Linac. Because of the small beam emittances and high beam intensity, intra-beam scattering (IBS) can be a source of significant particles loss in the horizontal plane. It will result in radiation doses which should be carefully examined for adequate radiation protection. Additionally, scattering on the residual gas (RGS) causes particle losses in the vertical plane. With Mote-Carlo type simulations of the scattering processes and transport matrixes for particle-trajectory propagation we found the beam loss distribution along ERL. It indicated that 99% of the total beam loss will be due to IBS. However, the RGS contribution can not be ignored because it dominates scattering in the vertical plane causing IDs irradiation and damage. For both (IBS and RGS) processes the highest beam losses will occur at the end of deacceleration due to adiabatic anti-damping causing traverse betatron amplitudes to increase. These beamlosses can be consentrated in collimation sections. Knowing RGS beam loss rates at the ID locations, we estimate the ID’s life time and suggest a radiation protection scheme.

MOPC065	Wake Field Simulations for Structures of the PITZ RF Photoinjector: Emittance growth estimations	emittance, diagnostics, gun, electron	217
	E. Arevalo, W. Ackermann, E. Gjonaj, W. F.O. Müller, S. Schnepp, T. Weiland TEMF, Darmstadt
	One of the main concerns in the design of electron guns is the generation of low-emittance beams. One source of emittance growth is the beam-surrounding effect, which can be estimated from the wake potentials along the beam path. For the calculation of these potentials an accurate knowledge of the short range wake fields induced in the different parts of the gun with geometrical discontinuities is necessary. The computation of these wake fields is a challenging problem, as an accurate resolution for both the small bunch and the large model geometry is needed. Here with the help of numerical wake-potential calculations we analytically estimate the emittance growth for the RF electron gun of the Photoninjector Test Facility at DESY Zeuthen (PITZ).

MOPC067	Normal Conducting CW RF Gun Design for High Performance Electron Beams	gun, cathode, emittance, electron	223
	H. Bluem, T. Schultheiss, L. M. Young AES, Medford, NY R. A. Rimmer Jefferson Lab, Newport News, Virginia
	High repetition rate (>1 MHz), high charge (1 nC), low emittance (1 micron) electron beams are an important enabling technology for next generation light sources. Advanced Energy Systems has begun the development of an advanced, continuous-wave, normal-conducting radio frequency electron gun. This gun is designed to minimize thermal stress, allowing fabrication in copper, while providing low emittance electron beams. Beam dynamics performance will be presented along with thermal and stress analysis of the gun cavity design.

MOPC074	3D Simulations of a Non-axisymmetric High Average Current DC Photocathode Electron Gun	cathode, gun, electron, ion	238
	J. W. McKenzie, B. L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	At high average currents, GaAs photocathode based electron guns are limited by the short operational lifetime of the photocathodes. One method to improve the cathode lifetime is to situate the photocathode off-axis to reduce the flow of ions back-bombarding the emitting surface. The results of 3D electrostatic and beam dynamic simulations are presented to demonstrate the feasibility of this scheme and the resultant beam quality achievable.

MOPC087	The MERIT (nTOF-11) High Intensity Liquid Mercury Target Experiment at the CERN PS	target, proton, factory, collider	262
	I. Efthymiopoulos, A. Fabich, A. Grudiev, F. Haug, J. Lettry, M. Palm, H. Pernegger, R. R. Steerenberg CERN, Geneva J. R.J. Bennett STFC/RAL/ISIS, Chilton, Didcot, Oxon O. Caretta, P. Loveridge STFC/RAL, Chilton, Didcot, Oxon A. J. Carroll, V. B. Graves, P. T. Spampinato ORNL, Oak Ridge, Tennessee H. G. Kirk, H. Park, T. Tsang BNL, Upton, Long Island, New York K. T. McDonald PU, Princeton, New Jersey N. V. Mokhov, S. I. Striganov Fermilab, Batavia, Illinois
	The MERIT (nTOF-11) experiment is a proof-of-principle test of a target system for high power proton beams to be used as a front-end for a neutrino factory complex or a muon collider. The experiment took data in autumn 2007 using the fast extracted beam from the CERN Proton Synchrotron (PS) with a maximum intensity of about 30TP per pulse. The target system, based on a free mercury jet, is capable of intercepting a 4-MW proton beam inside a 15-T magnetic field Such a field is required to capture the low-energy secondary pions which will provide the source of the required intense muon beams. Particle detectors have been installed around the target setup in order to measure the secondary particle flux out of the target and probe cavitation effects in the mercury jet when hit with variable intensity beams. The data analysis is ongoing: the results presented at this conference will demonstrate the validity of the liquid mercury target concept. For the MERIT collaboration.

MOPC090	Driver Beam-led EURISOL Target Design Constraints	target, proton, ion, ion-source	271
	E. Noah, R. Catherall, Y. Kadi, C. Kharoua, J. Lettry, T. Stora CERN, Geneva
	The EURISOL (European Isotope Separation Online) Design Study is addressing new high power target design challenges. A three-step method* was proposed to split the high power linac proton driver beam into one H^- branch for the 4 MW mercury target that produces radioactive ion beams (RIB) via spallation neutron-induced fission in a secondary actinide target and three 100 kW H⁺ branches for the direct targets producing RIBs via fragmentation and spallation reactions. This scheme minimises transient thermo-mechanical stresses on targets and preserves the cw nature of the driver beam in the four branches. The heat load for oxides, carbides, refractory metal foils and liquid metals is driven by the incident proton driver beam while for actinides, exothermic fission reactions are an additional contribution. This paper discusses the constraints that are specific to each class of material and the target design strategies. An emphasis is placed on the modern engineering numerical tools and experimental methods used to validate the target designs. *A. Facco, R. Paparella, D. Berkovits, Isao Yamane, "Splitting of high power, cw proton beams", Physical Review Special Topics - Accelerators and Beams (2007).

MOPC091	Benchmarking of Collimation Tracking Using RHIC Beam Loss Data	collimation, beam-losses, proton, insertion	274
	G. Robert-Demolaize, K. A. Drees BNL, Upton, Long Island, New York
	State-of-the-art tracking tools were recently developed at CERN to study the cleaning efficiency of the Large Hadron Collider (LHC) collimation system. These tools can be benchmarked using data taken from operations of the Relativistic Heavy Ion Collider (RHIC) multi-stage collimation system. This article reviews preliminary simulation results on both the location and the intensity of proton losses around the RHIC lattice. Comparison with live measurements from the beam loss monitors are also shown in order to assess the accuracy of the predictions in the LHC case.

MOPC092	Single Particle Multi-turn Dynamics During Crystal Collimation	proton, collimation, scattering, betatron	277
	G. Robert-Demolaize, K. A. Drees, S. Peggs BNL, Upton, Long Island, New York R. P. Fliller Fermilab, Batavia, Illinois
	As the increase in luminosity remains a high-profile issue for current and future accelerator projects, protecting superconducting magnets from beam induced quenches implies using state-of-the-art halo cleaning devices given the required beam intensities. In CERN's LHC case, a multi-stage collimation system is being set up so as to provide a halo cleaning efficiency up to 99.995%. In order to improve this system even further, US-LARP funded studies have started to appreciate the use of a silicon-based crystal as a primary target for the halo particles. Dedicated experiments have recently been performed in an SPS extraction line for a bent silicon crystal in case of single-pass particles. This article compares the published results of this experiment with simulations using established tracking codes. The goal is to better describe the main physics mechanisms involved in the beam-crystal interaction. A simple algorithm is then introduced to allow for fast tracking of the effect of a crystal on a high energy proton beam over many turns. The general feasibility of single particle, multi-turn crystal experiments at the SPS (CERN) and Tevatron (Fermilab) and their outline are discussed.

MOPC095	Mechanical and Thermal Prototype Testing for a Rotatable Collimator for the LHC Phase II Collimation Upgrade	collimation, power-supply, beam-losses, impedance	286
	J. C. Smith, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz SLAC, Menlo Park, California
	The Phase II upgrade to the LHC collimation systems calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. A series of prototype collimator jaws have been tested for both mechanical and thermal compliance with the design goals. Collimator jaw shape after thermal expansion benchtop tests were compared to ANSYS simulation results. Mechanical tests were also performed to demonstrate fabrication precision and collimator movement operation as designed.

MOPC096	Design of a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade	collimation, impedance, shielding, insertion	289
	J. C. Smith, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The Phase II upgrade to the LHC collimation systems calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. Design issues include: Collimator jaw deflection due to heating and sagita must be small when operated in the steady state condition, Collimator jaws must withstand transitory periods of high beam impaction with no permanent damage, Jaws must recover from accident scenario where up to 8 full intensity beam pulses impact on the jaw surface and The beam impedance contribution due to the collimators must be small to minimize coherent beam instabilities. The current design will be presented.

MOPC104	A New Method of Beam Stacking in Storage Rings	antiproton, emittance, storage-ring, synchrotron	307
	C. M. Bhat Fermilab, Batavia, Illinois
	Use of barrier buckets at synchrotron storage rings has paved way for development of new techniques for beam stacking in storage rings. The Fermilab Recycler, anit-proton storage ring, has been augmented with multipurpose broad-band barrier rf systems. Recently we have developed a new beam accumulation scheme called "longitudinal phase-space coating" that can be used for stacking beam over already e-cooled high intensity low emittance antiproton beam and demonstrated with beam experiments. Multi-particle beam dynamics simulations convincingly validate the concepts and practicality of the method. Starting with a proof-of-principle beam experiment both protons and anti-protons have been stacked a number of times using this technique in the Recycler. We present the results from both simulations and experiments. The method presented here is the first of its kind.

MOPC113	Head-on Beam-beam Compensation with Electron Lenses in the Relativistic Heavy Ion Collider	proton, electron, emittance, resonance	328
	Y. Luo, N. P. Abreu, E. N. Beebe, J. Beebe-Wang, C. Montag, M. Okamura, A. I. Pikin, G. Robert-Demolaize BNL, Upton, Long Island, New York
	The working points for polarized proton operation in the Relativistic Heavy Ion Collider (RHIC) are currently constrained between 2/3 and 7/10, and the beam and luminosity lifetimes are limited by head-on beam-beam effects. To further increase the bunch intensity, we propose a low energy Gaussian electron beam, or electron lens, to collide head-on with the proton beam in order to compensate the large tune shift and tune spread generated by the proton-proton collisions in 2 interaction points. In this article, outline of the RHIC head-on beam-beam compensation with e-lenses and parameters for both proton and electron beams are presented.

MOPC116	On the Possibility of Realizing Shortest Bunches in Low-energy Storage Rings	antiproton, storage-ring, ion, emittance	334
	A. I. Papash, K.-U. Kuehnel, C. P. Welsch MPI-K, Heidelberg A. A. Alzeanidi, M. O.A. El Ghazaly KACST, Riyadh A. I. Papash JINR, Dubna, Moscow Region
	For some very interesting experiments in future low-energy storage rings it is highly desirable to realize ultra-short bunches in the nanosecond regime. These bunches could then be used for collision studies with atomic or molecular gas jet targets where the time structure of the bunches would be used as a trigger for the experiment. Thus, the control of the longitudinal time structure of the stored beam is of central importance since it directly determines the resolution of the envisaged experiments. Since many years, it has been a significant challenge for the storage ring accelerator-physics community to develop techniques to reduce the duration of bunches. Up to now, all methods that have been developed go along with various difficulties, which can include reduced stored-beam lifetimes. Thus, novel and innovative concepts for the manipulation and control of the longitudinal beam structure have to be developed. In this paper, novel approaches to realize shortest bunches in storage rings are presented.

MOPC130	Space Charge Loss Mechanisms Associated with Half Integer Resonance on the ISIS Synchrotron	resonance, emittance, space-charge, synchrotron	373
	C. M. Warsop, D. J. Adams, B. G. Pine STFC/RAL/ISIS, Chilton, Didcot, Oxon
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a 50 Hz proton synchrotron, which accelerates ~3·10¹³ ppp from 70 to 800 MeV, corresponding to mean beam powers of 0.2 MW. Beam loss limits operational intensity, and a main contributing mechanism is the action of half integer resonance under high space charge. Progress on studies using particle in cell simulations to explore the evolution of envelope motion, associated 2:1 parametric halo, growth of particles from the outer core, and effects of dispersion and longitudinal motion is presented. Comparisons are made with relevant theoretical models and progress on experimental studies summarised, presently emphasising the simplified 2D coasting beam case.

MOPC136	Beam Bunch Leakage and Control in the SNS Ring	beam-losses, extraction, accumulation, linac	391
	Y. Zhang, J. Galambos ORNL, Oak Ridge, Tennessee
	In recent neutron production operations at SNS, beams contaminated the longitudinal extraction gap of the accumulator ring due to the limitation of the beam choppers. It caused significant beam loss and activation in the ring and in the extraction beam line. From simulations with computer models and in experimental measurements, properly utilizing the ring RF systems with additional storage turns after the beam accumulations in the ring effectively reduced beam loss in the SNS accelerator systems. Simulations and beam measurement results will be discussed

MOPC156	ECR Ion Source for the KEK All-ion Accelerator	ion, extraction, vacuum, plasma	442
	H. Suzuki, Y. Arakida, T. Iwashita, M. Kawai, T. Kono, K. Takayama KEK, Ibaraki S. I. Inagaki Kyushu University K. Okazaki Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
	R&D works to realize an all-ion accelerator (AIA)* -capable of accelerating all ions of any possible charge state, based on the induction synchrotron concept, which was demonstrated using the KEK 12 GeV-PS*, are going on. As an ion source for the KEK-AIA, an electron cyclotron resonance (ECR) ion source has been developed. Permanent magnets made of NdFeB to generate a cusp field and 9.4 GHz microwave to energize plasma electrons have been employed. The microwave power of 750 W generated in a traveling wave tube is focused into the interaction region with a horn antenna. Regarding the cut off density for 9.4 GHz, the vacuum and the gas feeding system has been designed. The base pressure of 1·10^-5 Pa is reached with a single turbo molecular pump of 300 l/min, and the gas flow rate less than 1 cc/min is maintained with a mass flow controller. The plasma chamber is water-cooled against Joule heating. The geometry of the extraction electrodes and the downstream transport line have been optimized by IGUN simulations. The whole system will be embedded in the high voltage terminal box of 200 kV. Details of the design and the preliminary test will be described at this conference. K. Takayama, Y. Arakida, T. Iwashita, Y. Shimosaki, T. Dixit, and K. Torikai, J. of Appl. Phys. 101, 063304 (2007). **K. Takayama et al., Phys. Rev. Lett. 98, 054801 (2007).

MOPD017	G4Beamline Program for Radiation Simulations	radiation, shielding, target, controls	481
	K. B. Beard, T. J. Roberts Muons, Inc, Batavia P. Degtiarenko Jefferson Lab, Newport News, Virginia
	G4beamline, a program that is an interface to the Geant4 toolkit that we have developed to simulate accelerator beamlines, is being extended with a graphical user interface to quickly and efficiently model experimental equipment and its shielding in experimental halls. The program is flexible, user friendly, and requires no programming by users, so that even complex systems can be simulated quickly. This improved user interface is of much wider application than just the shielding simulations that are the focus of this project. As an initial application, G4beamline is being extended to provide the simulations that are needed to determine the radiation sources for the proposed experiments at Jefferson Laboratory so that shielding issues can be evaluated. Since the program already has the capabilities needed to simulate the transport of all known particles, including scattering, attenuation, interactions, and decays, the extension involves implementing a user-friendly graphical user interface for specifying the simulation, and creating general detector and shielding component models and interfacing them to existing Geant4 models of the experimental halls.

MOPD019	Construction and Quality Control of Synchrotron SOLEIL Beam Position Monitors	vacuum, controls, synchrotron, impedance	487
	E. Cenni, M. Canetti, F. Gangini RIAL VACUUM S.p. A, Parma J. L. Billaud Saint-Gobain C. R.E. E., Cavaillon L. Cassinari, J.-C. Denard, C. Herbeaux SOLEIL, Gif-sur-Yvette
	SOLEIL is a third generation synchrotron light source located near Paris. Due to the high performance required for SOLEIL’s diagnostics, a special production procedure was tailored. During the production of 131 Beam Position Monitors (BPM) more than 500 feedthroughs were inspected; all of them passed strict tests at different stages of the production: Leak test (< 10^-10 mbar l/s), Dimensional control (Displacement <0.050 mm), Vacuum test (Specific Outgassing < 10^-12 mbar l/s cm², Residual Gas Analysis) and Electrical test (Capacitance measure ~8pF, Insulation >50 MΩ, Impedance <0.1 Ω). All the established procedures and tests have been performed in a tight partnership that was more than a simple contractual framework, in which an intensive collaboration led to a knowledge transfer between SOLEIL and Rial Vacuum. The result has been a high percentage of success (few feedthroughs over 500 were replaced) during preliminary tests and a deeper knowledge of “BPM problem solving”; in this article are presented different test procedures to obtain high quality and high performance BPMs.

MOPD037	Safety Testing for LHC Access System	controls, site, monitoring, extraction	532
	F. Valentini, T. Ladzinski, P. Ninin, L. Scibile CERN, Geneva
	This paper presents the validation and verification activities carried out for the LHC Access Control and Safety System. It also presents a new strategy for the future that includes the application of formal methods based on model checking techniques, commonly used to prove the correctness of software algorithms or system functional specifications through automatic exploration of the system state space. We will show how to apply these techniques in order to automate the testing process. The paper also presents the results of the performances and the applicability of a series of tools that have been tested in order to carry out a formal correctness proof for the LHC Access System.

MOPP001	Beam-Based Alignment for the CLIC Decelerator	alignment, quadrupole, lattice, dipole	547
	E. Adli, D. Schulte CERN, Geneva
	The CLIC Drive Beam decelerator requires the beam to be transported with very small losses. Beam-based alignment is necessary in order to achieve this, and various beam-based alignment schemes have been tested for the decelerator lattice. The decelerator beam has an energy spread of up to 90%, which impacts the performance of the alignment schemes. We have shown that Dispersion-Free-Steering works well for the decelerator lattice. However, because of the transverse focusing approach, modifications of the normal DFS schemes must be applied. Tune-up scenarios for the CLIC decelerator using beam-based alignment are also discussed.

MOPP002	A Study of Failure Modes in the CLIC Decelerator	quadrupole, lattice, linac, power-supply	550
	E. Adli, D. Schulte, I. Syratchev CERN, Geneva
	The CLIC Drive Beam decelerator is responsible for producing the RF power for the main linacs, using Power Extraction and Transfer Structures (PETS). To provide uniform power production, the beam must be transported with very small losses. In the paper failure modes for the operation of the decelerator are investigated, and the impact on beam stability, loss level and machine protection issues is presented. Quadrupole failure, PETS inhibition and PETS break down scenarios are being considered.

MOPP003	Study of Abnormal Vertical Emittance Growth in ATF Extraction Line	emittance, extraction, multipole, quadrupole	553
	M. Alabau, A. Faus-Golfe IFIC (CSIC-UV), Valencia M. Alabau, P. Bambade, J. Brossard, G. Le Meur, C. Rimbault, F. Touze LAL, Orsay D. Angal-Kalinin, J. K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire R. Appleby, A. Scarfe UMAN, Manchester S. Kuroda KEK, Ibaraki G. R. White, M. Woodley SLAC, Menlo Park, California F. Zimmermann CERN, Geneva
	Since several years, the vertical emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This long-standing problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experienced by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.

MOPP006	Machine Induced Backgrounds for FP420	proton, background, scattering, betatron	559
	R. Appleby, K. M. Potter, F. Roncarolo, G. J. Sellers UMAN, Manchester I. Azhgirey, I. Baishev, I. L. Kurochkin, V. Talanov IHEP Protvino, Protvino, Moscow Region M. Ruspa INFN-Torino, Torino
	The LHC FP420 collaboration is assessing the feasibility of installing forward proton detectors at 420m from the ATLAS and/or CMS interaction points. Such detectors aim at measuring diffracted protons, which lost less than 2% of their longitudinal momentum. The success of this measurement requires a very good understanding of the charged and neutral particle environment in the detector region in order to avoid the signal being swamped as well as for detector survivability. This background receives contributions from beam-gas interactions, halo particles surviving from the Betatron and momentum cleaning systems and secondary showers produced by particles from the 14TeV collision region striking the beampipe upstream of the FP420 detectors. In this paper, such background sources are reviewed, and the expected background rates calculated.

MOPP007	Wakefield Calculations - Comparison between Simulations and Experimental Data	emittance, collider, impedance, dipole	562
	A. Bungau, R. J. Barlow UMAN, Manchester
	In linear colliders the collimator wakefields have a significant effect on emittance growth, beam jitter and background estimates. Each simulation code models the collimator wakefields using a different approach and a discussion of the formalism for incorporating wakefields into the particle tracking code Merlin is included in this paper. Using simple collimator types we present the different predictions for bunch shape effects, and also for the wakefield kicks. These kicks are also compared with experimental results from SLAC End Station A.

MOPP009	Copper Prototype Measurements of the HOM, LOM and SOM Couplers for the ILC Crab Cavity	dipole, polarization, coupling, damping	568
	G. Burt, P. K. Ambattu, A. C. Dexter Cockcroft Institute, Lancaster University, Lancaster L. Bellantoni Fermilab, Batavia, Illinois P. Goudket, P. A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire Z. Li, L. Xiao SLAC, Menlo Park, California
	The ILC Crab Cavity is positioned close to the IP and hence is very sensitive to the wakefields induced by the beam. A set of couplers were designed to couple to and hence damp the spurious modes of the crab cavity. As the crab cavity is a deflecting mode cavity, it operates using a dipole mode and has different damping requirements than an accelerating mode cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz, known as the LOMs, the opposite polarization of the operating mode, the SOM, and the modes above the operating frequency, the HOMs. Each of these couplers have been manufactured out of copper and measured attached to an aluminium nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.

MOPP011	Fast Vertical Beam Instability in the CTF3 Combiner Ring	linac, injection, beam-losses, closed-orbit	574
	R. Corsini, D. Schulte, P. K. Skowronski, F. Tecker CERN, Geneva D. Alesini, C. Biscari, A. Ghigo INFN/LNF, Frascati (Roma)
	The CLIC Test Facility CTF3 is being built at CERN by an international collaboration, in order to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. The facility includes an 84 m combiner ring, which was installed and put into operation in 2007. High-current operation has shown a vertical beam break-up instability, leading to high beam losses over the four turns required for nominal operation of the CTF3 ring. Such instability is most likely due to the vertically polarized transverse mode in the RF deflectors used for beam injection and combination. In this paper we report the experimental data and compare them with simulations. Possible methods to eliminate the instability are also outlined.

MOPP027	Placet Based Start-to-end Simulations of the ILC with Intra-train Fast Feedback System	luminosity, linac, emittance, feedback	604
	J. Resta-López, P. Burrows, A. F. Hartin JAI, Oxford A. Latina, D. Schulte CERN, Geneva
	Integrated simulations are important to assess the reliability of the luminosity performance of the future linear colliders. In this paper we present multi-bunch tracking simulation results for the International Linear Collider (ILC) from the start of the LINAC to the interaction point. The tracking along the LINAC and the beam delivery system is done using the code Placet. This code allows us to introduce cavity wakefield effects, element misalignment errors and ground motion. Static beam based alignment of the LINAC are also considered. The luminosity and beam-beam parameters are calculated using the code Guinea-Pig. In the framework of the Feedback On Nano-second Timescales (FONT) project, we describe and simulate an updated fast intra-train feedback system in order to correct for luminosity degradation mainly due to high frequency ground motion.

MOPP034	Large Scale Linac Simulations Using a Globalised Scattering Matrix Approach	scattering, linac, dipole, electromagnetic-fields	619
	I. R.R. Shinton, R. M. Jones UMAN, Manchester
	A globalised cascaded scattering matrix scheme serves as practical method to simulate the electromagnetic (e.m.) fields in the groups of cavities which constitute the main accelerating structures of a linac. The cascaded scattering matrix technique is a well-proven method which allows realistic fabrication errors to be incorporated in an efficient manner without the necessity to re-mesh the entire geometry. Once the unit cell structures have been determined using a numerical scheme, such as finite element method utilized here, the overall cascaded scattering matrix calculation requires little in the way of computational resources or time and is consequently an efficient means of characterizing the e.m. field. Details of the e.m. field, shunt impedance and trapped modes for large scale linac simulations applied to the baseline and alternate high gradient cavities for the ILC and applications to XFEL are presented.

MOPP036	Dark Current Model for ILC Main Linac	linac, electron, quadrupole, focusing	625
	N. Solyak, N. V. Mokhov, G. V. Romanov Fermilab, Batavia, Illinois Y. I. Eidelman BINP SB RAS, Novosibirsk W. M. Tam IUCF, Bloomington, Indiana
	In the ILC Main Linac the dark current electrons, generated in SRF cavity can be accelerated to hundreds of MeV before being kicked out by quadrupoles and thus will originate electromagnetic cascade showers in the surrounding materials. Some of the shower secondaries can return back into vacuum and re-accelerated again. The results of simulation of the dark current dynamics and energy deposition along the linac are discussed in paper.

MOPP037	Alignment of the CLIC BDS	alignment, multipole, luminosity, radiation	628
	A. Latina, D. Schulte, R. Tomas CERN, Geneva
	Aligning the CLIC Beam Delivery System faces two major challenges, the tight tolerances for the emittance preservation and its strong non-linear beam dynamics. For these reasons conventional beam-based alignment techniques, like dispersion free steering, are only partially successful and need to be followed by optimization algorithms based on other observables, like beam sizes.

MOPP043	Transverse Wake Field Simulations for the ILC Acceleration Structure	emittance, acceleration, linac, linear-collider	640
	V. P. Yakovlev, A. Lunin, N. Solyak Fermilab, Batavia, Illinois
	Details of wake potential simulation in the acceleration structure of ILC, including the RF cavities and input/HOM couplers are presented. Transverse wake potential dependence is described versus the bunch length. Beam emittance dilution caused by main and HOM couplers is estimated, followed by a discussion of possible structural modifications allowing a reduction of transverse wake potential.

MOPP050	Electron Cloud Build Up and Instability in the CLIC Damping Rings	electron, wiggler, damping, positron	661
	G. Rumolo, Y. Papaphilippou CERN, Geneva W. Bruns WBFB, Berlin
	Electron cloud can be formed in the CLIC positron damping ring and cause intolerable tune shift and beam instability. 2D and 3D build up simulations with the Faktor2 code, developed at CERN, have been done to predict the cloud formation in the arcs and wigglers of the damping rings. HEADTAIL simulations have been used to study the effect of this electron cloud on the beam and assess the thresholds above which the electron cloud instability would set in.

MOPP051	Effect of Fill Patterns on Extraction Jitter in Damping Rings	damping, extraction, injection, coupling	664
	K. M. Hock, A. Wolski Cockcroft Institute, Warrington, Cheshire
	Injection of fresh bunches into a storage ring can induce jitter on stored bunches, as a result of wake field coupling. This transient effect can lead to an undesirable increase in the emittance of stored bunches; in the case of linear collider damping rings, there can also be jitter in the extracted bunches, which can adversely affect performance. We consider how the wake field coupling in a storage ring depends on the fill pattern, and, for the ILC damping rings, present the results of simulations of the transverse dynamics with a resistive wall wake field for a number of different fill patterns. We draw correlations between the extraction jitter and various machine parameters, including the fill pattern.

MOPP063	A New Chicane Experiment in PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders	electron, dipole, resonance, vacuum	688
	M. T.F. Pivi, D. Arnett, F. D. Cooper, D. Kharakh, F. King, R. E. Kirby, B. Kuekan, J. J. Lipari, M. Munro, J. S.T. Ng, J. Olszewski, T. O. Raubenheimer, J. Seeman, B. Smith, C. M. Spencer, L. Wang, W. Wittmer SLAC, Menlo Park, California C. M. Celata, M. A. Furman LBNL, Berkeley, California
	Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders such as ILC and CLIC. Possible remedies for the electron cloud effect include thin-film coatings, surface conditioning, antechamber, clearing electrodes, and chamber with grooves or slots. The effect is expected to be particularly severe in magnetic field regions. To test this and possible mitigation methods, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER). We have also installed test chambers in straight field free regions. The associated chamber consists of bare aluminum and TiN-coated inner surface sections. Each section is instrumented with arrays of readout electrodes and retarding grids. Installation of a grooved chamber is also planned. In this paper, we describe the ongoing R&D effort at SLAC to reduce the electron cloud effect in linear colliders. We present the design of the chicane, the chambers and diagnostics, as well as the experimental results obtained.

MOPP064	Secondary Electron Yield Measurements and Groove Chambers Update Tests in the PEP-II Beam Line	electron, vacuum, storage-ring, positron	691
	M. T.F. Pivi, F. King, R. E. Kirby, T. W. Markiewicz, T. O. Raubenheimer, J. Seeman, L. Wang SLAC, Menlo Park, California
	In the Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in straight sections to test this possible mitigation technique for the electron cloud effect in the positron damping ring (DR) of the future Linear Colliders such as ILC and CLIC. We have also installed chambers to monitor the secondary electron yield (SEY) of TiN, TiZrV (NEG) and technical accelerator materials under the effect of electron and photon conditioning in situ. Furthermore, we have also installed test chambers in a new 4-magnet chicane. We describe the ongoing R&D effort to mitigate the electron cloud effect in the ILC damping ring, the chambers installation in the PEP-II and latest results.

MOPP065	Microwave Transmission Measurement of the Electron Cloud Density in the Positron Ring of PEP-II	electron, dipole, plasma, vacuum	694
	M. T.F. Pivi, A. Krasnykh SLAC, Menlo Park, California J. M. Byrd, S. De Santis, K. G. Sonnad LBNL, Berkeley, California F. Caspers, T. Kroyer, F. Roncarolo CERN, Geneva
	Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energy electron clouds over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave which is independently excited and transmitted over a section of the accelerator. We infer the absolute phase shift with relatively high accuracy from the phase modulation of the transmission due to the modulation of the electron cloud density from a gap in the positively charged beam. We have used this technique for the first time to measure the average electron cloud density over a 50 m straight section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center. We have also measured the variation of the density by using low field solenoid magnets to control the electrons.

MOPP067	Coupling Correction Simulations for the ILC Damping Rings	emittance, damping, quadrupole, lattice	700
	K. G. Panagiotidis, A. Wolski Cockcroft Institute, Warrington, Cheshire
	The ILC damping rings are specified to operate with a vertical emittance of 2 pm. To achieve this challenging goal, an effective diagnostic and correction system will be needed; however, BPMs add impedance to the ring, and diagnostics and correctors add complexity and cost. It is therefore desirable to understand how the final achievable emittance depends on the numbers, locations, and performance of the BPMs and correctors, and to determine the minimum number of these components required. We present the results of simulations for the damping rings, indicating the effectiveness of coupling correction for different design scenarios of the diagnostics and correction systems.

MOPP068	Simulation Study of Fast Ion Instability in the ILC Damping Ring	damping, feedback, ion, electron	703
	G. X. Xia, Eckhard. Elsen DESY, Hamburg
	The so-called fast ion instability potentially constitutes a performance limitation for the damping ring of the International Linear Collider (ILC). Based on the latest baseline lattice of the ILC damping ring the fast ion instability is simulated using a weak-strong code. Various fill patterns are examined to mitigate the onset of the instability. Feedback mechanisms are explored. The growth time of the fast ion instability is estimated for various vacuum pressures on the basis of the simulated results.

MOPP069	A Prototype Target Wheel for the ILC Positron Source	target, positron, photon, undulator	706
	I. R. Bailey, L. J. Jenner, C. J. Nelson Liverpool University, Science Faculty, Liverpool I. R. Bailey Cockcroft Institute, Warrington, Cheshire D. G. Clarke, K. P. Davies, A. Gallagher STFC/DL, Daresbury, Warrington, Cheshire J. A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire J. Gronberg, L. B. Hagler, W. T. Piggott LLNL, Livermore, California
	In this paper we describe the design, construction and commissioning of a prototype based on the positron production target wheel planned for the ILC positron source. The efficiency of the current baseline positron source design for the ILC can be improved if the conversion target is partially immersed in the magnetic field of the capture optics, thereby increasing the overall capture efficiency for positrons by a factor of two or more. However, immersion of the rotating target wheel generates strong eddy currents leading to additional heating and stresses on the wheel. The primary purpose of our prototype, which had been assembled at Daresbury Laboratory, is to investigate the effects of eddy currents induced in a titanium alloy wheel moving with rim speeds up to 100 metres per second in magnetic fields of the order of 1 Tesla.

MOPP072	A Study of Mechanical and Magnetic Issues for a Prototype Positron Source Target	target, positron, photon, undulator	715
	L. J. Jenner, I. R. Bailey Cockcroft Institute, Warrington, Cheshire D. G. Clarke, K. P. Davies, A. Gallagher STFC/DL, Daresbury, Warrington, Cheshire J. A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire J. Gronberg, L. B. Hagler, W. T. Piggott LLNL, Livermore, California S. Hesselbach Durham University, Durham C. J. Nelson STFC/RAL, Chilton, Didcot, Oxon J. Rochford STFC/RAL/ASTeC, Chilton, Didcot, Oxon
	In order to construct a high yield, positron source that can meet the intensity requirements of future facilities, a robust conversion target is needed. One solution is to use a rotating titanium alloy wheel upon which a beam of photons is incident. The efficiency of capturing the resulting positrons can be optimised by immersing this system in a magnetic field. As described elsewhere, a prototype of such a target has been built at Daresbury Laboratory, to investigate the mechanical challenges associated with its construction and to study the magnetic effects that the wheel will experience. In this paper, calibration of the instrumentation, the data acquisition system and the initial results from operating the wheel in a strong magnetic field are described. Such phenomena as the eddy current heating experienced by the wheel are measured and compared to results from modelling codes. Vibrational issues surrounding the wheel and supporting structure at various speeds are studied. ID: 3894 A Prototype Target Wheel for the ILC Positron Source

MOPP073	Plasma Lens for Muon and Neutrino Beams	plasma, target, proton, focusing	718
	S. A. Kahn, S. Korenev Muons, Inc, Batavia M. B. Bishai, M. Diwan, J. C. Gallardo, A. Hershcovitch, B. M. Johnson BNL, Upton, Long Island, New York
	The plasma lens is examined as an alternate to focusing horns and solenoids for use in a neutrino or muon beam facility. The plasma lens concept is based on a combined high current lens/target configuration. The current is fed at electrodes located upstream and downstream form the target where pion capturing is needed. The current flows primarily in the plasma, which has a lower resistivity than the target. A second plasma lens section, with an additional current feed, follows the target to provide shaping of the plasma for optimum focusing. The plasma lens is immersed in an additional solenoidal magnetic field to facilitate the plasma stability. The geometry of the plasma is shaped to provide optimal pion capture. Simulations of this plasma lens system have shown a 25% higher neutrino production than the horn system. Plasma lenses have additional advantages: larger axial currents than horns, minimal neutrino contamination during antineutrino running, and negligible pion absorption or scattering. Results from particle simulations using plasma lens will be presented.

MOPP076	L-Band RF Gun with a Thermionic Cathode	gun, cathode, emittance, controls	727
	S. Nagaitsev, R. Andrews, M. Church, A. Lunin, O. A. Nezhevenko, N. Solyak, D. Sun, V. P. Yakovlev Fermilab, Batavia, Illinois
	In this talk we present a design for an L-band (1.3 GHz) rf gun with a two-grid thermionic cathode assembly. The rf gun is design to provide a 10-mA average beam current for 1ms at 5 Hz. These parameters match the requirements of both the ILC and Fermilab Project X test facilities. In our simulations we are able to attain the bunch length at 20-30 degrees (FW), while the output energy can vary 2-4 MeV. We will present the results of our simulations as well as preliminary designs.

MOPP079	Studies on the Role of a Photon Collimator for the ILC Positron Source	photon, undulator, radiation, positron	733
	L. Zang Cockcroft Institute, Warrington, Cheshire I. R. Bailey, A. Wolski, L. Zang Liverpool University, Science Faculty, Liverpool
	Use of a helical undulator in the ILC positron source provides the possibility of producing a polarised positron beam. The degree of polarisation of the positrons depends upon the polarisation of the photons produced from the undulator, where the polarisation depends on the photon energy and production angle. We calculate these quantities for one design of the helical undulator for the ILC, investigate approximations commonly made in calculating the undulator photon spectrum and explore the role of of a photon collimator in determining the positron polarisation.

MOPP080	Studies of Breakdown in a Pressurized RF Cavity	electron, ion, emittance, collider	736
	M. BastaniNejad, A. A. Elmustafa Old Dominion University, Norfolk, Virginia M. Alsharo'a, P. M. Hanlet, R. P. Johnson, S. Korenev, M. Kuchnir, D. J. Newsham, R. Sah Muons, Inc, Batavia C. M. Ankenbrandt, A. Moretti, M. Popovic, K. Yonehara Fermilab, Batavia, Illinois D. M. Kaplan Illinois Institute of Technology, Chicago, Illinois D. Li LBNL, Berkeley, California D. Rose, C. H. Thoma, D. R. Welch Voss Scientific, Albuquerque, New Mexico
	Previous studies of RF breakdown in a cavity pressurized with dense hydrogen gas have indicated that breakdown probability is proportional to a high power of the surface electromagnetic field. This behavior is similar to the Fowler-Nordheim description of electron emission from a cold cathode, and it implies that breakdown is a quantum mechanical effect that is characterized by the work function of the cavity metal. We describe our present efforts to measure the distributions of work functions at the nanoscale level on the surfaces of the electrodes used in breakdown studies, and to understand how the RF conditioning process affects them.

MOPP090	Incorporating RF into a Muon Helical Cooling Channel	lattice, emittance, quadrupole, vacuum	760
	S. A. Kahn, M. Alsharo'a, R. P. Johnson Muons, Inc, Batavia D. R. Broemmelsiek, A. Jansson, V. Kashikhin, V. S. Kashikhin, A. L. Klebaner, G. F. Kuznetsov, G. V. Romanov, A. V. Shemyakin, D. Sun, K. Yonehara, A. V. Zlobin Fermilab, Batavia, Illinois L. Thorndahl CERN, Geneva
	A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling for muon beams. The energy lost by muons traversing the gas absorber needs to be replaced by inserting RF cavities into the lattice. Replacing the substantial muon energy losses using RF cavities with reasonable gradients will require a significant fraction of the channel length be devoted to RF. However, to provide the maximum phase space cooling and minimal muon losses, the helical channel should have a short period and length. In this paper we shall examine three approaches to include RF cavities into the HCC lattice: Use higher frequency cavities that can be placed inside the magnetic channel, Interleave cavities between magnetic coil rings, and Place banks of RF cavities between segments of HCC channels. Each of these approaches has positive and negative features that need to be evaluated in selecting the proper concept for including RF into the HCC system.

MOPP095	Advanced Experimental Techniques for RF and DC Breakdown Research	plasma, electron, vacuum, ion	775
	J. W. Kovermann RWTH, Aachen S. Calatroni, A. Descoeudres, T. Lefevre, W. Wuensch CERN, Geneva
	Advanced experimental techniques are being developed to do in-situ analysis of DC and RF breakdowns. First measurements with a specially built spectrometer have been made with a DC spark setup at CERN and with CLIC accelerating structures in the 30GHz power test facility. This spectrometer measures the light intensity development during a breakdown for narrow wavelength intervals in the visible and near infrared range which will give information about the involved elements, temperature and plasma parameters and eventually precursors of a breakdown. Planned experiments for X-ray spectroscopy and imaging, measurements of RF-signals and ion and electron energy distribution and infrared imaging of breakdown sites are presented.

MOPP096	C-band Linac Optimization for a Race-track Microtron	linac, coupling, impedance, resonance	778
	Yu. A. Kubyshin UPC, Barcelona D. Carrillo, L. García-Tabarés, F. Toral CIEMAT, Madrid A. V. Poseryaev, V. I. Shvedunov MSU, Moscow
	Optimization results of a C-band standing wave on-axis coupled linac for a miniature race-track microtron (RTM) are presented. The optimization procedure includes three steps: choice of the linac cells lengths and field strength following requirements of the RTM beam dynamics, 2D cells geometry optimization to maximize the shunt impedance and minimize the surface field strength and, finally, full scale 3D optimization. The 3D calculations were done independently with two codes: ANSYS and HFSS. Various methods of calculation of the coupling slots dimensions, including the waveguide-linac coupling slot, are described in detail.

MOPP108	Status of HOM Damped Room-temperature Cavities for the ESRF Storage Ring	coupling, impedance, storage-ring, damping	808
	V. Serriere, A. K. Bandyopadhyay, L. Goirand, J. Jacob, D. Jalas, B. Ogier, A. Triantafyllou ESRF, Grenoble N. Guillotin SOLEIL, Gif-sur-Yvette
	At the ESRF, longitudinal coupled bunch instabilities driven by cavity HOM are currently avoided up to the nominal current of 200 mA by precisely controlling the temperatures of the six five-cell cavities installed on the storage ring. A longitudinal bunch by bunch feedback has recently allowed to overcome the remaining HOM and thereby increase the current in the storage ring to 300 mA. In parallel, HOM damped room-temperature cavities are being developed for highly reliable passive operation at 300 mA. They are designed for a possible later upgrade to higher currents.

MOPP115	Production and Qualification of Low Thermal Conduction Suspension Supports for the Cold Mass of Long Superconducting Acceleration Modules	cryogenics, radiation, site, controls	829
	S. Barbanotti, M. Bonezzi, M. Todero INFN/LASA, Segrate (MI) C. Engling, K. Jensch, R. Mattusch DESY, Hamburg
	A post is an assembly of a low thermal conduction composite material pipe (fiberglass pipe) and some shrink-fit aluminum and steel discs and rings, designed to provide a mechanical support and a thermal insulation to the cold mass of the long cryomodules of the TTF, which are foreseen also for the XFEL and ILC. We review here the production, testing and qualification for the production of post supports, which have been successfully provided for the cryomodules of the TTF in DESY, the STF in KEK and ILCTA in FNAL.

MOPP126	Experimental Characterization of a 700 MHz β=0.47 5 Cell Superconducting Cavity Prototype for Pulsed Proton Linac	proton, linac, electron, acceleration	853
	G. Devanz, J.-P. Charrier, S. Chel, Y. Gasser, P. Hardy, J. Plouin, J. P. Poupeau, D. Roudier CEA, Gif-sur-Yvette
	A 700 MHz 5 cell elliptical cavity has been developed to accelerate a high intensity proton beam in the lower energy part of a superconducting linac, starting at 80 MeV. The cavity is stiffened in order to minimize the Lorentz detuning which limits high field pulsed operation of the flatter, low beta elliptical cavities. It is equipped with a stainless steel helium vessel. The RF tests of the cavity have been carried out at 1.8 K. Cavity performance is reported in this paper. Measurements of the RF response to mechanical excitations are also presented.

MOPP128	Comparison of Stretched-wire, Bead-pull and Numerical Impedance Calculations on 3.9 GHz Dipole Cavities	dipole, impedance, higher-order-mode, radio-frequency	859
	P. Goudket, C. D. Beard, P. A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Burt, A. C. Dexter Cockcroft Institute, Lancaster University, Lancaster R. M. Jones Cockcroft Institute, Warrington, Cheshire
	In order to verify detailed impedance and wakefield simulations, the resonant modes in an aluminium model of the 9-cell ILC crab cavity were investigated using a stretched-wire frequency domain measurement, as well as frequency-domain bead-pull measurements. These measurements were compared to numerical simulations in order to verify that the complete cavity mode spectrum could be experimentally characterised for this high frequency structure. The analysis of the results and the accuracy and/or limitations of each method is presented.

MOPP137	MultiPac 2.1 - Multipacting Simulation Package with a 2D FEM Field Solver for a Microsoft Windows System	electron, RF-structure, superconductivity, vacuum	880
	Y. M. Li, S. An, Y.-S. Cho, L. Zhang KAERI, Daejon P. Ylä-Oijala Helsinki University of Technology, Helsinki
	MultiPac 2.1 is a multipacting simulation package for analyzing electron multipacting in axisymmetric RF structures with TM_0nl mode, such as RF cavities, coaxial input couplers and ceramic windows. The original package was written by P. Ylä-Oijala, and works with MATLAB 5.0 or 6.0 on Linux operating system. In order to use this code easily for Microsoft Windows customers, we have transferred the MultiPac 2.1 from the Linux system to the Microsoft Windows system. The revised MultiPac can work with Microsoft Windows MatLab 6.0 or later editions smoothly. In this paper, the installation and operation of the Windows MutiPac 2.1 have been introduced. This work was supported by the 21C Frontier R&D program in Ministry of Science and Technology of the Korean Government.

MOPP140	Status and Test Results of High Current 5-cell SRF Cavities Developed at JLAB	damping, dipole, impedance, quadrupole	886
	F. Marhauser, G. Cheng, G. Ciovati, W. A. Clemens, E. Daly, D. Forehand, J. Henry, P. Kneisel, S. Manning, R. Manus, R. A. Rimmer, C. Tennant, H. Wang Jefferson Lab, Newport News, Virginia
	A new compact CW cryomodule development for use in future ERLs and FELs is underway at JLAB. Five-cell SRF cavities have been built at 1497 MHz for moderate RF input power scenarios with waveguide endgroups to efficiently transfer the beam induced HOM energy to room temperature loads. Effort has been made as well to provide a good real-estate gradient, cryogenic efficiency and HOMs tuned to safe frequencies to minimize HOM power extracted from the beam. Preliminary tests carried out earlier for two single-cell cavities at 1497 MHz cavity -one with a waveguide endgroup- and a bare 1497 MHz five-cell cavity have exceeded gradient and Qo specifications with no signs of multipacting and encouraged us to built two fully equipped 1497 MHz five-cell cavities. We report on the latest test results and the HOM impedance budget of the cavity used to evaluate BBU limits based on special machine optics.

MOPP149	Recent Developments of the Superconducting CH-Cavities	cryogenics, beam-losses, linac, resonance	901
	H. Podlech, A. Bechtold, M. Busch, F. Dziuba, H. Liebermann, U. Ratzinger IAP, Frankfurt am Main
	The Crossbar-H-mode (CH)-structure which has been developed at the IAP in Frankfurt is a multi-cell drift tube structure for the efficient acceleration of low and medium energy protons and ions. The superconducting low energy CH-prototype cavity has reached gradients of up to 7 MV/m, corresponding to an effective voltage gain of 5.6 MV. This shows that high real estate gradients can be achieved in superconducting low energy multi-cell cavities. Additionally, microphonics and tuning measurements have been performed at room temperature and at 4K. Optimized cavity geometry for high power beam projects and plans for the construction of a new superconducting cavity will be presented.

MOPP155	Superconducting RF Deflecting Cavity Design and Prototype for Short X-ray Pulse Generation	damping, coupling, collider, dipole	913
	J. Shi, H. Chen, C.-X. Tang TUB, Beijing G. Cheng, G. Ciovati, P. Kneisel, R. A. Rimmer, G. Slack, L. Turlington, H. Wang Jefferson Lab, Newport News, Virginia D. Li LBNL, Berkeley, California A. Nassiri, G. J. Waldschmidt ANL, Argonne, Illinois
	Deflecting RF cavities are proposed to be used in generating short x-ray pulses (on ~1-picosecond order) at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL)* using a novel scheme by Zholents*. To meet the required deflecting voltage, impedance budget from higher order, lower order and the same order modes (HOM, LOM and SOM) of the APS storage ring, extensive deflecting cavity design studies have been conducted with numerical simulations and cavity prototypes. In this paper, we report recent progress on a single cell S-band (2.8-GHz) superconducting deflecting cavity design with waveguide damping. A copper and a niobium prototype cavity were fabricated and tested, respectively to benchmark the cavity and damping designs. A new damping scheme has been proposed which provides stronger damping to both HOM and LOM by directly coupling to a damping waveguide on the cavity equator. A. Nassiri, private communication, 2007 ** A. Zholents et al. NIM, 1999, A425:385-389.

MOPP156	Fabrication and Low Power Testing of an L-band Deflecting Cavity for Emittance-exchange at ANL	coupling, polarization, vacuum, emittance	916
	J. Shi, H. Chen, W.-H. Huang, C.-X. Tang, D. Tong TUB, Beijing W. Gai, C.-J. Jing, K.-J. Kim, J. G. Power ANL, Argonne, Illinois D. Li LBNL, Berkeley, California
	An L-Band RF deflecting cavity has been built at Tsinghua University for a planned transverse-to-longitudinal emittance exchange experiment at Argonne National Laboratory (ANL). The deflector is a 1.3-GHz, 3-cell cavity operated in a TM110-like mode that delivers a deflecting voltage of 3.4 MV. In this paper, we review the cavity design and present detail of the fabrication, cold testing and tuning progress. Cell radii were left undercut to account for simulation errors, which yielded a higher frequency in the first bench measurement but removed by the final tuning on the lathe. Field distribution on axis was measured using the ‘‘bead-pull'' method and tuned to balance in the 3 cells.

MOPP164	Improvements in Field Emission: A Statistical Model for Electropolished Baked Cavities	superconductivity, site	934
	J. L. Wiener, H. Padamsee Cornell University, Ithaca, New York
	A statistical model for field emission developed in 1993 has been applied to characterize the improvement in field emitter properties and field emitter occurrence due to improvements in treatment methods for 9-cell TESLA-style cavities. The improved treatments are electropolishing, high pressure rinsing and baking (120C, 48 hours). We model the Q vs. Eacc data from 24 9-cell tests and 32 1-cell tests, all conducted at TTF by DESY. The statistical model is able to successfully simulate the observed yields by applying a factor of 3 decrease in emitter density over the emitter density prevailing for treatments in 1993, which did not include high pressure rinsing. Both simulation and data show that at Eacc = 70 MV/m the yield for field emission power less than 100 watts (Q > 8x10⁹) is less than 20%. To raise this yield to 80% will require new treatments that will reduce the emitter density by another factor of 3 at least. Further comparisons of field emission behavior will be made with data for alcohol rinsed cavities.

MOPP165	FZJ Smallest SC Triple-Spoke Cavity	vacuum, coupling, cryogenics, site	937
	E. Zaplatin, W. Braeutigam, M. Pap, M. Skrobucha FZJ, Jülich P. Kneisel Jefferson Lab, Newport News, Virginia
	The paper describes the design, fabrication and test results of the smallest triple-spoke cavity (resonant frequency 760 MHz, β=0.2) developed at Forschungszentrum Juelich.

TUOBM02	The Development of the Separated Function RFQ Accelerator in Peking University	rfq, focusing, impedance, acceleration	1007
	X. Q. Yan, J.-E. Chen, J. X. Fang, S. L. Gao, Z. Y. Guo, Y. R. Lu, Z. Wang, K. Zhu PKU/IHIP, Beijing
	The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In order to demonstrate the feasibilities of the novel accelerator, a prototype cavity was designed and constructed. Correspondingly, a code SFRFQCODEV1.0 was developed specially for cavity design and beam dynamics simulation. The prototype cavity will be verified as a post-accelerator for ISR RFQ-1000 (Integral Split Ring RFQ) and accelerate O⁺ from 1 MeV to 1.6 MeV. To inject a higher current oxygen beam for the prototype cavity, the beam current of ISR RFQ-1000 was upgraded to 2 mA. The status of high power and beam test of the prototype cavity are presented in this paper.
	Slides

TUPC001	Optics Calculation and Emittance Measurement toward Automatic Beam Tuning of Linac	linac, emittance, optics, gun	1035
	T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, A. Mizuno, S. Suzuki, T. Taniuchi, H. Tomizawa, K. Yanagida JASRI/SPring-8, Hyogo-ken T. Watanabe SES, Hyogo-pref.
	The SPring-8 1-GeV linac has a total of 13 sets of 80MW klystron units. In usual operation, two klystron units are driven as the standby unit. If there's any problem with an arbitrary klystron unit, the beam operation is able to restart immediately by using the standby unit. In that case, the optimization of beam optics has carried out using beam screen monitors. This beam tuning spend about one hour. In order to reduce the beam tuning time, we are promoting the development of the automatic beam optics tuning system. Since the complete understanding of the beam envelope is important, the particles tracking simulation of the linac was carried out by using PARMELA and SAD. Five sets of beam size monitors were installed in the end of the linac for measurement of the real beam envelope. In a beam study applying the simulation results, the beam waist was actually formed at the 10-m long drift space after the 1-GeV chicane section as predicted by SAD. The values of the measured beam emittance were smaller than the simulation results.

TUPC005	Simulation Study of Laser-wires as a Post-linac Diagnostic for CLIC and ILC	background, linac, dipole, electron	1047
	G. A. Blair, L. Deacon, S. Malton Royal Holloway, University of London, Surrey I. V. Agapov, A. Latina, D. Schulte CERN, Geneva
	Realistic CLIC and ILC bunch trains are simulated in the linac, including intra-train collective effects, and then analysed via a realistic simulation of a laser-wire system, including effects of laser-wire signal extraction, detection and deconvolution. Implications are drawn for the use of laser-wires as a post-linac machine diagnostic.

TUPC011	Micron Size Laser-wire System at the ATF Extraction Line	laser, electron, diagnostics, optics	1065
	A. Aryshev, G. A. Blair, S. T. Boogert, G. E. Boorman, A. Bosco, L. Corner, L. Deacon, N. Delerue, B. Foster, F. Gannaway, D. F. Howell, V. Karataev, L. J. Nevay, M. Newman, R. Senanayake, R. Walczak JAI, Egham, Surrey H. Hayano, N. Terunuma, J. Urakawa KEK, Ibaraki
	The ATF extraction line laser-wire system has recently been upgraded allowing the measurement of micron scale transverse size electron beams. We report on the hardware upgrades, including focusing lens, laser and mechanical systems. First measurements using the new system from recent operation at the ATF in KEK are presented.

TUPC019	A Retarding Field Detector to Measure the Actual Energy of Electrons Participating in E-cloud Formation in Accelerators	electron, controls, power-supply, pick-up	1086
	R. Cimino, M. Commisso, T. Demma, S. Guiducci, P. Liu, A. R. Raco, V. Tullio, G. Viviani INFN/LNF, Frascati (Roma) P. Vilmercati ELETTRA, Basovizza, Trieste
	Electron cloud related phenomena can cause potentially detrimental effects on beam stability in many planned and under construction accelerators. The possibility to reduce such unwanted phenomena lies on the observation that, machine commissioning does reduce Secondary Electron Yield (SEY). Such SEY reduction (scrubbing) is due to the fact that electrons produced during e-cloud formation hit the accelerator wall, modifying their surface properties. ‘Scrubbing” has been studied only as a function of impinging electron dose but never as a function of the e-cloud electron energy. Simulations predict that the e-cloud is formed by electrons with very low energies (<50 eV). Given the potentially lower scrubbing efficiency for equal dose of very low energy electrons compared to medium energy one, it would be important to measure the actual energy of the electrons forming the cloud in real accelerators. For this reason we decided to construct an optimized retarding Field energy electrometer to be installed in accelerators. Here we will describe what solutions have been adopted during the design phase of such “home made” detector and some laboratory test will be showed and discussed.

TUPC023	Design of the Transverse C-band Deflecting Structure for Measurement of Bunch Length in X-FEL	resonance, coupling, RF-structure, klystron	1098
	H. Ego JASRI/SPring-8, Hyogo-ken Y. Otake RIKEN/SPring-8, Hyogo
	In SPring-8, the 8 GeV X-FEL with a short length of about 700 m is under construction. An electron beam with a bunch length in duration of less than 200 fs is indispensable for stable and brilliant X-ray radiation. We planned to measure the short bunch length with a transverse RF deflector. A bunch measuring system including the deflector must be located within 15 m of a bunch compressor at a beam energy of 1.45 GeV. To install the system in the restricted space, we need a deflector generating a transverse deflecting voltage over 40 MV. Therefore a new C-band deflecting structure was designed. It is a periodic disk-loaded structure with a racetrack-shaped iris in the center of each disk. The deflecting resonant mode is the HEM11-5π/6 mode of a backward traveling-wave and its transverse shunt impedance is more than 12 MΩ/m. The racetrack-shaped iris serves both as a cell-to-cell coupler and a beam passing hole, prevents rotation of the deflection plane of the HEM11 mode and makes the deflecting mode resonant stably. We represent the details and merits of the C-band structure with the demanded performance in this paper.

TUPC026	Simulating a UMER Beam Position Monitor	coupling, dipole, electron, quadrupole	1104
	K. Fiuza IF-UFRGS, Porto Alegre S. Bernal, I. Haber, R. A. Kishek UMD, College Park, Maryland
	We have investigated numerically and experimentally a beam position monitor (BPM), using the WARP code* to study image charge effects for an off-axis beam. In order to apply the theory of image charge, we calibrated the BPM response for the University of Maryland Electron Ring*. We studied the BPM linearity using several WARP simulations with different transverse offsets. The simulations were also compared with offsets measured employing a phosphor screen. In this paper we report the methodology used and results of this work. D. P. Grote et. all "New Developments in WARP Progress Toward End-to-End Simulation", Fus. Eng. & Des. 32-33 (1996) 193. ** J. Harris et. all "A fast beam position monitor for UMER", PAC'01, p 1387.

TUPC033	IP BPM Position Error at CLIC due to Secondary Emission from Beam-beam Backgrounds	background, feedback, extraction, luminosity	1122
	A. F. Hartin, R. Apsimon, P. Burrows, C. I. Clarke, C. Perry, C. Swinson OXFORDphysics, Oxford, Oxon G. B. Christian ATOMKI, Debrecen B. Constance, H. Dabiri Khah JAI, Oxford A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	Beam-beam background impacts on the IP BPM are studied for the CLIC machine. The large number of coherent pairs ( 1.8×10⁸ charges per BPM strip per bunch crossing) for the CLIC-G default parameter set, potentially leads to a large secondary emission in the BPM strips. Detailed GuineaPig++ and Geant studies reveal, however, that the coherent pairs travel down the extraction line without significant secondary showering. Geant studies of the CLIC incoherent pairs show a flux of secondary emission two orders of magnitude less than that expected for the ILC 1 TeV high luminosity scheme. Since previous studies showed that FONT IP BPM signal distortion for the ILC was of no concern, then it can also be neglected at CLIC.

TUPC037	Development, Production and Testing of 4500 Beam Loss Monitors	vacuum, radiation, beam-losses, target	1134
	E. B. Holzer, P. Chiggiato, B. Dehning, G. Ferioli, V. Grishin, J. M. Jimenez, M. Taborelli, I. Wevers CERN, Geneva A. Koshelev, A. Larionov, V. Seleznev, M. Sleptsov, A. Sytin IHEP Protvino, Protvino, Moscow Region D. K. Kramer TUL, Liberec
	Beam-loss monitoring (BLM) is a key element in the LHC machine protection. 4250 nitrogen filled ionization chambers (IC) and 350 secondary emission monitors (SEM) have been manufactured at the Institute for High Energy Physics (IHEP) in Protvino, Russia, following their development at CERN. Signal speed and robustness against ageing were the main design criteria. Each monitor is permanently sealed inside a stainless-steel cylinder. The quality of the welding was a critical aspect during production. The SEMs are requested to hold a vacuum of 1·10^-7 bar. Impurity levels from thermal and radiation-induced desorption should remain in the range of parts per million in the ICs. The difference in sensitivity is about 3·10⁴. To avoid radiation aging (up to 2·10⁸ Gy in 20 years) production of the chambers followed strict UHV requirements. IHEP designed and built the UHV production stand. Due to the required dynamic range of 1·10⁹, the leakage current of the monitors has to stay below 1 pA. Several tests during and after production were performed at IHEP and CERN. A consistently high quality during the whole production period was achieved and the tight production schedule kept at the same time.

TUPC041	Design of Cold BPM Feedthrough	resonance, insertion, impedance, cryogenics	1146
	K. Iwamoto, Y. Ikeda KFG, NEUSS T. Kitamura, T. Matsuoka KYOCERA Corporation, Higashiomi-city, Shiga
	We have designed many BPM feedthrough used metallized ceramic components. We select the best material of ceramic and metal ajusted for magnetism and the material of chamber. The request for accelerator application that low temperature and RF property has increased in recent years. In this presentation,we report on the design of the BPM feedthrough for low temperature and for the RF up to 20GHz. We appreciated the bonding strength for ceramic and metal in low temperature 4K,77K. Mo/Mn metallised ceramic is brazed between Fe-Ni-Co Alloy metal components using Ag-Cu brazing material. Ceramic is 99% Alumina which is commonly used for UHV application. The tensile strength in low temperature is lower than in R. T.approximately 10%, but the dispersion affected by brazing flow condition is bigger than this temperature effect. The influence of low temperature is less than brazing flow condition, therefore the bonding strength of metallised ceramic is enough for UHV application at 4K.

TUPC042	Limitations of Electro-optic Longitudinal Electron Bunch Length Measurements	laser, resonance, diagnostics, coupling	1149
	S. P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Berden FOM Rijnhuizen, Nieuwegein W. A. Gillespie, P. J. Phillips University of Dundee, Nethergate, Dundee, Scotland A. MacLeod UAD, Dundee
	Electro-optic (EO) techniques are becoming increasingly important in ultrafast electron bunch longitudinal diagnostics and have been implemented at various accelerator labs. A crucial aspect of any implementation is a robust assessment of its resolution capabilities. However the assessments of the temporal limitations often differ between groups and the assumptions employed in deriving these limitations are frequently not addressed. With EO measurements of intense CTR pulses and ultrafast Coulomb fields, it may also be necessary to reconsider the validity of the usual interpretation of the EO effect as a phase retardation proportional to the Coulomb field. From a generic analysis of various sources of the temporal limitations we present a summary of the capability of various EO techniques which can be applied to specific implementations with differing laser and bunch parameters. As well as specifying the quantitative limitations and their scaling with experimental parameters, the qualitative effects of distortion in the measured profile are also summarised. Additional limitations, which arise from a breakdown of the phase-retardation interpretation of the EO effect, are discussed.

TUPC043	Towards Sub-micrometer Resolution of Single Bunch Strip Line BPM	pick-up, feedback, vacuum, coupling	1152
	A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	A high resolution single bunch BPM set-up is designed based on a strip line pickup. One of the BPM modifications developed is a Difference-Sum BPM. In this BPM, each strip line signal is converted into a three 600MHz square wave burst in a cascaded irregular strip line coupler. The Difference and Sum bursts produced by a hybrid junction are detected in a pair of synchronous detectors. The synchronous detector reference signals, and single-sample ADC triggers are manufactured from the Sum burst. The set-up and features of this BPM are presented. The BPM resolution was measured using a KEK ATF beam. For a bunch intensity above 10⁹ electrons the resolution is about 1 μm (for BPM effective aperture 1/5). With appropriate ADCs, this BPM can measure individual bunches at a rate of up to 50 MHz. The BPM latency to the ADC inputs is as low as 10 ns. High resolution and low latency together, make this BPM suitable for beam-based fast feedback/feed-forward systems.

TUPC059	An Emittance Evaluation Toolbox	emittance, controls, ion, ion-source	1191
	D. A. Liakin ITEP, Moscow P. Forck, T. Hoffmann GSI, Darmstadt
	A long-time experience in emittance measurements and result evaluation at GSI were transformed into the set of the numerical instruments to perform basic and advanced data analysis for the data obtained in various emittance measurement devices. The common problems and differences between slit-grid-, pepper-pot- and longitudinal emittance data analysis are discussed. Some aspects of non-linear algorithms particularly for the case of non-zero slits or pepper-pot holes are presented.

TUPC065	Luminosity Measurement at DAΦNE for Crab Waist Scheme	luminosity, background, interaction-region, controls	1203
	M. Boscolo, F. Bossi, B. Buonomo, G. Mazzitelli, F. Murtas, P. Raimondi, G. Sensolini INFN/LNF, Frascati (Roma) N. Arnaud, D. Breton, A. Stocchi, V. Variola, B. F. Viaud LAL, Orsay P. Branchini roma3, Rome F. Iacoangeli, P. Valente INFN-Roma, Roma M. Schioppa INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
	Since the beginning of 2008 the DAΦNE complex started to test the "crabbed scheme" to improve the luminosity performance of the accelerator. In order to ensure a fast, accurate and absolute measurement of the luminosity and to fully understand the background conditions, the new interaction region has been equipped with three different luminosity monitors: a Bhabha calorimeter, a Bhabha GEM tracker and a gamma bremsstrahlung proportional counter. The detectors design, construction, and performance, as well as the first measurements performed at DAΦNE during the crab waist commissioning are here presented. Data are also compared with the Monte Carlo simulations of the full setup. First results acquired during the SIDDHARTA run are supposed to be presented.

TUPC067	Development of the Methods of Beam Energy Spread Determination in the VEPP-4M Collider	collider, diagnostics, photon, electron	1209
	O. I. Meshkov, V. A. Kiselev, N. Yu. Muchnoi, S. V. Sinyatkin, V. V. Smaluk, V. N. Zhilich, A. N. Zhuravlev BINP SB RAS, Novosibirsk
	The nearest experimental program of the VEPP-4M electron-positron collider and the KEDR detector includes a scan of the energy area below J/psi meson to search narrow resonances. The monitoring of beam energy spread is important for that. In this report we discuss the application of several diagnostics for beam energy spread measurement. The data obtained with Compton Back-Scattering (CBS) technique are compared with the value of the spread derived from the betatron motion of the beam. Similar experiments were carried out before. They demonstrated the necessity to improve the algorithm of beam energy spread derivation using CBS technique. New set of experiments was aimed on the examination of the improved algorithm. The measurements by all the methods were done at the same accelerator run, i.e., the different diagnostics are compared directly. The value of the energy spread was determined for a fixed collider energy E= 1855 MeV. The beam energy spread was changed by the wiggler current variation.

TUPC072	Design and Fabrication of an X-band Traveling Wave Deflection Mode Cavity for Longitudinal Characterization of Ultra-short Electron Beam Pulses	electron, diagnostics, dipole, betatron	1215
	A. Y. Murokh, R. B. Agustsson, S. Boucher, P. Frigola RadiaBeam, Marina del Rey D. Alesini INFN/LNF, Frascati (Roma) R. J. England, J. B. Rosenzweig, G. Travish UCLA, Los Angeles, California V. Yakimenko BNL, Upton, Long Island, New York
	An X-band Traveling wave Deflector mode cavity (XTD) has been developed at Radiabeam Technologies to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. An XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. RF design, fabrication procedure, and commissioning plans are presented. An experimental program at ATF to utilize the deflector for compressed beam characterization is discussed, including proposed measurements of the phase space filamentation due to non-linear processes in a chicane compressor.

TUPC076	TTF HOM Data Analysis with Curve Fitting Method	dipole, polarization, linac, optics	1227
	S. Pei, C. Adolphsen, K. L.F. Bane, Z. Li, J. C. Smith SLAC, Menlo Park, California
	To investigate the possibility of using HOM signal induced in SC cavities as beam and cavity diagnostics, experiments and analyses based on SVD have been done, which are very successful. In this paper, we described one new method based on curve fitting to analyze the HOM signal data, some results have been obtained. The new method can be used to extract the HOM mode frequency, Q and relative phase from the data. On the other hand, this method can also be used to find the HOM mode center, polarization axis, mode axis along the cavity, while careful handling of beam timing information need to be considered in analysis. Comparing with SVD, this method is more physical, and can also be used in the beam diagnostic data analysis to obtain the beam position and beam trajectory angle.

TUPC078	The Gun Spectrometer Design for the FERMI@Elettra Project	gun, quadrupole, space-charge, diagnostics	1233
	G. Penco, D. Castronovo, M. Trovo, D. Zangrando ELETTRA, Basovizza, Trieste
	In the FERMI linac layout the first spectrometer has been located close to the exit of the photoinjector gun at about 5 MeV. The main purpose of this equipment is measuring the energy and energy spread of the beam. Combining the spectrometer with Yag screens and Cerenkov radiators allows the investigation and characterization of eventual deterioration of the longitudinal profile due to the space charge forces and microbunching instabilities. The design specification of the magnet and multi-particle tracking code simulation results are presented in this paper.

TUPC079	Beam Emittance Measurement for the New Full Energy Injector at ELETTRA	emittance, booster, quadrupole, diagnostics	1236
	G. Penco, L. Badano, S. Bassanese, G. Ciani, P. Craievich, S. Di Mitri, M. Ferianis, M. Predonzani, M. Veronese ELETTRA, Basovizza, Trieste A. A. Lutman DEEI, Trieste
	An emittance measurement station was set up and operated with the quadrupole scan technique to characterize the electron beam transverse phase space at the Elettra laboratory. The diagnostic station, based on a YAG:Ce scintillation screen imaged by a CCD digital camera, was installed at the end of the 100 MeV booster pre-injector together with a beam longitudinal structure monitor. This equipment plays an important role for the bunching system optimization and for the optical matching of the injection transfer line to the booster ring. Experimental results and comparison with multi-particle tracking codes simulation are presented in this paper.

TUPC081	Single-shot Longitudinal Bunch Profile Measurements at FLASH Using Electro-optic Detection Techniques	electron, laser, resonance, linac	1242
	P. J. Phillips, W. A. Gillespie University of Dundee, Nethergate, Dundee, Scotland V. R. Arsov, H. Schlarb, B. Schmidt, P. Schmüser DESY, Hamburg G. Berden, A. F.G. van der Meer FOM Rijnhuizen, Nieuwegein S. P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire A. MacLeod UAD, Dundee B. Steffen PSI, Villigen
	At the superconducting linac of FLASH at DESY, we have installed an electro-optic experiment for single-shot, non destructive measurements of the longitudinal electric charge distribution of individual electron bunches. The profile of the electron bunch field is electro-optically encoded onto a streched Ti:Sa laser pulse. In the decoding step, the profile is retrieved from a spectral measurement of the encoded pulse or from a cross-correlation of the encoded pulse with a 35 fs laser pulse , obtained from the same laser. At FLASH, sub-100 fs electron bunches have been measured during FEL operation with a resolution of better than 50 fs. The electro-optic measurements have been validated with a tranverse deflecting cavity measurements.

TUPC087	4D Emittance Measurements Using Multiple Wire and Waist Scan Methods in the ATF Extraction Line	emittance, coupling, extraction, quadrupole	1257
	C. Rimbault, P. Bambade, J. Brossard LAL, Orsay M. Alabau IFIC, Valencia S. Kuroda KEK, Ibaraki A. Scarfe UMAN, Manchester M. Woodley SLAC, Menlo Park, California
	Emittance measurements performed in the diagnostic section of the ATF extraction line since 1998 lead to vertical emittances three times larger than the expected ones, with a strong dependence on intensity. An experimental program is pursued to investigate potential sources of emittance growth and find possible remedies. This requires efficient and reliable emittance measurement techniques. In the past, several phase-space reconstruction methods developed at SLAC and KEK have been used to estimate the vertical emittance, based on multiple location beam-size measurements and dedicated quadrupole scans. These methods have been shown to be very sensitive to measurement errors and other fluctuations in beam conditions. In this context new emittance measurements have been performed revisiting these methods and newly developed ones with a systematic approach to compare and characterise their performance in the ATF EXT line.

TUPC088	Statistical Weighting of the MICE Beam	emittance, target, coupling, lattice	1260
	C. T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon
	Conventionally only average properties such as means and variances of charged particle beams are measured. Such a technique is limited in that it is challenging to measure moments beyond the second and certain correlations are difficult to measure. In the Muon Ionisation Cooling Experiment (MICE), the beam rate is sufficiently low that particles pass singly through the accelerator and measurements can be made of the position, time (relative to RF phase) and momentum of individual particles. This makes a number of new analysis tools available. In this paper two particular tools are studied: the analysis of third and higher beam moments and the ability to select an input beam based on such moments.

TUPC090	Ionisation Profile Monitor to Determine Spatial and Angular Stability of FEL Radiation of FLASH	laser, ion, electron, photon	1266
	M. Sachwitz, A. Hofmann, S. Pauliuk DESY Zeuthen, Zeuthen K. I. Tiedtke, H. Wabnitz DESY, Hamburg
	An Ionization Profile Monitor (IPM) is used to detect lateral position changes of an FEL beam. By its help, beam position stability can be measured via the parasitic ionization of the residual gas in the beamline. We give an outline on operation, calibration and maintenance of the two IPM that have been developed at DESY Zeuthen and that have recently been built into FLASH at DESY Hamburg.

TUPC099	Wire Scanner for Transverse Beam Parameter Measurements in BEPCII	linac, electron, radiation, vacuum	1293
	Y. F. Sui, J. Cao, L. Ma IHEP Beijing, Beijing
	The wire scanner has been installed in the linac injector of BEPCII (Beijing Electron-Positron Collider II) to provide the transverse beam parameters. In the several fellowing months, some experiments will be done. The result will be presented and the reason will be analysed.

TUPC103	Digital Generation of Noise-signals with Arbitrary Constant or Time-varying Spectra	emittance, synchrotron, target, injection	1299
	J. Tuckmantel CERN, Geneva
	Noise sources in the RF system of an accelerator produce longitudinal emittance increase or loss. This noise is inherent, from the beam-control system electronics, external sources or high power components, or can be purposely injected for a specific need such as bunch distribution modification or controlled emittance increase. Simulations to study these effects on the beam require precise reproduction either of the total noise measured on the hardware, or of the noise spectrum to be injected and optimized to produce the desired changes. In the latter case the 'optimized' noise source has also to be created in real-time to actually excite the beam via the RF system. This paper describes a new algorithm to create noise spectra of arbitrary spectral density varying with cycle time. It has very good statistical properties and effectively infinite period length, important for long simulation runs. It is spectrally clean and avoids undesired mirror spectra. Coded in C++, it is flexible and fast. Used extensively in simulations it has also successfully created controlled emittance increase in the SPS by the injection of artificial real-time RF noise.

TUPC106	Optimization of Electron Linac Operating Conditions for Photonuclear Isotope Production	target, electron, radiation, isotope-production	1308
	V. L. Uvarov, A. N. Dovbnya, V. I. Nikiforov, Z. V. Zhiglo NSC/KIPT, Kharkov
	The communication describes the method for optimizing the high-power Linac regime (electron energy, pulsed current and beam size, pulse repetition rate) and the composition of output devices to provide the maximum photonuclear yield of isotope product with the maintenance of thermal stability of structural elements. To exemplify, the results of accelerator KUT-30 (45 MeV, 10 kW) optimization at conditions of medical isotope Cu-67 production are reported. Simulation based on a modified PENELOPE/2006 code was employed to compute the Cu-67 generation rate in the Zn target, and also the absorbed radiation power in output device elements for different operating conditions of the accelerator with due regard for its loading characteristic. The simulation results were used to calculate the target and the converter (Ta) temperature at various thicknesses of the latter and at real cooling parameters. Conditions have been established for the maximum Cu-67 yield with keeping thermal stability of the target device.

TUPC107	Feed-free Monitoring of Intense High-energy Bremsstrahlung	electron, radiation, monitoring, linac	1311
	V. L. Uvarov, V. I. Nikiforov, V. A. Shevchenko, I. N. Shlyakhov, A. Eh. Tenishev NSC/KIPT, Kharkov
	High-intensity (>10³ W/cm²) bremsstrahlung sources produced on the basis of electron linacs of energy E₀ up to 100 MeV find use in accelerator-driven subcritical assemblies, in photonuclear isotope production, activation analysis, etc. These processes, as a rule, call for maintaining a stable bremsstrahlung flow for one or more days. Therefore the diagnostic means of the radiation must function reliably under conditions of high-absorbed doses (≥10⁸ Gy). To solve the problem, it is proposed to use a direct charge detector (DCD). It consists of two vacuum gap-spaced metal plates of different thickness. The simulation method based on the software PENELOPE/2006 was used to investigate the conditions of equilibrium e, X-radiation formation in the area of detector location, the dependence of detector sensitivity in its standard geometry on the atomic number Z of the plate material and the gammas energy at E₀ ranging from 20 to 100 MeV. The realization of the method has been demonstrated by experiment with the use of the DCD prototype. The proposed detector requires no external power supply, is easy to operate and has a high radiation resistance.

TUPC109	Analysis of Measurement Errors in Residual Gas Ionisation Profile Monitors in a High Intensity Proton Beam	ion, space-charge, proton, synchrotron	1317
	R. E. Williamson, S. J. Payne, B. G. Pine, C. M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon
	ISIS is the pulsed neutron and muon source based at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss-limited 50 Hz proton synchrotron which accelerates ~3·10¹³ protons per pulse from 70 MeV to 800 MeV, corresponding to a mean beam power of 0.2 MW. Beam profile measurements are a key component of both ISIS operational running and R&D beam studies. Understanding and quantifying limitations in these monitors is essential, and has become more important as work to optimise and study the beam in more detail has progressed. This paper presents 3D field and ion trajectory modelling of the ISIS residual gas ionization profile monitors, including the effects of non-uniformity in longitudinal and transverse drift fields, and beam space charge. The simulation model allows comparison between the input beam profile, and that deduced from ion currents. The resulting behaviour, corrections and errors are then compared with experimental data from the ISIS synchrotron.

TUPC128	Air Temperature Analysis and Control Improvement for the EPU 5.6 at TLS	controls, storage-ring, insertion, insertion-device	1368
	J.-C. Chang, Y.-C. Chung, C.-Y. Liu, Z.-D. Tsai NSRRC, Hsinchu
	This paper presents the air temperature analysis and control improvement for area of the elliptically polarizing undulator EPU 5.6 in the Taiwan Light Source (TLS). To enhance uniformity of ambient air temperature, we applied mini environmental controls and installed five cross flow fans in this area. Eight temperature sensors were installed around the EPU to monitor temperature variation. We also simulated the flow field and temperature distribution in this area by using a computational fluid dynamics (CFD) code. The simulation results were validated by comparing to measured data. The temperature variation along time and spatial temperature differences were controlled within 0.1 degree C and 0.5 degree C, respectively.

TUPC132	The Strategy between Optimal Control and Energy Saving about Utility System Operation	controls, synchrotron, synchrotron-radiation, radiation	1380
	Z.-D. Tsai, J.-C. Chang NSRRC, Hsinchu J.-R. Chen NTHU, Hsinchu
	Previously, the Taiwan Light Source (TLS) at NSRRC has proven the good beam line quality depend on the utility system stability. Subsequently, several studies including the temperature control of cooling water and air conditioner was in progress for improving the system stability. Due to the importance of energy saving issue, the heavy power consumption of utility system are also discussed and intended to reduce extensively. The paper addresses some experience between optimal control and energy saving about operation of utility system in TLS. This provides a strategy between stability control and power reduction, including the flow balance, inverter usage, facility operation, control philosophy and so on.

TUPC134	Results from Commissioning of the Energy Extraction Facilities of the LHC Machine	extraction, dipole, superconducting-magnet, quadrupole	1383
	K. H. Mess, G.-J. Coelingh, K. Dahlerup-Petersen CERN, Geneva
	The risk of damage to the superconducting magnets, busbars and current leads of the LHC machine in case of a resistive transition (quench) is being minimized by adequate protection. The protection is based on early quench detection, bypassing the quenching magnets by cold diodes, energy density dilution in the quenching magnets using heaters and, eventually, energy extraction. For two hundred and twenty-six LHC circuits (600 A and 13 kA) extraction of the stored magnetic energy to external dump resistors was required. All these systems are now installed in the machine and the final hardware commissioning has been undertaken. After a short description of the topology and definitive features, layouts and parameters of these systems the paper will focus on the results from their successful commissioning and an analysis of the system performance.

TUPC144	Digital Low Level RF System for SOLEIL	feedback, beam-loading, controls, synchrotron	1407
	P. Marchand, M. D. Diop, F. Ribeiro, R. Sreedharan SOLEIL, Gif-sur-Yvette M. Luong, O. Piquet CEA, Gif-sur-Yvette
	In the SOLEIL storage ring, two cryomodules, each containing a pair of 352 MHz superconducting cavities, will provide the maximum power of 560, required at the nominal energy of 2.75 GeV with the full beam current of 500 mA. Presently, an analogue Low Level RF system is successfully operating to control the amplitude and phase of the accelerating voltage. A fast digital FPGA based I-Q feedback is currently under development. The digital I-Q loop is realised with a HERON IO2 FPGA module using a Virtex II with 1M gates. The performance of the digital LLRF system has been evaluated using a Matlab-Simulink based simulation tool taking into account different features (loop delays, bandwidth limitation, extra power budget). The hardware design is described and the first experimental results are reported.

TUPC146	Real Time, Distributed, Hardware-software Simulation of Multicavity RF Station for LLRF System Development in FLASH and XFEL	klystron, controls, diagnostics, resonance	1413
	P. Pucyk, S. Simrock DESY, Hamburg W. Jalmuzna TUL-DMCS, Łódź
	The paper describes the implementation of distributed (FPGA, DSP, GPP) system for simulation of multiple TESLA cavities together with high power distribution chain. The applied models simulate the system behavior with the performance close to the response time of the real RF station and cryomodules. Parametrized architecture of the simulator allows to find compromise between the features of the model and the available resources it can be implemented in. The results of driving the simulator using the FLASH LLRF system are presented and compared with the real measurements. Proposed solution is the important tool for LLRF system development and testing, and can be, in many cases, a replacement for the tests in the real superconducting test facilities reducing the development costs and time.

TUPC150	Ensemble Cavity Control System Simulation Using Pulse-to-pulse Calibration	coupling, controls, klystron, alignment	1422
	C. Serrano, L. R. Doolittle, A. Ratti, A. Vaccaro LBNL, Berkeley, California
	For cost reasons one klystron will supply RF power to multiple cavities in recent projects. Individual cavity field stability and optimal drive needs to be achieved considering beam propagation, cavity tuning, cavity coupling, and cable lengths. External environmental factors continuously modify physical properties of the accelerating structures and waveguides. Therefore a calibration system has been designed to adapt individual drive signals and vector-sum alignment in a pulse-to-pulse basis. An eight-cavity model and a calibration system have been tested in simulation using the hardware-software simulation tool developed at LBNL.

TUPC153	Hardware-software Simulation for LLRF Control System Development	controls, feedback, monitoring, radio-frequency	1428
	A. Vaccaro, L. R. Doolittle, A. Ratti, C. Serrano LBNL, Berkeley, California
	Field Programmable Gate Arrays (FPGA) have been used in accelerator controls for a long time. Stricter performance requirements in new accelerator designs force LLRF control systems to continuously improve, and the increasing density of available FPGAs enables such progress. The increased complexity in FPGA design is not always followed by new RF systems availability for development and testing. Therefore, a hardware-software simulation tool has been developed to model RF systems by a software simulator. It simulates the interaction of HDL code that is to be synthesized with both RF systems and communication ports to external controls software, reproducing realistic working conditions of the FPGA. The hardware-software interaction for LLRF control system design is discussed here.

TUPD002	Development of an Eddy Current Septum for LINAC4	septum, linac, injection, extraction	1434
	M. J. Barnes, B. Balhan, J. Borburgh, T. Fowler, B. Goddard, W. J.M. Weterings CERN, Geneva A. Ueda KEK, Ibaraki
	The bump for the new PS Booster injection from the future Linac4 will be made up of a set of four pulsed dipole magnets; the first of these (BS1) must act as a septum with a thin element dividing the high-field region of the circulating beam from the field-free region through which the injected H^- beam must pass. BS1 will provide a deflection of 66 mrad at 160 MeV; this will be achieved with a peak field of 630 mT and a length of 200 mm. The field must rise and fall in 40 microseconds and have a flattop of up to 120 microseconds. The ripple of the flattop should be below ±1%. This paper discusses the design of an eddy current septum for BS1.

TUPD014	Detailed Design, Manufacturing and Testing of a Strip-line Extraction Kicker for CTF3 Combiner Ring	kicker, vacuum, impedance, extraction	1458
	I. Rodriguez, L. García-Tabarés, E. Rodríguez García, F. Toral CIEMAT, Madrid D. Alesini, A. Ghigo, F. Marcellini, M. Zobov INFN/LNF, Frascati (Roma) T. Fowler, I. Syratchev CERN, Geneva
	The first calculations to design the CTF3 Combiner Ring extraction kicker are reported elsewhere. The last computing step before fabrication is the wakefield analysis, to determine if the bunch disturbance is acceptable. Two different codes have been used for cross-checking: CST Particle Studio and GDFidl. The computation is challenging because of the long structure (2.4 m) with a short bunch (3 mm). Besides, both transitions are not equal, because of different straight sections of the input and output beam pipe, and then the solution method is more complex. On the other hand, the main challenges for manufacturing are the long electrodes support via ceramic stand-offs and the flexible electrical connections to allow for electrodes thermal differential displacement. Special tooling has also been developed for assembly within the required tolerances. The device has been successfully leak tested. High frequency transmission coefficients and high voltage dielectric strength were also measured.

TUPD019	Inter-disciplinary Mechanical and Architectural 3D CAD Design Process at the European XFEL	controls, civil-engineering, cryogenics, feedback	1467
	L. Hagge, N. Bergel, T. H. Hott, J. Kreutzkamp, S. Suehl, N. Welle DESY, Hamburg
	Realising the European-XFEL involves creating and coordinating several types of 3D design models for many different subsystems like underground buildings, utilities, accelerator systems or photon beam lines. In order to handle the huge amount of data, reduced envelope models are needed for integrating the subsystems towards the complete facility and to ensure that the different subsystems connect properly and do not intersect. Detailed component design models are required for planning approval, tendering or in-house production. A key issue was to develop an optimized design for the facilities while still being able to accommodate possible late R&D-driven design changes of subsystems. The paper describes the procedures and tools which are used for planning and designing the European-XFEL and reports benefits and experience. The procedures in use allow visualization of the facilities, negotiation of requirements and solutions between all the working groups, optimized storing of the documentation as well as running approval and change management procedures. Tools in use include a requirements database, 3D-CAD systems and an engineering data management system.

TUPD031	Crystals Application in the TOTEM Experiment to Increase the Acceptance of a Roman Pot	proton, optics, scattering, closed-orbit	1491
	E. Laface, W. Scandale CERN, Geneva S. Hasan Univ. Insubria and INFN Milano, Como C. Santoni Université Blaise Pascal, Clermont-Ferrand
	Bent crystal may enhance the physics reach of a near-beam physics detector in the CERN-LHC, by increasing the acceptance of scattered protons in low transverse momentum reactions. As an example we present simulations demonstrating the increase of the Roman Pot acceptance in the TOTME apparatus. Starting from the MadX v6.5 nominal optic, a crystal is placed at different longitudinal and transversal positions: for each scheme a gaussian beam of protons with different kinematic variables is created and tracked along the optical line with crystal. The number of protons with transversal coordinates greater than 10σ+0.5mm, that is inside the Roman Pot, is compared with the total number of protons. The possible gain in acceptance is around 15-20%.

TUPD035	Modeling of the RF-shield Sliding Contact Fingers for the LHC Cryogenic Beam Vacuum Interconnects Using Implicit and Explicit Finite Element Formulations	vacuum, superconducting-magnet, alignment, shielding	1503
	D. Ramos CERN, Geneva
	The short interconnect length between the LHC superconducting magnets required the development of an optimised RF shielded bellows module, with a low impedance combined with compensation for large thermal displacements and alignment lateral offsets. Each bellows is shielded by slender copper-beryllium fingers working as pre-loaded beams in order to provide a constant force at the sliding contact. Unless the sliding friction and some geometrical parameters of the fingers are kept within a limited range, a large irreversible lateral deflection towards the vacuum chamber axis may occur and eventually block the beam aperture. The finite element analysis presented here simulates this failure mechanism providing a complete understanding of the finger behavior as well as the influence of the various design parameters. An implicit non-linear two-dimensional model integrating friction on the sliding contacts, geometrical non-linearity and plasticity was implemented in a first stage. The design was then verified through the whole working range using an explicit formulation, which overcame the instabilities resulting from the sudden release of internal energy stored in the finger.

TUPD036	G4Beamline Simulations for Detector Development	electron, radiation, electromagnetic-fields, photon	1506
	T. J. Roberts, K. B. Beard Muons, Inc, Batavia
	In current research programs to develop radiation detection instruments, simplifying assumptions are frequently made in estimating the resolutions and efficiencies attainable by neutron and gamma-ray instruments. Monte Carlo programs (such as Geant4) are capable of realistically modeling such problems, but the technical details of setting up, running, and interpreting the required simulations are beyond the ability of all but the most expert researchers. G4beamline, a program that is an interface to the Geant4 toolkit for the simulation of accelerator beam lines, is being extended to model detectors and related systems needed for applications related to nuclear nonproliferation and other users. The program is flexible, extremely user friendly, and requires no programming by users. Simulations of simple or complex detectors can be setup quickly and are accurately simulated using the power and accuracy of Geant4 for the transport of particles, including scattering, attenuation, interactions, and decays.

TUPD038	Beam Test of a Movable Collimator (Mask) with Low Beam Impedance	impedance, positron, vacuum, collider	1511
	Y. Suetsugu, K. Shibata KEK, Ibaraki A. Morishige, Y. Suzuki, M. Tsuchiya Kinzoku Giken Co. Ltd., Ebina
	A movable collimator with low beam impedance for future high-intensity machines has been investigated in KEK. The metal head of the collimator is supported by a dielectric material in order to reduce the interference with beams. The first test model was installed into the KEK B-factory (KEKB) positron ring last year. The head and the support was alumina ceramic, but only the head was coated by copper to realize a conductive layer. The support, however, was finally melted during the beam operation due to the overheating by intense electromagnetic fields induced by bunches. Based on the experience, the design was revised and the second test model was manufactured, where the head and the support were made of graphite and artificial diamond, respectively. Graphite is a conductive material with high thermal strength, and diamond, on the other hand, is a dielectric material with high thermal conductivity as well as the strength. The second test model is installed in the spring of this year, and tested again with beams during the beam operation to prove the principle. The results of the beam tests will be presented here. Y. Suetsugu, K. Shibata, A. Morishige, Y. Suzuki, M. Tsuchiya, “Design Study of a Movable Mask with Low Bema Impedance”, PRST-AB, 9, 2006, 103501.

TUPP003	Automatic Generation of SEU Immunity for FPGA Based Electronics for Accelerators	controls, radiation, free-electron-laser, laser	1529
	M. K. Grecki, G. W. Jablonski, W. Jalmuzna, D. R. Makowski TUL-DMCS, Łódź
	The modern accelerator control systems nowadays are build using digital technology based on FPGA circuits. However, digital circuits working in radioactive environment are exposed to disturbing effects, in particular SEU (Single Event Upset). One of the countermeasure is a redundancy in circuit that allow to detect and correct errors caused by radiation. Unfortunately CAD software provides no support to automatically include required redundancy in the FPGA project. Moreover, optimization procedure removes all redundant parts and special effort must be made to prevent that. The paper presents a software environment to process VHDL description of the circuit and automatically generate the redundant blocks together with voting circuits. The generated redundancy uses Triple Module Redundancy (TMR) scheme. It also supports the VHDL simulation with SEUs in order to enable identification of the most sensitive components*. Since the TMR is costly, the designer can indicate which parts of the circuit should be replicated based on the results of simulation. Baumann. Neutron-induced…, Int. Rel. Phys. Symp. 2000. Hentschke et al. Analyzing Area…, Symp. ICs and Systems Design, SBCCI02. *Grecki. VHDL Simulation…, Nanotech 2006, Vol.1.

TUPP018	Impact of Electromagnetic Fields in TESLA RF Modules on Transverse Beam Dynamics	emittance, electron, undulator, free-electron-laser	1568
	E. Prat, W. Decking, M. Dohlus, T. Limberg, I. Zagorodnov DESY, Hamburg
	Transverse electric fields in TESLA rf modules exist on one hand because of deformations of the longitudinal accelerating field in the presence of rf structure misalignments or in the vicinity of asymmetrically machine parts like input couplers. On the other hand, the beam itself induces transverse wake fields if it does not travel through the center of a perfectly rotationally symmetric structure. Transverse deflecting fields deflect beam particles. The average deflection causes a change in the beam trajectory; the phase dependence of the transverse field leads to a variation of the transverse kick along the longitudinal position of the bunch and thus in general to a change in projected emittance. If the strength of the transverse field component varies along the transverse direction itself, slice emittance will be also affected. We will present the amplitudes and spatial variations of transverse fields generated by the mechanisms described above, and discuss their impact on beam trajectories and shape.

TUPP020	Analysis of Collective Effects at the Diamond Storage Ring	impedance, single-bunch, collective-effects, storage-ring	1574
	R. Bartolini, C. Christou, R. T. Fielder, M. Jensen, A. F.D. Morgan, S. A. Pande, G. Rehm, C. A. Thomas Diamond, Oxfordshire
	The Diamond storage ring has achieved its nominal operating current of 300 mA in multi-bunch mode and up to 10 mA in single bunch mode. Several collective instabilities have been observed and their dependence on machine parameters such as chromaticities, RF voltage and fill pattern have been investigated. We report here the analysis of the observed current thresholds and rise times of the instabilities compared with analytical estimates and tracking simulations. We also present the results of the MAFIA simulations performed with the aim of understanding the main contribution to the impedance of the ring and establishing a machine impedance database.

TUPP023	Direct Detection of the Electron Cloud at ANKA	electron, vacuum, storage-ring, synchrotron	1580
	S. Casalbuoni, A. W. Grau, M. Hagelstein, A.-S. Müller FZK, Karlsruhe U. Iriso ALBA, Bellaterra E. M. Mashkina University of Erlangen-Nürnberg, Physikalisches Institut II, Erlangen R. Weigel Max-Planck Institute for Metal Research, Stuttgart
	Low energy electrons generated by the interaction of high energy particles with the beam pipe surface can be detrimental for accelerators performances increasing the vacuum pressure, the heat load and eventually producing beam instabilities. The low energy electrons accumulating in the beam pipe are often referred to as electron cloud. In this presentation we report on the direct evidence of the electron cloud in the electron storage ring of the synchrotron light source ANKA (ANgstrom source KArlsruhe).

TUPP024	Electron Cyclotron Resonances in Electron Cloud Dynamics	electron, resonance, cyclotron, wiggler	1583
	C. M. Celata, M. A. Furman, J.-L. Vay, J. W. Yu LBNL, Berkeley, California
	We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code “POSINST” was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. At magnetic field values, B, for which the bunch frequency is an integral multiple of the electron cyclotron frequency an enhancement of up to a factor of 3 in the electron cloud equilibrium density was found. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ~ (2πm_e/el_b), with l_b = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. We believe this accounts for the fact that this resonance has not been reported before in the electron cloud literature. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics will be discussed, along with results from 3D simulations.

TUPP026	Impedance of Ultrarelativistic Charged Distributions in Tapering Geometries	impedance, vacuum	1589
	D. A. Burton, D. C. Christie, R. W. Tucker Lancaster University, Lancaster
	We develop a scheme for obtaining the impedance, at any frequency, of a gradually tapered geometry of arbitrary cross-section containing a bunch of arbitrary profile travelling at the speed of light parallel to the axis of the taper. Coordinate-free expressions for Maxwell's equations are 2+2-split in a coordinate system adapted to the particle beam and the taper and, using an asymptotic expansion for a gradual taper, a coupled hierarchy of Poisson equations are obtained. Applications of the scheme are presented.

TUPP027	Electron Energy Dependence of Scrubbing Efficiency to Mitigate E-cloud Formation in Accelerators	electron, vacuum, monitoring, luminosity	1592
	R. Cimino, M. Commisso, T. Demma, A. G. Grilli, P. Liu, M. Pietropaoli, V. Sciarra INFN/LNF, Frascati (Roma) V. Baglin CERN, Geneva P. Barone, A. Bonanno INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza)
	Recently built and planned accelerators, base their ability to reach design parameters, on the capability to reduce Secondary Electron Yield (SEY) during commissioning, hence mitigating the potentially detrimental effects of e-cloud driven machine limitations. This SEY reduction (called "scrubbing"), is due to the fact that the electrons of the cloud, hit the vacuum chamber wall, modifying its surface properties and reducing its SEY. This minimise any disturbing effects of the e-cloud to the beam. "Scrubbing" has been studied only as a function of impinging electron dose. In reality SEY modifications are only studied by bombarding surfaces with 300-500 eV electrons, but no scrubbing dependence on the bombarding electron energy has ever been discussed. The actual energy of the electrons of the cloud hitting the wall in real accelerators has never been measured accurately, while simulations predict very low electron energies (<50 eV). For this reason and given the peculiar behaviour observed for low energy electrons, we decided to study this dependence accurately. Here we present some preliminary results discussing eventual implications to machine commissioning procedures. R. Cimino et al. Phys. Rev. Lett 93, 14801 (2004).

TUPP030	A Formula for the Electron Cloud Map Coefficient in the Presence of a Magnetic Field	electron, dipole, vacuum, cyclotron	1601
	T. Demma INFN/LNF, Frascati (Roma) S. Petracca U. Sannio, Benevento
	The evolution of the electron density during multibunch electron cloud formation can be reproduced using a bunch-to-bunch iterative map formalism. The reliability of this formalism has been proved for RHIC* and LHC. The coefficients that parameterize the map function are readily obtained by fitting the results of compute-intensive electron cloud simulations. An analytic expression for the linear map coefficient that describes weak cloud behaviour from first principles has been derivied for the case of staight sections of RHIC. In this paper we generalize the model presented in ** to the case of electron cloud evolution in presence of a dipolar magnetic field and compare the results with numerical simulations. U. Iriso and S. Pegg. Phys. Rev. ST Accel. Beams 9, 071002 (2006). T. Demma et al. Phys. Rev. ST Accel. Beams 10,114401 (2007). **U. Iriso and S. Pegg. Proc. of EPAC06, pp. 357-359.

TUPP031	Electron Cloud Simulations for DAΦNE	electron, wiggler, positron, vacuum	1604
	T. Demma, R. Cimino, S. Guiducci, C. Vaccarezza, M. Zobov INFN/LNF, Frascati (Roma)
	After the first experimental observations compatible with the presence of the electron cloud effect in the DAΦNE positron ring, a systematic study has been performed regarding the electron cloud build-up. To assess the effects of the electron cloud, simulations of the cloud build up were carried out using ECLOUD. In particular, we discuss modifications to the secondary emission model, build up for various filling patterns and different wiggler magnetic field models. The obtained numerical results are compared with experimental observations.

TUPP032	Trajectory Jitter and Single Bunch Beam Break Up Instability	linac, emittance, quadrupole, betatron	1607
	S. Di Mitri, P. Craievich ELETTRA, Basovizza, Trieste M. Borland ANL, Argonne, Illinois A. Zholents LBNL, Berkeley, California
	This paper addresses stability issues related to control of the beam break up (BBU) instability in the FERMI@Elettra linac using local trajectory bumps. Analytical study and simulations using the Elegant code are presented. Three different parameters have been used to characterize the BBU, i.e. the projected emittance, the bunch head-to-tail deviation, and the Courant-Snyder invariant for the slice centroid. It is shown that shot-to-shot trajectory jitter in the injector affects the efficiency of the control of the BBU.

TUPP033	Alternative Scheme of Bunch Length Compression in Linacs for Free Electron Lasers	damping, linac, bunching, laser	1610
	S. Di Mitri, M. Cornacchia, S. V. Milton, S. Spampinati ELETTRA, Basovizza, Trieste
	The aim of this paper is to investigate the effect of an alternative scheme of bunch compression on the development of the microbunching instability. Two cases have been considered, one in the presence of a linear energy chirp at the compressor end and another without it. It is shown that after removing the linear energy chirp, a properly tuned R56 transport matrix element is able to dilute the initial energy modulation without affecting the bunch length and to damp the associated current spikes. A by-product of this study indicates that the global compression scheme can be further optimized in the direction of a double compression scheme in which the longitudinal Landau damping is enhanced by increasing the compression factor of the first compressor while reducing that of the second one. The limiting case of such a configuration is the single compression scheme at low energy. The study is based on analytical calculations and on the simulation code LiTrack.

TUPP034	Transverse Effects due to Vacuum Mirror of RF Gun	emittance, gun, vacuum, laser	1613
	I. Zagorodnov, M. Dohlus, M. Krasilnikov DESY, Hamburg E. Gjonaj, S. Schnepp TEMF, Darmstadt
	The transverse kick due to the vacuum mirror in the RF gun can negatively affect the beam emittance. In this contribution we estimate numerically and analytically the transverse wake function of European XFEL RF gun and apply it in beam dynamics studies of the transverse phase space.

TUPP036	"Scrubbing" Process of Cu Surfaces Induced by Electron Bombardment	electron, background, vacuum, target	1619
	D. R. Grosso, P. Barone, A. Bonanno, M. Camarca, M. Commisso, A. Oliva, F. Xu INFN Gruppo di Cosenza, Arcavacata di Rende (Cosenza) R. Cimino INFN/LNF, Frascati (Roma)
	Energy distribution curves of electrons emitted from accelerator used metal surfaces have been measured for electron irradiation with a primary energy from 20 to 400 eV. We separated the contributions of reflected, rediffused and true-secondary electrons out from the spectra and observed significant differences in their incidence angle dependence. These results provide crucial information on the electron cloud formation in particle accelerators and may shed light on the involved physical mechanisms

TUPP040	Intra Beam Scattering in Linear Accelerators, Especially ERLs	scattering, linac, lattice, radiation	1631
	G. Hoffstaetter, M. P. Ehrlichman, A. Temnykh CLASSE, Ithaca
	The theories of beam loss and emittance growth by Touschek and Intra Beam Scattering have been formulated for beams in storage rings. It is there that these effects have hitherto been important because of their large currents. However, there are linear accelerators where these effects become important when considering loss rates and radiation damage. Prime examples are high current Energy Recovery Linacs (ERLs), managing these scattering effects can become challenging, and not only because of the large current, but also because the deceleration of the spent beam increases relative energy spread and transverse oscillation amplitudes. In this paper we describe two ways of simulating particle loss by these scattering affects, both implemented in BMAD. One that yields the places where scattering occurs, and another that yields loss rates along the chamber walls. BMAD includes nonlinear beam dynamics, wake effects, and more, which allows a rather complete propagation of scattered particle. For the example of the ERL x-ray facility that Cornell plans to build, we demonstrate that these capabilities are very important for designing a functional radiation protection system.

TUPP041	CSR Shielding in the Beam Dynamics Code BMAD	radiation, shielding, synchrotron, synchrotron-radiation	1634
	G. Hoffstaetter, C. E. Mayes, U. Sae-Ueng, D. Sagan CLASSE, Ithaca
	Short bunches radiate coherently at wavelengths that are longer than their bunch length. This radiation can catch up with the bunch in bends and the electromagnetic fields can become large enough to significantly damage longitudinal and transverse bunch properties. This is relevant for many accelerators that relies on bunch compression. It is also important for Energy Recovery Linacs, where spent beams are decelerated by a potentially large factor. Because this deceleration increases the relative energy spread, all sources of wake fields, especially Coherent Synchrotron Radiation (CSR), become much more important. In this paper we show how the beam dynamics code BMAD computes the effect of CSR and how the shielding effect of vacuum chambers is included by the method of image charges. We compare the results to established codes: to Elegant for cases without shielding and to a numerical solution of simplified Maxwell equations as well as to analytical csr-wake formulas. Good agreement is generally found, and in cases where numerical solutions of the simplified Maxwell equations do not agree with the csr-wake formulas, we show that BMAD agrees with these analytic formulas.

TUPP043	Computational Beam Dynamics Studies of Collective Instabilities Observed in SNS	proton, electron, impedance, kicker	1640
	J. A. Holmes, S. M. Cousineau, V. V. Danilov, A. P. Shishlo ORNL, Oak Ridge, Tennessee L. K. Jain UW/Physics, Waterloo, Ontario
	During the commissioning and early operation of the Spallation Neutron Source, some physcics shifts were set aside for high intensity stability studies. Under certain, especially contrived conditions, a number of beam instabilities were induced. These included both electron cloud and ring impedance driven phenomena. In this paper we apply both simple analytic models and the ORBIT Code to the description and simulation of these observed instabilities.

TUPP045	Studies of Beam Breakup in Dielectric Structures	focusing, quadrupole, single-bunch, electron	1643
	A. Kanareykin, C.-J. Jing, A. L. Kustov, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio W. Gai, J. G. Power ANL, Argonne, Illinois
	Beam breakup (BBU) effects resulting from parasitic wakefields provide a potentially serious limitation to the performance of dielectric structure based wakefield accelerators. We report on experimental and numerical investigation of BBU and its mitigation. The experimental program focuses on BBU measurements in a number of high gradient and high transformer ratio wakefield devices. New pickup-based beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable at the AWA facility. The numerical part of this research is based on a particle-Green’s function beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the results of detailed experimental measurements with the accurate numerical results and to design an external FODO channel for the control of the beam in the presence of strong transverse wakefields.

TUPP047	Simulation Studies on Coupler Wakefield and RF Kicks for the International Linear Collider with MERLIN	linac, emittance, higher-order-mode, linear-collider	1649
	D. Kruecker, I. Melzer-Pellmann, F. Poirier, N. J. Walker DESY, Hamburg
	One of the critical issues in the design of the superconducting cavities or the International Linear Collider (ILC) is the influence of the RF and higher order mode (HOM) couplers on the beam dynamics. Both types of couplers break the rotational symmetry of the cavity and introduce non vanishing transverse wakefields even on the cavity axis. Furthermore the RF input coupler introduces an asymmetry into the accelerating RF field and thereby additional transverse field components. We have implemented both effects following the calculations presented previously* into the MERLIN C++ library*. This allows us to study the influence of wakefield and RF kicks on the beam dynamics, the bunch shape and the overall performance of the ILC for different proposed coupler designs. I. Zagorodnov and M. Dohlus, ILC Workshop, DESY 2007; K. Bane and I. Zagorodnov, Wake Fest 07, SLAC 2007. **Merlin - A C++ Class Library for Accelerator Simulations; http://www.desy.de/~merlin.

TUPP048	Collective Effects in the EMMA Non-scaling FFAG	space-charge, acceleration, emittance, beam-loading	1652
	S. Machida, D. J. Kelliher STFC/RAL/ASTeC, Chilton, Didcot, Oxon J. S. Berg BNL, Upton, Long Island, New York S. R. Koscielniak TRIUMF, Vancouver
	EMMA is an electron machine to study beam dynamics in a linear nonscaling FFAG. We wish to verify that the behavior predicted by the theory and simulation is correct. In particular, we will study, with large emittance beams, a novel accelerating mode outside an rf bucket, and the effects of crossing "resonances." In EMMA, some collective effects become a concern even though the beam stays in the ring for only 10 to 20 turns. We report studies of direct and image space charge, beam loading, and other collective effects with a tracking simulation. Space charge effects, already potentially significant in EMMA, are enhanced by the fact that the beam passes through the beam pipe off-center. There is some possibility of a negative mass instability for some operation modes. We will show several 3D simulation results for space charge and beam loading effects and pure longitudinal simulation for the negative mass instability.

TUPP051	Coupling Impedance of DAΦNE Upgraded Vacuum Chamber	impedance, vacuum, coupling, electron	1661
	F. Marcellini, D. Alesini, P. Raimondi, G. Sensolini, B. Spataro, A. Stella, S. Tomassini, M. Zobov INFN/LNF, Frascati (Roma)
	The DAΦNE Phi-factory at INFN LNF has been ugraded in the second half of 2007 with a scope to test a recently proposed scheme of crab waist collisions. The vacuum chamber of the collider has been substantially modified: two new low impedance interaction regions have been designed and installed, the new stripline injection kickers have been implemented, the old bellows have been substituted by the new ones and all ion clearing electrodes have been removed. In the paper we present the machine impedance study of these new vacuum chamber components and compare bunch lengthening measurements in the modified DAΦNE with simulation results.

TUPP058	Impedance Estimation of Diamond Cavities	impedance, storage-ring, vacuum, resonance	1673
	S. A. Pande, R. T. Fielder, M. Jensen Diamond, Oxfordshire R. Bartolini JAI, Oxford
	The RF straight section of the Diamond storage ring presently consist of two CESR type SCRF cavities with a provision to install a third cavity in the future. The cavities are equipped with HOM loads and are joined to the adjacent storage ring beam pipe using tapered transitions. The RF cavities are simulated with MAFIA, CST Studio and ABCI to estimate their contribution to the total ring impedance. We also measured the resonant frequencies and Q factors of residual HOMs in these cavities. In this paper, we present the results of our measurements and simulations which lead us to an estimation of the impedance of the RF straight.

TUPP061	Comparison between Laboratory Measurements, Simulations and Analytical Predictions of the Resistive Wall Transverse Beam Impedance at Low Frequencies	impedance, coupling, damping, luminosity	1679
	F. Roncarolo UMAN, Manchester F. Caspers, T. Kroyer, E. Métral CERN, Geneva B. Salvant EPFL, Lausanne
	The prediction of the resistive wall transverse beam impedance at the first unstable betatron line (8 kHz) of the CERN Large Hadron Collider (LHC) is of paramount importance for understanding and controlling the related coupled-bunch instability. Until now only novel analytical formulas were available at this frequency. Recently, laboratory measurements and numerical simulations were performed to crosscheck the analytical predictions. The experimental results based on the measurement of the variation of a probe coil inductance in the presence of i) sample graphite plates, ii) stand-alone LHC collimator jaws and iii) a full LHC collimator assembly are presented in detail. The measurement results are compared to both analytical theories and simulations. In addition, the consequences for the understanding of the LHC impedance are discussed.

TUPP062	Beam Coupling Impedance Studies on LHC FP420 Multi-pocket Beam Pipe Prototype	impedance, coupling, resonance, scattering	1682
	F. Roncarolo, R. Appleby, R. M. Jones UMAN, Manchester
	The LHC FP420 collaboration is assessing the feasibility of installing forward proton detectors 420m from the ATLAS and/or CMS interaction points. The latest prototype of a FP420 station consists of a modified LHC beam pipe in which two pockets hosting the detectors introduce an abrupt cross-section variation of the pipe. During the FP420 proposed operation, each station is moved towards the beam as close as 3 mm (~ 10 σx). The impact on the LHC beam coupling impedance has been evaluated with a laboratory wire measurement and a suite of numerical simulations. In addition, we describe a proposed modification of the beam pipe design which minimizes the impedance of the resonances without compromising the FP420 detector signal to background ratio.

TUPP063	Characterization of the ATLAS Roman Pots Beam Coupling Impedance and Mechanics	impedance, vacuum, coupling, resonance	1685
	F. Roncarolo, R. M. Jones UMAN, Manchester F. Caspers, B. Di Girolamo, T. Kroyer CERN, Geneva
	At the LHC, four Roman Pot (RP) type detectors will be installed on both sides of the ATLAS experiment with the aim of measuring elastic scattering at very small angles and determining the absolute luminosity at the interaction point. During dedicated LHC runs, the detectors will be positioned at about 1 mm from the nominal beam orbit. Numerical simulations and laboratory measurements were carried out to characterize the RP impact on the total LHC beam coupling impedance. The measurement results assess the effectiveness of RF-absorbing ferrite plates that have been mounted in convenient locations in order to damp high Q resonances of the RP structure. In addition, we review the RP mechanics emphasizing the accuracy and reproducibility of the positioning system.

TUPP065	Experimental Study of the Electron Cloud Instability in the CERN-SPS	emittance, electron, injection, proton	1688
	G. Rumolo, G. Arduini, E. Benedetto, E. Métral, G. Papotti, E. N. Shaposhnikova CERN, Geneva R. Calaga BNL, Upton, Long Island, New York B. Salvant EPFL, Lausanne
	The electron cloud instability limits the performance of many existing proton and positron rings. A simulation study carried out with the HEADTAIL code revealed that the threshold for its onset decreases with increasing beam energy, if the 6D emittance of the bunch is kept constant and the longitudinal matching to the bucket is preserved. Experiments have been carried out at the CERN-SPS to study the dependence of the vertical electron cloud instability on the energy and on the beam size. The reduction of the physical transverse emittance as a function of energy is considered in fact to be the main reason for the unusual dependence of this instability on energy.

TUPP067	Transverse Mode-coupling Instability in the CERN SPS: Comparing MOSES Analytical Calculations and HEADTAIL Simulations with Experiments in the SPS	impedance, kicker, injection, coupling	1694
	B. Salvant EPFL, Lausanne G. Arduini, E. Métral, G. Papotti, G. Rumolo, R. J. Steinhagen, R. Tomas CERN, Geneva R. Calaga BNL, Upton, Long Island, New York
	Since 2003, single bunches of protons with high intensity (1.2·10¹¹ protons) and low longitudinal emittance (0.2 eVs) have been observed to suffer from heavy losses in less than one synchrotron period after injection at 26 GeV/c in the CERN Super Proton Synchrotron (SPS) when the vertical chromaticity is corrected. Understanding the mechanisms underlying this instability is crucial to assess the feasibility of an anticipated upgrade of the SPS, which requires bunches of 4·10¹¹ protons. Analytical calculations from MOSES and macroparticle tracking simulations using HEADTAIL with an SPS transverse impedance modelled as a broadband resonator had already qualitatively and quantitatively agreed in predicting the intensity threshold of a fast instability. A sensitive frequency analysis of the HEADTAIL simulations output was then done using SUSSIX, and brought to light the fine structure of the mode spectrum of the bunch coherent motion. A coupling between the azimuthal modes -2 and -3 was clearly observed to be the reason for this fast instability. The aim of the present paper is to compare the HEADTAIL simulations with dedicated measurements performed in the SPS in 2007.

TUPP073	Bench-top Impedance Measurements for a Rotatable Copper Collimator for the LHC Phase II Collimation Upgrade	impedance, vacuum, collimation, target	1703
	J. C. Smith, K. L.F. Bane, J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, C.-K. Ng, L. Xiao SLAC, Menlo Park, California
	The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite collimators with 30 high Z, low impedance Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and this design will be discussed here. Simulations have been performed in MAFIA to study both the resistive wall and geometric impedance contributions of our rotatable collimator design. Benchtop stretched coil probe impedance measurements have also been performed on prototype components to directly measure the low frequency impedance contributions. The design also calls for an RF contact interface at the jaw end. This contact resistance must be a small fraction of a milliohm in order to limit transverse impedance. DC resistance measurements in a custom built test chamber have been performed to test the performance of various metal pairs and surface coatings.

TUPP074	A New RF Shielded Bellows for the DAΦNE Upgrade	shielding, impedance, coupling, storage-ring	1706
	S. Tomassini, F. Marcellini, P. Raimondi, G. Sensolini INFN/LNF, Frascati (Roma)
	A new RF shielded bellows, using the technology of omega shaped strip of beryllium copper material, has been developed and tested on the DAΦNE Upgrade. The RF omega shield is composed by many Be-Cu strips held by an external floating ring. Thermal power loss on strips can be easily extracted and dissipated allowing high beam current operation. Leakage of beam induced e.m. fields through the RF shield is almost suppressed. Twenty omega bellows were manufactured and installed in the DAΦNE storage rings and showed good properties up to a stored beam current of 700 mA. DAΦNE upgrade: A New magnetic and mechanical layout. PAC07. pp. 1466-1468, Albuquerque. **Design and E. M. Analysis of the New DAΦNE Interaction Region. PAC07, Albuquerque, pp 3988.

TUPP084	Parallel Computation of Integrated Electromagnetic, Thermal and Structural Effects for Accelerator Cavities	gun, vacuum, emittance, space-charge	1724
	V. Akcelik, A. E. Candel, A. C. Kabel, K. Ko, L. Lee, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California
	The successful operation of accelerator cavities has to satisfy both rf and mechanical requirements. It is highly desirable that electromagnetic, thermal and structural effects such as cavity wall heating and Lorentz force detuning in superconducting rf cavities can be addressed in an integrated analysis. Based on the SLAC parallel finite-element code infrastructure for electromagnetic modeling, a novel multi-physics analysis tool has been developed to include additional thermal and mechanical effects. The speedup from parallel computation enables virtual prototyping of accelerator cavities on computers, which would substantially reduce the cost and time of a design cycle. The multi-physics tool will be applied to the LCLS rf gun and a superconducting rf gun cavity.

TUPP085	Beam Dynamics Using Graphical Processing Units (GPUs)	lattice, extraction, collimation, beam-transport	1727
	R. Appleby, D. Bailey, M. D. Salt UMAN, Manchester
	Simulation of particle beam dynamics in accelerators is computationally expensive, and requires very high particle statistics and accuracy. Conventional beam tracking tools operate sequentially on particle phase space to compute the trajectories of particles through many turns of circular, and linear, machines. Graphical Processing Units (GPUs) utilise stream processing techniques to dramatically speed up parallel computational tasks, and offer considerable performance benefits to particle beam dynamics processing. In this paper, the stream processing beam dynamics code GPMAD is presented, which exploits the NVidia GPU processor, and demonstrates the considerable performance benefits to particle tracking calculations. The accuracy and speed of GPMAD is benchmarked using the Diamond Light Source BTS lattice, and the collimation system is evaluated.

TUPP086	Efficient 3D Space Charge Calculations by Self-adaptive Multigrid Methods Using the Chombo Framework	space-charge, brightness, electron, vacuum	1730
	C. R. Bahls, G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
	Current and future accelerator design requires efficient 3D space charge computations for high brightness bunches which should be as precise and fast as possible. One possible approach for space charge calculations is the particle-mesh-method, where the potential is calculated in the rest frame of the bunch by means of Poisson's equation. For an efficient solution of this elliptic PDE an appropriate adaptive discretization of the domain is required. Especially it has to take into account discontinuities in the distribution of the particles. The solution method we investigate in this paper is a self-adaptive multigrid method applying composite grids. To accomplish this, we use the library Chombo* which is being developed as a framework for adaptive multiresolution solvers for elliptic and hyperbolic partial differential equations. *Developed and distributed by the Applied Numerical Algorithms Group of Lawrence Berkeley National Lab., http://seesar.lbl.gov/ANAG/chombo/

TUPP087	Short Range Wakepotentials Computed in a Moving Frame		1733
	W. Bruns WBFB, Berlin
	When computing wakepotentials in a frame moving in the same direction as the exciting charge, the relativistic charge is stretched by the factor gamma of the frame's velocity. Because the needed mesh density is proportional to the length of the charge, the moving frame allows a larger gridspacing. The paper presents some implementation details of the handling of the material boundaries moving though the computational volume, and reports some results.

TUPP088	Software Components for Electron Cloud Simulation	electron, proton, space-charge, background	1735
	D. R. Dechow, P. Stoltz Tech-X, Boulder, Colorado J. F. Amundson, P. Spentzouris Fermilab, Batavia, Illinois B. Norris ANL, Argonne, Illinois
	The Synergia2 beam dynamics code is an attempt to incorporate state-of-the-art space charge models from the Impact code into the Chef accelerator tracking code. The need to add new accelerator physics capabilities to the Synergia2 framework has led to software development efforts based on the Common Component Architecture (CCA). The CCA is a specification and a toolset for developing HPC from interchangeable parts, called components. Electron cloud is a potentially limiting effect in the performance of both high-intensity electron and proton machines. The modeling of electron cloud effects is important for the Fermilab main injector. Here, electron cloud effects are expected to play a significant role when the main injector operates in the regime of a high-intensity proton source for the neutrino program. In the ideal case, computational accelerator physicists would like to be able model electron cloud generation and dynamics in a single, self-consistent simulation. As a first step towards creating component-based, electron cloud generation simulations, this work describes a CCA component created from TxPhysics, a library of impact and field ionization routines.

TUPP089	Implementation of Fringe Field Dipole Magnets into the V-Code Beam Dynamics Simulation Tool	dipole, focusing, multipole, vacuum	1738
	S. S. Franke, W. Ackermann, B. Steiner, T. Weiland TEMF, Darmstadt J. Enders, C. Hessler, Y. Poltoratska TU Darmstadt, Darmstadt
	Fast online beam dynamics simulations can advantageously assist the machine operators at various particle accelerator machines because they provide a more detailed insight into the actual machine status. Based on the moment approach a fast tracking code named V-Code has been implemented at TEMF. Within the SFB 634 project the V-Code beam dynamics simulation tool is supposed to be installed at the Superconducting Darmstadt LINear ACcelerator S-DALINAC which is designed as a re-circulating linear accelerator. In order to be able to simulate the entire beam line, an implementation of fringe field dipole magnets is mandatory. Unlike a hard edged field approach the fringe fields influence the beam focusing and its inhomogeneity results in a non-circular bunch motion. For an accurate reproduction of the transverse motion specialized techniques to obtain and to handle the reference path in V-Code together with the 3D-field data along the curved trajectory had to be developed. In the paper a summary of implementation details together with simulation results will be provided.

TUPP090	A Kinetic Model of Multipaction for SRF Cavities for Accelerator Driven Sub-Critical System (ADSS)	electron, electromagnetic-fields, proton, superconductivity	1741
	S. Ghatak, N. Gupta IITK, Kanpur A. S. Dhavale, K. C. Mittal BARC, Mumbai
	This work simulates multipaction in a 700 MHz elliptical SRF cavity. The cavity design was optimized using SUPERFISH. Then the electromagnetic field was re-computed with FEMLAB, a package using the finite element method, to obtain a more accurate field-mapping, and to make the field values available for computation of multipaction. In the multipacting subroutine, electrons were assumed to be released into the system from various points with different initial parameters. The electrons trajectories were tracked until they hit the cavity surface. Leap-frog scheme was used to solve the Lorentz force equation for primary electrons, as it is easy to use and is accurate up to second order. The position, velocity, phase and kinetic energy of primary electrons at each time step were calculated and stored. An interpolation function was used to calculate secondary emission yield (SEY) at different impact energies. With the emission of secondary electrons, their trajectories too were tracked along with primary electrons, in order to identify parameters responsible for multipaction. By repeating this process for large number of electrons, the multipacting trajectories were identified.

TUPP091	WISE: a Simulation of the LHC Optics Including Magnet Geometrical Data	alignment, injection, optics, lattice	1744
	P. Hagen, M. Giovannozzi, J.-P. Koutchouk, T. Risselada, F. Schmidt, E. Todesco, E. Y. Wildner CERN, Geneva
	The beam dynamics in LHC strongly depends on the field quality and geometry of the magnets. A model of the LHC optics has been built, based on the information available at the end of the production as well as on statistical evaluations for the missing information The pre-processor WISE generates instances of the LHC field errors for the MAD X program, with the possibility of selecting various sources. This paper describes the progress since WISE was presented in EPAC06. The slot allocation in LHC is completed since all magnets are installed and interconnected. Geometric measurements have been added for all magnets. Furthermore, some statistical data is available relative to the precision of magnet installation (alignment) and tunnel movements. In this paper the code and the data are used to update the beta-beating estimate at injection and collision energy. The relevance of misalignments of the different magnets and their impact on beta-beating is compared to the sources that have been previously considered, i.e. the spread in the gradient of the cell quadrupoles and the uncertainty associated to the knowledge of the transfer functions of the stand-alone quadrupoles.

TUPP093	Crystalline Beam Simulations	ion, storage-ring, coupling, laser	1747
	D. A. Krestnikov JINR/DLNP, Dubna, Moscow region M. Grieser MPI-K, Heidelberg M. Ikegami JAEA/Kansai, Kizu-machi Souraku-gun Kyoto-fu I. N. Meshkov, A. O. Sidorin, A. V. Smirnov, G. V. Trubnikov JINR, Dubna, Moscow Region M. Nakao, A. Noda, H. Souda, H. Tongu Kyoto ICR, Uji, Kyoto K. Noda, T. Shirai NIRS, Chiba-shi
	A new program code was elaborated for the simulation of crystalline beams on the S-LSR storage ring (Kyoto Univ., Japan) under action of the cooling system. For the investigation of ordered proton beams, which recently were observed in first time on S-LSR, a special molecular dynamics technique was used. This article presents results of the numerical simulation and comparison with experimental data.

TUPP094	Recent Improvements in the Tracking Code PLACET	emittance, alignment, lattice, radiation	1750
	A. Latina, H. Burkhardt, G. Rumolo, D. Schulte, R. Tomas CERN, Geneva E. Adli University of Oslo, Oslo Y. Renier LAL, Orsay
	The Tracking Code PLACET has recently undergone several improvements. A redesign of its internal data structures and a new user interface based on the mathematical toolbox Octave have considerably expanded its simulation capabilities. Several new lattice elements, optimization algorithms and physics processes have been added to allow for more complete start-to-end simulations. The usage of the AML language and the Universal Parser Library extened its interfacing capability.

TUPP095	Computation of Resistive Wall Wakefields with the PBCI Code	impedance, resonance, linear-collider, collider	1753
	T. Lau, E. Gjonaj, T. Weiland TEMF, Darmstadt R. Maekinen TUT, Tampere
	Both geometric disturbances and resistive wall loss of accelerator cavities contribute to the impedance causing the beam to lose energy. Impedance due to arbitrary three-dimensional (3-D) geometries can be computed with the Parallel Beam Cavity Interaction (PBCI), a parallelized, 3D-wakefield code. However, the contribution of wall loss is often significant. The contribution of this work is to incorporate resistive wall loss into 3-D time-domain simulation. Surface-impedance concept is used to consider wide-band skin-effect loss of metal. In theory, the proposed approach can be extended to consider high-frequency phenomena such as frequency-dependent conductivity of metal and anomalous skin effect.

TUPP098	The 3D Space Charge Field Solver MOEVE and the 2D Bassetti-Erskine Formula in the Context of Beam - E-cloud Interaction Simulations	positron, space-charge, damping, electron	1759
	A. Markovik, G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock
	In this paper the fields computed with our 3D space charge field solver MOEVE are compared to those obtained by means of the Bassetti-Erskine formula, which is a widely used 2D approximation of the electric field of a Gaussian bunch. In particular we are interested in the transversal fields of very flat bunches as the ILC or the KEKB positron bunch. Supposing a longitudinal Gaussian distribution of the bunches, we compare the computed transversal fields for a certain line density of the positron bunch. It turns out that the fields from the 2D and the 3D computation coincide very good.

TUPP099	Improvement of RFQSIM	rfq, focusing, acceleration, multipole	1762
	J. M. Maus, A. Schempp IAP, Frankfurt am Main
	RFQSIM has constantly been developed at IAP to simulate multiple particles dynamic of RFQs which include simulations of high current applications, decelerators, debuncher and rebuncher e.g. for the medical application. The latest work to improve RFQSIM include the option to change the modulation and or the aperatur of the simulated RFQ to produce the same acceleration and or focusing efficiency than the two term potential gives for different electrode geometries. Additional work was done to improve the graphical analysis during runtime as well as the change of all routines to be compatible with the Fortran F95 standard. The maximum number of particles to be simulated was increased to 200k. The paper shows examples of results for the high current application like the of the p-linac and the new HLI injector for GSI and for transition sections.

TUPP100	A Four-dimensional Vlasov Solver for Microbunching Instability in the Injection System for X-ray FELs	collective-effects, electron, emittance, beam-transport	1764
	M. Migliorati, A. Schiavi Rome University La Sapienza, Roma G. Dattoli ENEA C. R. Frascati, Frascati (Roma) M. Venturini LBNL, Berkeley, California
	The phenomenon of microbunching instabilty arises from small charge-density fluctuations in the electron bunches that are amplified by the combined effect of space charge and coherent synchrotron radiation as the beam travels through magnetic compressors. In order to study the coupled longitudinal and transverse beam dynamics we propose to develop a four-dimensional grid-based Vlasov solver. The goal is to give an accurate characterization of the microbunching instability seeded by the random noise present in the initial bunch distribution. Solving directly the Vlasov equation instead of using macroparticle simulations has the advantage of avoiding the statistical fluctuations due to a limited number of macroparticles. Because a Vlasov solver in a high dimension phase-space tends to be particularly time consuming, to be practical a code implementing this method should run on parallel processors. In this paper we report progress toward the realization of such a 4D Vlasov solver.

TUPP102	Beam Transport with Scattering Using SRIM Supporting Software Routines Code	beam-transport, scattering, emittance, ion	1767
	M. Pavlovic, I. Strasik STU, Bratislava
	In many situations a particle beam is transported through matter-containing components separated by ion-optical elements. The matter-containing components scatter the beam and alter its emittance diagram. In order to include accurately the scattering in beam-transport a special beam-transport module was included in the SRIM Supporting Software Modules package (S3M). It uses transfer-matrix formalism in ion-optical elements. At the entry to a scattering element a beam-generation routine converts the actual σ-matrix into an ensemble of particles and writes a special SRIM input-file. The beam-transport in the scattering element is then calculated by SRIM MC particle tracking. At the exit of the scattering element, the module imports back the SRIM output data and can either continue with transfer-matrix transformations or generate a modified σ-matrix that can be used by other ion-optical programs. It means the beam transport with scattering can either be fully calculated by S3M, or data exchange between S3M and ion-optical programs can be provided. S3M beam-transport module is described in the paper with some typical application examples. M. Pavlovic, I. Strasik. Supporting Routines for the SRIM code, Nucl. Instr. and Meth. B 257 (2007) 601-604.

TUPP103	The Performance of 3D Space Charge Models for High Brightness Electron Bunches	space-charge, brightness, electron, cathode	1770
	G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock K. Floettmann DESY, Hamburg
	Precise and fast 3D space charge calculations for high brightness, low emittance electron beams are of growing importance for the design of future accelerators and light sources. The program package Astra (A space charge tracking algorithm) has been successfully used in the design of linac and rf photo injector systems. The Astra suite originally developed by K. Flöttmann tracks macro particles through user defined external fields including the space charge field of the particle cloud. In this paper we investigate the performance of the 3D space charge models implemented in Astra. These are the FFT-Poisson solver with the integrated Green's function and the iterative Poisson solver based on the multigrid technique. The numerical tests consider the accuracy of the solvers for model bunches as well as the performance within a typical simulation for the XFEL.

TUPP105	Theoretical Field Analysis for Superferric Accelerator Magnets Using Elliptic Multipoles and its Advantages	multipole, dipole, synchrotron, magnet-design	1773
	P. Schnizer, E. S. Fischer GSI, Darmstadt P. G. Akishin JINR, Dubna, Moscow Region B. Schnizer TUG/ITP, Graz
	FAIR will build a set of accelerators and storage rings at GSI Darmstadt. Nearly all of them transport beams of elliptical shape (SIS 100, CR, NESR, RESR, SuperFRS). Magnetic field calculations as well as magnetic measurements provide precise field information, which is used to improve the properties of machine using numerical simulations. We had developed elliptical multipoles fulfilling the Laplace equation which enable us to describe the field within the whole aperture consistently. Now the representation of these has been simplified considerably as compared to earlier ones. Meanwhile we found analytical expressions to derive circular multipoles directly from the elliptic multipoles. We illustrate the advantage of this data representation on SIS 100 magnet data and show how a concise set of harmonics can be derived from rotating coil measurements.

TUPP109	Meshless Solution of the Vlasov Equation Using a Low-discrepancy Sequence	site, synchrotron, controls, damping	1776
	R. L. Warnock SLAC, Menlo Park, California J. A. Ellison, K. A. Heinemann, G. Q. Zhang UNM, Albuquerque, New Mexico
	A successful method for solving the nonlinear Vlasov equation is the semi-Lagrangian method, in which the phase space density is represented by its values on a fixed Cartesian grid with interpolation to off-grid points. Integration for a time step consists of following orbits backward in time from initial conditions on the grid, with the collective force frozen during the time step. We ask whether it would be more efficient to use scattered data sites rather than grid points, namely sites from a low-discrepancy sequence as used in quasi - Monte Carlo integration. This requires a technique for interpolation of scattered data, and with such a technique in hand one can try either backward or forward orbits. Here we explore the forward choice, with the data sites themselves following forward orbits. We treat a problem well studied by the backward method, longitudinal motion in the SLAC damping rings. Over one or two synchrotron periods results are encouraging, in that the number of data sites can be reduced by a large factor. Over longer times it appears that the sites must be redistributed or changed in number from time to time, because of clustering.

TUPP116	Development of Scanning System at HIMAC	target, controls, synchrotron, heavy-ion	1794
	T. Furukawa, T. Inaniwa, Y. Iwata, T. Kanai, S. Minohara, S. Mori, T. Murakami, A. Nagano, K. Noda, N. Saotome, S. Sato, T. Shirai, E. Takada, Y. Takei NIRS, Chiba-shi
	A new treatment facility project, as an extension of the existing HIMAC facility, has been initiated for the further development of carbon-ion therapy. This new treatment facility will be equipped with a three-dimensional irradiation system with pencil beam scanning. For moving-tumor treatments with high accuracy, the most important part of the design study is how to realize this by scanning irradiation. For this purpose, we have studied a combination of the rescanning technique and the gated irradiation method. In order to avoid hot and/or cold spots even by a relatively larger number of rescannings within the acceptable irradiation time, we studied a fast scanning system. Further, this concept was experimentally demonstrated at the HIMAC. The design and the related study of the scanning system for the HIMAC new treatment facility will be presented.

TUPP120	Current Status of the IBA C400 Cyclotron Project for Hadron Therapy	cyclotron, extraction, proton, ion	1806
	Y. Jongen, M. Abs, A. Blondin, W. J.G. M. Kleeven, D. Vandeplassche, S. Zaremba IBA, Louvain-la-Neuve V. Aleksandrov, S. Gurskiy, G. A. Karamysheva, N. Yu. Kazarinov, S. A. Kostromin, N. A. Morozov, E. Samsonov, V. Shevtsov, G. Shirkov, E. Syresin, A. Tuzikov JINR, Dubna, Moscow Region
	Compact superconducting isochronous cyclotron C400 has been designed at IBA (Belgium) in collaboration with the JINR (Dubna). This cyclotron will be used for radiotherapy with proton, helium or carbon ions. ¹²C⁶⁺ and ⁴He²⁺ ions will be accelerated to 400 MeV/u energy and extracted by electrostatic deflector, H²⁺ ions will be accelerated to the energy 250MeV/u and extracted by stripping. We describe the parameters of the cyclotron, the current status of development work on the cyclotron systems. Reports on the status of the C400 project have been given regularly. Therefore, we will focus on the progress which has been achieved since recent reports in Cyclotron 2007 and EPAC 2006 conferences. The project will be ready to begin construction in the nearest future.

TUPP139	Variable Energy 2-MeV S-Band Linac for X-ray and Other Applications	linac, electron, emittance, target	1845
	H. Bender, D. D. Schwellenbach, R. Sturgess, C. P. Trainham NSTec, Los Alamos, New Mexico J. M. Potter JP Accelerator Works, Los Alamos, New Mexico
	We will describe the design and operation of a compact, 2-MeV, S-band linear accelerator (linac) with variable energy tuning and short-pulse operation down to 15 ps with 100-A peak current. The design consists of a buncher cavity for short-pulse operation and two coupled resonator sections for acceleration. Single-pulse operation is accomplished through a fast injector system with a 219-MHz subharmonic buncher. The machine is intended to support a variety of applications, such as X-ray and electron beam diagnostic development and, recently, electron diffraction studies of phase transitions in shocked materials.

TUPP147	Accelerator Driven Systems for Energy Production and Waste Transmutation	target, proton, lattice, acceleration	1854
	C. Bungau, S. C. Tygier Manchester University, Manchester R. J. Barlow UMAN, Manchester R. Cywinski University of Leeds, Leeds
	Due to their inherent safety features and waste transmutation potential, accelerator driven subcritical reactors (ADSRs) are the subject of research and development in almost all countries around the world. The neutrons needed to sustain fission are generated by the spallation process resulting from high energy protons impacting a target element installed at the centre of the core. In the present paper the possible benefits of FFAGs as accelerator drivers for ADSR systems are analysed. FFAGs afford fast acceleration as there is no need of synchronization between RF and magnets, high average current with large repetition rate and large acceptance. The present study also focuses on the Monte Carlo studies of the reactor core design. The impact of the subcriticallity, target material and proton beam energy on the ADSR performance was also examined. Entirely novel ADSR configurations involving multiple accelerator drivers and associated spallation targets within the reactor core have also been considered. Calculations were carried out using the GEANT4 simulation code.

TUPP148	Multigrid Negative Ion Source Test and Modeling	ion, plasma, electron, ion-source	1857
	M. Cavenago INFN/LNL, Legnaro, Padova V. Antoni, G. Serianni, P. Veltri Consorzio RFX, Euratom ENEA Association, Padova
	Negative ion sources are a fundamental ingredient of neutral ion beam injectors for tokamak, like the ITER project and beyond. While detail of formation of negative ions and meniscus of the plasma beam interface at source extraction at source extraction is still debated, reasonable modelling of the beam extraction is well possible. A project of a small source (up to 9 beamlet of 15 mA each of H-, 60 kV acceleration voltage) is here described, and relevant modeling tools are reviewed. Power load deposition on the extraction grid (about 1.5 kW total) and on the source walls (comparable) need accurate cooling design. The extracted beam is direclty useful for wall damage studies.

TUPP159	Dual Energy Material Recognition: Preliminary Results Obtained with the Radio-tomographic System Hosted in Messina	electron, linac, photon, target	1881
	D. Loria, L. Auditore, R. C. Barnà, U. Emanuele, E. Morgana, A. Trifirò, M. Trimarchi INFN - Gruppo Messina, S. Agata, Messina M. Carpinelli INFN-Cagliari, Monserrato (Cagliari) A. Franconieri, M. Gambaccini INFN-Ferrara, Ferrara
	Dual Energy technique is a very powerful tool for material recognition. It typically involves X-ray energy below 1 MeV, thus limiting to few mm the thickness of the inspected heavy materials. However, it would be interesting to investigate the chance to extend this technique to higher energies, to allow recognition of thick heavy samples too. Encouraging preliminary tests performed by means of the radio-tomographic system based on a 5 MeV electron linac have suggested to develop a dual energy technique for high energy x-ray beams. This can be done because first experimental tests have confirmed the chance to vary the electron beam energy in a continuous way. As a consequence, bremsstrahlung beams with different end points can be produced, thus allowing to work with different x-ray transmissions. The composition of two different energies X-ray transmission results, allows to perform material recognition. By means of the MCNP4C2 code, simulations have been performed to evaluate the theoretical x-ray transmission in different materials and thickness. These results allow us to choose two x-ray energies providing the best results in order to perform material recognition.

WEXG01	Performance of KEKB with Crab Cavities	luminosity, resonance, coupling, collider	1893
	Y. Funakoshi KEK, Ibaraki
	20 years after they were initially proposed, in February 2007 crab cavities are for the first time installed in an operating collider, KEKB. The commissioning of KEKB with crab cavities is presented, and the performance of the collider is compared to the performance without crab cavities. Lessons learned from the operation with such cavities for future projects are discussed.
	Slides

WEOAG02	Measurements of Heavy Ion Beam Losses from Collimation	ion, proton, collimation, beam-losses	1906
	R. Bruce, R. W. Assmann, G. Bellodi, C. Bracco, H.-H. Braun, S. S. Gilardoni, E. B. Holzer, J. M. Jowett, S. Redaelli, Th. Weiler, C. Zamantzas CERN, Geneva
	The collimation efficiency for Pb⁸²⁺ ion beams in the LHC is predicted to be much lower than for protons. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements of loss patterns caused by a prototype LHC collimator in the CERN SPS. The loss maps show a qualitative difference between Pb⁸²⁺ ions and protons, with the maximum loss rate observed at different places in the ring. This behaviour was predicted by simulations and provides a valuable benchmark of the simulations done for the LHC.
	Slides

WEOBG02	Experimental Results of a Plasma Wakefield Accelerator Using Multiple Electron Bunches	plasma, electron, resonance, diagnostics	1912
	E. Kallos, T. C. Katsouleas, P. Muggli USC, Los Angeles, California W. D. Kimura STI, Washington K. Kusche, J. H. Park, I. Pogorelsky, D. Stolyarov, V. Yakimenko BNL, Upton, Long Island, New York
	We present some preliminary experimental results of a plasma wakefield accelerator technique which utilizes multiple electron bunches in order to drive a plasma wave. The experiments were performed at the Accelerator Test Facility of Brookhaven National Laboratory where 5-8 equidistant bunches with a spacing which was varied between 100-250 m were fed into a 6mm-long capillary discharge plasma. By varying the time delay of the bunches with respect to the discharge different plasma densities could be tuned, and the effects of the plasma on the bunches were recorded. Such multiple bunch schemes are of great interest because they can provide increased efficiencies and high transformer ratios for advanced accelerators.
	Slides

WEOCG01	Orbit Feedback Trickery at the NSLS VUV Ring	controls, feedback	1931
	B. Podobedov BNL, Upton, Long Island, New York
	A couple of NSLS user groups has recently requested an unusual modification to the way the VUV ring orbit is controlled and stabilized. Rather than keeping the orbit as stable as possible they require a large (many transverse beam sizes) periodic orbit oscillation at the source points of their beamlines. During regular machine operations this has to co-exist with stable orbit throughout the rest of the ring. Achieving good orbit stability under these constraints presents an interesting control problem. Making use of control theory tools and Matlab / Simulink modeling we have explored various algorithms to allow for these new requirements. We then extended our digital orbit feedback system to incorporate these algorithms. In this paper we present commissioning results as well as comparison to the simulations.
	Slides

WEOBM02	Lessons Learned from PEP-II LLRF and Longitudinal Feedback	controls, feedback, klystron, kicker	1953
	J. D. Fox, T. Mastorides, C. H. Rivetta, D. Van Winkle SLAC, Menlo Park, California D. Teytelman Dimtel, San Jose
	The PEP-II B Factory is in the final phase of operation at 2X the design current and 4X the design luminosity. Since the original design the machine has added 8 1.2 MW Klystrons and 12 RF cavities, and the machine is operating with longitudinal instability growth rates roughly 5X in excess of the original estimates. Since commissioning there has been continual adaptation of the LLRF control strategies, configuration tools and new hardware in response to unanticipated technical challenges. This paper presents the LLRF and feedback system evolution from the original design estimates through to the 1.2·10³⁴ final machine. We highlight issues of RF station stability, the interplay of LLRF configuration and low-mode (cavity fundamental driven) longitudinal instabilities, impacts of non-linearities and imperfections in the LLRF electronics, control of HOM driven beam instabilities and the development of configuration tools and measurement techniques to optimally configure the LLRF over the wide range of operating currents. We present valuable "lessons learned" which are of interest to designers of next generation impedance controlled LLRF systems.
	Slides

WEPC044	Top-Up Safety Simulations for the Diamond Storage Ring	electron, sextupole, storage-ring, quadrupole	2085
	I. P.S. Martin, C. P. Bailey, E. C. Longhi, R. P. Walker Diamond, Oxfordshire R. Bartolini, I. P.S. Martin JAI, Oxford
	To ensure that it is not possible for a train of injected electron bunches to pass down an open beam-line during top-up operation at the Diamond Light Source, an extensive program of tracking studies has been performed. Various error scenarios have been investigated, with realistic magnetic field, trajectory, aperture and energy errors all taken into account. We describe the tracking methods used, scenarios considered and the interlocks required in order to maintain user safety during top-up operation.

WEPC051	Upgrade Plans for the ESRF Storage Ring Lattice	lattice, quadrupole, sextupole, resonance	2106
	A. Ropert, L. Farvacque ESRF, Grenoble
	The lattice of the ESRF storage ring is of the Double Bend Achromat type with 32 straight sections of alternating high and low horizontal beta values, currently providing 5 m of available space for insertion devices. As part of the ESRF Upgrade Programme, it is proposed to increase the length of selected insertion device straight sections from 5 to 7 m. In this paper, we will describe the different steps towards longer straight sections: implementation of a new lattice in which the straight section quadrupole triplets are replaced by doublets, design of modified straight sections with replacing the long quadrupoles by shorter ones and moving the adjacent sextupoles, experiments carried out to simulate the lattice symmetry breaking induced by a 7 m long straight section.

WEPC069	A Possible THz Radiation Source with a Train of Short Pulses in the SPARC High Brightness Photoinjector	radiation, electron, cathode, linac	2154
	M. Boscolo, M. Castellano, E. Chiadroni, M. Ferrario, A. Stella, C. Vaccarezza INFN/LNF, Frascati (Roma) V. Petrillo Universita' degli Studi di Milano, Milano
	A radiofrequency electron gun followed by a compressor can generate trains of THz sub-picosecond electron pulses by illuminating the photocathode with a comb laser pulse. This structure of the beam can be used to produce coherent radiation. A feasibility study for a possible experiment at SPARC to be realized with the addition of a dedicated magnetic chicane is discussed. An optimization study of a magnetic chicane with a negative and variable R56 is studied, together with a set of parameters relative to the SPARC machine with the intent of demonstrating the feasibility of this experiment. The dynamics is studied within the SPARC system with the PARMELA code and with the RETAR code for the evaluation of the radiation.

WEPC087	New Preinjector for the ESRF Linac	gun, emittance, cathode, bunching	2195
	T. P. Perron, B. Ogier, A. Panzarella, E. Plouviez, E. Rabeuf, V. Serriere ESRF, Grenoble
	A new preinjector of the 200 MeV Linac is under manufacture at the ESRF. Two operation modes are foreseen, a short pulse of 1ns-.4nC and a long pulse of 1000ns-10nC. The new triode type thermionic 100 Kev gun has been characterized experimentally. The transverse and longitudinal phase space measurements are compared with simulations. The design and the expected performance of the final set-up which includes vertical deflecting plates, pre-bunching and bunching sections will be presented.

WEPC095	Progress in Raising the Energy of the CAMD Linac to 300 MeV	linac, injection, klystron, controls	2216
	Y. Wang, K. J. Morris, V. P. Suller, S. Wang LSU/CAMD, Baton Rouge, Louisiana
	The possibilities and methods for higher energy injection at CAMD have been discussed previously. All components of the former HELIOS 1 linac have now been transferred to CAMD from Jefferson Laboratory. It is planned to reconfigure the CAMD injector linac by installing one of the HELIOS accelerating sections in addition to the two existing CAMD sections, thereby increasing the energy to 300MeV. The optimum arrangement for installing the 300 MeV linac in the existing tunnel has been established. Meanwhile, the arrangements and upgrades of sub-systems are being prepared, simulations of the electron beam trajectory by MATLAB based linear accelerator program are being made, and recommissioning the major HELIOS linac components is underway. In the paper, the detailed technical design of the 300 MeV linac is proposed, the key parameters of the linac are presented, and the benefits of 300 MeV injection to the CAMD synchrotron radiation light source are mentioned.

WEPC105	Construction of a Cryogenic Permanent Magnet Undulator at ESRF	undulator, cryogenics, vacuum, laser	2243
	J. Chavanne, M. Hahn, R. Kersevan, C. A. Kitegi, C. Penel, F. Revol ESRF, Grenoble
	A cryogenic permanent magnet undulator (CPMU) has been constructed at ESRF. The device is a full scale in-vacuum undulator with a magnetic length of 2 metres and a period of 18 mm. This prototype is still compatible with an operation at room temperature, it has been mainly used to investigate the technological issues connected to the operation at low temperature. An important effort has been dedicated to the construction of a complete measuring bench operated in-vacuum with the undulator at cryogenic temperatures around 150 K. The bench includes a stretched wire system for field integral measurement and a local field measurement assembly suitable for the accurate characterization of the optical phase error along the undulator. The main results of the magnetic measurements will be presented , they confirm the simulations performed with RADIA using NdFeB permanent magnet material models at low temperature. The cryogenic system used to cool the undulator is based on a reliable liquid nitrogen closed loop. The heat budget of the device will be discussed. The prototype has been installed on the ESRF ring in December 2007. The first results of operation will be presented.

WEPC116	FERMI@Elettra Undulator Frame Study	undulator, polarization, alignment	2276
	D. La Civita, R. Bracco, B. Diviacco, G. Tomasin, D. Zangrando ELETTRA, Basovizza, Trieste
	The FERMI@Elettra project foresees installation of both linear (LPU) and elliptical polarization undulators (EPU). Following the girder study presented last year, a detailed design of the undulator frame has been now carried out. The aim of this work was to find out a mechanical structure that guarantees minimum displacement of the girders supporting the magnet arrays. At the same time the undulator overall dimensions have been taken into account and the mechanical structure mass minimized. In this paper topology optimization result, finite element simulation and multi-objective optimization analysis are presented.

WEPC118	Study of Controllable Polarization SASE FEL by a Crossed-planar Undulator	undulator, polarization, radiation, electron	2282
	B. Faatz, Y. Li, J. Pflueger, E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	A potential and economical access to generate arbitrary polarized XFEL is to utilize crossed-undulator scheme instead of helical undulators. In this paper, the polarization of x-ray radiation for the European XFEL is investigated. The degree of polarization and the Stokes parameters are calculated for different configurations. The shot-to-shot fluctuation of polarization and the degree of polarization distribution over the transverse plane are also studied.

WEPC130	Shimming Correction of Dynamic Multipole Effects on Apple-II Type EPUs at the ALS	multipole, polarization, undulator, injection	2311
	C. Steier, A. Madur, S. Marks, S. Prestemon, T. Scarvie, D. Schlueter, W. Wan LBNL, Berkeley, California
	Elliptically Polarizing Undulators that provide full photon polarization control also have fast, intrinsic transverse roll-off of the magnetic field. The roll-off is particularly fast for vertical polarization settings, and can have big detrimental effects on the nonlinear single particle dynamics. Particularly low and medium energy light sources and long period EPUs are prone to those effects. The three existing 50mm period EPUs at the ALS have been retrofitted with shims to correct for these dynamic multipole effects and a new 90mm period device which otherwise would have caused a huge reduction in dynamic aperture has been shimmed before installation. Simulations and beam measurements will be presented, including frequency map measurements.

WEPC135	A New Concept for Reducing Phase Errors in Superconductive Undulators: Induction-shimming	undulator, permanent-magnet, electron, photon	2323
	D. Wollmann, T. Baumbach, A. Bernhard, P. Peiffer University of Karlsruhe, Karlsruhe R. Rossmanith FZK, Karlsruhe
	Undulators are the most advanced sources for the generation of synchrotron radiation. The photons generated by a single electron add up coherently along the electron trajectory. In order to do so the oscillatory motion of the electron has to be in phase with the emitted photons along the whole undulator. Small magnetic errors can cause unwanted destructive interferences. In standard permanent magnet undulators the magnetic errors are reduced by applying shimming techniques. Superconductive undulators have higher magnetic fields than permanent magnet undulators but shimming is more complex. In this paper it is shown that coupled superconductive loops installed along the surface of the superconductive undulator coil can significantly reduce the destructive effect of the field errors. This new idea might allow the building of undulators with a superior field quality.

WEPC146	Plasma Lens of the ITEP Heavy Ion Accelerator	plasma, ion, focusing, heavy-ion	2353
	A. A. Drozdovsky, V. Abramenko, M. M. Basko, A. Golubev, D. D. Iosseliany, A. V. Kantsyrev, A. P. Kuznetsov, Yu. B. Novozhilov, O. V. Pronin, P. V. Sasorov, S. M. Savin, B. Y. Sharkov, V. V. Yanenko ITEP, Moscow
	At ITEP, on the bases of the TWAC-ITEP (Terawatt Accumulator) complex, a new facility is being built to conduct research at high energy densities in matter. Application of a plasma lens to this area of research has a number of essential advantages in comparison with the traditional system based on quadruple lenses. In accordance with the principal goals of this project, a pulse-power generator has been developed, with which a stable discharge current of up to 250 kA and duration of 4 μs has been achieved and which was used for experimental and theoretical investigation of the plasma lens performance. The plasma lens was installed into the exit channel of the TWAC accelerator complex, and its testing began by focusing of a C+6 beam with the ion energy of 200 MeV/a.u.m. As one of the first results, a minimum focal spot diameter of 350 μm FWHM has been measured at a target distance of 50 mm from the end of the discharge tube. The lens parameters were as follows: capacitance – 24 μF, charging voltage – 13 kV, discharge current – 220 kA, current half-wave – 4 μs, argon pressure – 3 mbar. Sharkov B. Yu. et al. Nucl. Instr. Meth. A464 (2001), p. 1. ** D. H.H. Hoffmann et al. Nucl. Instr. Methods Phys. Res., Sect. B 161-163, (2000), p. 9.

WEPC151	Magnetic Field Design and Calculation for the FLNR U400R Cyclotron	cyclotron, ion, heavy-ion, acceleration	2359
	I. A. Ivanenko, J. Franko, B. Gikal, G. Gulbekyan, N. Yu. Kazarinov JINR, Dubna, Moscow Region V. P. Kukhtin, E. A. Lamzin, S. E. Sytchevsky NIIEFA, St. Petersburg
	Presently FLNR reconstructs the U400 cyclotron. The new, U400R cyclotron is intended to accelerate the ion beams with A/Z from 4 to 12 up to the energy 0.78 – 27 MeV/nucleon. The wide range of the magnetic field levels from 0.8T till 1.8T allows to make a smooth variation of the beam energy over the range ±60% from nominal. For optimization of the magnetic field the 14 pairs of radial correcting coils are used. The numerical formation of the magnetic field is carried out. At the present work the main problems and solutions of the magnetic field design are described.

WEPC157	A Hybrid Quadrupole Design for the RAL Front End Test Stand (FETS)	quadrupole, permanent-magnet, proton, beam-losses	2377
	D. C. Plostinar, M. A. Clarke-Gayther STFC/RAL/ASTeC, Chilton, Didcot, Oxon P. Davis STFC/RAL, Chilton, Didcot, Oxon S. J.S. Jago STFC/RAL/ISIS, Chilton, Didcot, Oxon
	The Front End Test Stand project being constructed at Rutherford Appleton Laboratory (RAL) aims to deliver a high current (60 mA) H^- chopped ion beam, at 3 MeV and 50 pps. The main components of FETS are the H^- ion source, the Low Energy Beam Transport line (LEBT), the Radio Frequency Quadrupole (RFQ) and the Medium Energy Transport (MEBT) line with beam chopper. Space restrictions in the MEBT line place constraints on component length and drive the requirement to identify compact component configurations. A description is given of a novel compact hybrid quadrupole magnet, whose design is based on the concentric combination of a permanent magnet quadrupole (PMQ) and a laminar conductor electromagnetic quadrupole (EMQ). Simulations of magnetic field distribution in 2 and 3D are presented, and possible applications and further developments are discussed.

WEPC163	Modification of a Spare Septum Magnet for SNS Ring Injection Dump Beam Line	septum, vacuum, proton, injection	2389
	J. G. Wang ORNL, Oak Ridge, Tennessee
	The SNS ring injection dump septum magnet has been suffering the heaviest beam losses since the ring commissioning. These beam losses are caused by a number of design and operation problems such as incorrect location of one chicane dipole, incorrect chicane dipole setting, and inadequate aperture of the injection dump septum. We have modified a spare septum by increasing its vertical and horizontal aperture and by adding specially designed z-bumps for one of the waste beams. This paper reports the detailed modification results, including 3D particle trajectory calculations and experimental measurements.

WEPD002	Magnetic Design Studies for the Final Focus Quadrupoles of the SuperB Large Crossing Angle Collision Scheme	quadrupole, factory, target, background	2401
	E. Paoloni University of Pisa and INFN, Pisa S. Bettoni CERN, Geneva M. E. Biagini, P. Raimondi INFN/LNF, Frascati (Roma)
	The vertical focusing element closest to the interaction point of the SuperB factory based on the large crossing angle collision scheme (~50 mrad), must provide a pure quadrupolar field on each of the two beams. This allows to avoid the high background rate in the detector which would be produced by the over-bend of the off-energy particles if a dipolar component were present. Because of the small separation of the two beams in the transverse dimension (only 2 cm) the influence of each winding on the other one is not negligible and, for the same space limitation, a multi-layer configuration is not suitable to compensate the high order multipoles. A novel design, based on 'helical-type' windings, has therefore been investigated. The windings generates the pure quadrupolar field as a superposition of the inner field of the surrounding coil and of the outer fringe field of the neighbor one. The same idea may be used to produce two pure quadrupolar fields with opposite strength, suitable for the final focus elements in colliders, as LHC, where the sign of the circulating particles are the same. In this paper the 2D concept and the 3D model of this design are presented.

WEPD014	Magnets for the MANX 6-D Muon Cooling Demonstration Experiment	dipole, quadrupole, multipole, superconductivity	2434
	V. S. Kashikhin, N. Andreev, V. Kashikhin, M. J. Lamm, K. Yonehara, A. V. Zlobin Fermilab, Batavia, Illinois M. Alsharo'a, R. P. Johnson, S. A. Kahn, T. J. Roberts Muons, Inc, Batavia
	MANX is a 6-dimensional muon ionization-cooling experiment that has been proposed to Fermilab to demonstrate the use of a helical cooling channel (HCC) for muon beam emittance reduction for future muon colliders and neutrino factories. The HCC for MANX has solenoidal, helical dipole, and helical quadrupole magnetic components, which diminish as the beam loses energy as it slows down in the liquid helium absorber inside the magnet. The proposed magnet system design is comprised of coil rings positioned along a helical path, which will provide the desired solenoidal and helical dipole and quadrupole fields. Additional magnets that provide emittance matching between the HCC and the upstream and downstream spectrometers are also described. The results of a G4Beamline simulation of the beam cooling behavior of the magnet and absorber system will be presented.

WEPD025	A Feasibility Study of Superconducting Dipole for the Early Separation Scheme of SLHC	luminosity, dipole, separation-scheme, shielding	2461
	G. Sterbini, D. Tommasini CERN, Geneva
	In the framework of the LHC luminosity upgrade an early separation scheme is being studied for the final phase (L~10³⁵ cm^-2 s^-1 with substantial changes in the IR). In this paper we compare a Nb3Sn and a Nb-Ti cos(θ) design: the aim is to explore the benefits and the limits of a compact solution with respect to the detector's constraints and the energy deposition issues. We propose to put the dipole system (cryostat and magnet) at a location starting at 6.8 m from the IP. The preliminary cross section, the achievable integrated field, the energy deposition on the magnet are presented and discussed.

WEPD038	Thermal and Structural Modeling of the TTF Cryomodule Cooldown and Comparison with Experimental Data	cryogenics, radiation, controls, monitoring	2494
	S. Barbanotti, P. Pierini INFN/LASA, Segrate (MI) K. Jensch, R. Lange, W. Maschmann DESY, Hamburg
	The study of thermal and structural behavior during cooldown/warmup of long SRF cryostats is important for both the XFEL and ILC, which base the design on the successful TTF design. We present the finite elements analysis of the main internal components of the cryomodules during the transient cooldown and warmup, comparing the data obtained with data taken at DESY on the linac.

WEPD039	Evolution of the Standard Helium Liquefier and Refrigerator Range designed by Air Liquide DTA, France	cryogenics, synchrotron, controls, neutral-beams	2497
	S. Crispel, G. Aigouy, A. Caillaud, F. Delcayre, V. Grabie Air Liquide, Division Techniques Avancées, Sassenage
	The standard helium liquefier and refrigerator range, called HELIAL, designed by Air Liquide DTA, has been upgraded with significant improvement of efficiency as a result of technological development.. Indeed in the demanding high tech markets, (international laboratories, aerospace applications, synchrotrons, HTS applications…), cryogenic systems must provide increasingly high performances. The new HELIAL Evolution is equipped with Air Liquide's expansion turbines, well known for their extremely high reliability and efficiency,. The results of this development endowing the HELIAL Evolution with twice liquefaction capacity, are presented in this paper.

WEPD042	Development of a Simulation Module for the Cryogenic System	cryogenics, controls, superconducting-magnet, synchrotron	2506
	H. C. Li, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H. H. Tsai NSRRC, Hsinchu
	In NSRRC two 450W cryogenic systems were installed on the year 2002 and 2006, respectively. After long time operation some behavior and setting parameters of the cryogenic system did not satisfy our requirement because of the deterioration of electrical sensors and valves. To ask the manufacturer to solve those problems, it took lots of time in the communication of problem description and the modification of control program. A simulation module for the cryogenic system is thus developed to trace the procedure before and after modification of the control program. This paper details the simulation module and shows the usefulness of this module on evaluation of the software modification for cryogenic system.

WEPD044	Efficiency Analysis for the Cryogenic System at NSRRC	cryogenics, superconducting-magnet, controls, synchrotron	2512
	H. H. Tsai, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H. C. Li NSRRC, Hsinchu
	Three superconducting magnets and one superconducting cavity for RF are cooled by two 450W liquid helium system at NSRRC. These two systems were made up of Claude cycle which is usually compared in their performance to that of the ideal Carnot cycle. This paper presents the efficiency analysis for the cryogenic system. Based on the analysis, the power transfer to the process change for the operation will be performed. In addition, it also shows the way to identify the problems when done the trouble shooting for part of erratic response of the plant. The carnot efficiency also provides an important index of the performance, especially when we done the process control.

WEPP002	The Effect of Head-on Beam-beam Compensation on the Stochastic Boundaries and Particle Diffusion in RHIC	emittance, proton, electron, resonance	2521
	N. P. Abreu, W. Fischer, Y. Luo, G. Robert-Demolaize BNL, Upton, Long Island, New York
	To compensate the effects from the head-on beam-beam interactions in the polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), an electron lens (e-lens) is proposed to collide head-on with the proton beam. We used an extended version of SixTrack for multiparticle beam-beam simulation in order to study the effect of the e-lens on the stochastic boundary and also on diffusion. The stochastic boundary was analyzed using Lypunov exponents and the diffusion was characterized as the average rms spread of the action after 10⁴ turns. For both studies the simulations were performed with and without the e-lens and with full and partial compensation.

WEPP005	Measurements and Effects of the Magnetic Hysteresis on the LHC Crossing Angle and Separation Bumps	beam-beam-effects, controls, cryogenics, dipole	2530
	N. J. Sammut, H. Burkhardt, C. Giloux, W. Venturini Delsolaro, S. M. White CERN, Geneva N. J. Sammut University of Malta, Faculty of Engineering, Msida
	The superconducting orbit corrector magnets (MCBC and MCBY) in the Large Hadron Collider (LHC) at CERN will be used to generate parallel separation and crossing angles at the interaction points during the different phases that will bring the LHC beams into collision. However, the field errors generated by the inherent hysteresis in the operation region of the orbit correctors may lead to unwanted orbit perturbations that could have a critical effect on luminosity. This paper presents the results obtained from dedicated cryogenic measurements on the orbit correctors from the simulated results on the impact of the hysteresis on the LHC orbit.

WEPP006	Effects of Ultraperipheral Nuclear Collisions in the LHC and their Alleviation	ion, collimation, beam-losses, luminosity	2533
	R. Bruce, S. S. Gilardoni, J. M. Jowett CERN, Geneva
	Electromagnetic interactions between colliding heavy ions at the LHC are the sources of specific beam loss mechanisms that may quench superconducting magnets. We propose a simple yet efficient strategy to alleviate the effect of localized losses from bound-free pair production by spreading them out in several magnets by means of orbit bumps. We also consider the consequences of neutron emission by electromagnetic dissociation and show through simulations that ions modified by this process will be intercepted by the collimation system, without further modifications.

WEPP010	Scheduling the Powering Tests	cryogenics, extraction, superconducting-magnet, instrumentation	2545
	K. Foraz, E. Barbero-Soto, B. Bellesia, M. P. Casas Lino, C. Fernandez-Robles, M. Pojer, R. I. Saban, R. Schmidt, M. Solfaroli Camillocci, A. Vergara-Fernández CERN, Geneva
	The Large Hadron Collider is now entering in its final phase before receiving beam, and the activities at CERN between 2007 and 2008 have shifted from installation work to the commissioning of the technical systems (“hardware commissioning”). Due to the unprecedented complexity of this machine, all the systems are or will be tested as far as possible before the cool-down starts. Systems are firstly tested individually before being globally tested together. The architecture of LHC, which is partitioned into eight cryogenically and electrically independent sectors, allows the commissioning on a sector by sector basis. When a sector reaches nominal cryogenic conditions, commissioning of the magnet powering system to nominal current for all magnets can be performed. This paper briefly describes the different activities to be performed during the powering tests of the superconducting magnet system and presents the scheduling issues raised by co-activities as well as the management of resources.

WEPP013	Increasing the Integrated Luminosity of SLHC by Levelling via the Crossing Angle	luminosity, separation-scheme, beam-beam-effects, dipole	2554
	J.-P. Koutchouk, G. Sterbini CERN, Geneva K. Ohmi KEK, Ibaraki
	With an increase of luminosity by a factor of 10, the luminosity lifetime in an upgraded LHC would be limited to a few hours. Furthermore, schemes relying on stronger focusing and reduced beam current increase (which are intrisically less dangerous for machine protection) are penalized by a very short lifetime of around 2 hours. We show in this paper that the "early separation" scheme and/or crab cavities scheme lend themselves to a very efficient luminosity leveling scheme. It allows constant luminosity over many hours as well as a significant increase of integrated luminosity above the performance announced so far. This is achieved by adjusting the crossing angle rather than the beam size by means of a bump closed inside the experimental straight section, i.e. operationally simple. The initially large crossing angle reduces the beam-beam tune shift, allowing an increased beam current and higher performance for lower pile-up in the detector and lower energy deposition in the triplet. The impact of the required large Piwinski angle is investigated.

WEPP026	Reliable Operation of the AC Dipole in the LHC	dipole, resonance, emittance, injection	2575
	R. Tomas, S. D. Fartoukh, J. Serrano CERN, Geneva
	The AC dipole in the LHC will not only provide transverse oscillations without emittance growth but also with a safety guarantee. These two features are due to the adiabaticity of the excitation. However chromaticity and non-linear fields spoil this adiabaticity. This paper assesses the margins of the relevant parameters for a reliable and safe operation of AC dipoles in the LHC.

WEPP034	Study of Beam-beam effect at various collision scheme in LHC	luminosity, emittance, resonance, proton	2593
	K. Ohmi KEK, Ibaraki
	LHC is designed as two major collision points with finite crossing angle of 140μrad (half). The Piwinski angle is 0.4 for the design. Upgrade plans have been studied to increase the luminosity 10 times. Large Piwinski angle scheme is one of the option for the upgrade. The one turn map with the two beam-beam interactions can be expanded by Taylor series. Analyzing the one turn map gives information of resonance behavior of the beam-beam interactions. We discuss the one turn map for the design LHC and upgrade scheme.

WEPP035	Study of Beam-beam Issue for KEKB Crab Crossing	luminosity, coupling, lattice, resonance	2596
	K. Ohmi, J. W. Flanagan, Y. Funakoshi, N. Iida, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, Y. Seimiya KEK, Ibaraki
	A short lifetime at collision is one of the limits on luminosity performance at KEKB in crab crossing mode. The beam-beam halo was evaluated via simulation. The beam lifetime and profile were measured for various beam conditions, vertical emittances, tunes and collision offsets. We discuss why the lifetime is shortened by the beam-beam interaction.

WEPP053	Beam Transport in Toroidal Magnetic field	injection, beam-transport, proton, ion	2641
	N. S. Joshi, M. Droba, O. Meusel, U. Ratzinger IAP, Frankfurt am Main
	The concept of a storage ring with toroidal magnetic field was presented in the two previous EPAC conferences. Here we report the first results of experiments performed with beam transport in toroidal magnetic fields and details of the injection system. The beam transport experiments were carried out with 30 degree toroidal segments with an axial magnetic field of 0.6T. The space charge force and dynamics of a proton beam near the brillouin flow limit are presented here. The multiturn injection system relies on a specified injection coil together with an electric kicker system. The scaling law for the complete storage ring is discussed. The advantages and disadvantages for such a stellarator type storage ring on the 5T level will be reviewed.

WEPP060	Abort Gap Cleaning Using the Transverse Feedback System: Simulation and Measurements in the SPS for the LHC Beam Dump System	octupole, kicker, feedback, proton	2656
	A. Koschik, B. Goddard, W. Höfle, G. Kotzian, D. K. Kramer, T. Kramer CERN, Geneva
	The critical and delicate process of dumping the beams of the LHC requires very low particle densities within the 3 microseconds of the dump kicker rising edge. High beam population in this so-called 'abort gap' might cause magnet quenches or even damage. Constant refilling due to diffusion processes is expected which will be counter-acted by an active abort gap cleaning system employing the transverse feedback kickers. In order to assess the feasibility and performance of such an abort gap cleaning system, simulations and measurements with beam in the SPS have been performed. Here we report on the results of these studies.

WEPP064	Apertures in the LHC Beam Dump System and Beam Losses during Beam Abort	extraction, kicker, vacuum, dumping	2665
	T. Kramer, B. Goddard, M. Gyr, A. Koschik, J. A. Uythoven, Th. Weiler CERN, Geneva
	The LHC beam dump system is used to dispose accelerated protons and ions in a wide energy range from 450 GeV up to 7 TeV. An abort gap of 3 microseconds is foreseen to avoid sweeping particles through the ring aperture. This paper gives a brief overview of the critical apertures in the extraction region and the two beam dump lines, and presents MAD-X tracking studies made to investigate the impact of particles swept through the aperture due to extraction kicker failures or spurious particles within the abort gap.

WEPP068	Impact Distribution of the Beam Losses at the LHC Collimators in Case of Magnet Failures	injection, quadrupole, dipole, collimation	2674
	A. Gomez Alonso CERN, Geneva
	During LHC operation, magnet failures may affect the beam optics leading to proton losses in the collimators. These losses, with about 360MJ of stored energy per beam at nominal collision operation, are potentially dangerous for the accelerator equipment. The LHC Machine Protection Systems ensure that the beam is extracted safely before these losses can produce any damage. As a magnet failure develops, so does the distribution of the lost particles, longitudinally along the ring as well as transversally at each collimator. The transversal impact distributions of lost particles at the most affected collimators and their evolution with time have been studied for representative magnet failures in the LHC. It has been found that the impact distribution at a given collimator can be approximated by an exponential function with time-dependent parameters. The average impact parameter ranges from about 7 to 620 μm for the cases studied.

WEPP069	Tracking Tools to Estimate the Quench Time Constants for Magnet Failures in LHC	insertion, superconducting-magnet, beam-losses, proton	2677
	A. Gomez Alonso CERN, Geneva
	At LHC, beam losses, with about 360MJ of stored energy per beam at nominal collision operation, are potentially dangerous for the accelerator equipment and can also affect the operational efficiency by inducing quenches in superconducting magnets. Magnet failures may affect the beam leading to proton losses primarily in collimators and secondary in superconducting magnets due to scattering of protons from collimator jaws. The evolution of the beam during magnet failures has been simulated using MAD-X with a variable magnetic field. The impacts of particles in the collimators have been recorded as a function of time. A second program, CollTrack, has been used to determine the loss patterns of scattered particles from each collimator as a function of the initial impact parameter. The magnets that are likely to quench are identified and an estimation of the time between the beginning of a failure and a quench is obtained by combining the results from the simulations. The time to a start of a quench is a relevant parameter to determine the dump threshold of beam loss monitors in order to optimize protection redundancy and operation smoothness for LHC.

WEPP070	High Efficiency Collimation with Bent Crystals	collimation, scattering, alignment, proton	2680
	S. Hasan Univ. Insubria and INFN Milano, Como
	A revolutionary collimation approach is being developed by the H8RD22 collaboration. The basic idea is to replace the amorphous jaws, which spread the beam halo in the whole solid angle, with bent crystals, which are able to deviate the halo particles in a given direction outside the beam core. Studies to investigate the bent crystal properties have been carried out over the past 3 years at the H8 beam line (CERN SPS) with a 400 GeV/c proton beam. The crucial result of these studies is the observation of the Volume Reflection effect, the coherent scattering of the beam on the crystalline plane which provides a small but very efficient (respectively, 14 μrad and 98% at 400 GeV/c) particle deflection. The high efficiency (which should increase at higher energy) combined with a large angular acceptance (~100 μrad) led to the development of multi-reflection systems to increase the deflection angle. Nowadays this system has reached the stage to be tested in a circular accelerator as a primary collimator to verify the effective collimation efficiency in a complex environment. The second phase of the LHC collimation could be the first application of this crystal based system.

WEPP071	Preliminary Exploratory Study of Different Phase II Collimators	collimation, radiation, luminosity, impedance	2683
	L. Lari, R. W. Assmann, A. Bertarelli, C. Bracco, M. Brugger, F. Cerutti, A. Dallocchio, A. Ferrari, M. Mauri, S. Roesler, L. Sarchiapone, V. Vlachoudis CERN, Geneva J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The LHC collimation system is installed and commissioned in different phases, following the natural evolution of the LHC performance. To improve cleaning efficiency towards the end of the low beta squeeze at 7TeV, and in stable physics conditions, it is foreseen to complement the 30 highly robust Phase I secondary collimators with low impedance Phase II collimators. At this stage, their design is not yet finalized. Possible options include metallic collimators, graphite jaws with a movable metallic foil, or collimators with metallic rotating jaws. As part of the evaluation of the different designs, the FLUKA Monte Carlo code is extensively used for calculating energy deposition and studying material damage and activation. This report outlines the simulation approach and defines the critical quantities involved.

WEPP072	Evaluation of Beam Losses and Energy Deposition for A Possible Phase II Design for LHC Collimation	beam-losses, collimation, proton, kicker	2686
	L. Lari, R. W. Assmann, C. Bracco, M. Brugger, F. Cerutti, A. Ferrari, M. Mauri, S. Redaelli, L. Sarchiapone, V. Vlachoudis, Th. Weiler CERN, Geneva J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

WEPP073	Simulation Studies of Impact of SPS Beam with Collimator Materials	target, proton, single-bunch, synchrotron	2689
	N. A. Tahir GSI, Darmstadt R. W. Assmann, M. Brugger, R. Schmidt CERN, Geneva V. E. Fortov, I. Lomonosov, A. Shutov IPCP, Chernogolovka, Moscow region D. Hoffmann TU Darmstadt, Darmstadt R. Piriz Universidad de Castilla-La Mancha, Ciudad Real
	Over the past years detailed simulations were carried out to study the impact of the full LHC 7 TeV beam on a target to assess the damage caused to the equipment as a result of an accident, especially to collimators and beam absorbers, and to estimate the thickness of a sacrificial absorber that would be required to stop the beam. This study has shown that the target material will be strongly heated by the beam and transformed into plasma. It has been estimated that the beam would tunnel up to 30 m in solid copper and to about 10 m in solid carbon. Another interesting outcome of this study was that the LHC beam could be used as a tool to study High-Energy-Density (HED) states in matter. Using the same tools, we recently studied the impact of the SPS 450 GeV proton beam on tungsten and copper targets. It has been found that the material will be seriously damaged and some tunneling of the beam into the target is expected. It should be possible to validate the predictions with a test facility to deflect the high energy high intensity SPS beam on collimator and absorber materials that will become operational in the next years. N. A. Tahir et al. J. Appl. Phys. 97 (2005) 083532. *N. A. Tahir et al. Laser Part. Beams 25 (2007) 639.

WEPP078	PHIL: a Test Beam line at LAL	gun, laser, vacuum, emittance	2698
	R. Roux, M. Bernard, G. Bienvenu, S. Cavalier, M. Jore, B. Leblond, B. M. Mercier, B. Mouton, C. P. Prevost, V. Variola LAL, Orsay
	For 2004, in the framework of a European contract, LAL is in charge of the construction of one photo-injector for the drive beam linac of the CLIC Test Facility 3 at CERN. This contract together with national funds allowed LAL to build a test accelerator with the same photo-injector as for CTF3. The goal is to undergo experiments on advanced RF guns but a part of the beam time will be also shared with users of the electron beam. So far, the construction of this accelerator at LAL was very much delayed because of the legal obligation to upgrade the radiation shielding in agreement with the actual radiation safety thresholds. The required civil engineering is now finished and the installation of the components is under way. We will first present a design of the accelerator and few dynamic simulation results. Finally we will give a status of the accelerator construction up to date.

WEPP081	Wake-fields and Beam Dynamics Simulations for ILC ACD Accelerating Cavities	emittance, damping, linac, higher-order-mode	2707
	C. J. Glasman, R. M. Jones UMAN, Manchester
	The ILC aims at colliding bunches of electrons and positrons at a centre of mass energy of 0.5 TeV and in a proposed upgrade to 1 TeV. These bunches of charged particle are accelerated in superconducting linacs. The baseline design for the ILC relies on the relatively mature TESLA-style cavities, with a proposed gradient of more than 30 MV/m and is known as the baseline configuration document (BCD). However, here we investigate electromagnetic fields in superconducting cavities, with the potential to reach accelerating gradients in excess of 50 MV/m, and these are the subject of the alternative configuration document (ACD). We analyse the band structure and necessary damping requirement of the wake-fields in two design configurations: Cornell's re-entrant cavity and KEK's Ichiro cavity. The emittance dilution arising from beams subjected to injection offsets and from cavity misalignments are studied in beam dynamics simulations.

WEPP085	RF Coupler Kicks and Wake-fields in SC Accelerating Cavities	dipole, linac, coupling, higher-order-mode	2719
	N. Juntong, R. M. Jones, I. R.R. Shinton UMAN, Manchester C. D. Beard STFC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Burt Cockcroft Institute, Warrington, Cheshire
	The main accelerating cavities of the ILC provide acceleration of both positron and electron beams to 250 GeV per beam and 500 GeV per beam in a proposed upgrade. The wake-field excited by each ultra-relativistic beam in the accelerating cavities can seriously dilute the emittance of the particles within the beams. Each cavity is supplied with both fundamental and higher order mode couplers. The geometrical configuration of these RF couplers results in an asymmetrical field and this gives rise to both an RF kick being applied to the beam and transverse wake-field. Detailed e.m. fields are simulated in the vicinity of the couplers in order to assess the impact on the beam dynamics. We investigate modified geometries with a view to alleviating the emittance dilution resulting from the e.m. field associated with the RF couplers.

WEPP092	Tuning of Waveguide to Cavity Coupling Coefficient Beta for a PWT Linac and a Photocathode Gun	coupling, gun, linac, electromagnetic-fields	2734
	S. Krishnagopal BARC, Mumbai U. Kale, S. Lal, K. K. Pant RRCAT, Indore (M. P.)
	The waveguide to cavity coupling coefficient beta for two types of accelerating structures: a Plane Wave Transformer (PWT) linac and a 1.6 cell photocathode gun has been tuned to obtain critical coupling in both. Analytical calculation of the dimensions of slot required for critical coupling have been done using Gao’s formulation based on Bethe’s theory for hole coupling. While the PWT linac structure, with high inter-cell coupling, shows good agreement between measured and predicted slot dimensions for different values of beta, the agreement is not so good in the photocathode gun on account of poor inter-cell coupling. This paper discusses details of the analytical calculation of slot dimensions for the two structures, their comparison with experimentally measured results, and the procedure adopted for tuning the two structures to critical coupling.

WEPP097	Simulation of Wakefield Effect in ILC IR Chamber	impedance, luminosity, linac, collider	2743
	S. Pei, T. O. Raubenheimer, A. Seryi, J. C. Smith SLAC, Menlo Park, California
	To achieve super high luminosity, high current beams with very short bunch length are needed, which carry high intensity EM fields. For ILC, two bunch trains with bunch length of 300μm and bunch charge of 3.2nC are needed to collide at the IR to achieve the ILC luminosity goals. When the 300μm bunches pass through the IR chamber, wakefields will be excited, which will cause HOM power flowing through the IR chamber beam pipe to the final doublets due to the high frequency characteristic of the induced wakefields. Since superconducting technology is adopted for the final doublets of ILC BDS, whose operation stability might be affected by the HOM power produced at the IR chamber, quench might happen. In this paper, we did some analytical estimation and numerical simulation on the wakefield effects in ILC IR chamber.

WEPP111	Modeling Breakdown in RF Cavities Using Particle-in-cell (PIC) codes	plasma, electron, background, ion	2767
	S. Mahalingam, J. R. Cary, P. Stoltz, S. A. Veitzer Tech-X, Boulder, Colorado
	A main limitation on future accelerator projects is breakdown of metallic structures. We have developed computer models of the process of breakdown using Particle-In-Cell (PIC) codes which include: Fowler-Nordheim field emission due to large surface electric fields, impact ionization of neutral gas, ion-induced secondary electron emission, ion-induced sputtering of neutrals, the effects of applied magnetic fields, plasma radiation effects, and surface heating. Two computational tools have been used to self-consistently model the breakdown. These are OOPIC Pro, a 2-Dimensional serial electromagnetic code with cylindrical coordinates, and VORPAL, a 3-Dimensional massively parallel electromagnetic code with cartesian grids. We describe here the results of our numerical experiments including the effects of applied magnetic field strength and direction on the breakdown process, sensitivity of breakdown triggers on field emission parameters, and the potential to measure the onset of breakdown by examining impurity radiation. We show comparison with breakdown experiments performed at Fermilab and Argonne for copper structures being considered for a future muon collider project.

WEPP120	G4Beamline Particle Tracking in Matter-dominated Beam Lines	collider, target, antiproton, space-charge	2776
	T. J. Roberts, K. B. Beard Muons, Inc, Batavia S. Ahmed, D. M. Kaplan, L. K. Spentzouris Illinois Institute of Technology, Chicago, Illinois D. Huang IIT, Chicago, Illinois
	Most computer programs that calculate the trajectories of particles in accelerators assume that the particles travel in an evacuated chamber. The development of muon beams, which are needed for future facilities such as muon colliders and neutrino factories, is limited by the lack of user-friendly numerical simulation codes that accurately calculate scattering and energy loss in matter. Geant4 is an internationally supported tracking toolkit that was developed to simulate particle interactions in large detectors for high energy physics experiments, and includes most of what is known about the interactions of particles and matter. Geant4 has been partially adapted in a program called G4beamline to develop muon beam line designs. We are continuing the development of G4beamline to enhance its graphical user-interface and add other features to the program to facilitate its use by a larger set of beam line and accelerator developers.

WEPP121	Recirculating Ring for an Ionization Cooling Channel	emittance, lattice, closed-orbit, factory	2779
	C. T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon
	In a muon acceleration facility such as a Neutrino Factory or Muon Collider, the muons created from pion decay occupy a large volume of phase space. For a good capture efficiency this phase space should be reduced and this is typically achieved using ionisation cooling channels. These are quite expensive but the cost can be reduced by recirculating muons through the cooling hardware. Recirculating a high emittance beam typical of a Neutrino Factory is very challenging if it is to be achieved without significant losses. I describe latest attempts to design a high acceptance recirculator for a muon front end.

WEPP125	Analysis of the Vertical Beam Instability in CTF3 Combiner Ring and New RF Deflector Design	controls, resonance, emittance, impedance	2791
	D. Alesini, C. Biscari, A. Ghigo, F. Marcellini INFN/LNF, Frascati (Roma)
	In the last CTF3 run (November 2007) a vertical beam instability has been found in the Combiner Ring during operation. Possible sources of the instability are the vertical deflecting modes excited by the beam in the RF deflectors. In the first part of the paper we illustrate the results of the beam dynamics analysis obtained by a dedicated tracking code that allows including the induced transverse wake field and the multi-bunch multi-passage effects. To reduce the effects of such vertical trapped modes, the RF deflectors have been modified and two new deflectors have been designed. They have been made in aluminium and have two more ports in the input and output coupler cells to absorb the beam induced field on the vertical modes. The design of the new deflectors and the RF measurements are then presented in the paper.

WEPP127	ALaDyn: a High Accuracy Code for the Laser-plasma Interaction	plasma, laser, electron, acceleration	2794
	C. Benedetti, A. Sgattoni Bologna University, Bologna P. Tomassini INFN-Milano, Milano
	ALaDyn (Acceleration by LAser and DYNamics of charged particles) is a relativistic fully parallelized PIC code to investigate the interaction of a laser pulse with a plasma and/or an externally injected beam. The code is based on compact high order finite differences schemes ensuring higher spectral accuracy compared to standard Yee schemes. We present the main features and the performances of the code together with a set of validation tests obtained comparing the results with well-established analytical/numerical results. A preliminary benchmarking with the PIC code VORPAL is also presented. An application to a physically relevant case concerning the externally-injected configuration proposed for the CNR-INFN experiment PLASMONX will be analyzed.

WEPP133	High-gradient Multi-mode Two-beam Accelerating Structure	acceleration, collider, coupling, linear-collider	2806
	S. V. Kuzikov, M. E. Plotkin IAP/RAS, Nizhny Novgorod J. L. Hirshfield Yale University, Physics Department, New Haven, CT S. Kazakov Omega-P, Inc., New Haven, Connecticut
	A new accelerating structure which is aimed to provide gradient >150 MV/m for next generation of multi-TeV linear colliders is suggested. The structure is based on periodic system of quasi-optical cavities. Each of these cavities is excited in several equidistantly-spaced eigen modes by the drive beam in such a way that the RF fields reach peak values only during the short time intervals when an accelerating bunch is resident in the cavities, thus exposing the cavity surfaces to strong fields for only a small fraction of time. This feature is expected to raise the breakdown and pulse heating thresholds. The proposed structure embodies most of additional attractive properties: the cavity is an all metallic structure, no transfer or coupling structures are needed between the drive and acceleration channels, the cavity fields are symmetric around the axes of the drive beam and the accelerated beam, the cavity can exhibit high transformer ratio. Calculations of single quasi-optical rectangular cavity with parameters of drive and accelerating beams close to ones adopted for the CLIC project show that high gradient as well as high efficiency are achievable. S. V. Kuzikov et al. "Quasi-optical accelerating structure operated with a superposition of synchronized modes," Conf. Digest of Joint 32nd IRMMW Conf., Cardiff, UK, 2007, Vol.2, p.797-798.

WEPP142	Simulation of and Progress towards a Micron-scale Laser-powered Dielectric Electron Source	laser, vacuum, coupling, resonance	2827
	G. Travish, J. B. Rosenzweig, J. Xu UCLA, Los Angeles, California S. Boucher RadiaBeam, Marina del Rey R. B. Yoder Manhattan College, Riverdale, New York
	A dielectric, slab-symmetric structure for generating and accelerating low-energy electrons has been under study for the past two years. The resonant device is driven by a side-coupled laser and is configured to maintain field provide necessary for synchronous acceleration and focusing of nonrelativistic particles. Intended applications of the structure include the production of radiation for medical treatments, imaging, and industrial uses. The details of the structure geometry and its resonant properties have been studied with 2D and 3D electromagnetic codes, the results of which are present here.

WEPP147	Aberration-free Muon Transport Line for Extreme Ionization Cooling: a Study of Epicyclic Helical Channel	resonance, cyclotron, collider, dipole	2833
	A. Afanasev, R. P. Johnson Muons, Inc, Batavia Y. S. Derbenev Jefferson Lab, Newport News, Virginia
	Once the normalized transverse emittances of a muon beam have been cooled to some hundreds of microns, new techniques such as Parametric-resonance Ionization Cooling and Reverse Emittance Exchange can be used to focus the beam very tightly on beryllium energy absorbers for further transverse emittance reduction. The transport lines for these techniques have stringent requirements for the betatron tunes so that resonance conditions are properly controlled and for the dispersion function so that the longitudinal emittance can be controlled by emittance exchange using wedge-shaped absorbers. The extreme angular divergence of the beam at the absorbers implies large beam extension between the absorbers such that these techniques are very sensitive to chromatic and spherical aberrations. In this work we describe general and specific solutions to the problem of compensating these aberrations for these new muon cooling channels.

WEPP153	Status of the MANX Muon Cooling Experiment	emittance, dipole, collider, beam-cooling	2844
	K. Yonehara, D. R. Broemmelsiek, M. Hu, A. Jansson, V. Kashikhin, V. S. Kashikhin, M. J. Lamm, M. L. Lopes, V. D. Shiltsev, V. Yarba, M. Yu, A. V. Zlobin Fermilab, Batavia, Illinois R. J. Abrams, M. A.C. Cummings, R. P. Johnson, S. A. Kahn, T. J. Roberts Muons, Inc, Batavia
	MANX is an experiment to prove that effective six-dimensional (6D) muon beam cooling can be achieved a Helical Cooling Channel (HCC) using ionization-cooling with helical and solenoidal magnets in a novel configuration. The aim is to demonstrate that 6D muon beam cooling is understood well enough to plan intense neutrino factories and high-luminosity muon colliders. The experiment consists of the HCC magnets that envelop a liquid helium energy absorber, upstream and downstream instrumentation to measure the particle or beam parameters before and after cooling, and emittance matching sections between the detectors and the HCC. Studies are presented of the effects of detector resolution and magnetic field errors on the beam cooling measurements.

WEPP158	Simulation of beam Halo in CLIC Collimation Systems	collimation, synchrotron, synchrotron-radiation, radiation	2859
	G. A. Blair, S. Malton Royal Holloway, University of London, Surrey I. V. Agapov, A. Latina, D. Schulte CERN, Geneva
	Full simulation of the CLIC and ILC collimation systems are performed to take account of collimator wakefield effects from the core beam on the halo. In addition full simulation of the interaction of the halo with the collimator material is performed to study the effect of multiple scattering and also the production of neutrons in the electromagnetic showers. The effect of beam-gas scattering downstream of the collimators is also included.

WEPP162	Beam Impact Studies on ILC Collimators	electron, photon, controls, target	2865
	G. Ellwood STFC/RAL, Chilton, Didcot, Oxon J.-L. Fernandez-Hernando, J. K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire M. Slater, N. K. Watson Birmingham University, Birmingham
	Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts of 250 GeV-500 GeV bunch of electrons or positrons, in addition to maintaining low geometric and resistive wall wake fields. Simulations were completed to determine the energy deposition of an ILC bunch to a set of different spoiler designs. These shower simulations were used as inputs to thermal and mechanical studies using ANSYS. This paper presents the results of testing carried out at the Accelerator Test Facility at KEK used to validate the simulations. Results from the first phase of testing, in which electron bunches of varying charge were incident on TI-6Al-4V foils, are presented and compared with simulations.

WEPP163	Measurements of Collimator Wakefields at End Station A	radiation, feedback, linear-collider, collider	2868
	J.-L. Fernandez-Hernando STFC/DL/ASTeC, Daresbury, Warrington, Cheshire S. Molloy SLAC, Menlo Park, California J. D.A. Smith Cockcroft Institute, Warrington, Cheshire N. K. Watson Birmingham University, Birmingham
	The angular kicks imparted to an electron beam with energy of 28.5 GeV when it passes through a collimator jaw with a certain offset, generating a wakefield, were measured in End Station A (ESA) in SLAC for fifteen different collimator configurations of geometry and material. Some configurations were chosen in order to compare with previous measurements while others served to study the effect of geometry and taper angles (geometrical contribution to the wakefield) and the effect of the material resistivity (resistive contribution) to the kick. This paper summarises the final experimental results. The reconstructed kick factor is compared to analytical calculations and simulations.

WEPP165	GdfidL Simulations of International Linear Collider Candidate Collimator Assemblies	linear-collider, collider, insertion, vacuum	2874
	J. D.A. Smith Cockcroft Institute, Warrington, Cheshire
	Collimator performance is critical to the successful operation of any collider. Building on previous GdfidL simulations of collimator jaws, this paper describes simulations where STL files of the complete assembly are investigated and wakefield performance is determined and optimised.

WEPP167	Effect of Collimator Wakefields in the Beam Delivery System of the International Linear Collider	emittance, lattice, collimation, linear-collider	2880
	A. M. Toader, R. J. Barlow UMAN, Manchester D. Angal-Kalinin, F. Jackson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	The collimators in the design of the International Linear Collider (ILC) Beam Delivery System (BDS) may be a significant source of wakefields and significantly degrade luminosity. New simulations are used to predict the effect of BDS collimator wakefields, and compared with previous analytical methods. BDS lattices optimised for improved collimation performance are also examined.

THXM01	CLIC Accelerating Structure Development	damping, site, collider, linac	2922
	W. Wuensch CERN, Geneva
	One of the most important objectives of the CLIC (Compact Linear Collider) study is to demonstrate the design accelerating gradient of 100 MV/m in a fully featured accelerating structure under nominal operating conditions including pulse length and breakdown rate. The development and testing program which has been put into place to achieve this objective is described. Recent advances in understanding and quantifying the effects which limit the accelerating gradient are presented.
	Slides

THXM03	Status of the European HOM Damped Normal Conducting Cavity	impedance, vacuum, brilliance, damping	2932
	E. Weihreter BESSY GmbH, Berlin
	Cavities with damped higher order modes (HOMs) are an essential ingredient for state of the art storage ring based high brilliance synchrotron radiation sources to avoid degradation of the beam quality due to coupled bunch instabilities. Starting with a review of the concepts of existing HOM damped cavities the status of a normal conducting 500 MHz cavity is presented which has been developed for low and medium energy high brilliance synchrotron light sources within the frame of an EC funded collaboration. The results of numerical simulations and of low power impedance measurements are reported together with conceptional improvements, expected performance, and first operational achievements in the Metrology Light Source in Berlin.
	Slides

THYM01	Simulation of Beam-beam Effects and Tevatron Experience	antiproton, proton, beam-beam-effects, emittance	2937
	A. Valishev Fermilab, Batavia, Illinois
	Simulations of beam-beam effects in the Tevatron correctly describe reality, have predictive power and have been used to support a change in the Tevatron working point to near the half integer. The simulation models and tools are discussed, and comparisons made with observations and measurements.
	Slides

THYM03	Advanced Computing Tools and Models for Accelerator Physics	space-charge, electron, linac, collider	2947
	R. D. Ryne LBNL, Berkeley, California
	The design of the next generation of accelerators will require a new level of simulation capability to perform high resolution, multi-physics modelling of beam dynamics phenomena and to design complex 3D electromagnetic structures. Thanks to the availability of computational resources that will soon reach the petascale, we will be able to perform simulations involving unprecedented size, complexity, and physical realism. This paper will review the state-of-the-art in scientific computing for accelerator physics.
	Slides

THPC006	Applications of a BPM-based Technique for Measuring Real Space Distributions in the Spallation Neutron Source Ring and Transport Lines	target, injection, coupling, diagnostics	2984
	S. M. Cousineau, T. A. Pelaia, M. A. Plum ORNL, Oak Ridge, Tennessee
	The SNS accumulator ring and associated transport lines are designed to accumulate and transport up to 1.5·10¹⁴ ppp to a liquid mercury target for neutron spallation. Since commissioning, a dedicated effort has been put forth to characterize the lattice and beam dynamics at low intensity. Toward this goal, a BPM-based technique for measuring real space beam distributions at low beam intensities was developed. Recently, this technique has been used to diagnose and localize a strong source of coupling in the lattice, to verify and troubleshoot complementary diagnostics devices, and to provide data for code benchmarking. Other potential applications of this technique include investigations of single particle dynamics and resonances, studies of injection painting techniques, and possibly measurement of quadrupole power supply errors in the ring. In this paper we present the results of applying this technique to various situations in the SNS ring and transport lines, including the first ORBIT benchmarks of the SNS ring and RTBT. T. Pelaia et al, Nucl. Instr. And Methods, in progress.

THPC010	Trajectory Correction in the Fermi@Elettra Linac	linac, quadrupole, electron, lattice	2993
	S. Di Mitri ELETTRA, Basovizza, Trieste A. Zholents LBNL, Berkeley, California
	The effect of the static magnetic field errors and misalignment of the magnetic elements and linac modules on the beam trajectory in the Fermi@elettra linac [1] has been studied. Analytical description has been used to guide simulations of the trajectory correction using three different techniques. A control over the residual R56 transfer matrix element along the linac lattice has been applied. The importance of the linac structural transverse wake field for a reliable prediction of the bunch centroid dynamics has been demonstrated. Transverse deviations of bunch slices along the electron bunch induced by the wake fields have been calculated. [1] S. Di Mitri, ST/M–07/01 (2007)

THPC013	Start to End Simulations of Transverse to Longitudinal Emittance Exchange at the A0 Photoinjector	emittance, radiation, space-charge, synchrotron	3002
	R. P. Fliller, H. T. Edwards, J. Ruan Fermilab, Batavia, Illinois T. W. Koeth Rutgers University, The State University of New Jersey, Piscataway, New Jersey
	Various schemes to exchange the transverse and longitudinal emittance have been proposed (Cornacchia and Emma, Kim et.al). One scheme involves a deflecting mode RF cavity between two doglegs to exchange the horizontal and longitudinal emittances. This will produce a complete and uncoupled emittance exchange in the thin cavity limit using first order matrix optics. Various other effects, such as a finite length cavity, can leave the emittances coupled after the exchange and dilute the final emittances. Other effects such as space charge and synchrotron radiation can only be investigated through simulations. An exchange experiment is underway at the A0 Photoinjector at Fermilab. In this paper we present start to end simulations of the experiment using various codes to account for space charge and Coherent Synchrotron Radiation effects. Astra is used to simulate all of the straight sections, including the deflecting mode RF cavity. CSR track simulates the doglegs, and the spectrometer. The results of these simulations are compared with analytical approximations and preliminary data. The effect on the exchange is also discussed.

THPC014	Investigation of Possible CSR Induced Energy Spread Effects with the A0 Photoinjector Bunch Compressor	radiation, emittance, electron, synchrotron	3005
	R. P. Fliller, H. T. Edwards, G. M. Kazakevich, J. Ruan, R. Thurman-Keup Fermilab, Batavia, Illinois T. W. Koeth Rutgers University, The State University of New Jersey, Piscataway, New Jersey
	The bunch compressor of the A0 Photoinjector at Fermilab was removed this past spring to install a transverse to longitudinal emittance exchange experiment. Prior to its removal questions arose about the possibility of observing the effects of Coherent Synchrotron Radiation on the compressed beam. The energy spread of the beam with and without compression was measured to observe any changes. Various beam charges were used to look for square law effects associated with CSR. No direct observation of CSR was attempted because the design of the vacuum chamber did not allow it. In this paper we report the results of these experiments and comparison with simulations using ASTRA and CSRTrack. The results are compared with analytical approximations. The implications for the ongoing transverse to longitudinal emittance exchange experiment are discussed.

THPC023	Optimization of the AGS Superconducting Helical Partial Snake Strength	resonance, polarization, betatron, acceleration	3026
	F. Lin, H. Huang, A. U. Luccio, T. Roser BNL, Upton, Long Island, New York
	Two helical partial snakes, one is superconducting (called cold snake) and one is normal conducting (called warm snake), have preserved the polarization of proton beam up to 65% at the AGS extraction energy with the inject 82% polarization. In order to overcome the spin resonances, stronger partial snake is required. However, the stronger partial snake, the more titled stable spin direction that results in stronger horizontal intrinsic resonance. The balance between raising the spin tune gap generated by the snakes and reducing the titled stable spin direction has to be considered to maintain the polarization. Because the magnetic field of the warm snake is constant, only the cold snake with a maximum 3T magnetic field can be varied to find out the optimized snake strength. The paper presents the simulation results from the spin tracking with different cold snake magnetic fields. Some experimental data are also analyzed.

THPC027	Pulsed RF Accelerator of Electrons with Beam Recirculation	linac, electron, acceleration, dipole	3038
	V. V. Mytrochenko, M. I. Ayzatskiy, P. Gladkikh, V. A. Kushnir, A. Opanasenko, A. Y. Zelinsky NSC/KIPT, Kharkov S. Chemerisov, D. Ehst ANL, Argonne, Illinois
	We discuss the project of upgrading existent 20 MeV L-band electron linac at Argonne National Laboratory aimed at electron energy increasing. It is shown that the proposed beam recirculation will provide on the accelerator output an electron beam with a pulse current 0.5 A and energy of particles 45 MeV. Problems of stability of recirculating beam are discussed.

THPC030	Simulation Studies of Correlated Misalignments in the ILC Main Linac and the Influence of Ground Motion	emittance, alignment, linac, survey	3044
	F. Poirier, D. Kruecker, I. Melzer-Pellmann, N. J. Walker DESY, Hamburg
	Component misalignments are an important source of emittance dilution in the main linac of the International Linear Collider (ILC). The impact of static uncorrelated alignment errors has been widely studied with various simulation codes and several beam based alignment algorithms. For a realistic scenario one has to take into account that the survey and alignment process will introduce correlations between the component errors. In the present paper we study the performance of the Dispersion Matched Steering (DMS) technique for the case of such correlated misalignments. Different models for the correlations are investigated including a proposed alignment strategy for the ILC main linac* which has been implemented into the Merlin C++ library*. In addition to the initial static errors, dynamic errors due to ground motion will produce an emittance growth with time. For this case we have also investigated the stability of DMS tuning over time. Kiyoshi Kubo, private communication ** Merlin - A C++ Class Library for Accelerator Simulations; http://www.desy.de/~merlin.

THPC032	Vertical Beam Size Reduction via Compensation of Residual Transverse Coupling	coupling, wiggler, optics, closed-orbit	3047
	T. F. Roque, X. R. Resende, P. F. Tavares LNLS, Campinas
	The Brazilian Synchrotron Light Source (LNLS) is currently constructing a beamline which will make use of the radiation produced by the EPU installed in the storage ring (SR) in 2007. Various force tasks have been triggered by this new beamline in order to achieve required beam properties and stability. One of these tasks has to do with reducing the SR's vertical beam size at the straight section where the EPU is located, hence improving the radiation brilliance from the EPU. This report will describe our recent efforts in understanding and controlling what residual effects there are in the ring that dominate the ring's vertical beam size. In particular, we study the effects of residual coupling perturbations on the beam size through the transfer matrix formalism which, we argue, is the most appropriate. A beam model including transverse linear coupling is validated with measured closed orbit response functions. By Analyzing this model we are able to propose new skew quadrupole elements to the SR that might reduce the vertical beam size at the EPU section and we can infer the validity of results with a pinhole beam imaging system which we have available in our diagnostic beamline.

THPC037	Studies of Orthogonal Bumps for ILC Main Linac	emittance, linac, alignment, coupling	3059
	N. Solyak Fermilab, Batavia, Illinois S. A. Glukhov BINP SB RAS, Novosibirsk
	To preserve small vertical emittance of the beam in ILC main linac a few beam-based alignment techniques were proposed and studied in recent years. Dispersion and wakefield bumps are one of the effective tool for final tuning of the machine. One of the modifications of bumps is so called orthogonal (or SVD) bumps, proposed for CLIC. In paper we present study of orthogonal bumps performances for final alignment of the ILC main linac.

THPC038	Beam Dynamic Simulations of the New Polarized Electron Injector of the S-DALINAC	electron, gun, emittance, linac	3062
	B. Steiner, W. Ackermann, S. S. Franke, W. F.O. Müller, T. Weiland TEMF, Darmstadt R. Barday, C. Eckardt, R. Eichhorn, J. Enders, C. Hessler, Y. Poltoratska, A. Richter, M. Roth TU Darmstadt, Darmstadt
	Aiming at an extension of the experimental possibilities at the Superconducting Darmstadt electron linear accelerator S-DALINAC, a polarized gun is going to be constructed at the moment. The new injector will be able to supply polarized electrons with kinetic energy in the 100 keV range and should add to the present unpolarized thermionic 250 keV source. The design requirements include a polarization degree of at least 80%, a mean current intensity of 60 μA and a 3 GHz cw time structure. The gun part is simulated in CST MAFIA whereas subsequent beam dynamics simulations are performed in V-Code. Initial conditions for the V-Code’s moment approach are extracted from the CST MAFIA simulations. The injector consists of short triplets, an alpha magnet, a Wien filter, a Mott polarimeter, a chopper/prebuncher system and beam diagnostic elements. For the simulations, the 3D electromagnetic fields of the beam line elements are used by means of a Taylor series expansion of variable order. All components except the chopper and a collimator is represented in the simulations. Recent beam dynamic results will be presented.

THPC046	Heating Rate of Highly Space-charge-dominated Ion Beams in a Storage Ring	emittance, lattice, ion, storage-ring	3080
	Y. Yuri JAEA/ARTC, Takasaki H. Okamoto HU/AdSM, Higashi-Hiroshima
	We investigate the heating process of highly space-charge-dominated ion beams in a storage ring, using the molecular dynamics simulation technique. To evaluate the heating rate over the whole temperature range, we start from an ultra-low-emittance state where the beam is Coulomb crystallized, apply perturbation to it, and follow the emittance evolution. When the ring lattice is properly designed, the heating rate is quite low at ultralow temperature because random Coulomb collisions are suppressed. It gradually increases after the ordered state is destroyed by perturbation, and comes to a peak when the beam reaches a liquid phase. The dependence of the heating behavior on the beam line density and betatron tune is explored systematically. The effect of lattice imperfection on the stability of crystalline beams is also confirmed. J. Wei and A. M. Sessler, EPAC'96, p.1179.

THPC047	Studies of Losses During Continuous Transfer Extraction at the CERN proton Synchrotron	extraction, septum, proton, quadrupole	3083
	S. S. Gilardoni, J. Barranco CERN, Geneva
	Proton beams can be extracted from the CERN-PS at 14 GeV/c on five turns, using a technique called Continuous Transfer (CT). In this case, large losses due to particles scattered by an electrostatic septum used to slice the beam on five turns are observed in straight sections where the machine aperture is large enough to accommodate the circulating beam without any loss. These losses limit the maximum intensity deliverable to the SPS, like for the CERN to Gran Sasso (CNGS) neutrino program, because of the large irradiation of the site outside the PS tunnel and at the CERN fence. New simulation tools for a parametric study have been developed to improve the understanding of the observed loss pattern. A proposed solution to displace the losses in less critical section of the machine has been simulated and implemented in the CERN-PS. Simulations and experimental results of the loss study and reduction are presented.

THPC056	Stability Change of Fourth-order Resonance with Application to Multi-turn Extraction Schemes	resonance, extraction, emittance, synchrotron	3110
	M. Giovannozzi, D. Quatraro CERN, Geneva G. Turchetti Bologna University, Bologna
	Recently, a novel multi-turn extraction scheme was proposed, based on particle trapping inside stable resonances. Numerical simulations and experimental tests confirmed the feasibility of such a scheme for low order resonances. While the 3rd order resonance is generically unstable and those higher than 4th order are generically stable, the 4th order resonance can be either stable or unstable depending on the details of the system under consideration. By means of the normal form approach a general formula to control the stability of the 4th order resonance is derived. Numerical simulations confirm the analytical results and show that by crossing the unstable 4th order resonance the region around the centre of phase space is depleted and particles are trapped only in the four stable islands. This indicates that a four-turn extraction could be envisaged based on this technique.

THPC057	Field Interference of Magnets in the Large Acceptance Storage Ring CR of the Fair Project	dipole, quadrupole, multipole, dynamic-aperture	3113
	O. E. Gorda, C. Dimopoulou, A. Dolinskii, F. Nolden, M. Steck GSI, Darmstadt
	The large acceptance storage ring CR is planned to be used for accumulation and cooling of rare isotope and antiproton beams at the future FAIR accelerator facility. The huge apertures as well as the close arrangement of the dipoles and quadrupoles make overlapping between the end fields of the magnets unavoidable. In addition, corrector magnets are planned to be installed in the drift sections between the dipoles and quadrupoles for closed orbit corrections. The presence of additional iron can have a significant influence on the magnetic field distribution. This interference can lead to a reduction of the integral field quality decline that is undesirable since it can affect the beam dynamics. In this contribution we present the results of 3D magnetic field simulations performed using the OPERA computer code. The field maps were derived and further analyzed. The corresponding sets of multipole components were calculated and were then implemented into one of the codes for the beam dynamics calculations. The MAD code was used to calculate the dynamic aperture and to estimate the effect of the field interference on the beam dynamics of the ring.

THPC059	Studies of Wire Compensation and Beam-beam Interaction in RHIC	emittance, dynamic-aperture, beam-losses, luminosity	3119
	H. J. Kim, T. Sen Fermilab, Batavia, Illinois N. P. Abreu, W. Fischer BNL, Upton, Long Island, New York
	Beam-beam interaction is one of the dominant source of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and the principle is now being experimentally investigated at RHIC. In this paper, we use simulations to study the effectiveness of wire compensation based on tune footprints, diffusive apertures, and beam loss rates using a parallel weak-strong beam simulation code (BBSIM). In addition we extensively study the diffusion properties of RHIC beams for different beam and wire parameters. Beam-beam effects on emittance growth are investigated through the solution of the diffusion equation for the transverse action variables.

THPC060	Spin Flip of Deuterons in COSY - Spink Tracking	resonance, dipole, polarization, betatron	3122
	A. U. Luccio BNL, Upton, Long Island, New York A. Lehrach FZJ, Jülich
	The spin tracking code Spink, as recently overhauled, has been used to study the deuteron spin resonances and spin flipping induced by a RF dipole and a RF solenoid. The modifications of the code followed extended discussions on the formalism used to model spin evolution in a synchrotron. The simulation shows a good agreement with published results of the measurements. A. U. Luccio et al. See another contribution to this Conference. **A. D. Krisch et al. PR-STAB 10, 07100-1, 2007.

THPC062	Multi-Particle Weak-Strong Simulations of RHIC Head-on Beam-Beam Compensation	emittance, proton, electron, dynamic-aperture	3125
	Y. Luo, N. P. Abreu, W. Fischer, G. Robert-Demolaize BNL, Upton, Long Island, New York
	An electron beam has been proposed in the Relativistic Heavy Ion Collider (RHIC) to compensate beam-beam effects in polarized proton collisions. This electron beam will collide head-on with the proton beam. Using the weak-strong beam-beam interaction model, we have carried out six-dimensional multiparticle simulations to investigate the effects of head-on beam-beam compensation. Beam lifetime, transverse emittances, and luminosity are calculated for cases with and without beam-beam compensation for up to 10 million turns. The migrations of particles between different actions and the beam spectrum are also calculated.

THPC066	Measuring Ring Nonlinear Components via Induced Linear "Feed-down"	sextupole, resonance, beam-losses, closed-orbit	3137
	A. S. Parfenova, G. Franchetti, I. Hofmann GSI, Darmstadt
	The knowledge of the distribution in a ring of the non-linear components is important for the resonance compensation. We present a method to measure the lattice nonlinear components based on the non-linear tune response to a locally controlled closed orbit deformation. A test of this concept in the SIS18 synchrotron is presented and discussed.

THPC073	Measurement of Resonance Driving Terms in the ATF Damping Ring	resonance, coupling, sextupole, kicker	3155
	R. Tomas, F. Zimmermann CERN, Geneva K. Kubo, S. Kuroda, T. Naito, T. Okugi, J. Urakawa KEK, Ibaraki
	The measurement of resonance driving terms in the Damping Ring of the Accelerator Test Facility in KEK could help finding possible machine imperfections and even to optimize single particle stability through the minimization of non-linearities. The first experimental attempts of this enterprise are reported in this note.

THPC078	Injection Scheme of X-rays Source NESTOR	injection, electron, storage-ring, quadrupole	3167
	A. Y. Zelinsky, I. M. Karnaukhov, A. Mytsykov, V. L. Skirda NSC/KIPT, Kharkov
	In the paper the injection scheme of the X-ray source NESTOR based on the compact storage ring and Compton scattering is described. It is supposed to inject electron beam through fringe fields of a bending magnet. For final beam deflection electrical inflector on the running wave will be used. The layout of the injection scheme and elements characteristics are presented. The results of simulations of electron beam motion through 3-d fields of electro-magnetic devices of the injection channel are presented.

THPC080	The VEPP-4M Dynamic Aperture Determination with Beam-beam Effects	dynamic-aperture, beam-beam-effects, collider, insertion	3170
	A. N. Zhuravlev, V. A. Kiselev, E. B. Levichev, O. I. Meshkov, P. A. Piminov, D. N. Shatilov, V. V. Smaluk BINP SB RAS, Novosibirsk
	To determine experimentally the particle stable area under the influence of beam-beam effects in the electron-positron collider VEPP-4M we measure the beam lifetime with high accuracy as a function of moving aperture. The measurement is performed by a photodiode installed in the collider diagnostic beam line. The experimental setup and the measurement results are described. Comparison with the tracking simulation is presented.

THPC081	RF Wire Compensator of Long-range Beam-beam Effects	coupling, emittance, dynamic-aperture, beam-beam-effects	3173
	U. Dorda, F. Caspers, T. Kroyer, F. Zimmermann CERN, Geneva
	The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC long-range beam-beam effect for nominal as well as for so-called 'PACMAN' bunches, i.e. bunches at the start or end of a bunch train, the wire compensator strength should be adjusted for each bunch individually. Here an RF-based compensator is proposed as a practical solution for the PACMAN compensation. We show that this approach also allows relaxing the power and precision requirements compared with those of a pulsed DC device, to a level within the state-of-the-art of RF technology. Furthermore it allows the use of a passive circulator in the tunnel close to the beam and thus a significantly reduction of the transmission line length and of the resulting multiple reflection issues. Simulations, issues related to RF phase noise and first experimental results from laboratory models as well as from a wire-compensator prototype installed in the CERN Super Proton Synchrotron (SPS) are presented.

THPC082	Wire Excitation Experiments in the CERN SPS	beam-losses, coupling, optics, resonance	3176
	U. Dorda, J.-P. Koutchouk, R. Tomas, J. Wenninger, F. Zimmermann CERN, Geneva R. Calaga, W. Fischer BNL, Upton, Long Island, New York
	In order to study the effect of long range interaction and its wire compensation experimentally, current carrying wires are installed in the CERN Super Proton Synchrotron (SPS). In this paper we summarize the main results of the 2007 wire excitation results at 26, 37 and 55 GeV including wire-current-, beam-wire distance and chromaticity scans. A strong dependence on the chromaticity and indications of a threshold effect at 37 and 55 GeV was found. The results are compared to simulation, to a simple analytic scaling law and to experimental results from RHIC. Wire-driven resonances have been observed through the Fourier spectrum of experimental BPM data and compared to simulations.

THPC083	Simulation Studies of Space-charge Effects in the LENS Nonlinear Transport Lines	octupole, space-charge, target, focusing	3179
	M. Hess, A. Bogdanov IUCF, Bloomington, Indiana
	The upgraded IUCF LENS beamline is designed to deliver a square shaped 13 MeV proton beam at 25 mA with a relatively uniform density using two octupole magnets for nonlinear focusing in both transverse directions. The space-charge effects in the LENS beamline (without nonlinear focusing) can vary the beam profile by roughly 8%-13% compared to a zero current beam. In this paper, we show the results of simulation studies of the LENS beamline which incorporate the effects of space-charge, as well as, nonlinear focusing from the octupole magnets. The simulations utilize self-consistent methods for computing the space-charge fields, since the beam density distribution can be nonlinear. We also show simulation results for beam currents in excess of 25 mA, which may be useful for future upgrades of LENS.

THPC084	Studies of Electromagnetic Space-charge Fields in RF Photocathode Guns	space-charge, emittance, gun, cathode	3182
	C. S. Park, M. Hess IUCF, Bloomington, Indiana
	In high-brightness rf photocathode guns, the effects of space-charge can be important. In an effort to accurately simulate the effects of these space-charge fields without the presence of numerical grid dispersion, a Green’s function based code called IRPSS (Indiana Rf Photocathode Source Simulator) was developed. In this paper, we show the results of numerical simulations of the Argonne Wakefield Accelerator photocathode gun using IRPSS, and compare them with the results of an electrostatic based simulation code. In addition, we show how electromagnetic space-charge fields can affect the designs of photocathode gun magnetic focusing schemes, such as emittance compensation. We will also show how a multipole moment method can be effectively utilized to compute the reflections of electromagnetic space-charge fields due to irises in photocathode guns. M. Hess, C. S. Park, and D. Bolton. Phys. Rev. ST Accel. Beams 10, 054201 (2007).

THPC085	VORPAL Simulations Relevant to Coherent Electron Cooling	electron, ion, plasma, hadron	3185
	G. I. Bell, D. L. Bruhwiler, A. V. Sobol Tech-X, Boulder, Colorado I. Ben-Zvi, V. Litvinenko BNL, Upton, Long Island, New York Y. S. Derbenev Jefferson Lab, Newport News, Virginia
	Coherent electron cooling (CEC)* combines the best features of electron cooling and stochastic cooling, via free-electron laser technology, to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the “modulator” and “kicker” regions, where the electron and hadron beams will co-propagate as in a conventional electron cooling section. Unlike previous VORPAL simulations* of electron cooling physics, where dynamical friction on the ions was the key metric, it is the details of the electron density wake driven by each ion in the modulator section that must be understood, followed by strong amplification in the FEL. We present some initial simulation results. In particular, we compare the semi-analytic binary collision model with electrostatic particle-in-cell (PIC). Ya. S. Derbenev, COOL ’07 Proc. (2007). V. N. Litvinenko and Ya. S. Derbenev, FEL ’07 Proc. (2007). **A. V. Fedotov et al. Phys. Rev. ST/AB 9, 074401 (2006).

THPC086	Transverse Mismatch Oscillations of a Bunched Beam in Presence of Space Charge and External Nonlinearities	emittance, synchrotron, lattice, space-charge	3188
	C. Benedetti, G. Turchetti Bologna University, Bologna G. Franchetti, I. Hofmann GSI, Darmstadt
	The damping of transverse mismatch oscillations depends on the combined effect of space charge as well as external nonlinearities. Previous studies of this problem for high intensity beams in a synchrotron have not included the combined effect of synchrotron oscillation and external nonlinearities on mismatch. In this paper we explore by 2.5D particle in cell simulations the effect on emittance growth, halo and beam loss caused by space charge, synchrotron oscillation and external nonlinearities. Different tunes are considered in order to understand the importance of external nonlinearities as function of the distance of the working point from the resonance condition.

THPC088	Beam Dynamics Simulation of Superconducting HWR Option for the IFMIF Linac	linac, rfq, beam-losses, emittance	3194
	N. Chauvin, A. Mosnier, P. A.P. Nghiem, D. Uriot CEA, Gif-sur-Yvette
	One of the requirements of the International Fusion Materials Irradiation Facility (IFMIF) is a 250 mA, 40 MeV cw deuteron beam provided by two 125 mA linacs. In this paper, a design based on superconducting half-wave resonators (HWR) for the 5 to 40 MeV section of the IFMIF driver accelerator is presented. Multi particle beam dynamics simulations have been performed in order to validate the linac design in such a high charge space regime. A Monte Carlo error analysis has been carried out to study the effects of misalignments or field variations. The results of the simulations are presented and the final specifications of the HWR linac are summarized.

THPC089	Electron-cloud Intrabunch Density Modulation	electron, dipole, proton, resonance	3197
	G. Franchetti GSI, Darmstadt F. Zimmermann CERN, Geneva
	During the passage of a proton bunch through an electron cloud a complicated electron density modulation arises, with characteristic ring and stripe patterns of high density regions that move radially outward along the bunch. We present simulation results as well as a simple analytical model to reveal the morphology and main features of this phenomenon as well as its dependence on key parameters like bunch length, beam size, and bunch charge.

THPC097	A Full Analytical Method to Determine Equilibrium Quantities of Mismatched Charged Particle Beams evolving in Linear Channels	emittance, focusing, coupling, resonance	3203
	R. P. Nunes, F. B. Rizzato IF-UFRGS, Porto Alegre
	The focus of this work is to show a full analytical expression to determine relevant equilibrium quantities of a magnetically focused and high-intensity charged particle beam when evolving in a linear channel. Through the current approach, some intermediate steps of our original hybrid model which have to be solved numerically now can be eliminated, leading to the obtainment of a full analytical expression. This expression relates initial beam parameters with those obtained at equilibrium, allowing that the fraction of halo particles f can be evaluated. As a consequence, through the developed model, beam quantities like the envelope and emittance can be naturally determined. This is important in the accelerator engineering, since halo characteristics is a factor to be considered in the design of its confinement structure. For validation, full self-consistent N-particle beam numerical simulations have been carried out and its results compared with the predictions supplied by the full analytical model. The agreement is shown to be nice as with the simulations as with the hybrid numerical-analytical version of the model.

THPC098	Halo characterization of initially mismatched beams through phase-space modeling	emittance, focusing, coupling, plasma	3206
	R. P. Nunes, F. B. Rizzato IF-UFRGS, Porto Alegre
	This work discusses a method of characterizing the beam particles with just some assumptions about the entire beam phase-space topology. At equilibrium, the beam phase-space can be recognized as composed by almost two distinct regions: a thin horizontal branch over the r axis that is populated by the core particles and a curve branch in the dr/ds x r plane, which is populated by the halo particles. Since these regions have a regular shape, then it is readily possible to convert them to an analytical expression. Two distinct shapes have been employed (circular and elliptical) to model the beam halo branch. With this, all usual initial beam mismatch values are covered with accuracy to determine the beam envelope and emittance at equilibrium. Full self-consistent N-particle beam simulations have been carried out and its results compared with the ones obtained with the model. Results agreed nice for all analyzed mismatch cases.

THPC100	Collisionless Relaxation in the Transport of Space Charge Dominated Beams	focusing, space-charge, resonance, plasma	3209
	R. Pakter, Y. Levin, T. N. Teles IF-UFRGS, Porto Alegre
	Relaxation to a final stationary state of particles interacting through long-range forces, such as Coulomb, is intrinsically different than that of systems with short-range interactions. While in the latter case it is known that the interparticle collisions drive the system to an equilibrium Maxwell-Boltzmann distribution, in the former case, the collision duration time diverges and the state of thermodynamic equilibrium is never reached. In this paper, a theory is presented which allows to quantitatively predict the final stationary state achieved by a transported space-charge dominated beam during a process of collisionless relaxation. It is shown that a fully matched beam relaxes to a Fermi-Dirac distribution. However, when a mismatch is present and the beam oscillates, halo formation leads to a phase separation. The theory developed allows to quantitatively predict both the density and the velocity distributions in the final stationary state, including the halo. Y. Levin, R. Pakter, and T. N. Teles, Phys. Rev. Lett., 100, 040604 (2008).

THPC102	Image Simulations on the ISIS Synchrotron	closed-orbit, vacuum, lattice, dipole	3215
	B. G. Pine, C. M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a loss-limited 50 Hz proton synchrotron, which accelerates ~3·10¹³ ppp from 70 to 800 MeV, corresponding to mean beam powers of 0.2 MW. A significant proportion of beam loss is attributable to space charge effects. One such effect is the image field which forms in the beam pipe. Off-centre beams resulting from closed orbit errors generate fields, which can perturb the beam and cause loss. Of particular interest on ISIS is the rectangular, varying aperture, vacuum vessel, as compared with the more usual constant aperture circular or elliptical geometries. A new 2D space charge code, Set, was developed to study these effects. The code simulates the effects of space charge using a 2D particle-in-cell model of the beam distribution, including an appropriate treatment of the rectangular beam pipe, and details of the ISIS lattice. The effects of images on closed orbits, driving terms, and the evolution of beam distributions at ISIS operational intensities were explored.

THPC103	Wave Breaking and Test Particle Dynamics in Inhomogeneous Beams	emittance, focusing, plasma, space-charge	3218
	F. B. Rizzato, Y. Levin, R. P. Nunes, R. Pakter, E. G. Souza IF-UFRGS, Porto Alegre
	This work analyzes the dynamics of inhomogeneous, magnetically focused high-intensity beams of charged particles. While for homogeneous beams the whole system oscillates with a single frequency, any inhomogeneity leads to propagating transverse density waves which eventually result in a singular density build up, causing wave breaking and jet formation. Wave breaking is shown to relax the mismatched beam and we make use of Lynden-Bell's theory of violent relaxation to estimate characteristics of the relaxed state.

THPC104	Optical Diagnostic on Gabor Plasma Lenses	electron, plasma, ion, emittance	3221
	K. Schulte, M. Droba, O. Meusel, U. Ratzinger IAP, Frankfurt am Main
	Gabor lenses have been built and successfully been used for the focussing of particle beams. In the case of a positive ion beam the space charge of the confined electron cloud may cause an over compensation of the ion beam space charge force and consequently focus the beam. The nonneutral plasma (NNP) is influenced by the external fields and its current state can be determined by the beam emittance growth. Experiments using a high field Gabor lens have shown a correlation between the thermalization of the enclosed electron cloud and the focussing quality. A three segmented Gabor lens was constructed recently for a more detailed investigation of the plasma parameters as a function of the external fields. The commissioning of the lens has been finished successfully and the light emitted by the interaction between the electron cloud and the residual gas has been observed. In a next step the experiments will concentrate on the spectral analyses of the emitted light to evaluate the temperature and density distribution of the confined NNP. Experimental results will be presented in comparison with numerical simulation.

THPC110	Investigation of Helical Cooling Channel	emittance, coupling, superconductivity, quadrupole	3233
	K. Yonehara, V. Balbekov Fermilab, Batavia, Illinois
	A helical cooling channel (HCC) has been proposed to quickly reduce phase space of muon beams. It is composed of solenoidal and helical coils to provide focusing and dispersion needed for the six-dimension cooling. A comprehensive investigation of the HCC is performed in presented work including theoretical analysis, particle tracking and Monte Carlo simulation. These results are also compared with the past simulation results* to confirm the helical cooling theory. Optimization of the channel and estimation of its ultimate performances are presented. Y. Derbenev and R. P. Johnson. PRSTAB 8, 041002 (2005). *K. Yonehara et al. TPPP052, Particle Accelerator Conference 2005.

THPC111	Simulation ofμBunching Instability Regimes in the FLASH Bunch Compressors	bunching, space-charge, gun, linac	3236
	M. Vogt, T. Limberg DESY, Hamburg D. H. Kuk The University of Texas at Austin, Austin, Texas
	The bunch compression scheme for the European XFEL will operate in a regime in which, at least without additional energy spread introduced by a laser heater, theμbunching effect proposed in the literature may severely degrade the performance of the FEL. However, clear, unambiguous signals of theμbunching effect have not yet been seen neither in simulation nor experiment. The proposedμbunching effect amplifies initial current modulations by interleaved application of longitudinal collective energy kicks and transformations of energy modulation into current modulation in magnetic chicanes. In order to establish a parameter regime for experimental verification ofμbunching at the FLASH VUV-FEL at DESY, we have scanned the relevant part of the parameter space using a linear, quasi-analytic, noise-free gain-model and complemented this with particle tracking simulations. The tracking was performed using interleaved runs of ASTRA for acceleration modules and CSRTrack for the chicanes, automatically linked by the start-to-end simulation tool box Gluetrack.

THPC112	KONUS Dynamics and H-mode DTL Structures for EUROTRANS and IFMIF	focusing, beam-losses, rfq, linac	3239
	C. Zhang, M. Busch, H. Klein, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt am Main
	During the last two decades, the combination of the KONUS beam dynamics and H-mode DTL structures has been developed as an efficient solution for accelerating low- and medium-energy proton and ion beams. EUROTRANS is a EUROpean Research Programme for the TRANSmutation of High Level Nuclear Waste in an Accelerator Driven System. IFMIF is a planned International Fusion Material Irradiation Facility to test materials for fusion reactors. For the driver linacs of both projects, two H-DTLs have been proposed to cover the energy ranges of 3–17MeV and 5–40MeV, respectively. The beam dynamics designs as well as the error studies of the H-DTLs are presented in this paper.

THPC119	Progress of TLS Fast Orbit Feedback System and Orbit Stability Studies	feedback, power-supply, controls, brilliance	3260
	C. H. Kuo, J. Chen, P. C. Chiu, K. T. Hsu, K. H. Hu, D. Lee NSRRC, Hsinchu
	The orbit feedback system of the TLS has been deployed for a decade and continuously upgraded. However, due to limitation of the existing hardware, the system cannot remove orbit excursion caused by the perturbation due to fast operation of insertion devices. The newly proposed orbit feedback system with the upgraded digital BPM system and switching corrector power supply system is planned to be installed and commissioned in late 2008. The preliminary calculation on the stability performance for the orbit feedback system is presented in the report. New fast orbit feedback system can be expected to achieve a submicron stability of the electron beam working at a bandwidth of at least 60 Hz.

THPC124	The Manufacturing and Tests of The New Vertical Feedback Stripline at Soleil	feedback, impedance, vacuum, kicker	3275
	C. Mariette, J.-C. Denard, R. Nagaoka SOLEIL, Gif-sur-Yvette
	This paper describes the development of the kicker striplines for the bunch-by-bunch transverse instability feedback system at Soleil. A careful design of the striplines and of their vacuum feedthroughs was aimed at maximizing the effectiveness of the excitation power and minimizing the power taken from the beam. The excitation effectiveness improves with the shunt impedance. But, simultaneously, the beam impedance should be made as small as possible. We also found useful to estimate the temperature of the feedthroughs at high beam currents, especially on the ceramic-to-metal seals. We also report on the difficulties encountered with obtaining good feedthroughs.

THPC125	Modeling and Simulation of the Longitudinal Beam Dynamics-RF Station Interaction in the LHC Rings	klystron, feedback, impedance, controls	3278
	T. Mastorides, J. D. Fox, C. H. Rivetta, D. Van Winkle SLAC, Menlo Park, California P. Baudrenghien, J. Tuckmantel CERN, Geneva
	A non-linear time-domain simulation has been developed to study the interaction between longitudinal beam dynamics and RF stations in the LHC rings. The motivation for this tool is to study the effect of RF station noise, impedance, and perturbations on the beam life and longitudinal emittance. It will be also used to determine optimal LLRF configurations, to study system sensitivity on various parameters, and to define the operational and technology limits. It allows the study of alternative LLRF implementations and control algorithms. The insight and experience gained from our PEP-II simulation is important for this work. In this paper we discuss properties of the simulation tool that will be helpful in analyzing the LHC RF system and its initial results. Partial verification of the model with data taken during the LHC RF station commissioning is presented.

THPC131	On the Optimal Number of Eigenvectors for Orbit Correction	feedback, quadrupole, storage-ring, closed-orbit	3295
	I. Pinayev, M. G. Fedurin BNL, Upton, New York
	The singular value decomposition method is widely used for orbit correction in the storage rings. It is a powerful tool for inverting of the usually rectangular response matrices, which usually have rectangular form. Another advantage is flexibility to choose number of eigenvectors for calculation of required strengths of orbit correctors. In particular, by reduction in number of eigenvectors one can average over ensemble noise in the beam position monitors. A theoretical approach as well as experimental results on the NSLS VUV ring are presented.

THPC133	Layout and Simulations of the FONT System at ATF2	kicker, extraction, feedback, pick-up	3300
	J. Resta-López, P. Burrows JAI, Oxford
	We describe the adaptation of a Feedback On Nano-second Timescales (FONT) system for the final focus test beam line ATF2 at KEK. This system is located in the ATF2 extraction line, and is mainly conceived for cancellation of transverse jitter positions originated in the damping ring and by the extraction kickers. This jitter correction is performed by means of a combination of feed-forward (FF) and fast-feedback (FB) beam stabilisation. We define optimal positions for the kicker and BPM pairs of the FONT FF/FB system, and estimate the required kicker performance and BPM resolutions. Moreover simulation results are presented.

THPC140	The Performance of a Fast Closed Orbit Feedback System with Combined Fast and Slow Correctors	feedback, closed-orbit, power-supply, vacuum	3315
	L.-H. Yu, S. Krinsky, O. Singh, F. J. Willeke BNL, Upton, Long Island, New York
	For NSLSII closed orbit feedback system, in order to reduce the noise caused by the step changes of the power supplies in the feedback system, the angular kick corresponding to the last bit of the power supplies for the fast correctors must be smaller than 3 nrad. On the other hand, in order to carry out closed orbit alignment or orbit correction after a long term drift, we need strong correctors with 0.8 mrad kick strength. In order to avoid the requirement of correctors with both large strength and very small minimum step size, we consider separate sets of slow correctors with large strength and fast correctors with smaller maximum strength. In order to avoid fast and slow feedback systems working in parallel, and avoid the possible interaction between two feedback systems, we consider the possibility of using only one fast feedback system with slow correctors periodically removing the DC components of the fast correctors so that the DC components in fast feedback system would not accumulate to reach saturation even after a large long term drift of the closed orbit motion. We report on simulation of the performance of this combined system for NSLSII in this paper. * NSLSII Preliminary Design Report (2007)

THPC145	Reliability Analysis of the LHC Machine Protection System: Terminology and Methodology	injection, beam-losses, hadron, diagnostics	3327
	S. Wagner Swiss Federal Institute of Technology Zurich (ETH), Laboratory for Safety Analysis, Zurich R. Schmidt, J. Wenninger CERN, Geneva
	The trade-off between LHC machine safety and beam availability is one of the main issues related to the LHC MPS. Several studies have addressed it for different subsystems. They are followed by a project aiming at the development of a methodology which combines agent-based modeling and fault-tree analysis thus allowing a global analysis of the entire MPS. During this project, the need for a clarification and specification of the terminology has become apparent. Besides involving basic terms like safety, reliability and availability, the analysis must take into account the implementation of common design principles such as redundancy, fault tolerance, 'fail-safe' and self-monitoring. These terms and in particular their interrelations easily cause confusion. Since the traceability of the analysis depends on a consistent understanding of the underlying terminology, a terminology frame is being compiled. The paper specifies the most relevant terms and their interrelations. General standard definitions are taken as basis for a specification related to the MPS and its analysis respectively. The developed analysis methodology building on this terminology frame is introduced.

THPC147	Generation of 1.5 Million Beam Loss Threshold Values	proton, beam-losses, insertion, collimation	3333
	E. B. Holzer, B. Dehning, L. Ponce, M. Sapinski, M. Stockner CERN, Geneva D. K. Kramer TUL, Liberec P. Priebe Poznan University of Technology, Poznan
	CERN's Large Hadron Collider will store an unprecedented amount of energy in its circulating beams. Beam-loss monitoring (BLM) is, therefore, critical for machine protection. It must protect against the consequences (equipment damage, quenches of superconducting magnets) of excessive beam loss. 4000 monitors will be installed at critical loss locations. Each monitor has 384 beam abort thresholds associated; for 12 integrated loss durations (40 us to 83 s) and 32 energies (450 GeV to 7 TeV). Depending on monitor location, the thresholds vary by orders of magnitude. For simplification, the monitors are grouped in 'families'. Monitors of one family have the same thresholds at start-up; they protect similar magnets against equivalent loss scenarios. The start-up calibration of the BLM system is required to be within a factor of five in accuracy; and the final accuracy should be a factor of two. Simulations (backed-up by control measurements) determine the relation between the BLM signal, the deposited energy and the critical energy deposition for damage or quench (temperature of the coil). The paper presents the details and systematic of determining 1.5 million threshold values.

THPC149	Beam Scraping to Detect and Remove Halo in LHC Injection	injection, proton, beam-losses, controls	3339
	P. A. Letnes, S. Bart Pedersen, A. Brielmann, H. Burkhardt, D. K. Kramer CERN, Geneva
	Fast scrapers are installed in the SPS to detect and remove beam halo before extraction of beams to the LHC, to minimize the probability for quenching of super-conducting magnets in the LHC. We shortly describe the current system and then focus on our recent work, which aims at providing a system which can be used as operational tool for standard LHC injection. A new control application was written and tested with the beam. We describe the current status and results and compare these with detailed simulations.

THPP007	Six-sector FFAG Ring to Demonstrate Bunch Rotation for PRISM	closed-orbit, target, vacuum, injection	3389
	A. Sato, M. Aoki, S. Araki, Y. Arimoto, Y. Eguchi, K. Hirota, I. Itahashi, Y. Kuno, Y. Kuriyama, Y. Nakanishi, M. Y. Yoshida Osaka University, Osaka Y. Iwashita Kyoto ICR, Uji, Kyoto A. Kurup Imperial College of Science and Technology, Department of Physics, London Y. Mori KURRI, Osaka C. Ohmori KEK, Ibaraki
	A monochromatic muon beam is one of the most important requirements to improve a sensitivity of mu-e conversion experiments. In the PRISM project, which searches for mu-e conversion at a sensitivity of BR~10^-18, makes such muon beams by using a bunch rotation technique in an FFAG ring. To demonstrate the bunch rotation, a FFAG ring has been constructed in RCNP, Osaka. The ring has six FFAG magnets and one RF cavity. Alpha particles from a radioactive isotope ²⁴¹Am will circulate in the ring for the demonstration of bunch rotation.

THPP019	Adjustment of a New Pre-stripping Section the Multicharge Ion Linear Accelerator (MILAC)	ion, focusing, vacuum, acceleration	3410
	O. F. Dyachenko, V. A. Bomko, Ye. V. Ivakhno, A. P. Kobets, V. I. Misjura, V. V. Mytrochenko, A. V. Zabotin, B. V. Zajtsev NSC/KIPT, Kharkov
	In the Kharkov Institute of Physics and Technology the works on commissioning of a new prestripping section (A/q = 4), intend for accelerating a high current beam of light ions from 30 keV/u to 975 keV/u come to the end. Results of final tuning of irregular interdigital accelerating structure with alternating phase focusing and stepped changing the synchronous phase along the focusing period are presented. Process of preliminary adjustment of structure by means of traditional developed earlier methods: the additional current-carrying stems and the end resonant tuning elements (ERTEs) is described. New effective inductance-capacitor tuning devices as rods located on the drift tube side, opposite to their holders (�contrivance�) are developed and their use in real structure is shown. �Contrivances� have proved as the effective element of tuning locally influencing value of an electric field in the nearest gaps and lowering resonant frequency without noticeable worsening of electrodynamic characteristics of resonant system.

THPP024	Detailed Study of the RF Properties of the FETS RFQ Cold Model	rfq, quadrupole, coupling, ion-source	3422
	S. Jolly, A. Kurup, D. A. Lee, J. K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London Y. Cheng IHEP Beijing, Beijing A. P. Letchford STFC/RAL, Chilton, Didcot, Oxon
	A 324MHz four vane RFQ cold model has been built, as part of the development of a proton driver Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. Previous measurements to determine the electric field profile were made using the bead-pull perturbation method: these measurements have been refined and expanded. New measurements of the electric field profile, Q-value and resonant modes are presented. Measurements of the fundamental frequency and Q-value of the RFQ as a result of modifications to the profile of the end flange inserts are also given. Finally, an experiment is outlined to determine the beam transmission properties of the cold model based on beam transport simulations with the General Particle Tracer package (GPT).

THPP026	IH Accelerating Structures with PMQ Focusing for Low-energy Light Ions	focusing, quadrupole, impedance, ion	3428
	S. S. Kurennoy, S. Konecni, J. F. O'Hara, L. Rybarcyk LANL, Los Alamos, New Mexico
	We are developing high-efficiency room-temperature RF accelerating structures for beam velocities in the range of a few percent of the speed of light by merging two well-known ideas: inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we have proved that such structures provide a very efficient and practical accelerator for light-ion beams of considerable currents. The IH accelerating structures with PMQ focusing following a short RFQ can be used in the front end of ion linacs or in stand-alone applications such as a compact deuteron-beam accelerator up to the energy of a few MeV.

THPP031	Upgrade of the ISAC DTL Tuning Procedure at TRIUMF	linac, diagnostics, acceleration, ion	3440
	M. Marchetto, J. Berring, R. E. Laxdal TRIUMF, Vancouver
	The TRIUMF ISAC facility has two variable energy heavy ion linacs as post accelerators for radioactive ion beams. The ISAC I linac is a warm IH-DTL with five accelerating tanks and three bunchers, the ISAC II one uses twenty independently phased superconducting cavities. The first linac operates between 150 keV/u and 1.8 MeV/u; the second boosts the 1.5 MeV/u injected beam by 20 MV. The DTL is tuned based on the energy beam profile given by an analysing magnet. The SC linac is tuned on energy and time profiles with a diagnostic based on a gold foil scattering ions to a silicon detector (SID). The SID requires lower beam intensity. Furthermore the tuning time is reduced and streamlined by means of a MATLAB graphical user interface (GUI). This GUI uses a simple cosine model to characterize the energy gain versus RF phase of each cavity. Based on this we have pursued a new tuning procedure for the DTL using a gold foil/SID diagnostic. The more complex RF structures of the DTL require measurements and beam dynamics simulations (with LANA code) to produce a model for a dedicated GUI. In the paper we describe the two existing tuning methods and present new DTL procedure and interface.

THPP034	Design Study of Alternate Injector at Pelletron Accelerator Facility	rfq, ion, ion-source, linac	3443
	N. Mehrotra, P. V. Bhagwat, R. K. Choudhury, A. K. Gupta, S. Kailas, S. Krishnagopal BARC, Mumbai R. G. Pillay TIFR, Mumbai
	An alternate injector system is contrived under the AIDNP project in the Xth plan to utilize the 150MHz supercond. LINAC to its full capability. This injection system consists of ECR ion source, RFQ Linac and supercond. QWR cavities. This configuration can deliver high current and wider mass range(1/7≤ q/m≤1/2) beam into the S-LINAC with the required velocity acceptance which otherwise is not possible from pelletron. The design study from ion source to exit of RFQ is presented in this paper. Prior to injection to s-linac,the beam needs to be accelerated to an equivalent of 12-14MV/q. Beam from a high frequency(18GHz) ECRsource producing Au³⁰⁺,U³⁴⁺ and pre accelerated to 10keV/u will be injected into heavy ion RFQ. The RFQ operating at f/2 i.e.75MHz of the linac frequency, will accept beams with β=0.46% and accelerate upto β=3.5%.These beams would then go through two sets of superconductiong cavities with β=5.0% and β=7.0% respectively. This acceleration is expected to bring all ion beams from carbon to uranium, in the velocity range β=8%-10% which is suitable for linac. After further acceleration in Linac~12 MeV/u light ions and 7 MeV/u uranium beams would be available.

THPP036	The Superconducting Solution for the EURISOL DS Postaccelerator Injector	rfq, emittance, ion, bunching	3446
	P. A. Posocco Consorzio RFX, Euratom ENEA Association, Padova G. Bisoffi, A. Palmieri, A. Pisent, P. A. Posocco INFN/LNL, Legnaro, Padova
	In the framework of EURISOL design study, the superconducting solution for the Post-Accelerator injector foresees the use of two RFQs, one Super Conducting and one Normal Conducting, both operating CW at 88 MHz. After the multiple ionization in the ECR breeder on low voltage platform, the rare ions beam (3 ≤ A/q ≤ 7) is bunched at the main frequency by the NC RFQ without both losses and transverse emittance increase and accelerated afterwards through the SC RFQ up to 560 keV/u. A 8.8 MHz pulsed beam can be delivered to experiments placing a 3 harmonic buncher before the NC RFQ with overall beam losses lower than 25%. The beam dynamics results of the study of this solution as well as the main RF design and construction analysis of the main components are presented. http://www.eurisol.org

THPP040	Choice of Accelerating System for Undulator Linear Accelerator	undulator, ion, linac, rfq	3455
	E. S. Masunov, N. V. Avreline, V. S. Dyubkov, S. M. Polozov MEPhI, Moscow A. L. Sitnikov ITEP, Moscow
	The undulator linear accelerators (UNDULAC) were suggested as a new type of high intensity low energy ion linac. Such accelerators can be realized in periodical IH structure. The RF field in UNDULAC has no spatial harmonics in synchronism with the beam. An accelerating force is to be driven by a combination of two non-synchronous space harmonics. The ratio of first to zero RF field harmonics amplitude must be equal to 0.25-0.4. The effective beam bunching and focusing could be provided in this case. The construction of UNDULAC accelerating channel is discussed to realize such ratio. The first results of IH resonator type choice are also presented. E. S. Masunov, Technical Physics, V. 46, 11, 2001, pp. 1433-1436.

THPP041	Beam Dynamics Simulation of the 1.5 MeV/u Proton/Deuteron Beams Measured at the SARAF RFQ Exit	rfq, proton, ion, linac	3458
	J. Rodnizki, B. Bazak, D. Berkovits, G. Feinberg, A. Shor, Y. Yanay Soreq NRC, Yavne K. Dunkel, C. Piel ACCEL, Bergisch Gladbach
	The Soreq Applied Research Accelerator Facility (SARAF) accelerator's front-end is composed of a 20 keV/u protons and deuterons ECR ion source, a 5 mA low energy beam transport and a 1.5 MeV/u, 4 mA, 176 MHz, 4-rod RFQ. In this work, beam dynamics simulations of the SARAF accelerator front-end is compared to the first beam measurements taken during commissioning. Beam transmission, ion energy and bunch width as a function of the RFQ power have been measured in the medium energy beam transport diagnostics and using a dedicated diagnostic plate. The simulations and measurements show similar trends. This agreement allows calibrating the RFQ power to its electrodes voltage, in the low electric field range, where the common x-ray measurement method is not feasible. The benchmark between simulation and measurement shows that the RFQ model in our simulation can well predict the measured values. The simulation is covering the beam tail as well and is used to find the optimal operating voltage by minimizing the low energy tail and hence the beam loss downstream the accelerator.

THPP055	Stochastic Cooling Developments for the HESR at FAIR	target, antiproton, lattice, luminosity	3491
	H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich T. Katayama CNS, Saitama L. Thorndahl CERN, Geneva
	The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt will be built as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combination of phase space cooled beams with internal targets. In addition to electron cooling transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. A detailed numerical analysis of the Fokker-Planck equation for longitudinal filter cooling including an internal target and intrabeam scattering has been carried out to demonstrate the stochastic cooling capability in the newly designed normal conducting ring lattice of the HESR. Theoretical predictions have been compared to experimental cooling results with internal targets at the COSY facility. Recent developments for the HESR stochastic cooling equipment will be discussed. The design of new high sensitive printed loop couplers and ring slot couplers for the (2-4) GHz range as well as prototype measurements with protons in the COSY accelerator will be presented.

THPP058	Progress with Electron Beam System for the Tevatron Electron Lenses	electron, gun, proton, cathode	3500
	V. Kamerdzhiev, G. F. Kuznetsov, G. W. Saewert, V. D. Shiltsev Fermilab, Batavia, Illinois
	We have developed , built and tested two novel electron guns for the Tevatron and RHIC electron lenses: the first, a gridded gun which generates electron beam profile with smoothed edges and broad flat-top; the second, Gaussian beam profile gun which can be used for generation of the profile with depressed emission in the center. We have also developed a new type of HV modulator for use in TELs. In this articel, we desicribe the guns and the modulator, and present results of the bench tests.

THPP063	Possible Particle Distributions at the Entrance of the Cyclotron Spiral Inflector	emittance, cyclotron, ion, extraction	3506
	N. Yu. Kazarinov, I. A. Ivanenko JINR, Dubna, Moscow Region
	The transverse particle distribution of the ion beam produced in the Electron Cyclotron Resonance Ion Source (ECRIS) is considered. It is shown that the beam emittance at the entrance of the cyclotron spiral inflector is strongly dependent on directions of both the ECRIS and cyclotron magnetic fields. The changing of the beam rms emittance and bunch lengthening in the spiral inflector for every considered distribution are obtained in the computer simulation.

THPP065	3D Simulation of the Axial Injection Beam Line of DC350 Cyclotron	cyclotron, ion, injection, focusing	3509
	N. Yu. Kazarinov, V. Aleksandrov, V. Shevtsov, A. Tuzikov JINR, Dubna, Moscow Region
	DC-350 is the novel cyclotron designed in Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research. It is intended for the nuclear and applied physics experiments. The axial injection channel of the DC-350 cyclotron gives possibility for transportation of the high intensity ion beam from Li to Bi obtained in the superconducting ECR-ion source (SECR). The beam focusing in the beam line after the analyzing bending magnet is provided by solenoidal lenses. The linear and sinusoidal bunchers installed in the vertical part of the channel are used for increasing of the accelerating efficiency. The 3D simulation results of the focusing and bunching systems of the axial injection beam line are presented.

THPP077	The IFMIF-EVEDA Accelerator Activities	rfq, emittance, linac, diagnostics	3539
	A. Mosnier CEA, Gif-sur-Yvette A. Facco INFN/LNL, Legnaro, Padova A. Ibarra CIEMAT, Madrid
	The International Fusion Materials Irradiation Facility (IFMIF) aims at producing an intense flux of 14 MeV neutrons, in order to characterize materials envisaged for future fusion reactors. This facility is based on two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV to the common lithium target. In the framework of the EU-JA Bilateral Agreement for the Broader Approach for Fusion, the Engineering Validation and Engineering Design Activities (EVEDA) phase of IFMIF has been launched in the middle of 2007. The objectives of EVEDA are to produce the detailed design of the entire IFMIF facility, as well as to build and test a number of prototypes, including a high-intensity CW deuteron accelerator (125 mA @ 9 MeV). The major components and subsystems will be designed and developed in Europe, and will be then assembled and operated at Rokkasho in Japan. The individual components are developed in Spain, Italy and France and an european accelerator team has been settled for the coordination of the accelerator activities. The design and the layout of the accelerator are presented as well as the development schedule.

THPP078	IFMIF-EVEDA RFQ Design	rfq, coupling, vacuum, beam-losses	3542
	A. Pisent, M. Comunian, E. Fagotti, A. Palmieri, P. A. Posocco, C. Roncolato INFN/LNL, Legnaro, Padova F. Grespan Università degli Studi di Milano, Milano A. Pepato INFN- Sez. di Padova, Padova
	The RFQ of IFMIF-EVEDA project is characterized by very challenging specifications, with 125 mA of deuteron accelerated up to 5 MeV. After the long period of conceptual and comprehensive design of IFMIF accelerator, the decision of the construction of its low energy part has implied a new analysis of the RFQ design. In particular the beam dynamics design has been optimized, with a consistent reduction of the structure length and power consumption, and improvement of the performances in terms of beam losses. The resonator, of four vanes kind, has been designed taking advantage of the theoretical background and experimental experience gained in Europe with IPHI and TRASCO projects. The mechanical design has been analysed considering different approaches, involving vacuum brazing, laser or e'beam welding.

THPP082	Residual Activity Induced by High-energy Heavy Ions in Stainless Steel and Copper	ion, target, beam-losses, proton	3551
	I. Strasik, I. Hofmann, E. Kozlova, E. Mustafin GSI, Darmstadt L. N. Latysheva, N. Sobolevskiy RAS/INR, Moscow M. Pavlovic STU, Bratislava A. Smolyakov ITEP, Moscow
	The activation of accelerator structures due to beam loss is already intensity limiting problem for existing (SNS or RHIC) and planned (LHC or FAIR) hadron facilities. While beam-losses of 1 W/m are recognized as a tolerable beam-loss level for proton machines, the beam-loss tolerances for high-power heavy-ion accelerators have not yet been quantified. In this work the residual activity was calculated by Monte-Carlo particle transport codes and compared with experimental data. Simulations were performed for projectiles from proton to uranium. Experiments were performed with uranium ions at 120, 500 and 950 MeV/u irradiating copper and stainless steel targets. It was found that the isotope inventory contributing over 90% to the total activity does not depend on the projectile species, it depends only on the target material and projectile energy. This allowed establishing a scaling law for induced activity as a function of ion mass. The activity per nucleon induced by ion scales down with increasing ion mass. For example, 1 GeV/u uranium ion induces 5-times less activity per nucleon compared to 1 GeV proton. The beam-loss criteria for different projectile species are presented.

THPP088	Design Considerations for the PS2 Beam Dumps	injection, extraction, kicker, shielding	3569
	T. Kramer, M. Benedikt, B. Goddard, H. Vincke CERN, Geneva
	Studies have been made to evaluate and differentiate necessary beam disposal functions for the proposed PS2 accelerator. The paper describes briefly the different beam dump functionalities required for the PS2 machine and its transfer lines, and makes some first estimates about the expected beam loads. This data has been taken as input for comparing the different technical options for the dump systems, in particular to simulate the radiological impact of different internal or external beam dump concepts. The numbers derived have been used to help in evaluating the feasibility of the technical alternatives.

THPP096	Injection Optimisation on the ISIS Synchrotron	injection, synchrotron, closed-orbit, betatron	3587
	B. Jones, D. J. Adams, C. M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon
	The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. At its core is a 50 Hz proton synchrotron which, as the commissioning of a new dual harmonic RF system concludes, can accelerate 3.75·10¹³ protons per pulse from 70 to 800 MeV, delivering a mean beam power of 0.24 MW. The multi-turn charge-exchange injection process strongly affects transverse beam distributions, space charge forces and beam loss, which ultimately limits operational intensity. The evolution of longitudinal distributions and subsequent trapping efficiency is also intimately linked with injection. Optimising injection is therefore a key consideration for present and future upgrades. This paper summarises injection studies including 2D space-charge simulations of the ISIS injection process using the ORBIT code. Comparisons of simulation results with measurements for a range of beam intensities are presented and an assessment is made of a correlated painting scheme in contrast to the usual anti-correlated configuration.

THPP098	Simulations on a Beam Transport System for the Frankfurt Funneling Experiment	rfq, ion, ion-source, resonance	3593
	P. Kolb, N. Mueller, A. Schempp IAP, Frankfurt am Main
	The goal of the Frankfurt Funneling Experiment is to multiply beam currents by mergeing two low energy ion beams. Our setup consists of two ion sources, a two beam RFQ accelerator, a multigap deflector and a beam diagnostics. Current work is the design of a new beam transport between RFQ accelerator and deflector and first simulations will be presented.

THPP100	Development of New Ion Sources for the Frankfurt Funneling Experiment	ion, ion-source, emittance, rfq	3596
	N. Mueller, U. Bartz, P. Kolb, A. Schempp IAP, Frankfurt am Main
	Funneling is a method to increase beam currents in several stages. The Frankfurt Funneling Experiment is a prototype of such a stage. The experimental setup consists of two ion sources with electrostatic lens systems, a Two-Beam RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ and the last parts of the RFQ electrodes achieve a 3d focus at the crossing point of the two beam axis. A funneling deflector combines the bunches to a common beam axis. The newly optimized ion sources are adapted to the front end bunching section. First results and measurements will be presented.

THPP101	Investigation of Lifetime of the Electronics and the Fiber Optics inside the Niche and the Tunnel in the Slow Extraction Area of SIS100	extraction, ion, antiproton, optics	3599
	A. B. Plotnikov, E. Mustafin, N. Pyka, P. J. Spiller GSI, Darmstadt
	The loss of ions in the slow extraction area of the SIS100 accelerator project at FAIR can be dangerous for the electronic equipment and fiber optics situated inside the tunnel and niches around. During the slow extraction lost ions irradiate the yoke of the quadrupole magnets and collimator and produce a neutrons flux, which can damage or make single event upset at the electronic devices. Also fiber optic cores fade under the action of irradiation. In the current work the investigation of the dose distribution and neutron fluxes, as well as the calculation of the lifetime of the electronics and fiber optics in different places of the tunnel have been done. By using these results the design of the niches and shielding is planned.

THPP111	A 250 kHz Chopper for Low Energy High Intensity Proton Beams	kicker, proton, rfq, septum	3623
	C. Wiesner, L. P. Chau, M. Droba, O. Meusel, U. Ratzinger IAP, Frankfurt am Main
	A neutron pulse with 1 ns pulse length and a repetition rate of 250 kHz is needed for the experiments on nuclear astrophysics using the Frankfurter Neutron source at the Stern-Gerlach-Zentrum. The time structure of the neutron flux is given by the primary proton beam witch hits a 7Li target. The creation of the required time structure on an intense proton beam of 200 mA dc with respect to emittance growth and beam losses is demanding. The pulsing of the ion source depends on the rise time of the plasma whereas the pulsing of the extraction voltage leads into high power deposition into the multi aperture extraction system. On the other hand a chopper system downstream of the RFQ results in rf power consumption due to beam loading and the problem of beam dumping at a beam power of several kW. Therefore it is planed to install a chopper as part of a resonant circuit in the LEBT – section consisting of four solenoids. Two different methods, magnetic and electric deflection, will be discussed with respect to emittance growth, beam losses and the influence on space charge compensation processes. Numerical simulations and preliminary results of experiments will be presented and compared.

THPP114	LHC Transverse Feedback Damping Efficiency	feedback, damping, injection, octupole	3632
	G. Kotzian, W. Höfle CERN, Geneva E. Vogel DESY, Hamburg
	A simulation model has been developed to predict the damping efficiency of the LHC transverse feedback system in the presence of coupled bunch instabilities and under realistic assumptions for the injection error. The model tracks both the centre of gravity of a bunch and the r.m.s beam size during and after injection. It includes the frequency characteristic of the transverse feedback system. Nonlinearities in the beam optics will cause the bunches to filament and lead to an increase of the transverse emittance after injection. The resistive wall instability reduces the effectiveness of the transverse feedback by slowing down the damping process. Possibilities for enhancing the performance of the feedback system by signal processing schemes are outlined.

THPP128	Failure Mechanisms of Power Systems in Particle Accelerator Environments and Strategies for Prevention	radiation, power-supply, shielding, proton	3661
	S. Sandler, C. Hymowitz AEI, Los Angeles
	This paper discusses the mechanisms that cause degradation and failure in DC-DC converters destined for high radiation and magnetic field environments, particularly those encountered in accelerators. Failure mechanisms discussed include transformer saturation, loss of PWM control, and power supply turn-off. Degradation mechanisms that produce circuit performance outages include circuit parameter drift in Mosfets due to temperature and Vgsth reduction. Environmentally induced drift of current limit, voltage references, and switching performance are also presented. The author’s background in worst case analysis of Space based power supplies gives them particular insight into the radiation impact, assessment, and mitigation of such phenomenon. A variety of techniques for identifying and reducing the probability of these failures are presented. Methods include analysis based strategies, modified switching timing and control, improved gate drive circuitry, proper component selection, and appropriate shielding. Results are provided for a 3kW supply developed for the LHC at CERN using COTS in an 45kRAD TID, 7.7·10¹² neutron fluence, and 300 Gauss magnetic field environment.

FRXBGM01	Impedance Computation and Measurement in Modern Storage Rings	impedance, storage-ring, kicker, single-bunch	3728
	R. Nagaoka SOLEIL, Gif-sur-Yvette
	Recent progress in the evaluation of machine impedance and instability thresholds will be reviewed, and comparisons made between measurements and predicted impedance in recently commissioned storage rings.
	Slides

FRYBGM01	The Challenge of Climate Simulation and Prediction		3739
	A. Navarra CMCC, Bologna
	The recently acquired capability of mankind to change our environment is posing unprecedented issues for complexity and outreach. Climate change is also strongly science-based. The base for this debate is rooted in sophisticated scientific arguments derived by using advanced numerical methods and techniques. This fact poses a special responsibility on the climate scientific community: we have to respond to society demands for information that has to be accurate, honest and timely. We can easily convince ourselves of the extreme complexity of the climate system, a system that contains unknown or poorly known processes, strong nonlinear interactions that enhance sensitivity to small perturbation. How is it possible a quantitative scientific consideration of such a system? This is the great challenge that climate science is facing today, to obtain a scientific method that will produce assessments that will be reliable, consistent and quantitative. The numerical approach to climate will be presented with a review of recent results and a critical assessment of its potential and limitations.
	Slides