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bunching

                                      
Paper Title Other Keywords Page
MOPKF055 A Study of CSR Induced Microbunching Using Numerical Simulations injection, wiggler, booster, cathode 434
 
  • M.A. Bowler, H.L. Owen
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Microbunching due to Coherent Synchrotron Radiation (CSR) has been predicted for high density bunches and has been 'observed' using numerical simulations by the code ELEGANT of M. Borland, which includes a 1D model of CSR. However, there is currently a debate as to whether this micro-bunching is a real physical effect or is a numerical artefact, possibly introduced by having to use macro-particles to model the electrons. In particular, the amplitude of the micro-bunching diminishes as the number of macroparticles increases, but the question remains open as to whether the amplitude converges to zero or a finite value. The micro-bunching produced by ELEGANT is being studied as a function of the numerical parameters of the code and also as a function of the range of bunch parameters and bending magnet strengths of relevance to the 180 degree bending arcs required for the proposed 4GLS at Daresbury Laboratory. Calculations with up to 2 million macroparticles have been carried out on a Linux workstation using gaussian bunches of FWHM of 2psec and charge of 1 nC, and show the existence of microbunching at the end of a 180 degree arc containing 5 TBA cells with magnet strengths of 0.5T. Further investigation of this problem is required.  
 
MOPKF056 Injector Design for the 4GLS Energy Recovery Linac Prototype injection, wiggler, cathode, gun 437
 
  • C. Gerth, F.E. Hannon
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Daresbury Laboratory has been given funding for the construction of an Energy Recovery Linac Prototype (ERLP) that operates at a target electron beam energy of 35 MeV and drives an IR oscillator FEL. The ERLP serves as a test-bed for the study of beam dynamics and accelerator technology important for the design and construction of the proposed 4th Generation Light Source (4GLS). A key component of the ERLP is a high-brightness injector. The injector consists of a DC photocathode gun, which is currently being built at Daresbury Laboratory and based on the design of the gun for the IR demonstrator FEL at Thomas Jefferson National Accelerator Facility. The gun section is followed by a conventional buncher cavity, a super-conducting booster and a transfer line to the main linac. In this paper, the design of the ERLP injector is discussed. The performance of the injector has been studied using the particle tracking code ASTRA.  
 
MOPKF058 Construction of an APPLE-II Type Undulator at Daresbury Laboratory for the SRS injection, wiggler, cathode, gun 440
 
  • F.E. Hannon, J.A. Clarke, C. Hill, A.A. Muir, D.J. Scott, B.J.A. Shepherd
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  A new variable polarisation undulator of the APPLE-II type has been designed and constructed at Daresbury Laboratory. Testing of the 56mm period device has recently started in the new Magnet Test Facility at Daresbury Laboratory. This paper presents the magnetic and mechanical design of the undulator, and the first magnetic measurement results.  
 
MOPKF059 Magnet Specification for the Daresbury Laboratory Energy Recovery Linac Prototype wiggler, cathode, gun, insertion 443
 
  • N. Thompson, N. Marks
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Daresbury Laboratory has funding for the design and construction of an Energy Recovery Linac (ERL) prototype to facilitate the R&D necessary for the 4th Generation Light Source (4GLS). In the prototype a 35MeV electron beam will be used to drive an Infra-Red Oscillator Free-Electron Laser. The ring consists of two 180°; triple bend achromats, two straight sections, an injection chicane, an extraction chicane and two bunch compression/decompression chicanes. A number of pre-existing magnets will be used in the ring so the new magnets have been designed to ensure compatibility with the existing designs, enabling common power supply, vacuum and control system specifications. This paper gives an overview of the magnet requirements for the facility and details of the engineering realisation.  
 
MOPKF060 Space Charge Effects for the ERL Prototype at Daresbury Laboratory wiggler, cathode, gun, insertion 446
 
  • B.D. Muratori, C. Gerth
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. Vinokurov
    BINP SB RAS, Novosibirsk
  Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will operate at a beam energy of 35 MeV. In this paper we examine the Space Charge effects on the beam dynamics in the ERLP injector line. This is done in two distinct ways. The first is based on an analytic formula derived by Vinokurov through the envelope equations and a Kapchinsky-Vladimirsky (KV) distribution. This formula gives a rough estimate of the space charge effects in the case that no quadrupoles or dipoles are present in the injector line. The second estimate is given by the multi-particle tracking code ASTRA for the whole injector line both with and without quadrupoles. Both methods are compared and are found to be in good agreement. Typical examples of injector lines are given together with specific calculations for the ERLP.  
 
MOPKF061 Optics Layout for the ERL Prototype at Daresbury Laboratory wiggler, cathode, gun, insertion 449
 
  • B.D. Muratori, H.L. Owen, J.A. Varley
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The overall optics for the Energy Recovery Linac Prototype (ERLP) at Daresbury Laboratory is summarised. This includes the layout of the injector line, all chicanes used, as well as details of both the outward and return TBA arcs. The tunability in several sections of the machine is examined under different operational modes and starting parameters from the end of the booster to the dump.  
 
MOPKF062 Choice of Arc Design for the ERL Prototype at Daresbury Laboratory wiggler, cathode, gun, insertion 452
 
  • H.L. Owen, B.D. Muratori
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The choice of arc design for the Energy Recovery Linac Prototype (ERLP) to be built at Daresbury Laboratory is investigated. Both the overall merits and disadvantages of a TBA arc and Bates bend are considered, and space restrictions particular to Daresbury Laboratory given. Some magnet parameters are given together with a summary of the layout of the ERLP.  
 
MOPKF063 4GLS and the Prototype Energy Recovery Linac Project at Daresbury wiggler, cathode, gun, insertion 455
 
  • M.W. Poole, E.A. Seddon
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The 4GLS project is a novel next generation solution for a UK national light source proposed to be sited at Daresbury. It is based on an energy recovery linac (ERL) operating at high average beam currents up to 100mA and with compression schemes producing pulses in the 10-100 fs range. This would provide a unique spontaneous emission source with high average brightness output both from undulators and bending magnets. In addition to this operating regime a high peak current mode would also be possible at lower duty cycle, enabling a high gain FEL amplifier to generate XUV radiation. Longer wavelength FELs are also planned. This challenging accelerator technology, new to Europe, necessitates a significant R&D programme and as a major part of this a low energy prototype, the ERLP, is being constructed at Daresbury. The paper summarises the ERLP design specification, describes the component solutions adopted and explains the 4GLS project status and plans.  
 
MOPKF064 Design Considerations for a Helical Undulator for the Production of Polarised Positrons for TESLA wiggler, cathode, gun, insertion 458
 
  • D.J. Scott, S.C. Appleton, J.A. Clarke, B. Todd
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • E. Baynham, T.W. Bradshaw, S.C. Carr, Y. Ivanyushenkov, J. Rochford
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  An efficient and simple method for the production of positrons, in the necessary quantities, is one of the problems facing proposals for any future e+ e- Linear Collider project. The possibility of colliding polarised beams would also be an advantage. One method to produce a polarised positron beam uses circularly polarised radiation generated by the main electron beam passing through a helical undulator. Design considerations and calculations for two undulators, based on super-conducting and pure permanent magnet technologies, for the TESLA machine, are presented.  
 
MOPKF065 Magnet Block Sorting for Variably Polarising Undulators wiggler, cathode, gun, insertion 461
 
  • D.J. Scott
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  Effective sorting of permanent magnet blocks for undulators can reduce the adverse effects of magnetic in-homogeneities and engineering tolerances on the electron beam. For variably polarising undulators the number of different modes of operation make defining the objective function of a particular permutation more difficult than for a planar device. Factors required in defining a good objective function for a new APPLE-II type helical undulator for the SRS are discussed. These factors include calculating the magnetic field integrals, the particle trajectory and rms optical phase error. The effects of different weighting of these functions in the objective function are also discussed. A comparison of different optimisation techniques, including simulated annealing and Monte Carlo methods is also made.  
 
MOPKF066 Magnetic Design of a Focusing Undulator for ALPHA-X undulator, wiggler, cathode, gun 464
 
  • B.J.A. Shepherd, J.A. Clarke
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  ALPHA-X is a four-year project shared between several research groups in the UK to build a laser-plasma accelerator and produce coherent short-wavelength radiation in an FEL. The FEL undulator will be a 1.5m long, 100 period permanent magnet device with a minimum gap of 3.5mm and a peak field of 0.7T. To focus the beam inside the undulator, several schemes were examined. In the scheme that was selected, the magnet blocks are designed so that the pole face is an approximation of a parabola. This focuses the beam horizontally and vertically. The magnetic design of the undulator is complete; design of the support structure is well under way. Test pieces have been built to ensure that the clamping arrangement is strong enough to cope with the magnetic forces involved. The complete undulator will be built in late 2004 at Daresbury Laboratory, and tested on-site in the new magnet test facility.  
 
MOPKF067 Comparison of Different Buncher Cavity Designs for the 4GLS ERLP undulator, wiggler, cathode, gun 467
 
  • E. Wooldridge, C.D. Beard, C. Gerth
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • A. Buechner
    FZR/FWFE, Dresden
  A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) currently built at Daresbury Laboratory. A buncher is required for the ERLP to decrease the bunch length off the gun. Three different single-cell cavity designs were investigated: The Cornell buncher, the Elbe Buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CST's Microwave Studio and ASTRA. The fundamental frequency and field pattern was investigated in Microwave Studio. The EU cavity had to be scaled from 500MHz as the required frequency for the buncher is 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.  
 
MOPKF068 Experimental Study of the Stability Margin with Beam Heating in a Short-Period Superconducting Undulator for the APS undulator, wiggler, cathode, gun 470
 
  • S.H. Kim, C. Doose, R. Kustom, E.R. Moog, K.M. Thompson
    ANL/APS, Argonne, Illinois
  A superconducting undulator with a period of 15 mm is under development at the Advanced Photon Source (APS). The undulator is designed to achieve a peak field on the beam axis of 0.8 T with an 8 mm pole tip gap and an NbTi coilpack current density of 1 kA/mm2. Because of the high current density in the coilpack, the superconducting magnet operates at about 75% of the short sample limit at 4.2K. Additional heat load to the coilpack, mainly due to the image currents and synchrotron radiation from the electron beam in the storage ring, will reduce the stability margin. An experiment was conducted to measure the reduction in the stability margin of the coilpack due to heat load on the beam chamber. The heat load was deposited in a 12-period prototype undulator using thin-film heaters attached to the inner surface of a simulated vacuum chamber. Evaluation of the stability margin based on the experiment and calculations of the beam heating and thermal conduction between the undulator and beam chamber will be discussed.  
 
MOPKF069 Engineering Design of the LUX Photoinjector undulator, wiggler, cathode, gun 473
 
  • J.W.  Staples, S.P. Virostek
    LBNL, Berkeley, California
  • S.M. Lidia
    LBNL/AFR, Berkeley, California
  The photoinjector for the LBNL LUX project, a femtosecond-regime X-ray source, is a room-temperature 1.3 GHz 4-cell structure producing a 10 MeV, nominal 30 psec, 1 nanocoulomb electron bunch at a 10 kHz rate. The first cell is of reentrant geometry, with a peak field of 64 MV/m at the photocathode surface, the geometry of which will be optimized for minimum beam emittance. The high repetition rate and high peak power results in a high average surface power density. The design of the cavity, its cooling structure and power couplers, is coordinated with the configuration of the RF system, including a short, high-power driving pulse and active removal of stored energy after the beam pulse to reduce the average power dissipated in the cavity. An RF and thermal analysis will be presented, along with plans for a high average and peak power test of the first cell.  
 
MOPKF070 Design of Injector Systems for LUX undulator, wiggler, cathode, insertion 476
 
  • S.M. Lidia
    LBNL/AFR, Berkeley, California
  The LUX concept [1] for a superconducting recirculating linac based ultrafast x-ray facility features a unique high-brightness electron beam injector. The design of the injector complex that meets the baseline requirements for LUX are presented. A dual-rf gun injector provides both high-brightness electron beams to drive the cascaded, seeded harmonic generation VUV-soft x-ray FELs as well as the ultra- low-vertical emittance ('flat') beams that radiate in hard x-ray spontaneous emission synchrotron beamlines. Details of the injector complex design and performance characteristics are presented. Contributions by the thermal emittance and optical pulse shaping to the beam emission at the photocathode and to the beam dynamics throughout the injector are presented. Techniques that seek to optimize the injector performance, as well as constraints that prevent straightforward optimization, are discussed.  
 
MOPKF071 Study of Row Phase Dependent Skew Quadrupole Fields in Apple-II type EPUs at the ALS undulator, wiggler, cathode, insertion 479
 
  • C. Steier, S. Marks, S. Prestemon, D. Robin, R.D. Schlueter, A. Wolski
    LBNL, Berkeley, California
  Since about 5 years, Apple-II type Elliptically Polarizing Undulators (EPU) have been used very successfully at the ALS to generate high brightness photon beams with arbitrary polarization. However, both EPUs installed so far cause significant changes of the vertical beamsize, especially when the row phase is changed to change the polarization of the photons emitted. The effect has been measured in detail and turned out to be caused by a row phase dependent skew quadrupole term in the EPUs. Magnetic measurements revealed the same effect for the third EPU to be installed later this year. All measurements to identify and quantify the effect with beam will be presented, as well as results of magnetic bench measurements and numeric field simulations.  
 
MOPKF072 Towards Attosecond X-ray Pulses from the FEL undulator, wiggler, cathode, laser 482
 
  • A. Zholents, J.M. Byrd, W. Fawley, Z. Hao, M.C. Martin, D. Robin, F. Sannibale, R.W. Schoenlein, M. Venturini, M.S. Zolotorev
    LBNL, Berkeley, California
  The ability to study ultrafast phenomena has been recently advanced by the demonstrated production and measurement of a single, 650-attosecond, soft x-ray pulses precisely synchronized to the pump laser pulse consisted of just few optical cycles. The next frontier is a production of attosecond x-ray pulses at even shorter wavelengths. Here we propose the method of ?seeded attosecond x-ray radiation? where an isolated, attosecond duration, short-wavelength x-ray pulse is radiated by electrons selected by their previous interaction with a few-cycle, intense laser pulse. In principle this method allows excellent synchronization between the attosecond x-ray probe pulse and a pump source that can be the same few-cycle laser pulse or another signal derived from it.  
 
TUPLT133 Test Results of Injector Based on Resonance System with Evanescent Oscillations linac, booster, optics, injection 1437
 
  • S.A. Perezhogin, M.I. Ayzatskiy, E.Z. Biller, K. Kramarenko, V.A. Kushnir, V.V. Mytrochenko, Z.V. Zhiglo
    NSC/KIPT, Kharkov
  Report presents results of tune-up and tests of the compact electron S ? band injector consisting of the low-voltage diode electron gun and the bunching system based on the resonant system with the evanescent oscillation. In the considered bunching system electrical field increased from beam entrance to an exit of the buncher. The injector designed for bunching of electron beam with initial energy of 25 keV and pulse current of 300 mA and accelerating it to the energy of 1 MeV.  
 
TUPLT134 Lattice of NSC KIPT Compact Intense X-ray Generator NESTOR linac, electron, booster, optics 1440
 
  • A.Y. Zelinsky, P. Gladkikh, I.M. Karnaukhov, V. Markov, A. Mytsykov, A.A. Shcherbakov
    NSC/KIPT, Kharkov
  The new generation of the intense X-rays sources based on low energy electron storage ring and Compton scattering of laser beam allows to produce X-rays with intensity up to 1014 phot/s. One of the main traits of a storage ring lattice for such generator type is using of magnetic elements with combined focusing functions such as bending magnets with quadrupole and sextupole field components. In combination with very low bending radius and dense magnetic elements setting along ring circumference it leads to increasing of 3D magnetic field effects on electron beam dynamics and can decrease generated radiation intensity drastically. For the reasons of very low electron beam size at the interaction point and strong focusing in a compact storage ring the questions of determination of accuracy of bending magnet is very important too. The paper is devoted to the description of lattice of NSC KIPT Compact X-ray generator NESTOR. The results of investigations of the effects of 3D magnetic field and harmonic compound due to manufacture errors of bending magnets, bending magnet and lenses edges on electron beam dynamics are presented.  
 
TUPLT136 Proton Beam Line for the ISIS Second Target Station target, linac, electron, booster 1443
 
  • D.J. Adams
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, is an intense pulsed source of Muons and Neutrons used for condensed matter research. The accelerator facility delivers an 800 MeV proton beam of 2.5x1013 protons per pulse at 50 Hz. As part of the facility upgrade, which includes increasing the source intensity to 3.7x1013 protons per pulse using a dual harmonic RF system, it is planned to share the source with a second, 10 Hz, target station. A beam line supplying this target will extract from the existing target station beam line. Measurements and models characterising the optical functions around the extraction point of the existing line are discussed. The optical design, diagnostics and beam correction systems for second target station beam line are presented.  
 
TUPLT137 Comparative Simulation Studies of Electron Cloud Build-up for ISIS and Future Upgrades target, linac, optics, injection 1446
 
  • G. Bellodi
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  Electron cloud effects currently limit the performance of several proton accelerators operating with high beam current. Although ISIS, the 160 kW 70-800 MeV proton synchrotron at the Rutherford Appleton Laboratory (UK), has never appeared to be affected by the problem in its 15 years of operations, e-p instabilities could potentially be a cause of concern for future machine upgrades to higher beam powers. In this paper we review the present status of simulations for ISIS and compare it to preliminary results for two upgrade options: a 0.5MW 180-800 MeV scheme and a 1MW 0.8-3 GeV scheme with an additional synchrotron using ISIS as a booster (see C. Prior et al., ISIS megawatt upgrade plans, in Proceedings of the 2003 Particle Accelerator Conference PAC 2003, Portland, Or, USA).  
 
TUPLT138 A Fast Beam Chopper for Next Generation High Power Proton Drivers target, optics, injection, focusing 1449
 
  • M.A. Clarke-Gayther
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  The identification and development of a successful beam chopper design is regarded as key for the European Spallation Source (ESS), and for all next generation high intensity proton driver schemes that adopt the linac-accumulator ring configuration. A description is given of refinements to the beam line design of a 'Tandem' chopper system, developed to address the requirements of the ESS. Particle tracking using the 'General Particle Tracer' (GPT) code has enabled efficient optimisation of beam apertures, and the analysis of beam power density distributions on chopper beam dumps. Preliminary results of 'proof of principle' testing on prototype fast, and slower transition high voltage pulse generators, are presented.  
 
TUPLT139 Extending the Duty Cycle of the ISIS H Minus Ion Source, Thermal Considerations target, optics, injection, ion 1452
 
  • D.C. Faircloth, J.W.G. Thomason
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  The ISIS H minus ion source is currently being developed on the Ion Source Development Rig (ISDR) at Rutherford Appleton Laboratory (RAL) in order to meet the requirements for the next generation of high power proton drivers. One key development goal is to increase the pulse width and duty cycle, but this has a significant effect on ion source temperatures if no other changes are made. A Finite Element Analysis (FEA) model has been produced to understand the steady state and dynamic thermal behavior of the source, and to investigate the design changes necessary to offset the extra heating.  
 
TUPLT140 Redesign of the ISIS Main Magnet Power Supply Storage Choke target, optics, injection, ion 1455
 
  • A.J. Kimber, J.W. Gray, A. Morris
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  The ISIS facility, based at the Rutherford Appleton Laboratory in the UK, provides intense pulsed neutron and muon beams for condensed matter studies. As part of the facilities upgrade and refurbishment program, the 1MJ storage choke which forms part of the main magnet power supply system, will be replaced with a number of smaller units. The present storage choke, which consists of a split secondary winding transformer, is incorporated into a series-parallel resonant circuit known as the 'white circuit'. This circuit ensures that each magnet receives identical currents, but is not subjected to excessive voltages. Although the storage choke is essentially a transformer, its secondary magnetising inductance is relatively low and a precisely defined value. This paper discusses the design and development of ten smaller units which will eventually replace the present equipment, and the testing of a one fifth scale model, which will be used to prove the technology.  
 
TUPLT141 The Effect of Extraction Geometry on the Measured ISIS H Minus Ion Source Beam target, injection, beamloading, lattice 1458
 
  • J.W.G. Thomason, D.C. Faircloth, R. Sidlow, C.M. Thomas, M. Whitehead
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  Recent Finite Element Analysis (FEA) electromagnetic modelling of the extraction region of the ISIS H minus source has suggested that the present set up of extraction electrode and 90 degree sector magnet is sub-optimal, with the result that the beam profile is asymmetric, the beam is strongly divergent in the horizontal plane and there is severe aberration in the focusing in the vertical plane. The FEA model of the beam optics has demonstrated that relatively simple changes to the system should produce a dramatic improvement in performance. These changes have been incorporated on the Ion Source Development Rig (ISDR) at Rutherford Appleton Laboratory (RAL), and their effects on the H minus beam are presented here.  
 
TUPLT142 Status of Design of Muon Beamline for the Muon Ionisation Cooling Experiment target, injection, beamloading, lattice 1461
 
  • K. Tilley
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  The MICE collaboration proposes to install a Muon Ionisation Cooling Experiment at the ISIS facility, at Rutherford Appleton Laboratory. This experiment will be the first demonstration of ionisation cooling as a means to reduce the large transverse emittance of the muon beam, produced during the early stages of a neutrino factory. In order to permit a realistic demonstration of cooling, a source of muons must be produced, possessing particular qualities, notably in emittance and momenta. This paper describes the present design for the muon beamline source, and the plans for its implementation at RAL.  
 
TUPLT143 Studies of Beam Loss Control on the ISIS Synchrotron target, injection, beamloading, lattice 1464
 
  • C.M. Warsop
    CCLRC/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. The ISIS 800 MeV Proton Synchrotron presently provides up to 2.5·1013 protons per pulse at 50 Hz, corresponding to a mean power of 160 kW. A dual harmonic RF system upgrade is expected to increase the intensity and power by about 50%. The tighter constraints expected for higher intensity running are motivating a detailed study of beam loss distributions and the main factors affecting their control. Main aims are maximising the localisation of activation in the collector straight, and minimising risk of damage to machine components. The combination of experimental work, developments of the loss measurement systems, and simulation studies are summarised. Key factors considered include: the effects of primary collector geometry and material; the nature of the beam loss; and methods for experimentally determining spatial loss distributions.  
 
TUPLT144 Upgrade of the ISIS Main Magnet Power Supply target, injection, beamloading, lattice 1467
 
  • S. West, J.W. Gray, A. Morris
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  ISIS, situated at the Rutherford Appleton Laboratory (RAL) is the world?s most powerful pulsed neutron source. At the heart of the ISIS accelerator is a proton synchrotron which uses a ring of magnets connected in series and configured as a ?White Circuit?. The magnets are connected in series with capacitor banks so that they form a resonant circuit with a fundamental frequency of 50 Hz. The circuit allows the magnets to be fed with an AC current superimposed on a DC current. The AC is currently provided by a 1MVA Motor-Alternator set and it is now proposed to replace this by a solid state UPS (Uninterruptible Power Supply) system. Tests on a smaller 80kVA unit have shown that it is possible to control the magnet current with a modified UPS system in such a way that both the frequency, phase and output voltage are under the direct influence of the control system. This paper discusses the issues surrounding the upgrading of AC supply to the main magnets with a view to improving the system reliability, improving magnet current stability and reducing the risk of mains failure.  
 
TUPLT145 Transverse Coupling Measurement using SVD Modes from Beam Histories target, injection, beamloading, antiproton 1470
 
  • C.-X. Wang
    ANL, Argonne, Illinois
  • R. Calaga
    BNL, Upton, Long Island, New York
  In this report we investigate the measurement of local transverse coupling from turn-by-turn data measured at a large number of beam position monitors. We focus on a direct measurement of coupled lattice functions using the Singular Value Decomposition (SVD) modes and explore the accuracy of this method. The advantages and shortcomings of this model-independent method for coupling measurement will be also discussed.  
 
TUPLT146 Techniques to Extract Physical Modes in Model-independent Analysis of Rings target, injection, beamloading, antiproton 1473
 
  • C.-X. Wang
    ANL, Argonne, Illinois
  SVD mode analysis is a basic techinique in Model-Independent Analysis of beam dynamics. It decomposes the spatial-temporal variation of a beam centroid into a small set of orthogonal modes based on statistical analysis. Although such modes have been proven to be rather informative, each orthogonal mode may not correspond to an individual physical source but a mix of several in order to be orthogonal. Such mixing makes it difficult to quantitatively understand the SVD modes and thus limits their usefulness. Here we report a new techinique to untangle the mixed modes in storage ring analysis based on the fact that most of the physical modes in a ring have identifiable characteristics in frequency domain.  
 
TUPLT147 Multiple-charge-state Beam Steering in High-intensity Heavy-ion Linacs target, injection, beamloading, antiproton 1476
 
  • E.S. Lessner, P.N. Ostroumov
    ANL/Phys, Argonne, Illinois
  An algorithm suitable for correction to steering of multiple-charge-state beams in heavy-ion linacs operating at high currents has been developed [*]. It follows a four-dimensional minimization procedure that includes coupling of the transverse beam motions. A major requirement is that it obeys the restricted lattice design imposed by the acceleration of multiple-charge-state heavy-ion beams [**]. We study the algorithm efficiency in controlling the beam effective emittance growth in the presence of random misalignments of cavities and focusing elements. Limits on misalignments are determined by quantifying beam losses and effective steering requirements are selected by examining several correcting schemes within the real-state constraints. The algorithm is used to perform statistically significant simulations to study beam losses under realistic steering.

* E. S. Lessner and P. N. Ostroumov, Proc. Part. Accel. Conf. (2003)** P. N. Ostroumov, Phys. Rev. STAB Vol. 5, 0030101 (2002)

 
 
TUPLT149 Beam Manipulation and Compression Using Broadband RF Systems in the Fermilab Main Injector and Recycler target, injection, beamloading, antiproton 1479
 
  • G.W. Foster, C.M. Bhat, B. Chase, J.A. Mac Lachlan, K. Seiya, P. Varghese, D. Wildman
    Fermilab, Batavia, Illinois
  Successful tests of new method for beam manipulation, compression, and stacking using the broadband RF systems in the Fermilab Recycler and Main Injector are described. Under usual conditions an unbunched beam can be confined to a fraction of the azimuth of the ring by a set of "Barrier Pulses" which repel particles trying to escape from the ends of the segment of beam. One way to compress or expand the azimuthal extent of the segment of beam is to slowly change the distance between barrier pulses. However when it is desired to rapidly compress or expand the length of the segment, a linear ramp can be superimposed on the waveform between barrier pulses. This causes particles at the front and back of the beam segment to be accelerated or decelerated by differing amounts, and the velocity correlation along the length of the beam segment causes it to expand or contract. When the expansion or contraction is halfway completed, the ramp voltage is reversed so the all particles will come relatively to rest at the end of the process. With the Barrier pulses following appropriately, no particles leak out the ends of the beam segment and the emittance is preserved.  
 
TUPLT150 Vector Sum Control of an 8 GeV Superconducting Proton Linac target, injection, beamloading, antiproton 1482
 
  • M. Huening, G.W. Foster
    Fermilab, Batavia, Illinois
  Fermilab is investigating the feasibility of an economical 8 GeV superconducting linac for H-. In order to reduce the construction costs it is considered to fan out the rf power to a string of accelerating structures per klystron. Below 1 GeV the individual fluctuations of the cavities will be compensated by high power phase shifters, above 1 GeV the longitudinal dynamics are sufficiently damped to consider omitting the phaseshifters. The impact of this setup on the field stability of individual cavities and ultimately the beam energy has been studied.  
 
TUPLT151 Status of the Fermilab Electron Cooling Project electron, target, injection, beamloading 1485
 
  • J.R. Leibfritz, D.R. Broemmelsiek, A.V. Burov, K. Carlson, B. Kramper, T. Kroc, M. McGee, S. Nagaitsev, L. Nobrega, G. Saewert, C.W. Schmidt, A.V. Shemyakin, M. Sutherland, V. Tupikov, A. Warner
    Fermilab, Batavia, Illinois
  • G. Kazakevich
    BINP SB RAS, Novosibirsk
  • S. Seletsky
    Rochester University, Rochester, New York
  Fermilab has constructed and commissioned a full-scale prototype of a multi-MV electron cooling system to be installed in the 8.9 GeV/c Fermilab Recycler ring. This prototype was used to test all of the electron beam properties needed for cooling. However, because the prototype is not located within proximity of the Recycler ring, the actual electron cooling of antiprotons can not be demonstrated until it is relocated. The Fermilab electron cooling R&D project is scheduled to be completed in May, 2004 at which time it will be disassembled and relocated to a newly constructed facility where it will be installed in the Recycler. This paper describes the experimental results obtained with the prototype cooler system, gives an overview of the new electron cooling facility, and discusses the overall status of the project.  
 
TUPLT153 Orbit Response Matrix Analysis Applied at PEP-II electron, target, lattice, injection 1488
 
  • C. Steier, A. Wolski
    LBNL/AFR, Berkeley, California
  • S. Ecklund, J.A. Safranek, P. Tenenbaum, A. Terebilo, J.L. Turner, G. Yocky
    SLAC, Menlo Park, California
  Beam-based techniques to study lattice properties have proven to be a very powerful tool to optimize the performance of storage rings. The analysis of orbit response matrices has been used very successfully to measure and correct the gradient and skew gradient distribution in many accelerators. The first applications were mostly in synchrotron light sources, but the technique is also used increasingly at colliders. It allows determination of an accurately calibrated model of the coupled machine lattice, which then can be used to calculate the corrections necessary to improve coupling, dynamic aperture and ultimately luminosity. At PEP-II, the Matlab version of LOCO has been used to analyze coupled response matrices for both the LER and the HER. The large number of elements in PEP-II and the very complicated interaction region present unique challenges to the data analysis. The orbit response matrix analysis will be presented in detail, as well as results of lattice corrections based on the calibrated machine model.  
 
TUPLT154 Aperture Studies for the Fermilab AP2 Anti-proton Line electron, injection, beamloading, antiproton 1491
 
  • I. Reichel, M. Placidi, M.S. Zisman
    LBNL, Berkeley, California
  • K. Gollwitzer, S. Werkema
    Fermilab, Batavia, Illinois
  The AP2 beamline transports anti-protons from the production target to the Debuncher ring. In the past the observed aperture has been smaller than that estimated from linear, on-energy optics. We have investigated possible reasons for the aperture limitation and have identified possible sources, including residual vertical dispersion from alignment errors and chromatic effects due to very large chromatic lattice functions. Some experiments have already been performed to study these effects. We present results of the experimental and theoretical studies and possible remedies.  
 
TUPLT156 Progress in Ideal High-intensity Unbunched Beams in Alternating Gradient Focusing Systems electron, focusing, injection, beamloading 1494
 
  • R. Bhatt, C. Chen, J. Zhou
    MIT/PSFC, Cambridge, Massachusetts
  A persistent challenge in high-intensity accelerator design is the optimization of matching conditions between a beam injector and a focusing system in order to minimize non-laminar flows, envelope oscillations, emittance growth, and halo production. It has been shown [*] that the fluid motion of a thin space-charge dominated beam propagating through a linear magnetic focusing channel consisting of any combination of uniform or periodic solenoidal fields and alternating gradient quadrupole fields can be solved by a general class of corkscrewing elliptic beam equilibria. The present work extends this discussion to asymmetric PPM focusing and derives conditions under which a uniform density elliptical beam can be matched to such a focusing channel by considering the fluid equilibrium in the paraxial limit. Methods of constructing such a beam are also discussed, with particular attention devoted to analytic electrode design for Pierce-type gun diodes of elliptical cross-section. Several applications are discussed, including heavy-ion fusion and a high-efficiency ribbon beam microwave amplifier for accelerator applications.

* C. Chen, R. Pakter, R. Davidson, "Ideal Matching of Heavy Ion Beams," Nucl. Inst. And Methods, A 464 (2001) p. 518-523

 
 
TUPLT159 First Commissioning Experiments at DARHT-II focusing, injection, beamloading, antiproton 1497
 
  • C. Ekdahl, E.O. Abeyta, L. Caudill, K.C.D. Chan, D. Dalmas, S. Eversole, R.J. Gallegos, J. Harrison, M. Holzscheiter, E. Jacquez, J. Johnson, B.T. McCuistian, N. Montoya, K. Nielsen, D. Oro, L. Rodriguez, P. Rodriguez, M. Sanchez, M. Schauer, D. Simmons, H.V. Smith, J. Studebaker, G. Sullivan, C. Swinney, R. Temple
    LANL, Los Alamos, New Mexico
  • H. Bender, W. Broste, C. Carlson, G. Durtschi, D. Frayer, D. Johnson, K. Jones, A. Meidinger, K. Moy, R. Sturgess, C.-Y. Tom
    Bechtel Nevada, Los Alamos, New Mexico
  • Y.-J. Chen, T. Houck
    LLNL, Livermore, California
  • S. Eylon, W. Fawley, E. Henestroza, S. Yu
    LBNL, Berkeley, California
  • T. Hughes, C. Mostrom
    Mission Research Corporation, Albuquerque, New Mexico
  The second axis of the Dual Axis Radiographic Hydro-Test (DARHT) facility will provide up to four short(< 150 ns) radiation pulses for flash radiography of high-explosive driven implosion experiments[1]. The DARHT-II linear induction accelerator (LIA) will produce a 2-kA,18-MeV,2-micro-s electron beam. A fast kicker will cleave four short pulses out of the beam, which will focused onto a tantalum target for conversion to bremsstrahlung pulses for radiography. The first tests of the second axis accelerator were designed to demonstrate the technology, and to meet the modest performance requirements for closing out the DARHT-II construction project. These experiments demonstrated that we could indeed produce a 1.2 kA beam with pulse length 0.5-1.2 s and accelerate it to 12.5 MeV. These de-rated parameters were chosen to minimize risk of damage in these first experiments with this novel accelerator. The beam was stable to the BBU instability for these parameters. In fact, we had to reduce the magnetic guide field by a factor of 5 before any evidence of BBU was observed. We will discuss the results of these experiments and their implications, as well as our plans for continuing with DARHT-II commissioning.  
 
TUPLT160 Development of a 25-mA, 12% Duty Factor (df) H- Source for LANSCE focusing, injection, emittance, beamloading 1500
 
  • G. Rouleau, A. Arvin, E. Chacon-Golcher, E. Geros, G. Jacobson, J. Meyer, P. Naffziger, S. Schaller, J.D. Sherman, J. Stelzer, J. Zaugg
    LANL/LANSCE, Los Alamos, New Mexico
  Present operations at the Los Alamos Neutron Science Center (LANSCE) accelerator use a surface conversion source to provide 80-keV, 16 to 18-mA H- beams with typical rms normalized emittance of 0.13 (pmm-mrad). Operational flexibility of the 800-MeV linac and proton storage ring will be increased by a higher current H- source. The present goal is to achieve a 25-mA H- surface converter source with modest (10-20%) emittance increase without sacrificing the present LANSCE production source 12% df and 28 day lifetime. The LANSCE 80-kV ion source test stand (ISTS) has been brought into reliable 24-hour per day operation with computer control and modern electronics. A fourth production source has been fabricated, and is now operating on the ISTS. H- currents up to 25mA have been observed with 0.15 to 0.18(pmm-mrad) rms normalized emittances. An experimental study of surface converter geometries and electron filters at the emitter electrode are planned to optimize source current and emittance.  
 
TUPLT161 Normal Form Analysis of Linear Beam Dynamics in a Coupled Storage Ring focusing, betatron, injection, emittance 1503
 
  • M. Woodley
    SLAC/NLC, Menlo Park, California
  • A. Wolski
    LBNL/AFR, Berkeley, California
  The techniques of normal form analysis, well known in the literature, can be used to provide a straightforward characterization of linear betatron dynamics in a coupled lattice. Here, we consider both the beam distribution and the betatron oscillations in a storage ring. We find that the beta functions for uncoupled motion generalize in a simple way to the coupled case. Defined in the way that we propose, the beta functions remain well behaved (positive and finite) under all circumstances, and have essentially the same physical significance for the beam size and betatron oscillations as in the uncoupled case. Application of this analysis to the online modeling of the PEP-II rings is also discussed.  
 
TUPLT162 Computation of the Longitudinal Space Charge Effect in Photoinjectors focusing, betatron, injection, beamloading 1506
 
  • C. Limborg-Deprey, P. Emma, Z. Huang, J.J. Welch, J. Wu
    SLAC, Menlo Park, California
  The LCLS Photoinjector produces a 100A, 10 ps long electron bunch which is later compressed down to 100 fs to produce the peak current required for producing SASE radiation. SASE saturation will be reached in the LCLS only if the emittance and uncorrelated energy spread remain respectively below 1.2 mm.mrad and 5. 10-4. This high beam quality will not be met if the Longitudinal Space Charge (LSC) instability develops in the injector and gets amplified in the compressors. The Longitudinal Space Charge instability originates in the injector beamline, from an initial modulation of the current density. Numerical computations, performed with Multiparticle Space Charge tracking codes, showing the evolution of the longitudinal phase space along the LCLS Photoinjector beamline, are presented. Those results are compared with an analytical model for various regimes of energy and acceleration. This study justifies the necessity to insert a "laser heater" in the LCLS Photoinjector beamline to warm up the beam and thus prevent the amplification of the LSC instability in the compressors. Numerical calculations of the 'laser heater' performances are presented.  
 
TUPLT163 Achieving Beam Quality Requirements for Parity Experiments at Jefferson Lab focusing, electron, betatron, injection 1509
 
  • Y.-C. Chao, H. Areti, F.J. Benesch, B. Bevins, S.A. Bogacz, S. Chattopadhyay, J.M. Grames, J. Hansknecht, A. Hutton, R. Kazimi, L. Merminga, M. Poelker, Y. Roblin, M. Tiefenback
    Jefferson Lab, Newport News, Virginia
  • D. Armstrong
    The College of William and Mary, Williamsburg
  • D. Beck, K. Nakahara
    University of Illinois, Urbana
  • K. Paschke
    University of Massachusetts, Amherst
  • M. Pitt
    Virginia Polytechnic Institute and State University, Blacksburg
  Measurement of asymmetry between alternating opposite electron polarization in electron-nucleon scattering experiments can answer important questions about nucleon structures. Such experiments impose stringent condition on the electron beam quality, and thus the accelerator used for beam creation and delivery. Of particular concern to such ?parity? experiments is the level of correlation between beam characteristics (orbit, intensity) and electron polarization that can obscure the real asymmetry. This can be introduced at the beam forming stage, created due to scraping, or not damped to desired level due to defective transport. Suppression of such correlation thus demands tight control of the beam line from cathode to target, and requires multi-disciplined approach with collaboration among nuclear physicists and accelerator physicists/engineers. The approach adopted at Jefferson Lab includes reduction of correlation source, improving low energy beam handling, and monitoring and correcting global transport. This paper will discuss methods adopted to meet the performance criteria imposed by parity experiments, and ongoing research aimed at going beyond current performance.  
 
TUPLT164 CEBAF Injector Achieved World's Best Beam Quality for Three Simultaneous Beams with a Wide Range of Bunch Charges focusing, betatron, injection, beamloading 1512
 
  • R. Kazimi, K. Beard, F.J. Benesch, A. Freyberger, J.M. Grames, T. Hiatt, A. Hutton, G.A. Krafft, L. Merminga, M. Poelker, M. Spata, M. Tiefenback, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
  The CEBAF accelerator simultaneously provides three 499 MHz interleaved continuous electron beams spanning 5 decades in beam intensity (a few nA to 200 uA) to three experimental halls. The typical three-user physics program became more challenging when a new experiment, G0, was approved for more than six times higher bunch charge than is routine. The G0 experiment requires up to 8 million electrons per bunch (at a reduced repetition rate of 31 MHz) while the lowest current hall operates at 100 electrons per bunch simultaneously. This means a bunch destined to one hall may experience significant space charge forces while the next bunch, for another hall, is well below the space charge limit. This disparity in beam intensity is to be attained while maintaining best ever values in the beam quality, including final relative energy spread (<2.5x 10-5 rms) and transverse emittance (<1 mm-mrad norm. rms). The difficulties related to space charge emerge in the 10m long, 100 keV section of the CEBAF injector during initial beam production and acceleration. A series of changes were introduced in the CEBAF injector to meet the new requirements, including changes in the injector setup, adding new magnets, replacing lasers used for the photocathode and modifying typical laser parameters, stabilizing RF systems, and changes to standard operating procedures. In this paper, we will discuss all these modifications in some detail including the excellent agreement between the experimental results and detailed simulations. We will also present some of our operational results.  
 
TUPLT165 A PARMELA Model of the CEBAF Injector valid over a Wide Range of Parameters focusing, betatron, injection, beamloading 1515
 
  • Y. Zhang, K. Beard, F.J. Benesch, Y.-C. Chao, A. Freyberger, J.M. Grames, R. Kazimi, G.A. Krafft, R. Li, L. Merminga, M. Poelker, M. Tiefenback, B.C. Yunn
    Jefferson Lab, Newport News, Virginia
  A pre-existing PARMELA model of the CEBAF injector has been recently verified using machine survey data and also extended to 60 MeV region. The initial distribution and temperature of an electron bunch are determined by the photocathode laser spot size and emittance measurements. The improved injector model has been used for extensive computer simulations of the simultaneous delivery of the Hall A beam required for a hypernuclear experiment, and the Hall C beam, required for a parity experiment. The Hall C beam requires a factor of 6 higher bunch charge than the Hall A beam, with significantly increased space charge effects, while the Hall A beam has an exceedingly stringent energy spread requirement of 2.5x 10-5 rms. Measurements of the beam properties of both beams at several energies (100 keV, 500 keV, 5 MeV, 60 MeV) and several values of the bunch charge were performed using the standard quad-wire scanner technique. Comparisons of simulated particle transmission rate, longitudinal beam size, transverse emittance and twiss parameters, and energy spread against experimental data yield reasonably good agreement. The model is being used for searching for optimal setting of the CEBAF injector.  
 
TUPLT166 Beam Invariants for Diagnostics focusing, betatron, injection, beamloading 1518
 
  • V.V. Danilov, A.V. Aleksandrov
    ORNL/SNS, Oak Ridge, Tennessee
  This paper deals with some measurable quantities of beams preserved under symplectic transformations. General beam distributions have no determined area, and rms quantities of the beam do not provide invariants in general nonlinear case. It is shown, though, that in the 1D case there exist some integral and local invariants, directly linked to Liouville's theorem. Beam invariants, related to general properties of symplectic transformations, are also found and presented for 2D and 3D cases. If measured at different locations, they can tell whether the transformation is symplectic or there exist diffusion, friction, or other non-Hamiltonian dynamic processes in the beam.  
 
TUPLT167 Installation of the Spallation Neutron Source (SNS) Warm Linac focusing, linac, betatron, injection 1521
 
  • P.E. Gibson, C. Deibele, J.J. Error, G.A.J. Johnson, P. Ladd
    ORNL/SNS, Oak Ridge, Tennessee
  • N.K. Bultman
    LANL, Los Alamos, New Mexico
  The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built at Oak Ridge National Laboratory. The SNS project design and construction is a partnership involving six DOE national laboratories including Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Oak Ridge, and Los Alamos. When completed in 2006, the SNS will provide the most intense, pulsed neutron beams in the world for scientific research and industrial development. At the present time we are installing and commissioning the warm linac system, designed by Los Alamos, and have to date had good success. The warm linac is comprised of six Drift Tube Linac (DTL) tanks and four Coupled Cavity Linac (CCL) modules. These accept an incoming negative hydrogen ion beam from the Front End injector at 2.5 MeV, and accelerate to a final energy of 185 MeV. At this time we have installed and commissioned DTL tanks 1-3 and installed CCL module 1 . Experience and information gained during installation will be presented. The performance in terms of alignment, vacuum and field tuning will be described.  
 
TUPLT168 SNS Beam Commisioning Status focusing, linac, betatron, injection 1524
 
  • S. Henderson, A.V. Aleksandrov, S. Assadi, W. Blokland, C. Chu, S.M. Cousineau, V.V. Danilov, G.W. Dodson, J. Galambos, M. Giannella, D.-O. Jeon, S. Kim, L.V. Kravchuk, M.P. Stockli, E. Tanke, R.F. Welton, T.L. Williams
    ORNL/SNS, Oak Ridge, Tennessee
  The Spallation Neutron Source accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The accelerator complex consists of an H- injector capable of producing 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The linear accelerator consists of a Drift Tube Linac, a Coupled-Cavity Linac and a Superconducting Linac which provide 1.5 mA average current to the accumulator ring. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. In three separate beam commissioning runs, the H- injector and Drift Tube Linac tanks 1-3 have been commissioned at ORNL. Several important performance goals have been achieved, namely 38 mA peak beam current, 1 msec beam pulse length and 1 mA average beam current. Results and status of the beam commissioning program will be presented.  
 
TUPLT170 The SNS Beam Power Upgrade focusing, betatron, beamloading, antiproton 1527
 
  • S. Henderson, S. Assadi, R. Cutler, V.V. Danilov, G.W. Dodson, R.E. Fuja, J. Galambos, J.A. Holmes, N. Holtkamp, D.-O. Jeon, S. Kim, L.V. Kravchuk, M.P. McCarthy, G.R. Murdoch, D.K. Olsen, T.J. Shea, M.P. Stockli
    ORNL/SNS, Oak Ridge, Tennessee
  The Spallation Neutron Source (SNS) accelerator systems, which consist of an H- injector, a 1 GeV linear accelerator, an accumulator ring and associated transport lines, will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The SNS is presently under construction at Oak Ridge National Laboratory and will begin operations in 2006. Even in the baseline design, many of the accelerator subsystems are capable of supporting higher beam intensities and higher beam energy. We report on upgrade scenarios for the SNS accelerator systems which increase the 1.44 MW baseline beam power to at least 3 MW, and perhaps as high as 5 MW. The increased SNS beam power can be achieved primarily by increasing the H- ion source current, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3-1.4 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The upgrade beam parameters will be presented, the required hardware modifications will be described, and the beam dynamics implications will be discussed.  
 
TUPLT171 ORBIT Simulations of the SNS Accumulator Ring focusing, betatron, beamloading, antiproton 1530
 
  • J.A. Holmes, S.C. Bunch, S.M. Cousineau, V.V. Danilov, S. Henderson, A. Shishlo
    ORNL/SNS, Oak Ridge, Tennessee
  • M. Plum
    LANL, Los Alamos, New Mexico
  • Y. Sato
    IUCF, Bloomington, Indiana
  As SNS undergoes construction, many detailed questions arise concerning strategies for commissioning and operating the accumulator ring. The ORBIT Code is proving to be an indispensible tool for addressing these questions and for providing guidance to the physicists and decision makers as operation draws near. This paper shows the application of ORBIT to a number of ring issues including exclusion of the HEBT RF cavities during commissioning, the detailed effect of the injection chicane magnets on the beam, the effects and correction of magnet alignment and multipole errors, debunching of the linac 402.5 MHz beam structure, the injection of self consistent uniform beam configurations, and initial electron cloud simulations.  
 
TUPLT172 Measurement of Halo Mitigation Schemes for the Spallation Neutron Source Linac focusing, betatron, emittance, beamloading 1533
 
  • D.-O. Jeon
    ORNL/SNS, Oak Ridge, Tennessee
  A series of emittance measurements were performed at the end of Drift Tube Linac tank 1 of the Spallation Neutron Source to verify experimentally the previously proposed halo generation mechanism and its mitigation schemes [1]. The emittance measurements clearly showed a visible reduction in the halo as well as a significant reduction in the rms emittance when the proposed round beam optics is employed. This confirms experimentally the halo generation mechanism we identified.  
 
TUPLT173 Experimental Test of Transverse Matching Routine for the SNS Linac focusing, betatron, emittance, beamloading 1536
 
  • D.-O. Jeon, S. Assadi
    ORNL/SNS, Oak Ridge, Tennessee
  • J. Stovall
    LANL, Los Alamos, New Mexico
  Transverse matching for a high intensity linac was proposed based on minimizing rms emittances. A MATLAB routine was developed and applied during the SNS linac commissioning. The result was also compared with the simulations.  
 
TUPLT175 Operation of the SNS Ion Source at High Duty-Factor focusing, betatron, ion, beamloading 1538
 
  • R.F. Welton, T.A. Justice, S.N. Murray, M.P. Stockli
    ORNL/SNS, Oak Ridge, Tennessee
  • R. Keller
    LBNL/AFR, Berkeley, California
  The ion source for the Spallation Neutron Source* (SNS) is a radio frequency, multi-cusp, source designed to deliver ~ 45 mA of H- with a normalized rms emittance of less than 0.2 pi mm mrad to the SNS accelerator. Once the SNS is fully operational a beam current duty factor of 6% (1 ms pulse length, repetition rate of 60 Hz) will be required from the ion source. To date, the source has been utilized in the early commissioning of the SNS accelerator and has already demonstrated stable, satisfactory operation at beam currents of ~30 mA with duty factors of ~0.1% for operational periods of several weeks. This work summarizes the results of a series of lifetime tests performed at a dedicated ion source test facility where the source was pushed closer to the operational goal of 6% duty factor.  
 
TUPLT177 RHIC Optics Measurements at Different Working Point focusing, betatron, ion, beamloading 1541
 
  • R. Calaga, M. Bai, S. Peggs, T. Roser, T. Satogata
    BNL, Upton, Long Island, New York
  Working point scans at RHIC were performed during 2004 to determine the effect on lifetime and luminosity. Linear optics were measured for different working point tunes by exciting coherent oscillations with the aid of RHIC AC dipoles. Two methods to measure the beta functions and phases are presented and compared: a conventional technique, and a new method based on singular value decomposition (SVD). The performance of a 3-bump beta wave algorithm to identify quadrupole error sources is also presented.  
 
TUPLT179 Mini-bunched and Micro-bunched Slow Extracted Beams from the AGS focusing, betatron, ion, beamloading 1544
 
  • K.A. Brown, L. Ahrens, J.M. Brennan, J. Glenn, M. Sivertz, N. Tsoupas
    BNL, Upton, Long Island, New York
  • S.R. Koscielniak
    TRIUMF, Vancouver
  BNL's AGS has a long history of providing slow extracted proton beams to fixed target experiments. This program of providing high quality high intensity beams continues with two new experiments currently being designed for operation at the AGS; both of these new experiments require slow extracted beam, but with an added requirement of those beams experiments require slow extracted beam, but with an added requirement of those beams experiments and initial tests have been performed. In this report we will describe the beam requirements for the two experiments, and present results of detailed simulations and initial beam tests.  
 
TUPLT180 Results of the NASA Space Radiation Laboratory Beam Studies Program at BNL focusing, betatron, radiation, ion 1547
 
  • K.A. Brown, L. Ahrens, R.H. Beuttenmuller, I.-H. Chiang, D.C. Elliott, D. Gassner, Z. Li, I. Marneris, J. Mead, J. Morris, D. Phillips, V. Radeka, A. Rusek, N. Tsoupas, B. Yu, K. Zeno
    BNL, Upton, Long Island, New York
  The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. The purpose of the NSRL beam studies program is to develop a clear understanding of the beams delivered to the facility, to fully characterize those beams, and to develop new capabilities in the interest of understanding the radiation environment in space. In this report we will describe the first results from this program.  
 
TUPLT181 Results of the First Run of the NASA Space Radiation Laboratory at BNL focusing, betatron, beamloading, antiproton 1550
 
  • K.A. Brown, L. Ahrens, J.M. Brennan, J. DeLong, C. Gardner, D. Gassner, J. Glenn, Y. Kotlyar, I. Marneris, A. Rusek, N. Tsoupas, K. Zeno
    BNL, Upton, Long Island, New York
  The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The results of commissioning of this new facility were reported in [*]. In this report we will describe the results of the first run. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. Many modes of operation were explored during the first run, demonstrating all the capabilities designed into the system. Heavy ion intensities from 100 particles per pulse up to 2×109 particles per pulse were delivered to a large variety of experiments, providing a dose range up to 70 G/min over a 5x5 cm2 area. Results presented will include those related to the production of beams that are highly uniform in both the transverse and longitudinal planes of motion [**].

* K.A.Brown, et al, ‘‘Commissioning Results of Slow Extraction of Heavy Ions from the AGS Booster‘‘, Proceedings of the 2003 Particle Accelerator Conference, Portland, OR, 2003** N.Tsoupas, et al, ‘‘Commissioning of the Beam Transfer Line of the Booster Application Facility (BAF) at BNL'', These Proceedings

 
 
TUPLT182 Measuring Local Gradient and Skew Quadrupole Errors in RHIC IRs focusing, betatron, beamloading, antiproton 1553
 
  • J.F. Cardona
    UNAL, Bogota D.C
  • S. Peggs, F.C. Pilat, V. Ptitsyn
    BNL, Upton, Long Island, New York
  The measurement of local linear errors at RHIC interaction regions using an "action and phase" analysis of difference orbits has already been presented [*]. This paper evaluates the accuracy of this technique using difference orbits that were taken when known gradient errors and skew quadrupole errors were intentionally introduced. It also presents action and phase analysis of simulated orbits when controlled errors are intentionally placed in a RHIC simulation model.

* J. Cardona, S. Peggs, T. Satogata, F. Pilat and V. Ptitsyn,"Determination of Linear and Non Linear Components in RHIC Interaction Regions from difference Orbit Measurements", EPAC 2002, Paris, 2002, p.311-313.

 
 
TUPLT183 Magnetized Beam Transport in Electron Coolers with Opposing Solenoid Fields focusing, electron, beamloading, antiproton 1556
 
  • J. Kewisch, C. Montag
    BNL, Upton, Long Island, New York
  To improve cooling capability of electron coolers magnetized beams in strong solenoid fields are used. Too avoid betatron coupling in the ion coupling compensation is required. For the RHIC electron cooler we propose a scheme consisting of two identical solenoids with opposing fields, connected by a quadrupole matching section that preserves the electron beam magnetization. Since the fringe fields of the individual magnets overlap, the matching section can not be designed with standard optics codes. We developed an optimization code based on particle tracking instead. Input for the program are the simulated/measured field maps of the magnets. We demonstrate that the transverse temperature of the electron beam does not increase.  
 
TUPLT184 Operational Measurement of Coupling by Skew Quadrupole Modulation focusing, coupling, electron, beamloading 1559
 
  • Y. Luo, P. Cameron, R. Lee, A. Marusic, F.C. Pilat, T. Roser, D. Trbojevic, J. Wei
    BNL, Upton, Long Island, New York
  The measurements of betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been recently developed and tested at RHIC. By modulating the current of different skew quadrupole families with different frequencies and measuring the resulting eigentunes response with a high resolution phase lock loop (PLL) system, it is possible to determine the projections of the residual coupling coefficients. We report the results of extensive beam studies carried on at RHIC injection, store energy and on the ramp. The capability of measuring coupling on the ramp opens the possibility of continuous coupling corrections during acceleration.  
 
TUPLT185 Principle of Skew Quadrupole Modulation to Measure Betatron Coupling focusing, electron, beamloading, antiproton 1562
 
  • Y. Luo, F.C. Pilat, T. Roser, D. Trbojevic, J. Wei
    BNL, Upton, Long Island, New York
  The idea of modulating Skew Qudrupoles to measure the ring betatron coupling was put forth by T. Roser. In this paper, analytical solutions for this technique is given. Simulation are also carried out based on RHIC. And other relevent issues concerning this technique's application are also discussed. All of them show this idea of modulating skew qudrupoles to measure the betatron coupling are applicable.  
 
TUPLT186 Managing System Parameters for SNS Magnets and Power Supplies focusing, electron, beamloading, antiproton 1565
 
  • W.J. McGahern, S. Badea, F.M. Hemmer, H.-C. Hseuh, J.W. Jackson, A.K. Jain, F.X. Karl, R.F. Lambiase, Y.Y. Lee, C.J. Liaw, H. Ludewig, G.J. Mahler, W. Meng, C. Pai, C. Pearson, J. Rank, D. Raparia, J. Sandberg, S. Tepikian, N. Tsoupas, J. Tuozzolo, P. Wanderer, J. Wei, W.-T. Weng
    BNL, Upton, Long Island, New York
  • R. Cutler, J.J. Error, J. Galambos, M.P. Hechler, S. Henderson, P.S. Hokik, T. Hunter, G.R. Murdoch, K. Rust, J.P. Schubert
    ORNL/SNS, Oak Ridge, Tennessee
  The Spallation Neutron Source (SNS), currently under construction at Oak Ridge, Tennessee, is a collaborative effort of six U.S. Department of Energy partner laboratories. With over 312 magnets and 251 power supplies that comprise the beam transport lines and the accumulator ring, it is a challenge to maintain a closed loop on the variable parameters that are integral to these two major systems. This paper addresses the input variables, responsibilities and design parameters used to define the SNS magnet and power supply systems.  
 
TUPLT187 SNS Extraction Kicker Power Supply Control focusing, electron, beamloading, antiproton 1568
 
  • J.-L. Mi, L. Hoff, R.F. Lambiase, Y.Y. Lee, J. Sandberg, Y. Tan, N. Tsoupas, R. Zapasek, W. Zhang
    BNL, Upton, Long Island, New York
  There are fourteen PFN power supplies, which will be installed in the SNS Extraction Kicker System. This paper will introduce these fourteen-power supplies arrangement and control schematic. These control instruments and boards are installed into four standard racks. Some of the control boards functions will be list in this paper. Control racks and some control boards pictures will be shown in this paper.  
 
TUPLT188 SNS Extraction Kicker Power Supply Manufacture Status focusing, electron, kicker, extraction 1571
 
  • J.-L. Mi, H. Hahn, R.F. Lambiase, Y.Y. Lee, C. Pai, J. Sandberg, Y. Tan, N. Tsoupas, D.S. Warburton, R. Zapasek, W. Zhang
    BNL, Upton, Long Island, New York
  There are fourteen PFN power supplies, which will be installed in the SNS Extraction Kicker System. The Pulse Forming Network (PFN) power supplies for the SNS Extraction kicker were designed by Brookhaven. The basic configuration of the PFN is a lumped element Blumlein pulse forming network (BPFN). The PFN and power supply are fabricated by an industrial company. The first article of. PFN and power supply has been manufactured and tested with a dummy load at the company and onsite with the prototype magnet. The PFN has been tested beyond its specification and has met all requirements including rise time, pulse flatness, amplitude and pulse repetition rate. Additional heat runs are scheduled. The transverse coupling impedance of the kicker system with attached PFN has been measured. This paper will report on the SNS Extraction Kicker Power Supply engineering status, and will include output waveforms, impedance measurements, and production projections.  
 
TUPLT189 Dipole and Quaqdrupole Sorting for the SNS Ring focusing, electron, kicker, extraction 1574
 
  • D. Raparia, A.V. Fedotov, Y.Y. Lee, J. Wei
    BNL, Upton, Long Island, New York
  The Spallation Neutron Source (SNS) accumulator ring is a high intensity ring and must have low uncontrolled losses for hands on maintenance. To achieve these low losses one needs very tight tolerance. These tight tolerances have been achieved through shimming the magnets and sorting. Dipoles are solid core magnets and had very good field quality but magnet to magnet variation were sorted out according to ITF, since all the dipole are powered with one power supply. Typically, sorting is done to minimize linear effects in beam dynamics. Here, sorting of quadrupoles was done according to a scheme which allows to reduce unwanted strength of nonlinear resonances. As a result, the strength of sextupole resonances for our base line tune-box was strongly reduced which was confirmed by a subsequent beam dynamics simulation.  
 
TUPLT190 Acceleration of Polarized Beams using Multiple Strong Partial Siberian Snakes focusing, electron, kicker, beamloading 1577
 
  • T. Roser, L. Ahrens, M. Bai, E.D. Courant, J. Glenn, R.C. Gupta, H. Huang, A.U. Luccio, W.W. MacKay, N. Tsoupas, E. Willen
    BNL, Upton, Long Island, New York
  • M. Okamura, J. Takano
    RIKEN, Saitama
  Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20 - 30 % partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction.  
 
TUPLT191 Transverse Optics Improvements for RHIC Run 4 focusing, electron, kicker, beamloading 1580
 
  • J. Van Zeijts
    BNL, Upton, Long Island, New York
  The magnetic settings in RHIC are driven by an online model, and the quality of the resulting lattice functions depend on the correctness of the settings, including knowledge of the magnet transfer-functions. Here we first present the different inputs into the online model, including dipole sextupole compenents, used to set tunes and chromaticities along the ramp. Next, based on an analysis of measured tunes and chromaticities along the fy03 polarized proton ramp, we present predictions for quadrupole transfer-function changes. The changes are implemented for the fy04 Au ramp, and we show the improved model agreement for tunes, and chromaticities along the ramp, and measured transverse phase-advance at store. We also describe model improvements for derived observables like the quality of transverse bump closure and observed luminosity ratios between individual interaction points.  
 
TUPLT192 Transition Crossing for the BNL Super Neutrino Beam focusing, electron, kicker, beamloading 1583
 
  • J. Wei, N. Tsoupas
    BNL, Upton, Long Island, New York
  The super neutrino beam facility proposed at the Brookhaven National Laboratory requires proton beams to cross the transition energy in the AGS to reach 1 MW beam power at top energy. High intensity beams are accelerated at a fast repetition rate. Upon transition crossing, such high intensity bunches of large momentum spreads suffer from strong nonlinear chromatic effects and self-field effects. Using theoretical and experimental methods, we determine the impact of these effects and the effectiveness of transition-jump compensation schemes, and determine the optimum crossing scenario for the super neutrino beam facility.  
 
WEXCH01 Experience with LHC Magnets from Prototyping to Large-scale Industrial Production and Integration focusing, electron, kicker, beamloading 118
 
  • L. Rossi
    CERN, Geneva
  The construction of the LHC superconducting magnets is approaching one third of its completion. At the end of 2003, main dipoles cold masses for more than one octant were delivered; meanwhile the winding for the second octant was almost completed. The other big magnets, like the main quadrupoles and the insertion quadrupoles, have entered into series production as well. Providing more than 20 km of superconducting magnets, with the quality required for an accelerator like LHC, is an unprecedented challenge in term of complexity that has required several steps from the construction of 1 meter-long magnets in the laboratory to today production of more than one 15 meter-long magnet per day in Industry. The work and its organization is made even more complex by the fact that CERN supplies most of the critical components and part of the main tooling to the magnet manufacturers, both for cost reduction and for quality issues. In this paper the critical aspects of the construction and the time plan will be reviewed and the actual achievements in term of quality and construction time will be compared with the expectations.  
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WEOACH01 High Field Gradient Cavity for J-PARC 3 GeV RCS focusing, electron, kicker, beamloading 123
 
  • C. Ohmori, S. Anami, E. Ezura, K. Hara, Y. Hashimoto, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
  • M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  A new type of rf cavity will be used for J-PARC project. To minimize the beam loading effects, the quality factor of the core stack is increased by a cut core configuration. High power test of the rf system has been performed. Temperature rise around the cut surface of the cores were observed. It is minimized by improving the cooling efficiency.  
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WEOACH02 Gas Condensates onto a LHC Type Cryogenic Vacuum System Subjected to Electron Cloud focusing, kicker, beamloading, antiproton 126
 
  • V. Baglin, B.J. Jenninger
    CERN, Geneva
  In the Large Hadron Collider (LHC), the gas desorbed via photon stimulated molecular desorption or electron stimulated molecular desorption will be physisorbed onto the beam screen held between 5 and 20 K. Studies of the effects of the electron cloud onto a LHC type cryogenic vacuum chamber have been performed with the cold bore experiment (COLDEX) installed in the CERN Super Proton Synchrotron (SPS). Experiments performed with gas condensates such as H2, H2O, CO and CO2 are described. Implications to the LHC design and operation are discussed.  
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WEOACH03 Achievement of 35 MV/m in the TESLA Superconducting Cavities Using Electropolishing as a Surface Treatment focusing, kicker, beamloading, antiproton 129
 
  • L. Lilje
    DESY, Hamburg
  The Tera Electronvolt Superconducting Linear Accelerator TESLA is the only linear electron-positron collider project based on superconductor technology for particle accelaration. In the first stage with 500 GeV center-of-mass energy an accelerating field of 23.4MV/m is needed in the superconducting niobium cavities which are operated at a temperature of 2 K and a quality factor Q0 of 1010. This performance has been reliably achieved in the cavities of the TESLA Test Facility (TTF) accelerator. The upgrade of TESLA to 800 GeV requires accelerating gradients of 35 MV/m. Using an improved cavity treatment by electrolytic polishing it has been possible to raise the gradient to 35 - 43 MV/m in single cell resonators. Here we report on the successful transfer of the electropolishing technique to multi-cell cavities. Presently four nine-cell cavities have achieved 35 MV/m at Q_0 = 5 × 109, and a fifth cavity could be excited to 39 MV/m. In two high-power tests it could be verified that EP-cavities preserve their excellent performance after welding into the helium cryostat and assembly of the high-power coupler. One cavity has been operated for 1100 hours at the TESLA-800 gradient of 35 MV/m and 57 hours at 36 MV/m without loss in performance.  
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WEYCH01 Fast Pulsed SC Magnets focusing, kicker, beamloading, antiproton 132
 
  • G. Moritz
    GSI, Darmstadt
  The demand for high beam intensities leads to the requirement of fast pulsed magnets for synchrotrons. An example is the proposed 'International Facility for Beams of Ions and Antiprotons' at GSI, which will consist of two synchrotrons in one tunnel and several storage rings. The high field ramp rate and repetition frequency introduce many magnet design problems and constraints in the operation of the accelerator. Persistent currents in the superconductor and eddy currents in wire, cable, iron and vacuum chamber reduce the field quality and generate cryogenic losses. Due to the large number of magnet cycles during the lifetime of such a magnet, special attention has to be paid to magnet material fatigue problems. The large charging voltages put some constraints on the use of cold diodes for quench protection. R&D has started at GSI, in collaboration with many institutions, to comply with the constraints mentioned above. Model dipoles were built and tested. The results of the R&D are reported. The advantages of the use of low field, fast pulsed superconducting, compared to resistive, magnets will be discussed  
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WEYCH02 Technical Issues for Large Accelerators based on High Gradient SC Cavities focusing, kicker, beamloading, antiproton 137
 
  • C. Pagani, C. Pagani
    DESY, Hamburg
  The perspective to build large accelerators based on high gradient superconducting cavities is posing a number of new problems that have been addressed in the preparation of the TESLA project. Starting from the experience gained with the past large installations, such as LEP2 at CERN and CEBAF at JLab, in this paper I discuss the new demands and the solution envisaged. Industrial production issues are focussed in terms of large scale production, reviewed quality control criteria and cost reduction. The impact on component design and engineering together with the expected improvements in term of performances and reliability are also outlined.  
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WEYCH03 Low and Medium Beta Superconducting Cavities focusing, kicker, beamloading, antiproton 142
 
  • A. Facco
    INFN/LNL, Legnaro, Padova
  The use of low- and intermediate-beta superconducting cavities, once confined to low current heavy ion linacs, is steadily increasing in accelerators. The progress in this technology allowed a significant increase in cavity performance during the last 10 years; a large number of resonators, with different geometries, frequencies and gap numbers have been built for a large variety of applications and the development is still going on. The main boost is given by new projects of radioactive beam facilities and high power proton accelerators worldwide. While the advantages of SC resonators, compared with normal conducting structures, are rather well established in high-beta linacs, this is not always the case at low-beta. The choice of the optimum transition beam energy in a linac, where superconducting cavities should replace the room temperature ones, requires a careful evaluation that depends on the linac specifications.  
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WEOBCH01 Performance Requirements for Monitoring Pulsed, Mixed Radiation Fields around High-energy Acclerators radiation, focusing, kicker, beamloading 147
 
  • D. Forkel-Wirth, S.M. Mayer, H.G. Menzel, A. Muller, T. Otto, M. Pangallo, D. Perrin, M. Rettig, S. Roesler, L. Scibile, H. Vincke
    CERN, Geneva
  • C. Theis
    TUG/ITP, Graz
  Radiation protection survey around CERN's High Energy Accelerators represents a major technical and physical challenge due to the pulsed and complexity of the mixed radiation fields. The fields are composed of hadrons, leptons and photons ranging in energy from fractions of eV to several 10 GeV. In preparation of the implementation of a Radiation Monitoring System for the Environment and Safety (RAMSES) of the future Large Hadron Collider (LHC) and its injectors comprehensive studies were performed to evaluate the suitability of different existing monitors for this task. Different ionization chambers were exposed to short, high-intensity radiation pulses and their saturation levels for high dose rates determined. Limiting factors such as recombination effects and the capacity of the electronics to process a high number of charges within very short time were studied in detail. These results are being used to optimize the design of the read-out electronics. In additional studies, the response of two different types of ionization chambers to high-energy radiation was investigated by measurements in the mixed radiation fields of the CERN EU high-energy Reference Field (CERF) facility. The results of the experiments agreed well with calculations, clearly demonstrating that modern Monte-Carlo simulation techniques can be used to design radiation monitors and to optimize their performance.  
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WEOBCH02 Design, Construction, and Initial Operation of the SNS MEBT Chopper System radiation, focusing, kicker, beamloading 150
 
  • R.A. Hardekopf, S.S. Kurennoy, J. Power
    LANL, Los Alamos, New Mexico
  • A.V. Aleksandrov, D.E. Anderson
    ORNL/SNS, Oak Ridge, Tennessee
  The chopper system for the Spallation Neutron Source (SNS) provides a gap in the beam for clean extraction from the accumulator ring. It consists of a pre-chopper in the low-energy beam transport (LEBT) and a faster chopper in the medium-energy beam transport (MEBT). We report here on the final design, fabrication, installation, and first beam tests of the MEBT chopper. The traveling-wave deflector is a meander-line design that matches the propagation of the deflecting pulse with the velocity of the beam at 2.5 MeV, after the radio-frequency quadrupole (RFQ) acceleration stage. The pulser uses a series of fast-risetime MOSFET transistors to generate the deflecting pulses of ± 2.5 kV with rise and fall times of 10 ns. We describe the design and fabrication of the meander line and pulsers and report on the first operation during initial beam tests at SNS.  
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WEOCCH01 A New 180 MeV H- Linac for Upgrades of ISIS radiation, focusing, kicker, target 153
 
  • F. Gerigk
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  Several options have been studied to raise the beam power of the ISIS spallation neutron source to a level of 1 MW with the possibility of going to 4-5 MW in the longer term. All scenarios can operate in 2 modes, where the beam power is either delivered to a spallation target or, alternatively, to a target suitable to produce muons via pion decay for a neutrino factory. A more recent upgrade option takes an intermediate step and uses a 180 MeV H- linac, which is also foreseen for the 4-5 MW upgrade, as a replacement for the current 70 MeV injector. First estimates indicate that, due to the lower space charge forces, the ring would be able to carry twice as many particles, thus doubling the final beam power to 0.5 MW. This paper presents a first design for the 180 MeV linac, using a triple frequency jump from 234.8 to 704.4 MHz. The design profits from the development of 704.4 MHz cavities and RF equipment within the framework of the European HIPPI collaboration. The low frequency for the front-end was chosen to ease the DTL design as well as the development of a low energy beam chopper, which will be necessary to reduce beam losses at injection into the synchrotron.  
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WEOCCH02 Construction Status and Issues of the Spallation Neutron Source Ring radiation, focusing, kicker, target 156
 
  • J. Wei
    BNL, Upton, Long Island, New York
  (For the Spallation Neutron Source collaboration) The Spallation Neutron Source (SNS) accelerator complex is now in its sixth year of a seven-year construction cycle. The design, fabrication, test, and assembly of the accumulator ring and its transport lines is approaching the final stage. In order to reach the design goal of this high-power ring to deliver 1.5 MW beam power (1.5$× 1014 protons of 1 GeV kinetic energy at a repetition rate of 60 Hz), stringent measures have been implemented to ensure the quality of the accelerator systems. This paper reviews the progress of the ring and transport systems with emphasis on the challenging technical issues and their solutions inccurred during the construction period.  
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WEODCH01 1.5-GeV FFAG Accelerator as Injector to the BNL-AGS radiation, focusing, acceleration, kicker 159
 
  • A. Ruggiero, M. Blaskiewicz, T. Roser, D. Trbojevic, N. Tsoupas, W. Zhang
    BNL, Upton, Long Island, New York
  A 1.5-GeV Fixed-Field Alternating-Gradient (FFAG) Accelerator has been recently proposed as a new injector to the Alternating-Gradient Synchrotron (AGS) of Brookhaven National Laboratory (BNL). It is being considered as a replacement of the present 1.5-GeV AGS Booster. The substitution will enhance the performance of the AGS accelerator facility in a variety of ways. It would still allow acceleration of all hadronic particles: protons, and heavy-ions. The major benefit is that it would considerably shorten the typical combined AGS acceleration cycle, and, consequently, may yield to an improvement of beam stability, intensity and size. The AGS-FFAG will also facilitate the proposed upgrade of the AGS facility toward a 1-MW average proton beam power. The paper describes a compact FFAG design for acceleration of protons from 200 MeV to 1.5 GeV. The circumference is about 250 m. The lattice is a periodic sequence of FDF triplets of combined-function magnets. An adjusted field profile has been calculated to compensate the variation of the main lattice functions with momentum. At injection, a beam pulse 130 μs long of negative-ions (H?) is stacked with the charge-exchange method. Acceleration of one pulse with 2.5 x 1013 protons takes about 130 μs, if harmonic-jump scheme is used in conjunction with the choice of 201.25 MHz. Four of such beam pulses are required to fill entirely the AGS. The entire filling process thus takes less than one millisecond.  
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WEYLH01 Emittance Control for Very Short Bunches electron, focusing, ion, kicker 179
 
  • K.L.F. Bane
    SLAC, Menlo Park, California
  Many recent accelerator projects call for the production of high energy bunches of electrons or positrons that are simultaneously short, intense, and have small emittances. Two examples of such projects are linear colliders, such as the GLC/NLC, and Self-Amplified Spontaneous Emission (SASE) FEL's, such as the Linac Coherent Light Source (LCLS). A major challenge in such projects is keeping in check forces that increase short bunch emittances in accelerator components, such as: wakefields of accelerator structures, collimators, and surface roughness, and coherent synchrotron radiation (CSR). We describe such forces and their control.  
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WEYLH02 Single Particle Linear and Non-linear Dynamics electron, focusing, ion, kicker 184
 
  • Y. Cai
    SLAC, Menlo Park, California
  I will give a comprehensive review of existing particle tracking tools to assess long-term particle stability for small and large accelerators in the presence of realistic magnetic imperfections and machine misalignments. The emphasis will be given to the tracking and analysis tools based upon the differential algebra, Lie operator, and "polymorphism". Using these tools, a uniform linear and non-linear analysis will be outlined as an application to the normal form. Finally I will compare simulation results with observations in existing circular accelerators. "Model independent analysis" will be treated as an example for measuring machine optics.  
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WEYLH03 Collective Effects and Instabilities in Space Charge Dominated Beams focusing, ion, kicker, beamloading 189
 
  • J.A. Holmes
    ORNL/SNS, Oak Ridge, Tennessee
  Significant progress in the detailed computational study of collective beam dynamics is being driven by the spectacular increase in computer power. To take advantage of this, sophisticated physics models are being applied to ever more realistic and detailed situations, so that it is no longer necessary to restrict computer studies to highly idealized depictions of beam dynamics questions. This presentation will illustrate the application of a number of collective beam dynamics models to a range of accelerator physics problems in high intensity proton rings. In particular, we will consider the effects of space charge, transverse and longitudinal impedances, and electron cloud formation on beam parameters, stability, halo formation, collimation and losses, and possible equilibrium configurations. Examples will be taken from PSR, the CERN PS Ring, and SNS.  
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WEILH00 Industrial Involvement in EC Supported Accelerator R&D in the 6th Framework Programme and in Preparing Large Scale Accelerator Projects focusing, ion, kicker, beamloading 194
 
  • D. Proch
    DESY, Hamburg
  The presentation will cover industrial involvement in EC supported accelerator R&D in the 6th framework programme and in preparing large scale accelerator projects (TESLA).  
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WEILH01 Methods for Successful Technology Transfer in Physics focusing, ion, kicker, beamloading 198
 
  • K.N. Hill
    Qi3, Cambridge
  The development of accelerators for scientific research generates significant technologies of interest to industry. As physicists and technologists we also require strong partnerships with industry in order that it may supply us with the instrumentation and systems we require for new apparatus. We will discuss the methods developed for the UK Particle Physics and Astronomy Research Council (PPARC) and applied on behalf of CERN to encourage successful knowledge transfer into industry. Case studies will illustrate the hurdles that must be surmounted and effective methods to build successful partnerships, licensing opportunities and spinout companies. Factors considered will include assessment of the commercial potential of technologies, personal motivations for academic/industrial collaboration, sources of funding, and effects on the academic groups involved in knowledge transfer activity.  
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WEILH03 Industrial Response to RF Power Requirements focusing, ion, kicker, beamloading 202
 
  • M. Wilcox
    e2v technologies, Chelmsford, Essex
  Today, high-energy physics machines are broadly speaking of two kinds. Some machines are dedicated to providing a service using particle acceleration as an intermediate step (light sources, neutron spallation sources, cancer therapy equipment etc.)and occasionally, particle colliders are built in which the particles are used directly to probe the nature and origin of matter. The latter machines have developed to a point where the technology needed is often at the extreme edge of what is understood, let alone of what is currently achievable. In addition the scope of supply and the level of equipment integration demanded of industry is increasing as RF skills become scarcer. This reduces the supplier base so placing greater demands on those remaining. To help offset this problem, companies should be brought 'inside' the project team at an early stage of the machine design so that better account can be taken of limitations, preferences and competing obligations that the companies may have. A more collaborative approach should result in projects being completed in a shorter time, to a lower cost, and with a more certain outcome.  
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WEILH04 Industrial Involvement in the Construction of Synchrotron Light Sources focusing, ion, kicker, beamloading 206
 
  • M.S. de Jong
    CLS, Saskatoon, Saskatchewan
  The design, construction and commissioning of a modern third-generation synchrotron light source facility is a major project, costing hundreds of millions of dollars. The delivery of these new facilities, usually on a fixed budget and schedule, requires an effective working relationship with all suppliers providing equipment and services to the project. This talk will examine some of the key issues in developing and maintaining such a relationship with industry during the construction of a third-generation synchrotron light facility. These issues include project planning, the contract specification, the tendering process, communication techniques over the contract term, and other aspects of contract control. Examples, primarily from our experience constructing the Canadian Light Source but also from other new facilities planned or under construction, will be used to examine the effectiveness of various approaches to working with industry.  
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WEPKF001 Diffusion Welding of Heterogeneous Materials in Accelerator Technique focusing, ion, kicker, beamloading 1586
 
  • V.S. Avagyan
    CANDLE, Yerevan
  • A. Babayan, N.M. Dobrovolski, I.V. Tunyan
    YerPhI, Yerevan
  The results of the joining of heterogeneous materials, such as titanium with stainless steel (serviceable at 4.2 K), copper with aluminum, titanium with niobium (this work has been carried out for TESLA project), stainless steel with aluminum, copper with stainless steel are presented in this work.  
 
WEPKF002 Magnets for the CANDLE Booster Synchrotron, Design and Prototyping focusing, ion, kicker, beamloading 1588
 
  • V.G. Khachatryan, Y.L. Martirosyan, A. Petrosyan
    CANDLE, Yerevan
  CANDLE booster synchrotron magnetic lattice contains 48 dipoles of H-shape. Detailed magnetic and mechanical design of those magnets is performed within the framework of the project. In this report, the design considerations of the dipole magnet, including the magnetic field simulation is presented. The main features of the fabricated first prototype dipole magnet are discussed.  
 
WEPKF003 Design of the End Magnets for the IFUSP Main Microtron focusing, ion, kicker, beamloading 1591
 
  • M.L. Lopes, A.A. Malafronte, M.N. Martins, J. Takahashi
    USP/LAL, Bairro Butantan
  • K.-H. Kaiser
    IKP, Mainz
  The Instituto de Física da Universidade de São Paulo (IFUSP) is building a two-stage 31 MeV continuous wave (cw) racetrack microtron. In this work we describe the characteristics of the end magnets for the IFUSP main microtron. The magnets are part of the main acceleration stage, which raises the energy from 4.9 to 31 MeV. We are studying the possibility of increasing the energy up to 38 MeV, so the magnets should have approximately 2x1 m2 region of useful field. The dipoles have a 0.1410 T magnetic field and 1 part in 1000 homogeneity without correcting devices. Using a 2D magnetic field code (FEMM), we illustrate the use of homogenizing gaps with different forms and non parallel pole faces to achieve the necessary homogeneity. The use of clamps to produce reverse fields to reduce the vertical defocusing strength on the beam is also described. In order to calculate the beam trajectories and to evaluate the magnetic field homogeneity within the useful region, a 3D magnetic field software (TOSCA) was used.  
 
WEPKF004 Magnetic Quadrupole Lenses for the IFUSP Microtron focusing, ion, kicker, quadrupole 1594
 
  • T.F. Silva, M.L. Lopes, A.A. Malafronte, M.N. Martins, P.B. Rios, J. Takahashi
    USP/LAL, Bairro Butantan
  The Instituto de Física da Universidade de São Paulo (IFUSP) is building a two-stage 31 MeV continuous wave (cw) racetrack microtron. In this work, we describe the design of the magnetic quadrupole lenses for the IFUSP microtron. The design consists of a laminar structure divided in four equal pieces. Because each piece corresponds to an individual pole, it eases the assembling of the coils and the installation of the quadrupole on the beam transport line without breaking the vacuum. Due to the fact that the quadrupole is laminated along the longitudinal axis, it is possible to change the length of a given lens by adding or subtracting foils. We also present the magnetic field distribution calculated using the POISSON code. A prototype presented good mechanical rigidity and thermal performance, showing that a refrigeration system is not necessary. The magnetic measurements show that the field distribution within the region of interest agrees with the POISSON simulation.  
 
WEPKF005 Pressure Field Distribution in a Cylindrical Geometry with Arbitrary Cross Section focusing, ion, kicker, vacuum 1597
 
  • F.T. Degasperi
    FATEC-SP, Sao Paulo, SP
  • M.N. Martins, J. Takahashi
    USP/LAL, Bairro Butantan
  • L.L. Verardi
    IBILCE - UNESP, Sao Jose do Rio Preto, SP
  This work presents analytical and numerical results for the pressure field distribution along the axis of tubular geometries with arbitrary axisymmetric cross sections with an arbitrary time- and position-dependent gas source. Several areas of applied physics deal with problems in high-vacuum and ultra high-vacuum technology that present tubular form. In many cases one finds tubes with non uniform cross sections, like parts of particle accelerators, colliders, storage rings, gravitational antennas, and electron devices, like klystrons, electron microscopes, and also parts of vacuum systems in general, for instance, bellows, conical pipes and others. In this work one can get the detailed pressure distribution is not determined. This work presents and describes in detail the pressure field in tubes with arbitrary axisymetric cross sections. Details of the mathematical and physical formulations and modeling are given; specific conductance and specific throughput are defined; and a detailed discussion about the boundary conditions is given. These concepts and approach are applied to usual realistic cases, like conical tubes and bellows, with typical laboratory dimensions.  
 
WEPKF006 Field Quality and Hysteresis of LHC Superconducting Corrector Magnets focusing, ion, kicker, vacuum 1600
 
  • A. Santrich Badal, M. Allitt, C. Giloux, M. Karppinen, A.M. Lombardi, V. Remondino, W.  Venturini Delsolaro, R. Wolf
    CERN, Geneva
  • M. Bagre, P. Khare, T. Maurya, A. Puntambekar
    CAT, Indore (M.P.)
  The Large Hadron Collider (LHC) will use some 6400 superconducting corrector magnets. There are 19 corrector types. These are assembled 14 different types of magnets of which 4 are nested. They are being manufactured by 4 firms in Europe and 3 in India. The magnetic field quality is measured at room temperature by 12 magnetic measurement benches employed by the corrector manufacturers. CERN performs magnetic measurement at 4.2K and at 1.9K on a small subset of corrector magnets. The paper discusses the correlation between the warm and cold field measurements. The field quality is compared to the magnet design expectations and to the target field quality for LHC. Many corrector circuits will be powered in a way which cannot be predicted before LHC will start operation and which even then may change between physics runs. The measured magnetic hysteresis and its influence on possible setting errors during operation is discussed, in particular for the orbit correctors and the tuning/trim quadrupole magnet circuits.  
 
WEPKF007 Vacuum Characterisation of a Woven Carbon Fiber Cryosorber in Presence of H2 focusing, ion, kicker, vacuum 1603
 
  • V. Baglin, H. Dupont, T. Garcin
    CERN, Geneva
  Some of the cryogenic components in the Large Hadron Collider (LHC) will operate at 4.5 K. The H2 desorption will rapidly increase to the saturated vapour pressure, 3 orders of magnitude larger than the design pressure. Therefore, the use of cryosorbers is mandatory to provide the required pumping capacity and pumping speed. The behaviour of a woven carbon fiber to be used as a cryosorber has been studied under H2 injection. The pumping speed and capacity measured in the range 6 to 30 K are described. Observations made with an electron microscope are shown. A proposed pumping mechanism and the implications to the LHC are discussed.  
 
WEPKF008 A Strategy for Sampling of the Field Quality of the LHC Dipoles focusing, ion, kicker, vacuum 1606
 
  • L. Bottura, S.D. Fartoukh, V. Granata, E. Todesco
    CERN, Geneva
  We have measured the magnetic field of a considerable fraction of the superconducting LHC main dipoles, of the order of 300 in warm conditions and 100 in cold conditions. All LHC dipoles will be measured in warm conditions at the manufacturers to steer the production inside the acceptance limits imposed by beam dynamics. Using the available data we analysed the distributions of the main field and higher order field errors in warm and cold conditions, as well as the distribution of the warm-to-cold correlation. Based on this analysis we predict the minimum number of magnets that should be measured in cold conditions in order to guarantee that (1) the production is controlled within the specified limits (2) the field is known to a sufficient level for a sound installation and (3) the uncertainty on the knowledge of the magnetic field of the LHC dipoles is small enough for the commissioning of the accelerator and to insure operation of the machine in any condition, including higher energy. The main outcome of this analysis is that cold measurements on a fraction of the order of one third of the total production, i.e. approximately 400 dipoles, will be sufficient to achieve the above objectives.  
 
WEPKF009 A Scaling Law for Predicting Snap-back in Superconducting Accelerator Magnets focusing, ion, kicker, vacuum 1609
 
  • T. Pieloni, L. Bottura, S. Sanfilippo
    CERN, Geneva
  • G. Ambrosio, P. Bauer
    Fermilab, Batavia, Illinois
  • M. Haverkamp
    METROLAB, Plan-les-Ouates
  The decay of the sextupole component in the bending dipoles during injection and the subsequent snap-back at particle acceleration are issues of common concern, albeit at different levels of criticality, for all superconducting colliders built (Tevatron, HERA, RHIC) or in construction (LHC) to date. The main difficulty is the correction of the relatively large and fast sextupole change during snap-back. Motivated by the above considerations, we have conducted an extended study of sextupole snap-back on two different magnet families, the Tevatron and the LHC bending dipoles, using the same measurement method. We show in this paper that it is possible to generalise all the results obtained by using a simple, exponential scaling law. Furthermore, we show that for magnets of the same family the parameters of the scaling law correlate linearly. This finding could be exploited during accelerator operation to produce accurate forecast of the snap-back correction based solely on beam-based measurements.  
 
WEPKF010 Design of an Automatic System for the Electrical Quality Assurance during the Assembly of the Electrical Circuits of the LHC focusing, ion, kicker, vacuum 1612
 
  • D. Bozzini, V. Chareyre, A. Jacob, K.H. Mess, S. Russenschuck, R. Solaz Cerdan
    CERN, Geneva
  During the assembly of the LHC one of the challenges will be the correct wiring of the 1712 circuits powering the 10094 magnet units, for which all-together 70000 splices have to be done. Considering the complexity of the electrical scheme the risk of wrong wiring is high. Errors, if not detected during the assembly phase, will perturb the LHC operation. A method has been developed to verify automatically the cabling scheme. It first detects the continuity of a portion of circuit and then verifies the correct polarity and type of the magnets in the circuit. A 108-meter LHC cell is the shortest length that can be tested. The system is composed of a unit to be placed at the center of the cell and two de-multiplexers positioned at the extremities of the cell. The central unit contains a data acquisition system where in total 217 signals can be acquired and more than 3000 voltage combinations are possible. Pointing to different databases, a LabVIEW program automatically executes the test procedure, generates, and stores the reports. The hardware and software design, the data flow between databases, and the testing methodology applied to the different circuit types are described.  
 
WEPKF011 Performance of the Superconducting Matching Quadrupoles for the LHC Insertions focusing, ion, kicker, vacuum 1615
 
  • N. Catalan-Lasheras, G. Kirby, R. Ostojic, J.C. Perez, H. Prin, W.  Venturini Delsolaro
    CERN, Geneva
  The optics flexibility of the LHC insertions is provided by the individually powered quadrupoles in the dispersion suppressors and matching sections. These units comprise special quadrupole magnets of the MQM and MQY type and range in length from 5.4 m to 11.4 m. In total, 82 insertion quadrupoles will be assembled at CERN. In this paper we present the advance in construction and report on the performance of the first series built quadrupoles. In particular, we present the quench performance of the individual magnets and alignment measurements of the cold masses, and discuss the field quality trends and possible implications.  
 
WEPKF012 LHC Dipole Axis, Spool Piece Alignment and Field Angle in Warm and Cold Conditions focusing, ion, kicker, vacuum 1618
 
  • M. Coccoli, M. Buzio, J. Garcia Perez
    CERN, Geneva
  The installation and commissioning of the LHC dipoles requires the knowledge of the magnetic axis and of the spool piece corrector alignment at the operating conditions. The installation is based at present on the use of geometric information derived from mechanical measurements performed in warm conditions, with the assumption that the geometric and magnetic axis are coincident. Any discrepancies between mechanical and magnetic axis and unforeseen geometry variations from ambient to cold operating temperature can introuduce important uncertaintes in the prediction of the alignment at operational conditions. Such prediction is studied through correlations between measurements performed at room and liquid helium temperature. A statistic analysis of the measurement data available is presented showing uncertainties on the correctors alignment. They are compared with beam-based specifications of the positioning of the spool piece.  
 
WEPKF014 Magnetic Field Tracking Experiments for LHC focusing, ion, kicker, vacuum 1621
 
  • V. Granata, J. Billan, F. Bordry, L. Bottura, P. Coutinho Ferreira, E. Effinger, G. Fernqvist, P. Galbraith, Q. King, J. Pett, A. Raimondo, A. Rijllart, H. Thiesen
    CERN, Geneva
  At the Large Hadron Collider (LHC) at CERN one of the fundamental requirements during the energy ramp is that the ratio between the field produced by the quadrupoles and the field in the dipoles remains constant in order to minimize the variation of the betatron tune that could induce particle loss. With a series of tracking experiments it has been demonstrated that this ratio can be maintained constant to better than 10-4 throughout the same current ramp as foreseen for the LHC. A technique has been developed to optimise the dipole and quadrupole current ramps to obtain the required ratio of B2/B1. Measurements performed by modulating the current with a harmonic function (so-called k-modulation) demonstrated that it is possible to modulate the strength of an individual quadrupole to determine the magnetic center through beam-based measurements.  
 
WEPKF015 The Design of Cold to Warm Transitions of the LHC focusing, ion, kicker, alignment 1624
 
  • J. Knaster, B.J. Jenninger, D.R. Ramos, G. Ratcliffe, R. Veness
    CERN, Geneva
  The Large Hadron Collider (LHC) is the next accelerator being constructed on the CERN site to be operational in 2007. It will accelerate and collide 7 TeV protons and heavier ions up to lead. More than 2000 cryomagnets working at 1.9 or 4.5 k will form part of the magnetic lattice of the LHC. The transitions from cryogenic temperatures to room temperature zones will be achieved by 200 cold to warm transitions (CWTs). The CWTs will compensate for longitudinal and transversal displacements between beam screens and cold bores, ensuring vacuum continuity without limiting the aperture for the beam. The transverse impedance contribution is kept below the assigned total budget of 1 MΩ/m by means of a 5 μm thick Cu coating that also minimises the dynamic heat load through image currents. Tests have been performed that confirm that the static heat load per CWT to the cryomagnets remains below 2.5 W, hence validating the design.  
 
WEPKF016 Instrumental Uncertainty in Measuring the Geometry of the LHC Main Dipoles. focusing, ion, kicker, alignment 1627
 
  • M. La China, G. Gubello, W. Scandale
    CERN, Geneva
  In the Large Hadron Collider 1232 superconducting dipoles will bend the two 7 TeV energy beams along a 27 km-circumference trajectory. The series production (assigned to three European firms) will require a well-defined procedure to check, in every magnet, the respect of the dimensional specifications. To verify the tolerances of few tenths of millimeter over the 15-meter length in each cold mass, a laser tracker is necessarily used. To access the two beam apertures and to increase the measurement accuracies, the laser tracker is placed in different stations around the dipole defining a 'multi-station measuring procedure'. The noise affecting all the data taken so far suggested a careful analysis of the procedure itself. Through the computer modeling (based on a Monte Carlo algorithm), the statistical error was quantified and compared to the experimental error. From this comparison the critical aspects of low accuracy rooted in the multi-station procedure were better understood, allowing the optimization of the procedure itself for the forthcoming series production.  
 
WEPKF017 The 5 T Superconducting Undulator for the LHC Synchrotron Radiation Profile Monitor focusing, kicker, undulator, alignment 1630
 
  • R. Maccaferri, M. Facchini, R. Jung, D. Tommasini, W.  Venturini Delsolaro
    CERN, Geneva
  A Synchrotron Radiation Profile Monitor will be used in the LHC to measure the beam profiles from the injection energy of 450 GeV to the nominal energy of 7 TeV. The radiation will be provided by a sequence of two separate magnets: a two-periods 5 T superconducting undulator and the beam separation dipole D3. After a short description of the profile monitor layout, the paper reviews the electromagnetic and mechanical design of the undulator, and reports on the fabrication and cold test results of a first half period prototype.Finally, for the LHC operation with lead ion beams,a proposal for a monitor sensitivity upgrade by using a 12 T. superconducting undulator is presented and discussed.  
 
WEPKF018 Beam-loss Induced Pressure Rise of LHC Collimator Materials Irradiated with 158 GeV/u In49+ Ions at the CERN SPS focusing, ion, kicker, undulator 1633
 
  • E. Mahner, I. Efthymiopoulos, J. Hansen, E. Page, H. Vincke
    CERN, Geneva
  During heavy ion operation, large pressure rises, up to a few orders of magnitude, were observed at CERN, GSI, and BNL. The dynamic pressure rises were triggered by lost beam ions that impacted onto the vacuum chamber walls and desorbed about 104 to 107 molecules per ion. The deterioration of the dynamic vacuum conditions can enhance charge-exchange beam losses and can lead to beam instabilities or even to beam abortion triggered by vacuum interlocks. Consequently, a dedicated measurement of heavy-ion induced molecular desorption in the GeV/u energy range is important for LHC ion operation. In 2003, a desorption experiment was installed at the SPS to measure the beam-loss induced pressure rise of potential LHC collimator materials. Samples of bare graphite, sputter coated (Cu, TiZrV) graphite, and 316 LN stainless steel, were irradiated under grazing angle with 158 GeV/u indium ions. After a description of the new experimental set-up, the results of the pressure rise measurements are presented, and the derived desorption yields are compared with data from other experiments.  
 
WEPKF019 Magnetic Measurement Systems for the LHC Dipole Assembly Firms focusing, ion, kicker, undulator 1636
 
  • H. Reymond, J. Billan, J. Garcia Perez, D. Giloteaux, A. Raimondo, V. Remondino, A. Rijllart
    CERN, Geneva
  The LHC lattice superconducting dipole magnets are actually under construction in three European industries. Due to the extremely high magnet performance required for the LHC, these magnets have to be built with high accuracy during all the steps of their assembling. In order to detect defects in the earliest production phases and to ensure the quality of the magnetic field as specified by the CERN contracts, dedicated measurement benches have been built and installed in each industry to validate the magnetic field quality at two important production stages. This paper describes the initial requirements and the implementation of the magnetic measurement systems. Details on the technical solutions, the present status and measurement results are presented.  
 
WEPKF020 The Design of the Special Magnets for PIMMS/TERA focusing, kicker, undulator, vacuum 1639
 
  • L. Sermeus, J. Borburgh, T. Fowler, M. Hourican, K.D. Metzmacher
    CERN, Geneva
  • M. Crescenti
    TERA, Novara
  In the framework of a collaboration agreement with the TERA Foundation CERN provided the design, drawings and engineering specifications for 2 kickers, 1 chopper and 3 bumper magnets as well as 3 magnetic and 2 electrostatic septa, power supplies for the electrostatic septa, kickers and bumpers including control electronics for the PIMMS/TERA proton and carbon ion medical synchrotron. The first application will be in the Italian National Centre for Hadron Therapy, to be constructed in Pavia. The main features of the devices are described along with the strategic design choices, directed by the demand for very high reliability and minimum maintenance.  
 
WEPKF021 Non-destructive Testing of Bus-bar Joints Powering LHC Superconducting Magnets, by Using Gamma Sources focusing, kicker, undulator, vacuum 1642
 
  • B. Skoczen
    CERN, Geneva
  • J. Kulka
    AGH, Cracow
  The main LHC superconducting magnets (dipoles and quadrupoles) are powered by using Rutherford type cables, stabilized electrically and thermally with copper profiles. The portions of cables are connected to each other by a soft soldering technique (Sn96Ag4) with the overlapping length corresponding to one pitch of the superconducting strands. The splice constitutes a ?composite? structure with the interchanging layers of Sn96Ag4 and NbTi superconductor, located inside a Cu cage. In order to assure a high level of reliability (failure probability not exceeding 10-8) for some 10000 connections in the LHC, a non-destructive technique of checking the quantity of solder in the joint is planned to be implemented. The technique is based on a gamma ray source (241_Am) and the detection is position-sensitive in the transmission mode. 5 scintillating detectors of gamma rays are used and their accumulated length corresponds to the length of the radioactive source (120 mm). The method can be used in-situ, the equipment being optimized and portable, with implementation of direct on-line operation mode. The relevant criteria of acceptance of the splices have been defined. The first results of application of this technique will be shown.  
 
WEPKF022 Electro-mechanical Aspects of the Interconnection of the LHC Superconducting Corrector Magnets kicker, undulator, vacuum, alignment 1645
 
  • J.-P.G. Tock, D. Bozzini, F. Laurent, S. Russenschuck, B. Skoczen
    CERN, Geneva
  In addition to the main 1232 bending dipoles and 474 focusing and defocusing quadrupoles, more than 6800 superconducting corrector magnets are included in the LHC machine. They are housed in the superfluid helium enclosures of the main cryomagnets. Among them, the closed orbit correctors (sextupole and octupole) are integrated in the main quadrupole helium vessel and they are powered via an externally routed cryogenic line (line N). During the assembly, these corrector magnets have to be connected according to a complex electrical scheme based on the optical requirements of the LHC machine. Along the 27-km long LHC machine, 440 interconnection boxes are installed and will allow the powering of the correctors by means of a 42-wires auxiliary bus-bar cable, of which the corresponding wires have to be routed to the SSS from the interconnection box. Stringent requirements in terms of volume, mechanical resistance, electrical conductance and insulation, reliability, and respect of the electrical schematics apply during the assembly and splicing of the junctions inside the line-N box. The activities and their sequence, aiming at ensuring the fulfilment of these requirements are presented. The planned activities (assembly, ultrasonic welding, general and electrical inspection, and electrical qualification) and the interactions between the various intervening teams are described.  
 
WEPKF024 The Geometry of the LHC Main Dipole kicker, undulator, vacuum, beamloading 1648
 
  • E.Y. Wildner, J. Beauquis, G. Gubello, M. La China, W. Scandale
    CERN, Geneva
  The 15 m long main dipole of the Large Hadron Collider has a curvature following the beam trajectory with the aim to minimize the necessary coil aperture. To avoid feed-down effects and mechanical aperture restrictions strong constraints have to be imposed on the construction of the magnet in terms of tolerances and stability of the cold mass during transport, cryostating, cold tests and installation in the LHC tunnel. In this paper we show the behaviour of the shape of the magnet using available measurements taken at different stages of construction and assembly. In particular we discuss the evolution of the sagitta and the positioning of the corrector magnets that are used to compensate the multipole field errors. We propose alignment procedures to be used in case magnets are out of tolerance after transport and cold tests. The twist of the magnet and its relation to the field angle will also be discussed.  
 
WEPKF025 Experience with the Hydrostatic Levelling System of the SLS kicker, undulator, vacuum, beamloading 1651
 
  • F.Q. Wei, L. Rivkin, A. Wrulich
    PSI, Villigen
  The Hydrostatic Levelling System (HLS) of the SLS was installed and commissioned in year 2000. It is a measurement system for monitoring the vertical positions of the SLS storage ring girders. It is integrated in the concept of dynamic alignment. The HLS was modified and re-calibrated in 2002. Since January 2003 the system has collected approximately 2 million measurements. The analysis of the data shows that displacement of the SLS storage ring foundation and the girder support was in the range of 0.15 mm in year 2003. The long term HLS stability was significantly improved. The short term precision of the HLS is in the micrometer range. The experience gained on the HLS is presented.  
 
WEPKF026 Kicker Pulser with High Stability for the BESSY FEL kicker, undulator, vacuum, beamloading 1654
 
  • J. Feikes, O. Dressler, J. Kuszynski
    BESSY GmbH, Berlin
  In the BESSY FEL design a kicker system is forseen to extract electron bunches from the main LINAC into two FEL beam lines, beside the straigth main beamline. Sine half wave pulsers with a repetion rate of up to 1 kHz and modest pulse currents of 120A will be used. To receive the maximum FEL gain, it is crucial, that the extracted bunches enter well centered into the undulators. Hence, the extraction demands for very high short-term stability of the magnetic field (shot to shot). A kicker pulse amplitude with a relative amplitude jitter smaller than 5* 10-5 would be tolerable ?more than one order smaller than the jitter of conventional BESSY II kicker systems in use. A new highly stable semiconductor based kicker pulser prototype was designed, built and tested at BESSY. It was shown that the stability of the pulse current fulfills the FEL requirements. The pulser design, its layout and the corresponding pulse current jitter measurements are presented.  
 
WEPKF027 R&D Vacuum Issues of the Future GSI Accelerator Facilities ion, kicker, undulator, beamloading 1657
 
  • H.R. Sprenger, M.C. Bellachioma, M. Bender, H. Kollmus, A. Krämer, J. Kurdal, P.J. Spiller
    GSI, Darmstadt
  The new GSI accelerator facilities are planned to deliver heavy ion beams of increased energy and highest intensity. Whereas the energy is planned to be increased roughly by a factor of 10, the ion beam intensities are planned to be enlarged by three orders of magnitude. To achieve highest beam intensities, medium charged heavy ions (e.g. U28+) are accelerated. Since the ionization cross sections for these ions are comparably high, a UHV-accelerator system with a base pressure in the low 10-12mbar regime is required, even under the influence of ion beam loss induced desorption processes. An intensive program was started to upgrade the UHV system of the existing synchrotron SIS18 (bakeable) and to design and lay out the UHV systems of the future synchrotron SIS100 and SIS300 (mainly cryogenic). The strategy of this program includes basic research on the physics of the ion induced desorption effects as well as technical developments, design and prototyping on bakeable UHV components (vacuum chambers, diagnostics, bakeout-control, pumping speed), collimator for controlled ion beam loss, NEG coating and cryogenic vacuum components.  
 
WEPKF028 High Charge Transfer Operation of Light Trigged Thrystor Crowbars ion, kicker, undulator, beamloading 1660
 
  • W. Merz
    DESY, Hamburg
  High power klystrons are protected by the application of crowbar switches. The closing switch approach is most commonly used. It is characterized by establishing a short circuit path to bypass the klystron fault current. During short circuit operation the crowbar switch must be capable to carry both puls current of the filter capacitor and follow through current of the high voltage dc power supply. Depending on the main circuit parameters both the capacitor charge and the follow through charge can achieve significant amounts. The application of line controlled and uncontrolled hvdc power converters requires special attention regarding the follow through current charge transfer. This paper presents first practical results of series connected Light Triggered Thyristors (LTT) operating as closing crowbar switches. Measured data are discussed, which have been obtained from the DESY-II installation operating with thyristor controllers and the PETRA installation operating with uncontrolled rectifiers. Beside the puls operation the follow through current capability of the crowbar is pointed out.  
 
WEPKF029 The Vacuum System of the Australian Synchrotron vacuum, kicker, undulator, beamloading 1663
 
  • E. Huttel
    FZK-ISS-ANKA, Karlsruhe
  • B. Barg, A. Jackson, B. Mountford
    ASP, Melbourne
  A 3 GeV Synchrotron Radiation Source is being built in Melbourne, Australia. The storage ring has a circumference of 216 m and has a 14 fold DBA structure. The vacuum chambers of the storage ring will be made from stainless steel. They consist of a beam chamber (width 70, height 32mm ) connected to an ante chamber, where lumped absorbers and lumped ion pumps are installed. No distributed absorber and pumps are foreseen. The nominal pumping speed of the complete ring is 31 000 l/s. The vacuum chamber of an achromat will be baked ex situ and installed under vacuum. The design of the chamber, the pump configuration and the expected vacuum behaviour will be presented.  
 
WEPKF030 The Storage Ring Magnets of the Australian Synchrotron vacuum, kicker, undulator, beamloading 1666
 
  • E. Huttel
    FZK-ISS-ANKA, Karlsruhe
  • B. Barg, A. Jackson, G. LeBlanc
    ASP, Melbourne
  • J. Tanabe
    SLAC, Menlo Park, California
  A 3 GeV Synchrotron Radiation Source is being built up in Melbourne, Australia. The storage ring has a circumference of 216 m and has a 14 fold DBA structure. For the storage ring the following magnets are required: 28 gradient dipoles, with B = 1.3 T, B’ = 3.35 T/m, 56 quadrupoles with a gradient of B’ = 18 T/m, 28 quadrupoles with a gradient of 9 T/m, 56 sextupoles with d2B/dr2 = 320 T/m2 and 42 with 150 T/m2. The design of pole faces was done by scaling the SPEAR III pole face to the required gap and bore of the ASP storage ring magnets. The sextupoles will be equipped with coils for horizontal and vertical correction and for a skew quadrupole. The design of the magnets and the calculated magnetic properties will be presented.  
 
WEPKF031 Magnetic Field Correction of the Bending Magnets of the 1.5 GeV HDSM vacuum, kicker, undulator, beamloading 1669
 
  • F. Hagenbuck, P. Jennewein, K.-H. Kaiser
    IKP, Mainz
  Beam dynamics of the Harmonic Double Sided Microtron (HDSM), the fourth stage of MAMI, require a very precise magnetic field in the inhomogeneous bending magnets. By measuring the vertical field component By in and on both sides of the midplane, the complete set of field components Bx, By, Bz was determined in the whole gap. Starting from this the asymmetric pole surface current distribution necessary to correct both symmetric and antisymmetric field errors was calculated. However, tracking calculations showed that the influence of skewed field components on the beam deflection are negligible, so that symmetric field corrections are sufficient. Nevertheless, in order to demonstrate the functioning, a set of asymmetric correction coils was built and successfully tested. The symmetric coils are designed to reduce field errors below 2*10-4. Deflection errors in the fringe field region near the magnet corners, which cannot be corrected by surface currents, will be compensated by vertical iron shims in combination with small dipoles on each beam pipe.  
 
WEPKF032 A General Method for 2d Magnet Pole Design vacuum, kicker, undulator, beamloading 1672
 
  • Z. Martí, J. Campmany, M. Traveria
    LLS, Bellaterra (Cerdanyola del Vallès)
  Accurate conventional combined magnets working in saturation are currently required to fulfil the increasing demands on low emittance accelerators with long straight sections required by the newest Synchrotron Light Sources. This fact yields stringent requirements on pole profile design, manufacture and characterization. The aim of this poster is to present a general method for designing two-dimensional pole profiles. To this end, we have set up a procedure with which to select an optimum pole profile in 2D without the constraint of relying on a set of initial assumptions, not only a particular set of initial parameters but even a particular pole profile model. Moreover, we have developed a group of codes that can be compiled and run on MS-DOS or UNIX which use POISSON or OPERA-2d codes. This procedure also includes the evaluation of the sensitivity of the final pole profile to geometrical and current intensity errors for tolerance estimation, a big requirement in this context. In order to test the feasibility of this method, we have applied it to the case of the 1.2 T combined magnet of the new synchrotron to be built nearby Barcelona.  
 
WEPKF033 Application of Finite Volume Integral Approach to Computing of 3D Magnetic Fields Created by Distributed Iron-dominated Electromagnet Structures vacuum, kicker, beamloading, antiproton 1675
 
  • O.V. Chubar, C. Benabderrahmane, O. Marcouillé, F. Marteau
    SOLEIL, Gif-sur-Yvette
  • J. Chavanne, P. Elleaume
    ESRF, Grenoble
  Iron-dominated electromagnet structures are traditionally considered as a domain of applications of the Finite-Element Method (FEM). FEM computer codes provide high accuracy for "close circuit" type geometries, however they are much less efficient for distributed geometries consisting of many spatially separated magnets interacting with each other. Examples of such geometries related to particle accelerators are insertion devices, quadrupole and sextupole magnets located close to each other, magnets with combined functions. Application of the finite volume integral approach implemented in the Radia 3D magnetostatics code to solving such geometries is described. In this approach, space around individual magnets does not require any meshing. An adaptive segmentation of iron parts, with the segmenting planes being roughly perpendicular or parallel to the expected directions of magnetic flux lines, minimizes dramatically the necessary CPU and memory resources. If a geometry is, nevertheless, too big for its complete interaction matrix to fit into memory, a special scheme of relaxation "by parts" can be applied. The results of calculations made for the SOLEIL electromagnet undulator HU256 will be presented.  
 
WEPKF034 The Modified DAFNE Wigglers vacuum, kicker, beamloading, antiproton 1678
 
  • S. Guiducci, S. Bertolucci, M. Incurvati, M.A. Preger, P. Raimondi, C. Sanelli, F. Sgamma
    INFN/LNF, Frascati (Roma)
  Modifications to the pole shape of a spare wiggler have been tested to increase the width of the good field region, with the aim of reducing the effect of nonlinearities affecting the dynamic aperture and the beam-beam interaction. Additional plates realized with the same material of the pole have been machined in several shapes and glued on the poles. Accurate measurements of the vertical field component on the horizontal symmetry plane of the magnet have been performed to find the best profile. The particle motion inside the measured field has been simulated to minimize the field integral on the trajectory, to determine the wiggler transfer matrix and to estimate the amount of non linear contributions. All wigglers in the collider have been modified to the optimized pole shape. Measurements with beam performed with the modified wigglers show a significant reduction of nonlinearities.  
 
WEPKF035 Analysis of the Cold Mass Displacements at the TTF vacuum, kicker, beamloading, antiproton 1681
 
  • A. Bosotti, C. Pagani, P. Pierini
    INFN/LASA, Segrate (MI)
  • R. De Monte, M. Ferianis
    ELETTRA, Basovizza, Trieste
  • R. Lange
    DESY, Hamburg
  Few of the TTF cryomodules have been equipped with wire position monitors (WPM) in order to monitor on line the displacements of the cold mass to verify alignment stability and reproducibility . Based on the operation experience of the first prototypical cryomodules, equipped with up to 36 WPMs distributed in two strings, on the last generation cryomodules a single string of 7 sensors has been installed. Here we review and analyze the data collected so far to prove that the the proposed cryomodule design is consistent with the TESLA alignment requirements.  
 
WEPKF037 Structural Analysis of an Integrated Model of Short Straight Section, Service Module, Jumper Connection and Magnet Interconnects for the Large Hadron Collider kicker, beamloading, antiproton, damping 1684
 
  • S. Dutta, J. Dwivedi, A. Kumar, H.C. Soni
    CAT, Indore (M.P.)
  • B. Skoczen
    CERN, Geneva
  The Short Straight Section (SSS) of the Large Hadron Collider (LHC) houses a twin quadrupole.The cryogens are fed to the SSS through a Jumper Connection between service modules of Cryogenic Distribution Line (QRL) and SSS.A Finite Element analysis has been performed in collaboration with CERN for the unified model of SSS of LHC,consisting of cold mass, cold supports,vacuum vessel and its bellows, interconnects, jumper connection and alignment jacks. The model has been developed to understand coupling between the quadrupole magnet and the service module due to ground motion and during the realignment or global smoothening of the LHC arc. The model incorporates experimental stiffness values for support posts, internal pipes and jacks and calculated stiffness for magnet-to-magnet interconnects. The computation space and time has been reduced by executing a two step linear static analycal approach with an initial trial analytical approach cycle in which the program estimates the behavior of the flexibles. A special routine is developed within ANSYS,using APDL which selects the correct secant stiffness of flexibles(by applying a user interactive logical algorithm)from their non-linear force displacement characteristics.  
 
WEPKF038 The Alignment Jacks of the LHC Cryomagnets alignment, kicker, beamloading, antiproton 1687
 
  • J. Dwivedi, S.G. Goswami, A. Kumar, V. Madhumurthy, H.C. Soni
    CAT, Indore (M.P.)
  • V. Parma
    CERN, Geneva
  The precise alignment of the some 1700 cryomagnets of the LHC collider, requires the use of some 7000 jacks. The specific requirements and the need for an cost-effective solution for this large production, justified the development and industrialisation of a dedicated mechanical jack which was developed, and is now being produced, in the framework of a collaboration between CERN and the Center for Advanced Technology in India. Three jacks support each of the 32-ton heavy, 15-meter long cryo-dipoles of LHC, and provide the required alignment features. The main requirements are a setting resolution of 0.05 mm, and a range of movement of 20 mm in the horizontal and 40 mm in the vertical direction. Each jack has two degrees of controlled movement in the horizontal and vertical direction, whereas the remaining horizontal movement is left free. By a suitable choice of the layout of the three jacks, the full range of alignment of a cryo-magnet can be obtained. The design of the jacks evolved from a preliminary value analysis between various concepts, towards the complete engineering of the retained concept, selection of the most appropriate and cost-effective industrial production processes and setting-up of an effective quality assurance policy. Building and testing of 36 prototype jacks allowed an extensive experimental validation of their performance at CERN, where they were operated in the String 2 facility, and yielded an improved understanding for cost-effective steering of the production processes before launching the series production. Presently, the mass production of the jacks is in progress with two Indian manufacturers, and some 1500 jacks have already been delivered to CERN. Considering the successful performance of the jacks, it is now envisaged to extend the use of the same type of jacks to provide the even higher-demanding alignment of the low-beta quadrupoles of LHC.  
 
WEPKF039 The Vacuum System of Super SOR alignment, kicker, beamloading, antiproton 1690
 
  • H. Sakai, M. Fujisawa, A. Kakizaki, T. Kinishita, H. Kudo, N. Nakamura, O. Okuda, S. Shibuya, K. Shinoe, H. Takaki
    ISSP/SRL, Chiba
  • K. Kobayashi
    KEK, Ibaraki
  • T. Koseki
    RIKEN/RARF/BPEL, Saitama
  • H. Ohkuma
    JASRI/SPring-8, Hyogo
  • S. Suzuki
    LNS, Sendai
  The Super-SOR light source is a Japanese VUV and soft X-ray third-generation synchrotron radiation source, which consists of 1.8GeV storage ring and injector. The beam current is circulated up to 400mA. These accelerators are designed so as to fully meet requirements for top-up injection. In order to realize these operation modes, our vacuum system are required on following conditions. One is to obtain the long lifetime. The other is not to melt the vacuum chamber by irradiating the high flux synchrotron radiation. Finally beam instability is not occurred by large wake fields. We describe the design of the vaccum chamber of Super-SOR and present the recent R&D concerning this system.  
 
WEPKF040 Magnetic Field Measurement of Quadrupole Magnets for S-LSR alignment, kicker, beamloading, antiproton 1693
 
  • T. Takeuchi, K. Noda, S. Shibuya
    NIRS, Chiba-shi
  • H. Fadil, M. Ikegami, A. Noda, T. Shirai, H. Tongu
    Kyoto ICR, Uji, Kyoto
  S-LSR is a low energy ion storage/cooler ring. It has 12-quadrupole magnets (QM) with a bore radius of 70 mm and a maximum field gradient of 5 T/m. To suppress and control a magnetic flux in a fringing field of a bending magnet (BM), a field clamp with a thickness of 25 mm was installed in between BM and QM. The distance between the field clamp and QM is 80 mm. 3D calculation represented that the QM field is strongly influenced by the field clamp. Therefore, QMs were designed and optimized in considering the influence of the field clamp. Magnetic field measurements were performed by means of a Hall probe and a long search coil. A magnet field measurement by a Hall probe was carried out together with the field clamp and BM for S-LSR. For 12-quadrupole magnets, the measurement by the long search coil which moves in horizontal direction was carried out. The results for each measurements will be discussed.  
 
WEPKF041 Permanent Magnet Generating High and Variable Septum Magnetic Field and its Deterioration by Radiation alignment, kicker, radiation, septum 1696
 
  • T. Kawakubo, E. Nakamura, M. Numajiri
    KEK, Ibaraki
  • M. Aoki, T. Hisamura, E. Sugiyama
    NEOMAX Co., Ltd., Mishima-gun, Osaka
  Conventional high field septum magnet is fed by DC current or pulse current. In the case of DC, the problem of coil support is not very important, but the cooling of the coil is serious problem. While, in the case of pulse, the problem of support is much important than that of cooling. However, if the septum magnet is made of permanent magnet, those problems are dissolved. And the cost for electricity and cooling water can be exceedingly decreased. Therefore, we made the model septum magnet which has 1/4 scale of the real size and generates 1[T] with the variable range of ± 10%. The magnetic field distribution in the gap by changing the representative field is reported. When this permanent magnet is set in an accelerator, the deterioration of the permanent magnet by radiation will be serious problem. We also report the dependence of the magnetic fields generated by permanent magnet samples on accumulated radiation by various types of radiation source.  
 
WEPKF042 Installation and Operation of New Klystron Power Supply with Fast Solid-State Switch for Klystron Protection at the Photon Factory Storage Ring alignment, kicker, radiation, septum 1699
 
  • S. Sakanaka, M. Izawa, T. Takahashi, K. Umemori
    KEK, Ibaraki
  In the 2.5-GeV Photon Factory storage ring at KEK, there are four klystron power supplies which typically operate at an output voltage of -40 kV with 8 A. We replaced one of these power supplies during 2003 and the new power supply is in operation. This power supply is equipped with a solid-state high-voltage (HV) switch for klystron protection. This HV switch is made up of eighty insulated gate bipolar transistors (IGBT), and it can turn the high-voltage off within a few tens of microseconds in cases of any discharges in the klystrons. We report the performance of this new power supply.  
 
WEPKF043 Measurement of the Vertical Quadrupolar Tune Shift in the Photon Factory Storage Ring alignment, kicker, radiation, quadrupole 1702
 
  • S. Sakanaka, T. Mitsuhashi, T. Obina
    KEK, Ibaraki
  We measured the frequencies of vertical quadrupole oscillations in the 2.5-GeV Photon Factory storage ring at KEK. The measured vertical quadrupole tunes showed remarkable dependence of about -7.5E-5/mA on the bunch current. This contrasts with our previous result of about +4.8E-5/mA (presented in PAC2003) for the horizontal quadrupole tune shift. These results will suggest that the transverse wake forces in a quadrupolar mode contribute significantly to the transverse motions of particles in the Photon Factory storage ring.  
 
WEPKF046 Gradient Field Generation in a Uniform Gapped Magnet alignment, kicker, radiation, quadrupole 1705
 
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • Y. Arimoto, A. Sato
    Osaka University, Osaka
  Magnets with gradient field (indexed magnets) usually have different gap distances with the different entrance positions. This situation will break a uniformity of the effective length. Trim coils, which are usually used in Cyclotron, are not practical to modify a field distribution when a large gradient is required such as FFAG. In order to generate a gradient field in a constant gapped magnet, a novel method with use of inter-pole is devised. This magnet has not only constant gap but also smaller fringing field compared with a conventional one. This technique should widen the recipe to design a magnet with such a complex magnetic field.  
 
WEPKF047 A Super Strong Adjustable Permanent Magnet for the Final Focus Quadrupole in a Linear Collider alignment, kicker, radiation, quadrupole 1708
 
  • T. Mihara, Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • E. Antokhin, M. Kumada
    NIRS, Chiba-shi
  • C.M. Spencer
    SLAC, Menlo Park, California
  • E. Sugiyama
    NEOMAX Co., Ltd., Mishima-gun, Osaka
  A super strong magnet, which utilizes permanent magnet material and saturated iron, is considered as a candidate for the final focus quadrupole in a linear collider beamline. This modified Halbach magnet configuration can have a higher magnetic field gradient than a normal permanent magnet quadrupole (PMQ) or electromagnet. There are some issues to be solved if a PMQ is to be used as a final focus quadrupole: the variation of its strength with temperature and the need for the field strength to be deliberately changed. One can use special temperature compensation material to improve the temperature dependence with just a small decrease in field gradient compared to a magnet without temperature compensation. The required field variability can be obtained by slicing the magnet into pieces along the beamline direction and rotating these slices. Results of performance measurements on the PMQ with variable strength will be reported including the realization of the temperature compensation technique.  
 
WEPKF048 Characteristics of Ground Motion at KEK and SPring-8 alignment, kicker, site, radiation 1711
 
  • Y. Nakayama, T. Ito
    JPOWER, Kanagawa-ken
  • S. Matsui, C. Zhang
    JASRI/SPring-8, Hyogo
  • R. Sugahara, S. Takeda, H. Yamaoka, M. Yoshioka
    KEK, Ibaraki
  • S. Yamashita
    University of Tokyo, Tokyo
  Authors Y. Nakayama, T. Ito, (JPOWER); R. Sugahara, S. Takeda, H.Yamaoka, M.Yoshioka (KEK); S.Matsui, C.Zhang (SPring-8); S. Yamashita (ICEPP): Abstract Stability of ground is preferable for accelerator beam operation. We have measured ground motion of ground at the KEKB and SPring-8 site, where the ground has quite different characteristics each other. In this paper, some of analysis results are shown, and the characteristics of the ground motion at the KEKB site and those at the Spring-8 site are compared.  
 
WEPKF049 Stretched Wire Flip Coil System for Magnetic Field Measurements alignment, kicker, site, radiation 1714
 
  • D.E. Kim, C.W. Chung, H.S. Han, Y.G. Jung, H.G. Lee, W.W. Lee, K.-H. Park, H.S. Suh
    PAL, Pohang
  A flip-coil system using a stretched wire measuring the magnetic field properties of accelerator magnets is described. This system is similar to the conventional rotating coil system except that the stretched wires are used instead of wires wound on the machined surface. This system has advantage of simple fabrication and flexible operation so that different length and bore magnets can be easily measured using the same system. The system also has two loop coils to buck the dominant fundamental field so as to increase the measurement accuracy. This kind of system has issues related to the reproducibility, accuracy of the measured results. The system is evaluated to verify its performances and its results were discussed. The analyzing methods and various efforts to keep the system in high accuracy are presented. Measurement results with this loop coil system were compared with that of the other system.  
 
WEPKF050 Measurement of Fast High Voltage Pulse and High Noisy DC Siganla for Modulator at the PLS Linac alignment, kicker, site, radiation 1717
 
  • S.-C. Kim, Y.J. Han, S.H. Kim, S.-H. Nam, S.S. Park
    PAL, Pohang
  The 2.5-GeV electron linac at Pohang accelerator laboratory (PAL) has been operated continuously as a full energy injector for the Pohang Light Source (PLS) since Dec. 1994. There have been continuous efforts to improve the klystron-modulator system more stable and reliable. At pulse operated modulator system, important pulse and DC signals are beam voltage, beam current, EOLC current HVDC voltage and HVDC current. Pulse signals are fast high voltage pulse 30 Hz, 5ms. These signals are adequate level down from modulator but including high level switching noisy. To amplitude measure of these signals for every trigger signal, we developed special module sampling hold, A/D, calculating and D/A. The output signals of these modules are 0 ~ 10 V DC signal and not include any noise signal. These output signals are connected interlock interface module of the modulator controller. Therefore computer system (PC) of the modulator controller is free to noise of these signals and can precise monitor pulse & noise DC signal. In these paper, we are described itself characteristics pulse and high noisy DC signals of the modulator, signal conditioning technique after noise elimination and operation status of the modulator controller.  
 
WEPKF051 Operational Analysis of PLS 2-GeV Electron Linac Klystron-modulator System klystron, alignment, kicker, site 1720
 
  • S.S. Park, Y.J. Han, S.H. Kim, S.-C. Kim, S.-H. Nam
    PAL, Pohang
  The klystron-modulator(K&M) system of the Pohang Light Source(PLS) had been supplying high power microwaves for the acceleration of 2 GeV electron beams. There are 11 sets of K&M systems to accelerate electron beams to 2 GeV nominal beam energy without operating one klystron-modulator. One module of the K&M system consists of an 80 MW S-band (2856 MHZ) klystron tube and the matching 200 MW modulator. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 68,000 hours as of Dec. 2003 and the summation of all the units' high voltage run-time is approximately 820,000 hours. The overall system availability is well over 95%. There have been continuous efforts to improve the klystron-modulator system more stable and reliable. To improve self-diagnostic, operation, monitoring, and remote communication, we developed a new modulator controller based on an industrial PC platform in 2002. In this paper, we are able to review overall system performance of the high-power K&M system and the operational characteristics of the klystrons and thyratrons, and overall system's availability analysis from Jan. to Dec. 2003.  
 
WEPKF053 Status and Development for the JAERI ERL-FEL for High-Power and Long-Pulse Operation klystron, alignment, kicker, site 1723
 
  • M. Sawamura, R. Hajima, N. Kikuzawa, E.J. Minehara, R. Nagai, N. Nishimori
    JAERI/FEL, Ibaraki-ken
  After the success of energy recovery linac (ERL) for the superconducting free-electron laser (FEL) in the Japan Atomic Energy Research Institute (JAERI), the JAERI ERL-FEL has been upgrading for high-power and long-pulse operation. The new grid pulser for the thermoionic cathode gun is under development and test to increase the beam current by increasing the repetition rate of 10MHz to 20MHz. The new RF sources of CW mode for higher power for non-energy-recovery parts have been installed and tested for long-pulse operation. The properties of the superconducting linac required for the long-pulse operation were also measured such as pressure in the cryomodule, vibration of frequency and piezo tuner response. The RF control systems have been also upgraded to reduce the fluctuation to less than 0.1% for amplitude and 0.1 deg for phase.  
 
WEPKF054 Auto-filling Cryogenic System for Superconducting Wiggler klystron, alignment, kicker, site 1726
 
  • F.-Y. Lin, C.-H. Chang, H.-H. Chen, T.-C. Fan, M.-H. Huang, C.-S. Hwang
    NSRRC, Hsinchu
  A 3.2 Tesla superconducting wiggler with period length of 6.0 cm (SW6) was installed in January of 2004 at the National Synchrotron Radiation Research Center (NSRRC). A cryogenic plant for superconducting rf cavity will also provide liquid helium and liquid nitrogen for SW6 by using an independent automatic filling system. To facilitate a stable and precise auto-filling process, a PID controller, the kernel of the auto-filling system, will control the valves of liquid helium and liquid nitrogen, respectively. The authors shall present the control algorithm of different operation modes, namely the pre-cooling mode and normal auto-filling mode. The boil off rate of liquid helium and liquid nitrogen will be discussed.  
 
WEPKF055 Design and Implementation of a Switching Mode Bipolar Power Stage of the Correction Power Supply klystron, alignment, kicker, site 1729
 
  • C.-Y. Liu, C.H. Kuo, K.-B. Liu
    NSRRC, Hsinchu
  In order to enhance efficiency of the correction power supply, the switching mode bipolar power stage was to implement and to substitute for the original power stage of the correction power supply. To ensure higher efficiency, the programming dc bus voltage of the power stage of the correction power supply must be working in accordance with the output current state and load. A new power conversion stage was constructed and employs power MOSFET operating at higher switching frequency then old 60 Hz energy conversion mode system. This will not only improve the efficiency but also decrease the weight of the correction power supply. The new switching mode power stage supply a bipolar power dc bus power and automatic turning working voltage by the feedback balance circuit. Results and working performance will be presented in this paper.  
 
WEPKF056 Reducing Output Current Ripple of Power Supply with Component Replacement klystron, alignment, kicker, site 1732
 
  • K.-B. Liu, C.-S. Fann
    NSRRC, Hsinchu
  Correction magnets of synchrotron storage ring are served with linear power supplies (correction power supply) with 100 ppm output current ripple in National Synchrotron Radiation Research Center. Reducing output current ripple of correction power supply might reduce perturbation of beam position of storage ring. Replace correction power supplies with lower output current ripple ones is straightforward but costs lots of money. Without adding any other circuit and electronic component, some components of correction power supply are replaced by ones with more precious and lower output fluctuation; so that the same circuitry structure of correction power supply is kept without increasing its complexity and could reach 25 ppm output current ripple.  
 
WEPKF057 Design and Study of a Superferric Model Dipole and Quadrupole Magnets for the GSI Fast-pulsed Synchrotron SIS100. klystron, alignment, kicker, site 1735
 
  • A.D. Kovalenko, N.N. Agapov, V. Bartenev, A. Donyagin, I. Eliseeva, H.G. Khodzhibagiyan, G.L. Kuznetsov, A. Smirnov, M.A. Voevodin
    JINR, Dubna, Moscow Region
  • E. Fischer, G. Moritz
    GSI, Darmstadt
  New experimental results from the investigation of a model superferric Nuclotron-type dipole and quadrupole magnets are presented. The magnets operate at pulse repetition rate f = 1Hz, providing peak magnetic field B = 2 T and the field gradient G = 34 T/m in the dipoles and quadrupoles respectively. The superconducting coil is made from a hollow multi-filamentary NbTi cable cooled with two phase helium flow. Different possibilities were investigated to reduce AC power losses in the case of a cold iron yoke (T=4.5K). The achieved results are discussed. The value of 9W/m has been obtained for dipole magnet with the yoke at T=50K. The first 50 K yoke quadrupole was designed and tested. Other problems, connected with the magnetic field quality, mechanical and cryogenic stability of the magnets under SIS100 operating conditions are also discussed.  
 
WEPKF060 Bending Magnets for the SAGA Storage Ring: Manufacturing and Magnetic Measurements klystron, alignment, kicker, site 1738
 
  • S.V. Sinyatkin, I.N. Churkin, O.B. Kiselev, V. Korchuganov, A.B. Ogurtsov, A.V. Philipchenko, L.M. Schegolev, K.K. Schreiner, A.G. Steshov, V. Ushakov
    BINP SB RAS, Novosibirsk
  • M. Kuroda, Y. Tsuchida
    Saga Synchrotron Light Source, Industry Promotion Division, Saga City
  The paper describes the design, the manufacture and the magnetic measurement of the dipole bending magnets (BM) for SR Source storage ring (prefecture SAGA, Japan) carried out in BINP, Novosibirsk, Russia. The requirement was to create the laminated C-shape BMs with the 3.2 m radius and parallel edges. The magnetic field homogeneity must be not worth than ±2? 10-4 inside the working area: H = 30+40mm and V = ±20mm at 0.26T (250 MeV), and H = ± 28mm and V = ±20mm at 1.46 T (1.4GeV). The BMs were designed on the basis of the 2-D 3-D modeling taking into account the laminated core. The BMs yokes were produced with the help of the technology of the high temperature gluing. The computer simulations are in a good agreement with the magnetic measurements. The main parameters of the magnetic fields satisfy to the requirements and are presented. The features of the design, manufacturing and precise magnetic measurements of SAGA BMs are discussed.  
 
WEPKF061 Study of Electrical Steel Magnetic Properties for Fast Cycling Magnets of SIS100 and SIS300 Rings klystron, alignment, kicker, site 1741
 
  • I. Bogdanov, S. Kozub, A. Shcherbakov, L. Tkachenko
    IHEP Protvino, Protvino, Moscow Region
  • E. Fischer, F. Klos, G. Moritz, C. Muehle
    GSI, Darmstadt
  The operation conditions of yoke steels in superconducting magnets of the SIS100 and SIS300 are at 4.2 K and unipolar cycles with high magnetic induction. The results of measurements of different classes of electrical steels, both isotropic and anisotropic, in the operating conditions of superconducting dipoles are presented. The measurements are carried out on ring samples in quasistatic mode. Dependence of B(H) as well as values of Hc and hysteresis losses in bipolar and unipolar cycles are determined from hysteresis loops at different temperatures. The anisotropy of steels is measured at room temperature on the strip samples, cut along the rolling direction and across one. The comparison of results on ring and strip samples is carried out. The results of calculations of hysteresis and eddy current losses in iron yoke of fast-cycling dipole for the SIS300 are presented. The recommendations on choice of grade steels for fast cycle superconducting magnets are given.  
 
WEPKF062 Study of the Quench Process in Fast-cycling Dipole for the SIS300 Ring klystron, alignment, kicker, site 1744
 
  • I. Bogdanov, S. Kozub, A. Shcherbakov, L. Tkachenko, S. Zintchenko, V. Zubko
    IHEP Protvino, Protvino, Moscow Region
  • J. Kaugerts, G. Moritz
    GSI, Darmstadt
  The results of numerical quench process simulation in the coil of superconducting dipole with magnetic field of 6 T and 100-mm aperture for high-energy ion and proton synchrotron facility SIS300 are presented. The peculiarities of quench process developed in dipole are discussed for several variants of quench conditions. The coil quench behavior determines the features, scopes, and limitations in possible quench protection scheme. Main design characteristics of the preferable protection system are considered.  
 
WEPKF063 Comparison of Three Designs of Wide Aperture Dipole for SIS300 Ring klystron, alignment, kicker, site 1747
 
  • L. Tkachenko, I. Bogdanov, S. Kozub, A. Shcherbakov, I. Slabodchikov, V. Sytnik, V. Zubko
    IHEP Protvino, Protvino, Moscow Region
  • J. Kaugerts, G. Moritz
    GSI, Darmstadt
  The GSI Fast-Pulsed Synchrotron Project is found now under development. The last stage of this machine is the SIS300 ring, which will use superconducting dipoles with 100-mm aperture, 6-T magnetic field amplitude and 1-T/s field ramp rate. This dipole has to posses minimal heat losses both in the coil and in the iron yoke. This article considers three designs of such dipole. The main distinction of these designs is the different thickness of stainless steel collars, which are supported the coil. The collars in the first design hold all forces arisen in the magnet. The second design needs collars only for assembly of the coil and cooling down of the magnet. An iron yoke in this design will withstand ponderomotive forces. The third design has no collars and the iron yoke will hold all forces, including preload, forces originated during cooling down and ponderomotive forces. The different mechanical, magnetic and thermal characteristics are presented and comparative analysis of these designs is carried out.  
 
WEPKF064 Methods for Reducing Cable Losses in Fast-Cycling Dipoles for the SIS300 Ring klystron, alignment, kicker, site 1750
 
  • L. Tkachenko, I. Bogdanov, S. Kozub, A. Shcherbakov, I. Slabodchikov, V. Zubko
    IHEP Protvino, Protvino, Moscow Region
  • G. Moritz
    GSI, Darmstadt
  • V. Sytnikov
    RCSRDI, Moscow
  A new synchrotron facility is being designed for the acceleration of high intensity and high-energy ion and proton beams at GSI, Darmstadt. The main magnetic elements of the second stage (SIS300) are superconducting dipoles with 100 mm aperture, 6-T magnetic field amplitude, and 1 T/s field ramp rate. The main requirements for these magnets, in addition to high field quality, are minimal heat losses, both in the coil and in the iron yoke, at an acceptable temperature margin. An increase of the temperature margin can be achieved by increasing the volume of superconductor in the cable. However, increasing the number of strands in the cable results in a growth of the cable width. Since coupling losses in the cable are proportional to the fourth power of cable width, these losses rise dramatically. This presentation considers and analyses different ways of reducing these cable heat losses. The calculated results of heat losses for different geometries, based on various cable designs, as well as the parameters of optimal cable designs, based on computer simulations, are presented.  
 
WEPKF065 Study of Thermal Stability and Quench Process of HTS Dipole klystron, alignment, kicker, site 1753
 
  • V. Zubko, I. Bogdanov, S. Kozub, A. Shcherbakov, L. Tkachenko
    IHEP Protvino, Protvino, Moscow Region
  The dipole with a coil made from HTS composite on a Bi2223 basis and placed in the ferromagnetic yoke has been developed and produced in IHEP. A designed magnetic field of the dipole in 20-mm aperture is 1 T at temperature of liquid nitrogen. The numerical analysis of factors, having influence on thermal stability of the magnet, as well as the computer simulations of dipole heating during quench was carried out. An anisotropy of voltage-current characteristics of HTS tapes in a magnetic field is taken into account in calculations of quench process. The measured results of voltage-current characteristics during powering and quench of the coil are in a good agreement with the numerical calculations  
 
WEPKF066 Stability of Fast-cycling Dipole for SIS300 Ring klystron, alignment, kicker, site 1756
 
  • V. Zubko, I. Bogdanov, S. Kozub, A. Shcherbakov, L. Tkachenko, S. Zintchenko
    IHEP Protvino, Protvino, Moscow Region
  • M. Kauschke, G. Moritz
    GSI, Darmstadt
  Funding AgencyShould not exceed 200 charactersFootnotesFootnotes: Not exceeding 200 chaThe main requirement to the superconducting dipole with 100-mm aperture, 6-T magnetic field amplitude and 1-T/s field ramp rate for the SIS300 accelerator, developed in the GSI, Darmstadt, is a stability of the magnet influenced by various heat releases arising during operation mode. The computer simulation of the heating of superconducting dipoles and cooling helium during the SIS300 operating cycle was carried out. The analysis of stability is based on the numerical solution of the heat balance equation in the coil and in a single?phase helium flow. Temperature margin of the superconducting dipole during the SIS300 operating cycle was calculated. Possible ways to increase the temperature margin are discussed.  
 
WEPKF068 Developments in Magnet Power Converters at the SRS klystron, alignment, site, beamloading 1759
 
  • G.D. Charnley, J. Cartledge, P.A.D. Dickenson, S.A. Griffiths, S.H. Hands, R.J. Smith, J.E. Theed, C.J. White
    CCLRC/DL, Daresbury, Warrington, Cheshire
  A project to upgrade the magnet power converters of the SRS has commenced to ensure its efficient operation for its remaining operational lifetime. A recent risk analysis of the facilities equipment identified that the main areas for concern were the Storage Ring magnet power converters, kicker and septum pulse power supplies and the Booster Dipole "White Circuit" and associated power converters. This report detail the development and replacement programs currently active at Daresbury Laboratory, including future work identified to support and improve SRS utilisation.  
 
WEPKF069 52 kV Power Supply for Energy Recovery Linac Prototype RF klystron, alignment, site, beamloading 1762
 
  • J.E. Theed, M. Dykes, A. Gallagher, S.A. Griffiths, S.H. Hands, A.J. Moss, J.F. Orrett, C.J. White
    CCLRC/DL, Daresbury, Warrington, Cheshire
  Daresbury Laboratory is constructing a Radio-Frequency (RF) Test Facility to be capable of testing RF cavities for accelerator applications. Electrical power for the RF equipment will be provided from an existing -52 kV 6-pulse rectifier and transformer system capable of delivering 16A DC continuous current. A crowbar circuit will be provided to divert the large amount of stored energy in the smoothing capacitor bank in the event that a spark should occur between the cathode and the body or modulating anode. Traditionally, the crowbar has been provided by using an ignitron, but modern solid state devices have sufficient performance to meet the requirements. This paper discusses the numerous design options that were considered for the circuit parameters.  
 
WEPKF070 Design Issues for the Superconducting Magnet that goes around the Liquid Hydrogen Absorber for the Muon Ionization Cooling Experiment (MICE) vacuum, focusing, klystron, alignment 1765
 
  • M.A. Green, G. Barr, J. Cobb, W. Lau, R.S. Senanayake, H. Witte, S.Q. Yang
    OXFORDphysics, Oxford, Oxon
  • E. Baynham, T.W. Bradshaw, P. Drumm, Y. Ivanyushenkov, J. Rochford
    CCLRC/RAL, Chilton, Didcot, Oxon
  This report describes the design issues that are associated with a superconducting focusing solenoid that goes around a liquid hydrogen absorber for the Muon Ionization Cooling Experiment (MICE) proposed for the Rutherford Appleton Laboratory. The solenoid consists of two superconducting coils that may operated at the same polarity or at opposite polarities. As a result, the coils and their support structure must be designed to carry a 300 ton inter-coil force that is forcing the coils apart along their axis. The basic design parameters for the focusing magnet are discussed. The magnet and its cryostat are designed so that the absorber can be assembled and tested before installation into the pre-tested focusing solenoid. A safety requirements for MICE dictate that the insulating vacuum for the superconducting magnet be separated from the insulating vacuum for the absorber and that both vacuum be separated from the experiment vacuum and the vacuum within adjacent RF cavities. The safety issues associated with the arrangement of the various vacuums in the MICE focusing modules are presented. The effect of magnet operation and magnet quench on the liquid hydrogen absorber is also discussed.  
 
WEPKF071 A New Current Regulator for the APS Storage Ring Correction Magnet Bipolar Switching Mode Power Converters vacuum, focusing, klystron, alignment 1768
 
  • J. Wang
    ANL, Argonne, Illinois
  The correction magnets in the Advanced Photon Source's storage ring are powered by PWM-controlled bipolar switching-mode converters. These converters are designed to operate at up to ± 150 A. The original current regulator used a polarity detection circuit, with a hysteresis, to determine which IGBT was needed to regulate the current with a given polarity. Only the required IGBT was switched while others were held on or off continuously. The overall IGBT switching losses were minimized by the design. The shortcoming of the design is that the converter's output is unstable near zero current because of the hysteresis. To improve the stability, a new current regulator, using a different PWM method, has been designed to eliminate the requirement of the polarity detection. With the new design, converters can operate smoothly in the full range of ±150 A. The new design also meets tighter specs in terms of the ripple current and dynamic response. This paper describes the design of the new regulator and the test results.  
 
WEPKF072 Clearing Electrodes for Vacuum Monitoring at the Fermilab Recycler focusing, klystron, alignment, site 1771
 
  • D.R. Broemmelsiek, S. Nagaitsev
    Fermilab, Batavia, Illinois
  The Fermilab Recycler is a fixed 3.3-km 8-GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel. Each split-plate beam position monitor in the Recycler is also used to generated an ion clearing field for ions trapped by the antiproton beam. Approximately 100 locations have been instrumented with pico-amp meters to measure the electron current, generated by the beam-ionized residual gas in the vacuum chamber. This electron current is found to be proportional to the beam current and to the residual gas pressure in the Recycler and may be used to monitor the Recycler vacuum.  
 
WEPKF073 2nd Generation LHC IR Quadrupoles Based on Nb3Sn Racetrack Coils focusing, klystron, alignment, site 1774
 
  • V. Kashikhin, J. Strait, A.V. Zlobin
    Fermilab, Batavia, Illinois
  After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the baseline NbTi low-beta quadrupoles with a higher performance magnets based on advanced superconducting materials and magnet technologies is one of the most straightforward ways in this direction. Preliminary studies show that high-performance Nb3Sn strands to be available within the next few years allow increasing the quadrupole aperture up to 110 mm using a 4-layer shell-type coil and providing the same 200 T/m field gradient with 20% margin as the baseline magnets. It will allow reduction of b* by a factor of 3. An alternative approach to the quadrupole design is based on simple flat racetrack coils. This paper discusses the possibilities and limitations of large-aperture racetrack quadrupole designs and compares them to the shell-type magnets.  
 
WEPKF074 Magnetic Field Measurements of the LHC Inner Triplet Quadrupoles Produced at Fermilab focusing, klystron, site, quadrupole 1777
 
  • G. Velev, R. Bossert, R. Carcagno, J. DiMarco, S. Feher, H. Glass, V. Kashikhin, J.S. Kerby, M. Lamm, T. Nicol, L. Nobrega, D. Orris, T. Page, T. Peterson, R. Rabehl, P. Schlabach, J. Strait, C. Sylvester, M. Tartaglia, J. Tompkins, A.V. Zlobin
    Fermilab, Batavia, Illinois
  Production of 18 superconducting low-beta quadrupoles (MQXB) for the LHC is well advanced. These 5.5 m long magnets are designed to operate at 1.9 K with a peak field gradient of 215 T/m in the 70 mm apertures. Two MQXB cold masses with a dipole orbit corrector between them form a single cryogenic unit (LQXB) which is the Q2 optical element of the final focus triplets in the LHC interaction regions. A program of magnetic field quality and alignment measurements of the cold masses are performed at room temperature during magnet fabrication and LQXB assembly as well as at superfluid helium temperature. Results of these measurements are summarized in this paper.  
 
WEPKF075 Measurements of Sextupole Decay and Snapback in Tevatron Dipole Magnets focusing, klystron, site, quadrupole 1780
 
  • G. Velev, J. Annala, P. Bauer, J. DiMarco, H. Glass, R. Hanft, R. Kephart, M. Lamm, M. Martens, P. Schlabach, C. Sylvester, M. Tartaglia, J. Tompkins
    Fermilab, Batavia, Illinois
  To optimize the performance of the Fermilab Tevatron accelerator in Collider Run II, we have undertaken a systematic study of the drift and subsequent snapback of dipole magnet harmonics. The study has mostly focused on the dynamic behavior of the normal sextupole component, b2, as measured in a sample of spare Tevatron dipoles at the Fermilab Magnet Test Facility. We measured the dependence of the decay amplitude and the snapback time on Tevatron ramp parameters and magnet operational history. A series of beam studies was also performed [*]. This paper summarizes the magnetic measurement results and describes an optimization of the b2 correction scheme which is derived from these measurements.

* P.Bauer et al. These proceedings.

 
 
WEPKF076 Solid-state Marx Bank Modulator for the Next Linear Collider focusing, site, quadrupole, beamloading 1783
 
  • M.A. Kempkes, F.O. Arntz, J.A. Casey, M.P.J. Gaudreau
    Diversified Technologies, Inc., Bedford
  The Next Generation Linear Collider (NLC) will require hundreds to thousands of pulse modulators to service more than 3300 klystrons. DTI recently investigated the use of a solid-state Marx switch topology for the NLC, and has transitioned this work into the development of a full-scale, 500 V solid state Marx system. Combined with recent advances in semiconductor technology and packaging, these efforts have moved the performance of the Marx pulser far ahead of early estimates. The Marx pulser eliminates the pulse transformer, which is associated with significant loss of performance and a 15-20% penalty in the efficiency of a conventional modulator. The increase in efficiency attributable to the Marx topology can account for over $100M in power cost savings over ten years of NLC operation, an amount comparable to the acquisition costs of the pulsed power systems. In this paper, DTI will discuss the design and development of the Marx Bank modulator. Its performance scales to 125 ns risetime (10-90%) for either a 500 kV, 265 A pulse (for one klystron), or a 500 kV, 530 A pulse (for two klystrons). The use of a unique, common mode inductive charging system allows transfer of filament power without separate isolation transformers.  
 
WEPKF079 A Kicker Design for the Rapid Transfer of the Electron Beam between Radiator Beamlines in LUX focusing, site, quadrupole, beamloading 1786
 
  • G.D. Stover
    LBNL/ALS, Berkeley, California
  I present in this paper preliminary design concepts for LUX - A ?fast kicker design for rapid transfer of the electron beam between radiator beamlines. This paper is a very simple feasibility study to find a rougly optimized subset of engineering parameters that would satisfy the initial design specifications of: Pulse width < 30us, time jitter < 1ns, magnetic length < 0.5meter, gap hight = 15mm, gap width = 25mm, peak field = .6Tesla, bend angle = 1.7 deg. for beam energy of 3.1 Gev, repetition rate = 10KHz. An H magnet core configuration was chosen. Through an iterative mathematical process a realizable design was chosen. Peak current, Peak voltages across the coils, conductor losses due to proximity and skin effects, di/dt rates, eddy and beam current heating in the ceramic vacuum chamber, and basic circuit topology were investigated. Types and losses of core material were only briefly discussed. The final topology consists of two magnets in series running at 10KHz, .3Tesla, 630 amp peak current, 10us pulse width, 364 Watts per coil section, driven by fast solid state switch with an energy recovery inductor. Eddy and beam image current losses were ~ 164 watts.  
 
WEPKF080 Secondary Electron Yield Measurements from Thin Surface Coatings for NLC Electron Cloud Reduction focusing, electron, site, quadrupole 1789
 
  • F. Le Pimpec, F. King, R.E. Kirby, M.T.F. Pivi
    SLAC, Menlo Park, California
  In the beam pipe of the positron damping ring of the Next Linear Collider, electrons will be created by beam interaction with the surrounding vacuum chamber wall and give rise to an electron cloud. Several solutions are possible for avoiding the electron cloud, without changing the beam bunch structure or the diameter of the vacuum chamber. Some of the currently available solutions include reducing residual gas ionization by the beam, minimizing photon-induced electron production, and lowering the secondary electron yield (SEY) of the chamber wall. We will report on recent SEY measurements performed at SLAC on TiN coatings and TiZrV non-evaporable getter thin films.  
 
WEPKF081 Prototype Development Progress toward a 500kV Solid State Marx Modulator focusing, electron, site, quadrupole 1792
 
  • G. Leyh
    SLAC, Menlo Park, California
  Recent advances in high voltage IGBT capabilities have made possible a range of novel solid-state modulator concepts that were unthinkable a decade ago. At present, there are two prototype solid-state modulator designs under evaluation at SLAC – A conventional pulse-transformer design using an 80kV solid-state switch in place of a thyratron, and an 'induction modulator', which uses a stack of magnetic cores to couple many paralleled primary windings to a common secondary winding. Both of these prototype modulators are currently driving actual klystron loads at SLAC. Another promising solid-state modulator concept still in the early stages of development is the Marx configuration – where an array of stacked modules generates high-voltage output pulses directly from a low DC input supply voltage. This scheme eliminates the large and costly magnetic cores inherent in the other two designs, resulting in a considerably simpler and cheaper mechanical solution. The main disadvantage to this approach is that the individual Marx sections must float at high voltages, complicating the distribution of power and timing signals. Several research groups have produced limited scale Marx prototypes in recent years. The largest prototype built to date [DTI] generates an output pulse of approximately 50kV, with plans to eventually move to higher voltage levels. This paper examines in closer detail the practical advantages and pitfalls of a solid-state Marx configuration, and explores a design approach with emphasis on performance, wall-plug efficiency, cost of manufacture, availability and ease of service. The paper presents electrical diagrams, mechanical CAD layout and preliminary prototype test data.  
 
WEPKF082 Radiation Damage Studies with Hadrons on Materials and Electronics focusing, electron, site, quadrupole 1795
 
  • J.E. Spencer, J. Allan, S. Anderson, R. Wolf
    SLAC, Menlo Park, California
  • M. Boussoufi
    UCD/MNRC, McClellan, California
  • D.E. Pellet
    UCD, Davis
  • J.T. Volk
    Fermilab, Batavia, Illinois
  Many materials and electronic devices need to be tested for the radiation environment expected at the proposed linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, electrons and gammas during the life of the facility. Examples are NdFeB permanent magnets which are being considered for the damping rings and final focus, electronic and electro-optical devices which will be utilized in the detector readout and accelerator control systems and CCDs required for the vertex detector. The effects of gammas on a broad range of materials was presented at NSREC2002 and our understanding of the current situation concerning rare earth permanent magnets at PAC2003 where a program was proposed using neutrons from the McClellan Nuclear Reactor Center (MNRC) that has a number of areas for irradiating samples with neutron fluxes up to 4.5·1013 n/cm2s. A specialized area allows irradiation with 1 MeV-equivalent neutrons with fluxes of 4.2·1010 n/cm2s while suppressing thermal neutrons and gammas by large factors. We give our latest results and their interpretation using this facility.  
 
WEPKF083 SPEAR3 INTERMEDIATE DC MAGNET POWER SUPPLIES focusing, electron, site, quadrupole 1798
 
  • A.C. de Lira, P. Bellomo
    SLAC, Menlo Park, California
  The Stanford Synchrotron Radiation Laboratory (SSRL) has successfully commissioned SPEAR3, its newly upgraded 3-GeV synchrotron light source. First stored beam occurred December 15, 2003 and 100mA operation was reached on January 20, 2004. This paper describes the specification, design, and performance of the SPEAR3 intermediate DC magnet power supplies (IPS) that consist of tightly-regulated (better than 10 ppm) current sources ranging from 60 A to 500 A and output powers ranging from a few kW to 22.5kW. A total of 69 IPS are in successful operation. The SPEAR 3 upgrade performance and reliability requirements mandated new power supplies for both the SPEAR3 storage ring, and for the booster-to-SPEAR3 transport line. IPS are widely used at SPEAR3 to power single quadrupoles, dipoles, families of quadrupoles and sextupoles, and also on the Titanium sublimation pumps. IPS' topology allows them to be series operated for those magnet strings requiring higher voltages. A compact 19" standard rack-mounted design is common to all the units. These are off-line, switch-mode, operating at 16 kHz to reduce space and provide for fast output response and high efficiency.  
 
WEPKF084 SPEAR3 LARGE DC MAGNET POWER SUPPLIES focusing, electron, site, quadrupole 1801
 
  • A.C. de Lira, P. Bellomo
    SLAC, Menlo Park, California
  The Stanford Synchrotron Radiation Laboratory (SSRL) has successfully commissioned SPEAR3, its newly upgraded 3-GeV synchrotron light source. First stored beam occurred December 15, 2003 and 100mA operation was reached on January 20, 2004. This paper describes the specification, design, and performance of the SPEAR3 DC magnet large power supplies (LGPS) that consist of tightly-regulated (better than 10 ppm) current sources ranging from 100 A to 225 A and output powers ranging from 70kW to 135kW. A total of 6 LGPS are in successful operation and are used to power strings of quadrupoles, and sextupoles. The LGPS are isolated by a delta/delta-wye 60Hz step-down transformer that provide power to 2 series connected chopper stages operating phase-shifted at a 16 kHz switching frequency to provide for fast output response and high efficiency. Also described are outside procurement aspects, installation, in-house testing, and operation of the power supplies.  
 
WEPKF085 Secondary Electron Emission Measurements for TiN Coating on Stainless Steel of SNS Accumulator Ring Vacuum Chamber focusing, site, quadrupole, electron 1804
 
  • P. He, H.-C. Hseuh, R. Todd
    BNL, Upton, Long Island, New York
  • B. Henrist, N. Hilleret
    CERN, Geneva
  • S. Kato, M. Nishiwaki
    KEK, Ibaraki
  • R.E. Kirby, F. Le Pimpec, M.T.F. Pivi
    SLAC, Menlo Park, California
  BNL is responsible for the design and construction of the US Spallation Neutron Source (SNS) accumulator ring. Titanium Nitride(TiN) coating on the stainless steel vacuum chamber of the SNS accumulator ring is needed to reduce undesirable resonant multiplication of electrons. The Secondary Electron Yield(SEY) of TiN coated chamber material has been measured after coated samples were exposed to air and after electron and ion conditioning. We are reporting about the TiN coating system setup at BNL and SEY measurements results performed at CERN, SLAC and KEK. We also present updated electron-cloud simulation results for the SNS accumulator assuming different SEY values.  
 
WEPKF086 A Model for Determining Dipole, Quadrupole and Combined Function Magnet Costs focusing, site, quadrupole, electron 1807
 
  • R. Palmer, J.S. Berg
    BNL, Upton, Long Island, New York
  One of the most important considerations in designing large accelerators is cost. Magnet costs are a significant component of that. This paper describes a model for estimating magnet costs. The reasoning behind the cost model is explained, and the parameters of the model are chosen so as to correctly give the costs for existing magnets.  
 
WEPKF087 SNS Extraction Fast Kicker Pulsed Power System focusing, site, quadrupole, electron 1810
 
  • W. Zhang, H. Hahn, J.-L. Mi, C. Pai, J. Sandberg, Y. Tan, N. Tsoupas, J. Tuozzolo, D.S. Warburton, J. Wei
    BNL, Upton, Long Island, New York
  • R. Cutler, K. Rust
    ORNL/SNS, Oak Ridge, Tennessee
  The Spallation Neutron Source (SNS) is a next generation high intensity beam facility. Its Accumulator Ring Extraction Fast Kicker System is a very high peak power, high average power, high precision pulse-waveform, ultra-low beam impedance, and high repetition rated pulsed power system. It has been successfully design and developed at Brookhaven National Laboratory. This system will consist of fourteen identical high voltage modulators and fourteen extraction magnet sections located inside of the SNS accumulator ring. The overall system output will reach multiple GW peak power with 60 Pulse-per-second repetition rates. The techniques of reducing impedance, improving rise time, and minimizing ripples will be discussed. The lifetime considerations, issues of the system design, development and construction are presented in this paper.  
 
WEPLT001 Nonlinear Beam Dynamics Study with MATLAB focusing, site, quadrupole, beamloading 1813
 
  • Y.L. Martirosyan, M. Ivanyan, D. Kalantaryan
    CANDLE, Yerevan
  In this paper, we present description of MATLAB based computer code, which allows tracking of single particles by numerical integration of Hamilton's equations. For storage rings the damping time is of the order of few ms (102 '104 turns) and therefore the short-term stability time is determinant. For this reason symplecticity condition of the tracking method for the electron machines is not as important as in hadron machines. Applying recently introduced modern tools for post process analyzing, such as interpolated FFT, early indicators for long term stability, the determination of the onset of chaotic behavior using the maximal Lyapunov exponent, and etc, one can carry out simulations to evaluate the dynamic aperture, amplitude dependent tunes, phase space distortions, nonlinear resonances etc. The proposed code is applied for beam nonlinear dynamics study in CANDLE storage ring.  
 
WEPLT002 Shielding Design Study for CANDLE Facility focusing, site, quadrupole, beamloading 1816
 
  • K.N. Sanosyan, M. Aghasyan, R.H. Mikaelyan
    CANDLE, Yerevan
  • V.M. Vartanian
    Stanford University, Stanford, Califormia
  The radiation shielding design study for the third generation synchrotron light source CANDLE is carried out. The electron beam loss estimates have done for all the stages from linac to storage ring. A well-known macroscopic model describing the dose rate for point losses has been used to calculate the shielding design requirements of the facility.  
 
WEPLT003 The Study of 2D Sextupole Coupling Resonances at VEPP-4M focusing, site, quadrupole, beamloading 1819
 
  • V.A. Kvardakov, E. Levichev, A.I. Naumenkov, P.A. Piminov
    BINP SB RAS, Novosibirsk
  The Study of 2D Sextupole Coupling Resonances at VEPP-4M  
 
WEPLT005 Building Truncated Taylor Maps with Mathematica and Applications to FFAG focusing, site, quadrupole, beamloading 1822
 
  • D. Kaltchev
    TRIUMF, Vancouver
  Lie algebra tools coded directly in Mathematica have been used to compute the off-momentum closed orbit, orbit length and horizontal tune of Fixed Field Alternating Gradient (FFAG) lattices proposed for muon acceleration. The sample FFAG cell considered consists of quadrupoles and alternating gradient magnets. A high order Taylor map is needed, valid over a wide momentum range. We describe the algorithm and Mathematica operators needed to create and concatenate individual element maps (presented as Lie exponential operators) and compare our results with those obtained with a high-order differential algebra code – COSY. The speed achieved is inferior to the differential algebra method.  
 
WEPLT006 Expected Performance and Beam-based Optimization of the LHC Collimation System focusing, site, quadrupole, beamloading 1825
 
  • R.W. Assmann, E.B. Holzer, J.-B. Jeanneret, V. Kain, S. Redaelli, G. Robert-Demolaize, J. Wenninger
    CERN, Geneva
  The cleaning efficiency requirements in the LHC are 2-3 orders of magnitude beyond the requirements at other super-conducting circular colliders. The achievable ideal cleaning efficiency in the LHC is presented and the deteriorating effects of various physics processes and imperfections are discussed in detail for the improved LHC collimation system. The longitudinal distribution of proton losses downstream of the betatron cleaning system are evaluated with a realistic aperture model of the LHC. The results from simplified tracking studies are compared to simulations with complete physics and error models. Possibilities for beam-based optimization of collimator settings are described.  
 
WEPLT007 Installation of the LHC Experimental Insertions focusing, site, quadrupole, beamloading 1828
 
  • S. Bartolome-Jimenez, G. Trinquart
    CERN, Geneva
  The installation of the LHC experimental insertions, and particularly the installation of the low-beta quadrupoles, raises many technical challenges due to the stringent alignment specifications and to the difficulty of access in very confined areas. The compact layout with many lattice elements, vacuum components, beam control instrumentations and the presence of shielding does not allow for any improvisation in the installation procedure. This paper reviews all the constraints that need to be taken into account when installing the experimental insertions. It describes the chronological sequence of installation and discusses the technical solutions that have been retained.  
 
WEPLT008 Simulated Emittance Growth due to Electron Cloud for SPS and LHC focusing, site, quadrupole, beamloading 1831
 
  • E. Benedetto, D. Schulte, F. Zimmermann
    CERN, Geneva
  • G. Rumolo
    GSI, Darmstadt
  The emittance growth caused by an electron cloud is simulated by the HEADTAIL code. The simulation result depends on the number of beam-cloud "interaction points"(IPs), the phase advance between the IPs, the number of macro-particles used to represent beam and cloud, and on the betatron tune. Simulations include a transverse feedback system and, optionally, a large chromaticity, as employed in actual SPS operation. Simulation results for the SPS are compared with observations, and the emittance growth in the LHC is computed as a function of the average electron density.  
 
WEPLT009 Dynamics of the Electron Pinch and Incoherent Tune Shift Induced by Electron Cloud focusing, proton, site, quadrupole 1834
 
  • E. Benedetto, F. Zimmermann
    CERN, Geneva
  When a proton bunch passes through an electron cloud, the cloud electrons are attracted by the beam electric field; their density strongly increases near the beam centre. This gives rise to an incoherent proton tune shift, which depends on the longitudinal and radial position within the bunch. We present an analytical description of the 'electron pinch' and the resulting proton tune shift, for a circular symmetry and a Gaussian cloud. Benchmarking and extending the results by computer simulations, we explore the effects of different longitudinal beam profiles and of the nonlinear transverse force.  
 
WEPLT010 Design and Fabrication of Superfluid Helium Heat Exchanger Tubes for the LHC Superconducting Magnets focusing, proton, beamloading, beamlosses 1837
 
  • F.F. Bertinelli, G. Favre, L.M.A. Ferreira, S.J. Mathot, L. Rossi, F. Savary
    CERN, Geneva
  • E. Boter
    CELLS, Bellaterra (Cerdanyola del Vallès)
  The dipole and quadrupole cold masses of the LHC machine require about 1700 heat exchanger tubes (HET). In operation the HET carries a two-phase flow of superfluid helium at sub-atmospheric pressure. The HET consists of an oxygen-free, seamless copper tube equipped with stainless steel ends. After an evaluation of different design alternatives, a design based on the technologies of vacuum brazing and electron beam welding has been adopted. Presence of these multiple technologies at CERN and synergies with the cleaning, handling and transport of other 15-metre components for LHC, motivated CERN to undertake this series fabrication on site. The raw copper tubes are procured in Industry, presenting challenging issues of geometric precision. Organisation of the HET fabrication includes cryomeasurements to validate cleaning procedures, characterization of welding procedures, buckling design by FEA and experimental verification, quality control during series production. The series fabrication of these long, multi-technological components is continuing successfully, respecting the project?s tight budgetary and planning constraints.  
 
WEPLT011 Transport and Handling of LHC Components: a Permanent Challenge focusing, proton, beamloading, beamlosses 1840
 
  • C. Bertone, I. Ruehl
    CERN, Geneva
  The LHC project, collider and experiments, is an assembly of thousands of elements, large or small, heavy or light, fragile. Every one of those has own transport requirements that constituting for us a real challenge to handle. The manoeuvres could be simple, but the complex environment and narrow underground spaces may lead to difficulties in integration, routing and execution. Examples of transport and handling of typical LHC elements will be detailed: the 17m long, 35t heavy but fragile cryomagnets from the surface to the final destination in the tunnel, the delicate cryogenic cold-boxes down to pits and detector components. This challenge did not only require a lot of imagination but also the close cooperation between all involved parties, in particular with colleagues from safety, cryogenics, civil engineering, integration and logistics.  
 
WEPLT013 Investigation of Space Charge Effects and Intrabeam Scattering for Lead Ions in the SPS focusing, beamloading, beamlosses, impedance 1843
 
  • H. Burkhardt, D. Manglunki, M. Martini, F. Roncarolo
    CERN, Geneva
  • G. Rumolo
    GSI, Darmstadt
  Space charge effects and intrabeam scattering usually play a minor role in high energy machines like the SPS. They can potentially become a limitation for the heavy ion beams needed for the LHC at the injection plateau in the SPS. Experimental studies on space charge limitations performed on low energy proton beams in the SPS will be described. Theoretical studies have been performed to predict emittance growth times due to intrabeam scattering using several different codes.  
 
WEPLT014 Mechanical Dynamic Load of the LHC Arc Cryo-magnets during the LHC Installation focusing, acceleration, beamloading, monitoring 1846
 
  • O. Capatina, K. Artoos, G. Huet, B. Nicquevert
    CERN, Geneva
  About 1700 LHC main superconducting dipoles and quadrupoles will have to be transported and handled between the assembly, the magnet measurements and the storage that precedes the final installation in the LHC tunnel. To ensure the required mechanic and geometric integrity of the cryo-magnets, transport specifications and allowed acceleration loads were defined after detailed dynamic analysis. A large number of cryo-magnets are now arriving at CERN on a regular basis. The logistics for the handling and transport are monitored with tri-axial acceleration monitoring devices that are installed on each cryo-magnet. Measurements are made to commission new equipment like overhead cranes, tunnel transport and handling devices to guarantee that the defined acceleration limits are respected. The results from the acceleration monitoring that are stored in the same quality assurance system as the cryo-magnets allowed to give a first idea of the level of the mechanical dynamic load on each magnet throughout the logistics chain and were used to detect details such as out-of-specification accelerations that needed improvement.  
 
WEPLT015 Proposal for the Creation and Storage of Long Bunches in the LHC focusing, acceleration, luminosity, beamloading 1849
 
  • H. Damerau, R. Garoby
    CERN, Geneva
  Long bunches with a uniform longitudinal line density held by barrier buckets are considered for a future luminosity upgrade of the Large Hadron Collider (LHC). With such bunches, the luminosity is maximised for a fixed number of particles. Instead of conventional barrier buckets, periodic barriers are proposed. These are generated with multiple RF harmonics (e.g. multiples of 40 MHz). A possible scheme to create and hold long flat bunches in the LHC is described, and the resulting gain in luminosity is estimated.  
 
WEPLT016 Logistics of LHC Cryodipoles: from Simulation to Storage Management focusing, acceleration, luminosity, beamloading 1852
 
  • K. Foraz, B. Nicquevert, D. Tommasini
    CERN, Geneva
  The particles traveling in the Large Hadron Collider are guided by superconducting magnets. The main magnets (cryodipoles) are 16 m long, 30 tons objects placed with accuracies of few tenths of mm and therefore imposing challenging requirements for handling and transportation. Numerous contracts are constraining the production and installation of these cryodipoles. These contracts have been rated according to the baseline schedule, based on a "just in time" scheme. However the complexity of the construction and the time required to fully test the cryodipoles before installation in the LHC required to decouple as much as possible each contract from the others' evolutions and imposed temporary storage between different assembly and test steps. Therefore a tool simulating the logistics was created in order to determine the number of cryodipoles to store at the various stages of their production. In this paper the organization of cryodipole flow and the main challenges of logistics are analyzed on the basis of the planning of each main step before installation. Finally the solutions implemented for storage, handling and transportation are presented and discussed.  
 
WEPLT017 Numerical Studies of the Impact of the Separation Dipoles and Insertion Quadrupoles Field Quality on the Dynamic Aperture of the CERN LHC focusing, acceleration, insertion, beamloading 1855
 
  • M. Giovannozzi, O.S. Brüning, S.D. Fartoukh, T. Risselada, F. Schmidt
    CERN, Geneva
  A wide range of magnets, both warm and superconducting, will be used in the LHC. In addition to main dipoles, quadrupoles are used to focus the beam in regular arcs. Special dipoles separate or merge the two beams in insertion regions. A few very strong superconducting quadrupoles squeeze the beam to achieve the required luminosity, while warm quadrupoles are used in the collimation insertions. At injection the main dipoles largely dominate beam dynamics, but contributions from smaller classes of magnets should not be neglected. Peculiar optical configurations may dramatically enhance beam dynamics effects of few magnetic elements. This paper will focus on the effect of insertion quadrupoles, e.g. wide-aperture, and warm quadrupoles, as well as separation dipoles presenting on the dynamic aperture of the LHC machine.  
 
WEPLT018 Nonlinear Dynamics Studies at the CERN Proton Synchrotron: Precise Measurements of Islands Parameters for the Novel Multi-turn Extraction focusing, acceleration, insertion, beamloading 1858
 
  • M. Giovannozzi, P. Scaramuzzi
    CERN, Geneva
  Recently, a novel approach to perform multi-turn extraction from a circular accelerator was proposed. It is based on adiabatic capture of particles into islands of transverse phase space generated by nonlinear resonances. Sextupole and octupole magnets are used to generate these islands, while an appropriate slow variation of the linear tune allows particles to be trapped inside the islands. Intense experimental efforts showed that the approach is indeed performing rather well. However, good knowledge of the islands properties is a key ingredient for the success of this extraction type. In this paper, a series of measurements are presented dealing with the study of islands' parameters for the fourth-order resonance, such as detuning with amplitude, fixed points' position, betatron frequency, as well as detuning with amplitude inside the islands.  
 
WEPLT019 Towards a Unified General Purpose CAD System at CERN focusing, acceleration, insertion, beamloading 1861
 
  • T. Hakulinen, C. Andrews, B. Feral, P.-O. Friman, M. Mottier, T. Pettersson, C. Sorensen, E. Van Uytvinck
    CERN, Geneva
  Several different CAD systems are in use at CERN today. Most of the 3D design work for the LHC is being done using Euclid from MDTVision. For 2D design work AutoCAD is widely used. Also, various special design tools exist for tasks such as electrical design and schematics. Even though LHC design will be finished with Euclid, it has been clear since several years that a new 3D CAD system will be needed in the future. For this reason CERN carried out a comparison between the currently available 3D CAD software using a set of selection criteria important for CERN. The selected system was CATIA from Dassault together with local data base system SmarTeam. The aim is to use CATIA as a multi-disciplinary general purpose CAD tool which could eventually replace almost all of the other CAD systems at CERN. For this purpose, CATIA and SmarTeam are being integrated with the existing CAD utilities and data base systems developed in-house. Pilot users are using the system for real designs and the digital mock-up features of CATIA are used for integration studies of LHC experiments. The feature list of CATIA and SmarTeam is impressive and experience with the software has so far been almost exclusively positive. This is promising for software with which CERN will likely have to live for the next 20 years or more.  
 
WEPLT020 Installation of A Particle Accelerator: from Theory to Practice. The LHC Example focusing, acceleration, insertion, beamloading 1864
 
  • C. Hauviller, S. Weisz
    CERN, Geneva
  Installing and commissioning the thousands of equipments constituting a Particle Accelerator is a lengthy and complex process. A large number of multidisciplinary teams are involved over a long period lasting usually many years. Diverse boundary constrains must be taken into account: space, a long and narrow tunnel with few accesses, time, with milestones set many years in advance, and obviously budget. A strict organisation associated with the management tools and the right people is the only way to arrive to a success. The keywords are: Knowledge: A unique and up-to-date database of all the elements and their location, Integration: Study the physical position of the elements, suppress the interferences and define the installation methodology, Prevision: Schedule all the activities and update on-line, In-situ management and supervision: Teams dedicated to follow-up, corrective actions and orphan jobs, Safety. After presenting the planned overall organization, the paper will present practical achievements with the example of the LHC machine installation.  
 
WEPLT021 Towards an Ontology Based Search Mechanism for the EDMS at CERN focusing, acceleration, insertion, beamloading 1867
 
  • A. Jimeno Yepes, B. Rousseau
    CERN, Geneva
  CERN is building its new accelerator, the LHC. All the data flow generated during its lifecycle is stored in the EDMS (Engineering Data Management System) developed at CERN. For such a system it is compulsory to have a performant search mechanism to guarantee that the involved people gets the data at the required time. Due to the size of the collection and the diversity of people, organizations, divisions . To overcome this problem, an approach based on a hand-crafted domain specific ontology has been tested in order to improve the information retrieval task within the technical documentation for the LHC Equipment Catalog. The experiments have shown that using the ontology an improvement on the base line has been produced and encorages IE techniques to refine the base ontology.  
 
WEPLT022 Transport and Installation of Cryo-magnets in CERN's Large Hadron Collider Tunnel focusing, acceleration, insertion, beamloading 1870
 
  • K. Kershaw, K. Artoos, O. Capatina, A.Y. Coin, M. Gielen, C. Hauviller
    CERN, Geneva
  The arcs of the Large Hadron Collider (LHC) will contain around 1700 main superconducting dipoles and quadrupoles. The long and heavy magnets are supported on fragile composite support posts inside a cryostat to reduce the heat in-leak to the magnets' super fluid helium bath. The presence of fragile components and the need to avoid geometry changes make the cryo-magnets very difficult to handle and transport. The transport and installation of the LHC cryo-magnets in the LEP tunnels originally designed for smaller, lighter LEP magnets has required development of completely new handling solutions. The paper explains the constraints imposed by the cryo-magnet characteristics, the existing tunnel infrastructure and schedule considerations. The development and realisation of transport and handling solutions are described, starting from conceptual design, through manufacture and testing to the installation of the first cryo-magnet. Integration studies to verify and reserve space needed for manoeuvre and the preparation of the infrastructure for transport and installation operations are also presented. The paper includes conclusions and some of the lessons learned.  
 
WEPLT023 Transverse Resistive Wall Impedance and Wake Function with Inductive Bypass focusing, acceleration, insertion, beamloading 1873
 
  • A. Koschik, F. Caspers, E. Métral, L. Vos
    CERN, Geneva
  • B. Zotter
    Honorary CERN Staff Member, Grand-Saconnex
  We analyze the resistive wall impedance with an "inductive bypass" due to alternate current paths in the outer vacuum chamber proper. Also the corresponding wake function has been obtained which is useful for the simulation of beam stability in the time domain. Results are presented for the LHC.  
 
WEPLT024 Scheduling the Installation of the LHC Injection Lines focusing, acceleration, insertion, beamloading 1876
 
  • L. Lari, H. Gaillard, V. Mertens
    CERN, Geneva
  The installation of the two LHC injection lines has to fit within tight milestones of the LHC project and of CERN?s accelerator activity in general. For instance, the transfer line from the SPS to LHC point 8 (to fill the anti-clockwise LHC ring) should be tested with beam before the end of 2004 since the SPS will not run in 2005. It will first serve during the LHC sector test in 2006. Time constraints are also very strong on the installation of the transfer line from the SPS to LHC point 2 (for the clockwise LHC ring): its tunnel is the sole access for the LHC cryo-magnets and a large part of the beam line can only be installed once practically all LHC cryo-magnets are in place. Of course, the line must be operational when the LHC starts. This paper presents the various constraints and how they are taken into account for the logistics and installation planning of the LHC injection lines.  
 
WEPLT025 LHC Reference Database : Towards a Mechanical, Optical and Electrical Layout Database focusing, acceleration, insertion, beamloading 1879
 
  • P. Le Roux, S. Chemli, A. Jimeno Yepes, B. Maire, H. Prin, A. Vergara-Fernández, M. Zerlauth
    CERN, Geneva
  The LHC project has entered a phase of integration and installation of thousands of diverse components. The Hardware Commissioning work has also started. Collecting and distributing reliable and coherent information on the equipments and their layout becomes a crucial requirement in the lifecycle of the project. Existing database tools had to evolve to a more generic model to cover not only optical layout, but also the mechanical and the electrical aspects. This paper explains the requirements, the implementation and the benefits of this new database model.  
 
WEPLT026 Dynamic Aperture Reduction from the Dodecapole Component in the LHC Main Quadrupoles and its Mechanism. focusing, acceleration, insertion, beamloading 1882
 
  • A.M. Lombardi, O.S. Brüning, S.D. Fartoukh, T. Risselada, F. Schmidt, A. Verdier
    CERN, Geneva
  The systematic dodecapole component in the Main Quadrupoles of the LHC lattice has a strong influence on the machine dynamic aperture at injection. In this paper we quantify this effect with the help of tracking studies, explain the mechanism for the loss in dynamic aperture and look into potential correction schemes. Finally, we provide an estimate for the maximum allowed systematic dodecapole component in the MQ.  
 
WEPLT027 Connection Cryostats for LHC Dispersion Suppressors focusing, acceleration, insertion, beamloading 1885
 
  • S. Marque, T. Colombet, M. Genet, B. Skoczen
    CERN, Geneva
  The lattice of the Large Hadron Collider (LHC) being built at CERN is based on 8 standard arcs of 2.8 km length. Each arc is bounded on either side by Dispersion Suppressors connected to the arc by connection cryostats providing 15m long drift spaces. As for a dipole magnet, the connection cryostat provides a continuity of beam and insulation vacuum, electrical powering, cryogenic circuits, thermal and radiation shielding. In total 16 modules will be constructed. The stringent functional specification has led to various analyses. Among them, a light mechanical structure has been developed to obtain a stiffness comparable to a dipole magnet, for alignment purpose. Thermal studies, included λ front propagation, have been performed to ensure a cooling time down to 1.9K within the time budget. A special cooling scheme around the beam tubes has been chosen to cope with heat loads produced during operation. We will report on the general design of the module and on the manufacturing process adopted to guarantee the tight alignment of the beam tubes once the module installed in the machine. Special emphasis will be given on thermo-mechanical analysis, λ front propagation and on beam-tubes cooling scheme.  
 
WEPLT028 High-intensity and High-density Charge-exchange Injection Studies into the CERN PS Booster at Intermediate Energies injection, focusing, acceleration, booster 1888
 
  • M. Martini
    CERN, Geneva
  • C.R. Prior
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  For the high brilliance LHC ultimate beam and the high intensity CNGS beam, single batch injections into the CERN Proton Synchrotron (PS) will be used to increase the overall machine intensity compared with the present double batch injections. Charge-exchange injection into the PS Booster with a new linac at intermediate energies is thus examined. A key parameter to consider is the energy dependence of beam incoherent tune shifts at injection. Increasing the linac energy from the present 50 MeV to 160 MeV should yield a safer tune shift. For each PS Booster ring, a charge-exchange injection scheme is envisaged inside a proper straight section, redesigned with new bends to make a local bump and using the existing fast bump magnets for horizontal phase-space painting. ACCSIM simulations for charge-exchange injection at 160 MeV have been investigated for both LHC and CNGS beams. After optimizing the parameters that are used for the space charge tracking routines, the results of the simulations agree well with expectations, signifying that the LHC ultimate and CNGS beams may be provided with single PS Booster batches within the required emittances. For assessment, simulation of injection at 50 MeV for the current LHC beam has been performed, yielding a fairly good agreement with measured performance. Concurrently, similar charge-exchange injection simulations have been carried out using an alternative programme developed at the Rutherford Appleton Laboratory.  
 
WEPLT030 Stability Diagrams for Landau Damping with Two-dimensional Betatron Tune Spread from Both Octupoles and Non-linear Space Charge applied to the LHC at Injection focusing, acceleration, resonance, booster 1894
 
  • E. Métral, F. Ruggiero
    CERN, Geneva
  The joint effect of space-charge non-linearities and octupole lenses is discussed for the case of a quasi-parabolic transverse distribution of a monochromatic beam. The self-consistent non-linear space-charge tune shift corresponding to the above distribution function is first derived analytically. The exact dispersion relation is also given but not solved. Instead, noting that a good approximation of the non-linear space-charge tune shift is obtained considering only linear terms in the action variables, the dispersion relation is solved analytically in this approximate case. As expected, in the absence of external (octupolar) non-linearities, the result of Möhl and Schönauer is recovered: there is no stability region. In the absence of space charge, the stability diagrams of Berg and Ruggiero are also recovered. Finally, the new result is applied to the LHC at injection.  
 
WEPLT031 The LHC Access Control System focusing, acceleration, resonance, booster 1897
 
  • P. Ninin, L. Scibile
    CERN, Geneva
  The LHC complex is divided into a number of zones with different levels of access controls. Inside the interlocked areas, the personnel protection is ensured by the LHC Access System. This system is made of two parts: the LHC Access Safety System and the LHC Access Control System. During machine operation, the LHC Access Safety System ensures the collective protection of the personnel against the hazards arising from the operation of the accelerator. By interlocking the LHC key safety elements, it will permit access to authorised personnel in the underground premises during the accelerator shutdowns and will deny access during accelerator operation. On the other hand, the LHC Access Control System, regulates the access to the accelerator and the numerous support systems. It allows a remote, local or automatic operation of the access control equipment that verifies the users? authorization, identifies them, locks and unlocks access control equipment and restricts the number of users working simultaneously in the interlocked areas. This paper introduces the main functions, architecture, technologies and methodology used to realise the LHC Access system.  
 
WEPLT038 Betatron Resonance Studies at the CERN PS Booster by Harmonic Analysis of Turn-by-turn Beam Position Data radiation, resonance, focusing, acceleration 1912
 
  • P. Urschütz, M. Benedikt, C. Carli, M. Chanel, F. Schmidt
    CERN, Geneva
  High brightness and high intensity beams are required from the PS Booster for LHC, CNGS and ISOLDE operation. The large space charge tune spreads associated with these beams, especially at injection, require an optimized resonance compensation scheme to avoid beam blow-up and subsequent beam losses. For this a detailed knowledge on strength and phase of resonance driving terms is needed. A new measurement system has been installed to determine resonance driving terms from turn-by-turn bpm data using fast Fourier transform. The multi-turn acquisition system as well as the specific measurement conditions at the PS Booster are discussed. As an example, the measurement and compensation of the linear coupling resonance driving term is presented. Excellent agreement between measurement and simulation for resonance phase and strength was found.  
 
WEPLT039 Measurement and Compensation of Second and Third Order Resonances at the CERN PS Booster radiation, focusing, acceleration, resonance 1915
 
  • P. Urschütz
    CERN, Geneva
  Space charge effects at injection are the most limiting factor for the production of high brightness beams in the CERN PS Booster. The beams for LHC, CNGS and ISOLDE feature incoherent tune spreads exceeding 0.5 at injection energy and thus cover a large area in the tune diagram. Consequently these beams experience the effects of transverse betatron resonances and efficient compensation is required. Several measurements have been performed at the PS Booster in 2003, aiming at a detailed analysis of all relevant second and third order resonances and an optimisation of the compensation scheme. Special attention was paid to the systematic 3Qy=16 resonance. To avoid this particularly dangerous resonance an alternative working point was tested. A comparison of resonance driving terms and compensation settings for both working points was made and important differences in the strengths of the resonances were found. The peculiarities when measuring third order coupling resonance driving terms are also mentioned.  
 
WEPLT040 Layout Drawings of the LHC Collider radiation, focusing, acceleration, resonance 1918
 
  • A. Vergara-Fernández, S. Chemli, B. Maire, Y. Muttoni
    CERN, Geneva
  • A. Kournossenko, R. Zalyalov
    IHEP Protvino, Protvino, Moscow Region
  The team in charge of the LHC integration largely uses 3D scenes combining functional positions of equipments and the 3D CAD model issued from the Cern Drawing Directory (CDD) repository. This is made possible through the Digital Mock-Up tool developed at CERN. Giving dimensions in 3D context is a challenge with the current 3D CAD tools used at CERN. Requirements from users groups have made clear a need for automatic production of 2D layout drawings. This paper presents the retained solution to create on-request dimensioned drawings, to publish them, while maintaining coherence and consistency with the 3D integration scenes. Reliability of the information, on-line availability of the latest layout changes on dimensions and positions of equipments, and the maintenance of the facility will also be described.  
 
WEPLT041 RF Amplitude Modulation to Suppress Longitudinal Coupled Bunch Instabilities in the SPS radiation, focusing, resonance, booster 1921
 
  • E. Vogel, T. Bohl, U. Wehrle
    CERN, Geneva
  In the SPS, even after a considerable impedance reduction including the removal of all RF cavities used for lepton acceleration in the past, longitudinal coupled bunch instabilities develop with an LHC beam of about one fifth of the nominal bunch intensity. The nominal LHC beam is stabilised using both, the 800 MHz Landau damping cavities, in bunch shortening mode, and pre-emptive emittance blow-up. An alternative method to increase the synchrotron frequency spread and thus stabilise the beam is amplitude modulation of the accelerating RF voltage. This method might be especially suitable in accelerators without a higher harmonic RF system, as will be the case in LHC. The main results of recent studies using this method in the SPS and considerations about its use in LHC are presented.  
 
WEPLT042 Scheduling the Installation of the Large Hadron Collider radiation, focusing, resonance, booster 1924
 
  • S. Weisz, K. Foraz, H. Gaillard, L. Lari
    CERN, Geneva
  The size and complexity of the LHC project at CERN calls for a strong co-ordination of all installation activities. The detailed installation planning has to take into account many constraints such as the component production rates, the installation contracts or the transport and handling requirements in a narrow tunnel with limited access points. The planning also needs to be flexible enough to cope with aleas that are unavoidable in such a large project that spans over many years. This paper describes the methodology followed by the team responsible for the planning and logistics in order to stay reactive to the actual progress of the installation and to keep optimizing the usage of resources.  
 
WEPLT043 Detecting Failures in Electrical Circuits Leading to Very Fast Beam Losses in the LHC radiation, focusing, resonance, booster 1927
 
  • M. Zerlauth, B. Goddard, V. Kain, R. Schmidt
    CERN, Geneva
  Depending on the beam optics, failures in the magnet powering at locations with large beta functions could lead to very fast beam losses at the collimators, possibly within less than 10 turns. Beam loss monitors would normally detect such losses and trigger a beam dump. However, the available time for detection with beam loss monitors before reaching the damage level of a collimator might not be sufficient, in particular for beams with few particles in the tails. This has always been of concern and becomes even more relevant since very fast losses have been observed recently at HERA. In this paper, we present particle tracking studies for the LHC to identify failures on critical magnets. We propose a fast detection of such failures in the electrical circuit, either with highly precise hall probes for current measurement or measurements of the induced inductive voltage during the current decay. In combination with a small and simple interlock electronics such detection system can provide reliable and fast interlock signals for critical magnets in the LHC main ring but could also be used to monitor injection and extraction magnets. Depending on the properties of the electrical circuit an increase of the natural time constant of the current decay using a serial superconducting magnet is also considered.  
 
WEPLT044 Electron-cloud Build-up Simulations and Experiments at CERN radiation, focusing, resonance, electron 1930
 
  • F. Zimmermann, G. Arduini, V. Baglin, T. Bohl, B.J. Jenninger, J.M. Jimenez, J.-M. Laurent, F. Ruggiero, D. Schulte
    CERN, Geneva
  We compare the predications of electron-cloud build-up simulations with measurements at the CERN SPS. Specifically, we compare the electron flux at the wall, electron-energy spectra, heat loads, and the spatial distribution of the electrons for two different bunch spacings, with variable magnetic fields, and for several chamber temperatures and associated surface conditions. The simulations employ a modified, improved version of the ECLOUD code. The main changes are briefly described. We finally present updated simulation results for the heat load in the cold LHC arcs.  
 
WEPLT045 Experiments on LHC Long-range Beam-beam Compensation in the CERN SPS radiation, focusing, resonance, electron 1933
 
  • F. Zimmermann, J.-P. Koutchouk, J. Wenninger
    CERN, Geneva
  Long-range beam-beam collisions may limit the dynamic aperture and the beam lifetime in storage-ring colliders. Their effect can be compensated by a current-carrying wire mounted parallel to the beam. A compensation scheme based on this principle has been proposed for the Large Hadron Collider (LHC). To demonstrate its viability, a prototype wire was installed at the CERN SPS in 2002. First successful machine experiments explored the dependence of beam loss, beam size, and beam lifetime on the beam-wire distance and on the wire excitation. They appear to confirm the predicted effect of the long-range collisions on the beam dynamics. In 2004, two further wires will become available, by which we can explicitly demonstrate the compensation, study pertinent tolerances, and also compare the respective merits of different beam-beam crossing schemes for several interaction points.  
 
WEPLT046 Localizing Impedance Sources from Betatron-phase Beating in the CERN SPS radiation, focusing, resonance, impedance 1936
 
  • F. Zimmermann, G. Arduini, C. Carli
    CERN, Geneva
  Multi-turn beam-position data recorded after beam excitation can be used to extract the betatron-phase advance between adjacent beam position monitors (BPMs) by a harmonic analysis. Performing this treatment for different beam intensities yields the change in phase advance with current. A local impedance contributes to the average tune shift with current, but, more importantly, it also causes a mismatch and phase beating. We describe an attempt to determine the localized impedance around the SPS ring by fitting the measured betatron phase shift with current at all BPMs to the expected impedance response matrix.  
 
WEPLT047 A Test Suite of Space-charge Problems for Code Benchmarking radiation, focusing, resonance, impedance 1939
 
  • A. Adelmann
    PSI, Villigen
  • J. Amundson, P. Spentzouris
    Fermilab, Batavia, Illinois
  • J. Qiang, R.D. Ryne
    LBNL/CBP, Berkeley, California
  A set of problems is presented for benchmarking beam dynamics codes with space charge. As examples, we show comparisons using the IMPACT, MaryLie/IMPACT, and MAD9P codes. The accuracy and convergence of the solutions as a function of solver algorithms, simulations parameters such as number of macro particles, grid size, etc. are studied.  
 
WEPLT048 Beam Dynamic Studies of the 72 MeV Beamline with a 'Super Buncher' radiation, focusing, resonance, impedance 1942
 
  • A. Adelmann, S. Adam, R. Dölling, M. Pedrozzi, J.-Y. Raguin, P. Schmelzbach
    PSI, Villigen
  A significant increase of the beam intensity increase of the PSI 590 MeV proton accelerator facility above 2 mA requires a higher accelerating voltage in the main RF cavities. A corresponding increase of the voltage in the flattop cavity would result in a complete rebuild of this device. As an alternative, a scheme with a strong buncher in the 72 MeV beam transfer line is being studied. The goal is to restore the narrow phase width (~ 2 deg/RF at 50 MHz) of the beam bunches observed at extraction from Injector 2 at injection into the Ring Cyclotron. If we can find and inject a stable particle distribution, as done in the Injector 2, the flat-top cavity might eventually be decommissioned. First results of multi particle tracking in full 6 dimensional phase space with space charge are presented.  
 
WEPLT049 Timekeeping Mechanism at SLS/APS Control System radiation, focusing, resonance, impedance 1945
 
  • B. Kalantari, T. Korhonen
    PSI, Villigen
  Time is one of the most important and critical parameters in a distributed control and measurement system. It is especially crucial when we need to interpret correlation of different archived process variables (PV) during the time. Advanced Light Source (APS) and Swiss Light Source (SLS) are using a very similar control system toolkit (EPICS) and the same mechanism for timekeeping. Many input/output controllers (IOC) around the accelerator complex (including beamlines), run under a real-time operating system, and carry out the controls and data acquisition. Each IOC is responsible of keeping its own local time and time-stamps the local PV?s but tightly synchronized with a central timing IOC. Dedicated timing hardware and network makes it possible to maintain synchronous timestamps with real-time clock. In this paper we describe the principle of this mechanism, its advantages, our experiences and further improvements.  
 
WEPLT050 Frequency Map Measurements at BESSY radiation, focusing, resonance, impedance 1948
 
  • P. Kuske, O. Dressler
    BESSY GmbH, Berlin
  With two dedicated diagnostic kicker magnets and a turn-by-turn, bunch-by-bunch beam position monitor frequency maps were measured under various operating conditions of the BESSY storage ring. Depending on the number and type of insertion devices in operation additional resonances show up. Details of the experimental setup as well as the data analysis are presented. The results will be compared with theoretical calculations which are based on the linear model of the storage ring lattice extracted from measured response matrices. Non-linear elements are added to the model in order to describe the effect of the strong sextupole magnets, the horizontal corrector magnets installed in these magnets, and of some of the insertion devices.  
 
WEPLT051 Sub-Picosecond Electron Bunches in the BESSY Storage Ring focusing, resonance, impedance, optics 1951
 
  • G. Wustefeld, J. Feikes, K. Holldack, P. Kuske
    BESSY GmbH, Berlin
  BESSY is a low emittance, 1.7 Gev electron storage ring. A dedicated, low alpha optics is applied to produce short electron bunches for coherent synchrotron radiation (CSR) in the THz range[*]. By a further detuning of the optics, stable pulses as short as 0.7 ps rms length were produced. The sub-ps pulse shape is analysed by an auto-correlation method of the emitted CSR. The CSR-bursting instability is measured and compared with theory to estimate the current for stable, sub-ps pulses. Present limits of the low alpha optics are discussed.

* M. Abo-Bakr et al., Phys. Rev. Lett. 88, 254801 (2002).

 
 
WEPLT052 A Method to Measure the Skew Quadrupole Strengths in the SIS-18 using Two BPMs focusing, impedance, optics, booster 1954
 
  • F. Franchi, T. Beier, M. Kirk, M. Moritz, G. Rumolo
    GSI, Darmstadt
  • R. Tomas
    BNL, Upton, Long Island, New York
  In the SIS-18 of GSI a new set of skew quadrupoles has been installed to improve the multi-turn-injection. A new method based on the measurement of the resonance driving terms has been proposed to cross-check the nominal values and polarities of their gradients. Once a beam is transversely kicked, it experiences oscillations whose spectrum contains both the betatron tune line and secondary lines. The amplitude of each line is proportional to the strength of the multipoles, such as skew quadrupoles and sextupoles, present in the lattice. In this paper a recursive algorithm to derive the magnet strength from the spectral lines and the application of this method to the eight skew quadrupoles in the SIS-18 are presented.  
 
WEPLT053 Dynamical Effects of the Montague Resonance focusing, impedance, optics, synchrotron 1957
 
  • I. Hofmann, G. Franchetti
    GSI, Darmstadt
  • J. Qiang, R.D. Ryne
    LBNL/CBP, Berkeley, California
  In high-intensity accelerators emittance coupling, known as Montague resonance, may be an issue if the tune split is small. For static tunes within the stop-band of this fourth order space charge driven coupling the final emittances may become equal (equipartition). Using 2D computer simulation we show, however, that slow crossing of the resonance leads to merely an exchange of emittances. In 3D this is similar, if the crossing occurs over a time-scale shorter or comparable with a synchrotron period. For much slower crossing we find, instead, that the exchange may be suppressed by synchrotron motion. We explain this effect in terms of the mixing caused by the synchrotron motion.  
 
WEPLT054 Electron Cloud Build up in Coasting Beams focusing, impedance, optics, synchrotron 1960
 
  • G. Rumolo
    GSI, Darmstadt
  • G. Bellodi
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • K. Ohmi
    KEK, Ibaraki
  • F. Zimmermann
    CERN, Geneva
  Electrons could in principle accumulate in the potential of coasting beams of positively charged particles until a balance between the beam force and space charge force from the electrons is reached. But the continuous interaction between a non-ideal perturbed coasting beam and the cloud of electrons being trapped by it, together with the reflection and secondary emission processes at the inner pipe wall, can alter this picture and cause a combined cloud or beam transverse instability long before the concentration of electrons reaches the theoretical equilibrium value. The issue is addressed in this paper by means of combined build-up and instability simulations carried out with the HEADTAIL code.  
 
WEPLT055 Observation of Ultracold Heavy Ion Beams with Micrometer Size by Scraping focusing, electron, ion, impedance 1963
 
  • M. Steck, K. Beckert, P. Beller, B.  Franzke, F. Nolden
    GSI, Darmstadt
  The existence of an ordered beam state for low intensity, electron cooled heavy ion beams has been evidenced by a sudden reduction of the momentum spread. The detection of a similar effect in the transverse degree of freedom by non-destructive diagnostics is ruled out by the limited resolution of beam profile detectors. A method to probe the horizontal beam size of an electron cooled beam in a dispersive section has been developed. It is based on beam scraping and allows a resolution on the order of micrometers. This good transverse resolution for the cooled ion beam is achieved by precise changes of the ion energy which is varied by changes of the electron beam energy. The lower resolution limit due to power supply ripple is estimated to be below 1 micrometer. This method evidenced that the reduction of the momentum spread by one order of magnitude coincides with a reduction of the transverse beam emittance by 2-3 orders of magnitude, at least. A horizontal beam radius of a few micrometer could be demonstrated for electron cooled heavy ion beams with less than 1000 particles. This gives new evidence for the formation of an ordered beam arranged as a linear string of ions.  
 
WEPLT056 An Electron Cooling System for the Proposed HESR Antiproton Storage Ring focusing, ion, impedance, optics 1966
 
  • M. Steck, K. Beckert, P. Beller, A. Dolinskii, B.  Franzke, F. Nolden
    GSI, Darmstadt
  • V.V. Parkhomchuk, V.B. Reva, A.N. Skrinsky, V.A. Vostrikov
    BINP SB RAS, Novosibirsk
  The HESR storage ring in the proposed new international accelerator facility will provide high quality antiproton beams for experiments with an internal target. In order to achieve the design luminosity for collisions with a hydrogen target powerful beam cooling is required. For dedicated experiments ultimate resolution is demanded. Therefore it is foreseen to provide cooled antiproton beams in the energy range 0.8-14 GeV with an energy spread of 100 keV or better. According to computer simulations the required cooling rates can be achieved by electron cooling with an electron current of 1 A. The conceptual design of an electron beam device which is based on electrostatic acceleration of the electrons and their transport in longitudinal magnetic fields into a cooling section with a strong magnetic field of up to 0.5 T will be presented. This design will allow cooling in the magnetized regime in order to reach the required high cooling rates. Some novel features for the generation and regulation of the accelerating voltage and for the beam transport are proposed.  
 
WEPLT057 Simulation Results on Cooling Times and Equilibrium Parameters for Antiproton Beams at the HESR focusing, antiproton, impedance, optics 1969
 
  • A. Dolinskii, O. Boine-Frankenheim, B.  Franzke, M. Steck
    GSI, Darmstadt
  • A. Bolshakov, P. Zenkevich
    ITEP, Moscow
  • A.O. Sidorin, G.V. Troubnikov
    JINR, Dubna, Moscow Region
  The High Energy Storage Ring HESR is part of the "International Accelerator Facility for Ion and Antiproton Beams" proposed at GSI. For internal target experiments with antiproton beams in the energy range 0.8 GeV to 14.5 GeV a maximum luminosity of 5 inverse nbarn per second and a momentum resolution on the order of 10 ppm have to be attained. Electron cooling is assumed to be the most effective way to counteract beam heating due to target effects and intra-beam scattering. Cooling times and equilibrium parameters have been determined by means of three different computer codes: BETACOOL, MOCAC, and PTARGET. The results reveal that the development of fast, "magnetized" electron cooling with beam currents of up to 1 A and variable electron energies of up to 8 MeV in an extremely homogeneous longitudinal magnetic field of up to 0.5 T is crucial to achieve the required equilibrium beam parameters over the envisaged range of antiproton energies.  
 
WEPLT058 A Space Charge Algorithm for Ellipsoidal Bunches with Arbitrary Beam Size and Particle Distribution focusing, antiproton, impedance, optics 1972
 
  • G. Franchetti, A. Orzhekovskaya
    GSI, Darmstadt
  For the GSI future project beam loss control of a high intensity bunched beam stored in SIS100 for 106 turns is an important issue. In a recent study (G. Franchetti et al., Phys. Rev. ST Accel. Beams 6, 124201 (2003)) an analytical space charge algorithm was proposed, which allowed noise-free calculations over a large number of turns. Here we present a generalization of this algorithm to arbitrary 3D dimensions and arbitrary distributions observing ellipsoidal symmetry. Applications to long-term tracking with space charge are presented  
 
WEPLT059 Beam Loss Modeling for the SIS100 focusing, antiproton, impedance, optics 1975
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  In long term storage dynamic aperture is typically regarded as the quantity which has to be maintained sufficiently large in order to prevent beam loss. In the SIS100 of the GSI future project, a beam size occupying a large fraction of the beam pipe is foreseen. This circumstance requires a careful description of the lattice magnetic imperfections. The dynamic aperture is estimated in relation with an optimization of the SIS100 working point. For a space-charge-free bunched beam, estimates of beam loss are computed and compared with dynamic aperture. The impact of space charge will be discussed, and preliminary results on its effect on dynamic aperture and beam loss are presented.  
 
WEPLT060 Linear Coupling Theory of High Intensity Beams focusing, antiproton, impedance, coupling 1978
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  • M. Aslaninejad
    IPM, Tehran
  It is planned to use linear coupling in the SIS18 in order to fully or partially equilibrate the transverse emittances before transfer to the projected SIS100 synchrotron. In this paper we show that space charge significantly modifies the coupling mechanism. In particular the width of the stop-band is dominated by the space charge tune shift for weak skew strength. The conditions are discussed, under which slow crossing of the coupling resonance leads to the desired goal of equalizing emittances while maintaining a sufficient matching of the beam to the ring and extraction optics.  
 
WEPLT061 Influence of Beam Tube Obstacles on the Emittance of the PITZ Photoinjector focusing, antiproton, impedance, coupling 1981
 
  • S. Setzer, W. Ackermann, S. Schnepp, T. Weiland
    TEMF, Darmstadt
  For detailed analysis of space charge dominated beams inside an RF Photoinjector PIC-Codes like MAFIA TS2/3 can be used. While the interaction of particles with the sourrounding geometries are taken into account, the applicability of such codes is restricted due to simulation time and memory consumption as well as by numercial noise. Therefore only smaller sections of the whole injector can be calculated. On the other hand codes like ASTRA can be used to simulate the whole injector but no interaction between bunch and geometry is included. To make use of the individual advantages of each code discribed above an interface for bidirectional bunch exchange between the two programs has been implemented. This approach allows for applying the right simulation method depending on the physical effects under investigation. To demonstrate the importance of such an approach the results of detailed numerical studies of the impact of beam tube obstacles like the laser mirror on the achievable emittance of the PITZ RF Photoinjector further downstream will be presented.  
 
WEPLT062 Wakefield Calculations for TTF-II focusing, antiproton, impedance, coupling 1984
 
  • I. Zagorodnov, T. Weiland
    TEMF, Darmstadt
  • M. Dohlus
    DESY, Hamburg
  In this paper we estimate long- and short-range wake functions for new elements to be used in TESLA Test Facility (TTF) - II. The wake potentials of the LOLA-IV structure and the 3rd harmonic section are calculated numerically for very short bunches and analytical approximations for wake functions in short and long ranges are obtained by fitting procedures based on analytical estimations. The numerical results are obtained with code ECHO for high relativistic Gaussian bunches with RMS deviation up to 0.015 mm. The calculations are carried out for the complete structures (including bellows, rounding of the irises and the different end cell geometries) supplied with ingoing and outgoing pipes. The low frequency spectra of the wake potentials is calculated using the Prony-Pisarenko method.  
 
WEPLT063 Investigation of Cavity Induced Longitudinal Coupled Bunch Mode Instability Behaviour and Mechanisms focusing, antiproton, coupling, electron 1987
 
  • R.G. Heine, P. Hartmann, H. Huck, G. Schmidt, T. Weis
    DELTA, Dortmund
  The narrowband impedances of RF-resonators in a circular accelerator can drive coupled bunch mode - CBI - instabilities which might spoil the overall beam quality. Often, as in synchrotron radiation light sources e.g. the instability does not lead to beam loss but to a severe degradation of the source brilliance. Investigations of longitudinal CBIs have been performed at the DELTA storage ring with a single DORIS-type cavity for future comparision with the behaviour of a HOM-damped cavity to be tested at DELTA. This resonator is presently developed and built within an EU-collaboration. The beam was deliberately driven into instability using the beam current as well as the cavity temperature as individual parameters. The instability characterisations at low (542 MeV) and high (1,5 GeV) energy exhibit a complex behaviour. The strength of the instability measured by the bunch excursions in the case of longitudinal CBIs, but also the spreading of the instability across neighbouring modes depends on parameters such as beam energy, resonant impedance but also on counteracting mechanisms like synchrotron radiation and Landau damping. The paper will cover the experimental results together with estimations of the influence and mechanism of Landau damping.  
 
WEPLT064 2-nd Order Sextupole Effects on the Dynamic Aperture in HERA-e focusing, antiproton, coupling, electron 1990
 
  • M. Vogt
    DESY, Hamburg
  During the first year after the luminosity upgrade HERA-e was operated in a mode for which the accessible area in transverse tune space was determined by resonances driven by sextupoles in 2-nd order. It turned out that with typical total incoherent beam beam tune shifts (.05,.08) for 2 IPs this space was too small for stable operation. We have used 2-nd order canonical perturbation theory to analyze the impact of the increased sextupole strengths in the upgraded lattice on the relevant resonance strengths and the detuning. Moreover, we have studied whether it is possible to compensate the resonances with localized octupole schemes (6 or 9 independent magnets) to 1-st and 2-nd order, computed the resulting detuning and compared the results with 6D tracking.  
 
WEPLT065 Hybrid Dry Coolers in Cooling Systems of High Energy Physics Accelerators focusing, antiproton, coupling, electron 1993
 
  • J.-P. Jensen, B. Conrad, U. Schuetz, F.-R. Ullrich, A. Wanning
    DESY, Hamburg
  Wet water cooling towers in high energy physics accelerators are state of the art. The advantages are robustness, effectiveness and cost-effectiveness. The return water temperature is lower than the air temperature due to cooling via evaporation. The disadvantages are the high water consumption, which becomes more costly in the future, and the soiling of the heat exchangers. If the water source is taken from wells then the drawdown of the ground water level has to be taken into account. DESY plans to use hybrid dry coolers for the two future projects: The XFEL linac and the PETRA 3 synchrotron light source. A hybrid dry cooler is a combination of a dry air cooler during cold and moderate seasons and additional wet cooling during the hot summer season. The cooling surface is wetted by adding water to increase the cooling capability by a factor of 250 %. The hybrid dry cooler saves a lot of water. The water consumption can be reduced by 70% compared to a wet cooling system. This contribution presents the auxiliary water consumption, the requirement of this water and an estimate of the temperature control behaviour of the hybrid dry cooling system.  
 
WEPLT066 Beam Dynamics Study for PETRA III Including Damping Wigglers focusing, antiproton, damping, coupling 1996
 
  • Y.L. Li, K. Balewski, W. Decking
    DESY, Hamburg
  Damping wigglers will be installed in the storage ring PETRA III to control the beam emittance to 1 nmrad. These wigglers will produce linear and nonlinear perturbations on beam dynamics. A new expanded transport matrix method is developed to solve linear dynamics, and used to match linear lattice functions. The symplectic method is adopted to track particle through the whole ring including the damping wigglers. Halbach?s formulae are used to describe the wiggler field. The main parameters of the wigglers are derived from field calculations. In order to avoid dangerous resonances, tune scanning is implemented to find suitable working points. According to presently known field quality, the nonlinear effects of damping wigglers will not degrade the performance of PETRA III and the dynamic aperture is still larger than the physical aperture.  
 
WEPLT067 Space Charge Problem in Low Energy Super-conducting Accelerator antiproton, damping, coupling, electron 1999
 
  • N.E. Vasyukhin, R. Maier, Y. Senichev
    FZJ/IKP, Jülich
  At present the super-conducting option of linear accelerators is considered for low energy, and new type of RF cavities is considered for this purpose. However, together with electrodynamics problems we should solve the transverse stability problem, since in structures with external focusing elements the focusing period is longer, and in higher accelerating field the defocusing factor increases as well. In this paper we consider the transverse stability problem, taking into account the non-linear space charge problem. The fundamental mechanism of hallo creation in super-conducting linear accelerators is investigated to minimize the particle losses. The theoretical results are supported by numerical simulation.  
 
WEPLT068 Momentum Compaction Factor and Nonlinear Dispersion at the ANKA Storage Ring antiproton, damping, coupling, booster 2002
 
  • A.-S. Müller, A. Ben Kalefa, I. Birkel, E. Huttel, M. Pont, F. Pérez
    FZK-ISS-ANKA, Karlsruhe
  The ANKA electron storage ring operates in the energy range from 0.5 to 2.5 GeV. In order to improve machine performance a precise modelling of linear and nonlinear optics is mandatory. Apart from higher order chromaticity also momentum compaction factor and dispersion have to be controlled. In this framework, the higher order momentum compaction factor has been determined exploiting the extraordinary precision of the resonant spin depolarisation method. Furthermore the nonlinear horizontal dispersion was measured as a function of the momentum deviation for different chromaticities. This paper discusses the experimental results and compares the findings to different simulations.  
 
WEPLT069 Investigation of Scraper Induced Wake Fields at ANKA antiproton, damping, coupling, booster 2005
 
  • A.-S. Müller, I. Birkel, E. Huttel, M. Pont, F. Pérez
    FZK-ISS-ANKA, Karlsruhe
  • F. Zimmermann
    CERN, Geneva
  The ANKA synchrotron light source operates in the energy range from 0.5 to 2.5 GeV. Typical requirements for light sources include small beam sizes, large lifetimes and high currents to provide the highest possible photon flux. The understanding of impedance and instability related issues is very important in order to improve the machine performance, in particular when small aperture insertion devices are installed that require protection by a scraper. In the framework of an impedance survey the transverse and longitudinal wake fields induced by a vertical scraper have been measured and analysed. This paper reports the beam observations and compares them with the expectation.  
 
WEPLT070 Studies of Current Dependent Effects at ANKA antiproton, damping, coupling, booster 2008
 
  • A.-S. Müller, I. Birkel, E. Huttel, M. Pont, F. Pérez
    FZK-ISS-ANKA, Karlsruhe
  • F. Zimmermann
    CERN, Geneva
  The ANKA electron storage ring is operated at energies between 0.5 and 2.5 GeV. A major requirement for a synchrotron light source, such as ANKA, is to achieve a high beam current. A multitude of mostly impedance related effects depend on either bunch or total beam current. This paper gives an overview over the various beam studies performed at ANKA in this context, specifically the observation of current dependent detuning, the dermination of the bunch length change with current from a measurement of the ratio between coherent and incoherent synchrotron tune and an assessment of the effective longitudinal loss factor from the current dependent horizontal closed orbit distortion.