• P. Raimondi
  

• A. Andersson
  
• J. P.H. Sladen
  CERN, Geneva

High precision beam phase measurements will be vital for synchronization of main and drive beams in CLIC. Development work is underway with the aim to demonstrate 0.1 degree resolution for a wideband 30GHz measurement. In order to be able to test this with a beam exhibiting much higher phase jitter, two prototypes have been built so that the difference in their outputs can be measured. Results of measurements made with bunch trains in CTF3 are presented.

• G. Fernqvist
  
• P. Dreesen, G. Hudson
  CERN, Geneva
• J. R. Pickering
  Metron, Norwich

• G. Fernqvist
  
• M. C. Bastos, A. Cantone, P. Dreesen, O. Fournier, G. Hudson
  CERN, Geneva

• A. Kumar
  
• S. C. Bapna, S. Dutta, K. Swarna
  RRCAT, Indore (M. P.)
• A. Poncet
  CERN, Geneva

Superconducting magnets are subjected to various forces during their cool down and alignment. Their construction invariably includes bellows, gimbals, hoses and composite supports. A good estimate of the deformations arising out of the cool down and alignment operations is necessary as these induce relative displacements between the fiducialised external vessel and hidden cold mass of the magnet. The nonlinear and orthotropic behaviour of these elements may make the model complicated and if solved as a nonlinear problem, would entail a large solution time as the overall model size runs into million nodes. Authors developed a unified Finite Element Model of the LHC Short Straight Section and during this process many innovative modeling techniques evolved. The developed model uses isotropic material constitutive laws with linear material properties. The paper is presenting some of the salient features of these modeling techniques.

• Y. Thurel
  
• B. Favre, D. Nisbet
  CERN, Geneva

• E. Todesco
  
• B. Bellesia, J.-P. Koutchouk
  CERN, Geneva
• C. Santoni
  Universite Blaise Pascal, Clermont-Ferrand

The aim of this analysis is to study if the field quality in a large aperture low-beta superconducting quadrupole for the LHC upgrade limits the beam performances due to increased geometric aberrations. Random field errors in superconducting quadrupoles are usually estimated by computing the effect of a random positioning of the coil blocks around the nominal position with an r.m.s. of 0.05 mm. Here, we review the experience acquired in the construction of 7 superconducting quadrupoles in the RHIC and in the LHC projects to estimate the precision in the block positioning, showing that there is no visible dependence on the magnet aperture. Different magnet models are then used to estimate the expected field quality in quadrupoles with apertures ranging from 50 to 200 mm. The impact on geometrical aberrations and scaling laws for their dependence on the aperture are finally evaluated.

• E. Y. Wildner
  
• N. Emelianenko
  CERN, Geneva

• S. A. Kahn
  
• M. Alsharo'a, R. P. Johnson, M. Kuchnir
  Muons, Inc, Batavia
• R. C. Gupta, R. B. Palmer, P. Wanderer, E. Willen
  BNL, Upton, Long Island, New York
• D. J. Summers
  UMiss, University, Mississippi

The ability of high temperature superconducting (HTS) conductor to carry high currents at low temperatures makes feasible the development of very high field magnets for uses in accelerators and beam-lines. A specific application of a very high field solenoid is to provide a very small beta region for the final cooling stages for a muon collider. This paper will describe a conceptual design of a 50 Tesla solenoid based on Bi-2223 HTS tape, where the magnet will be operated at 4.2 K to take advantage of the high current carrying capacity at that temperature. A 25 Tesla solenoid has been run using a 5 Tesla Bi-2212 insert. The current carrying capacity of the BSCCO wire has been measured to be 266 Amps/mm2 at 4.2 K at the NHFML. This paper will describe the technical issues associated with building this 50 Tesla magnet. In particular it will address how to mitigate the large Lorentz stresses associated with the high field magnet and how to design the magnet to reduce the compressive end forces.

• W. Wittmer
  
• W. S. Colocho, G. R. White
  SLAC, Menlo Park, California

The controls software in use at PEP II had originally been developed in the eighties. The functionality and maturity of the applications in that system have made it very successful in routine operation, but this same longevity and orientation toward fixed requirements, make it largely unsuitable for rapid machine development and ad-hoc online experimentation. A successful recent trend at light sources has been to use the so called MATLAB Middle Layer (MML). This package abstracts each underlying control system framework to which it is connected, such as Channel Access. We describe the middle layer implementation for PEP II and LCLS based on AIDA (described elsewhere in these proceedings), which is unusual in that it provides access to the high level functionality of the legacy control system, as well as to a very large assortment of useful data in addition to channel access read and control. The MML had to be adapted for the implementation at PEP II since colliders differ significantly from light sources by scale and symmetry of the lattice, and PEP II is the first collider at which such an implementation is being done.

• J. E. Spencer
  

We consider optimization of the generalized luminosity per unit cost of a linear collider in this ES&H era. Examples running over the length of the LC, starting at the source and ending at the dump, suggest that both costs (capital and operating) and environmental issues can be improved in a compatible way. Thus, a RoHS by any other name (WEES or OSHA) need not present thorny problems requiring unexpected R&D but a push to leverage many recent advances that might otherwise be overlooked or avoided. The physics is interesting and the true amortized cost may be seriously underestimated by ignoring such issues. For example, the entire, interior surface of a laser driven RF gun involves interesting materials science where the space requires continuous UHV to sustain stable, acceptable quantum efficiency as well as avoid RF breakdown damage in an environment that is also subject to radiation damage. All of these can seriously reduce a gun's output and LCs luminosity. Intelligent design of rad-hard systems can approach the ideal of bug-proof software that needn't produce overly slow or ponderous systems while providing opportunities to innovate that justify the costs.

• M. Yeddulla
  
• S. G. Tantawi
  SLAC, Menlo Park, California

*S. G. Tantawi et al., Physical Review Special Topics – Accelerator and Beams. 8, 042002 (2005)

• D. Bruno
  
• G. Ganetis, W. Louie, J. Sandberg
  BNL, Upton, Long Island, New York

The two rings in the Relativistic Heavy Ion Collider (RHIC) were originally constructed with 24 sextupole power supplies, 12 for each ring. Before the start of Run 7, 24 new sextupole power supplies were installed, 12 for each ring. Individual sextupole power supplies are now each connected to six sextupole magnets. A superconducting snake magnet and power supplies were installed in the Alternating Gradient Synchrotron (AGS) and commissioned during RHIC Run 5, and used operationally in RHIC Run 6. The power supply technology, connections, control systems and interfacing with the Quench Protection system for both these systems will be presented.

• D. Bruno
  
• G. Ganetis, G. Heppner, W. Louie, J. Sandberg, C. Schultheiss
  BNL, Upton, Long Island, New York

The two rings in the Relativistic Heavy Ion Collider (RHIC) require a total of 933 power supplies to supply current to highly inductive superconducting magnets. Failure statistics for the RHIC power supplies will be presented for the last three RHIC runs. The failures of the power supplies will be analyzed. The statistics associated with the power supply failures will be presented. Comparisons of the failure statistics for the last three RHIC runs will be shown. Improvements that have increased power supply availability will be discussed. Further improvements to increase the availability of the power supplies will also be discussed.

• H. G. Kirk
  
• J. R.J. Bennett
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• O. Caretta, P. Loveridge
  STFC/RAL, Chilton, Didcot, Oxon
• A. J. Carroll, V. B. Graves, P. T. Spampinato
  ORNL, Oak Ridge, Tennessee
• I. Efthymiopoulos, A. Fabich, F. Haug, J. Lettry, M. Palm
  CERN, Geneva
• K. T. McDonald
  PU, Princeton, New Jersey
• N. V. Mokhov, S. I. Striganov
  Fermilab, Batavia, Illinois

• R. P. Johnson
  
• Y. S. Derbenev
  Jefferson Lab, Newport News, Virginia

Advances in ionization cooling, phase space manipulations, and technologies to achieve high brightness muon beams are stimulating designs of high-luminosity energy-frontier muon colliders. Simulations of Helical Cooling Channels (HCC) show impressive emittance reductions, new ideas on reverse emittance exchange and muon bunch coalescing are being developed, and high-field superconductors show great promise to improve the effectiveness of ionization cooling. Experiments to study RF cavities pressurized with hydrogen gas in strong magnetic fields have had encouraging results. A 6-dimensional HCC demonstration experiment is being designed and a 1.5 TeV muon collider is being studied at Fermilab. Two new synergies are that very cool muon beams can be accelerated in ILC RF structures and that this capability can be used both for muon colliders and for neutrino factories. These advances are discussed in the context of muon colliders with small transverse emittances and with fewer muons to ease requirements on site boundary radiation, detector backgrounds, and muon production.

• A. Valishev
  
• Y. Alexahin, V. A. Lebedev, R. S. Moore, V. D. Shiltsev
  Fermilab, Batavia, Illinois

• V. D. Shiltsev
  
• Y. Alexahin, V. Kamerdzhiev, G. F. Kuznetsov, X. Zhang
  Fermilab, Batavia, Illinois
• K. Bishofberger
  LANL, Los Alamos, New Mexico

• W. Scandale
  

We report observations, performed by the H8-RD22 Collaboration*, of the so-called volume reflection effect with 400 GeV/c protons interacting with bent Silicon crystals in the H8 beam line at the CERN SPS. The volume reflection is closely related with particle channeling. This phenomenon occurs at the tangency point of a particle trajectory with the bent crystalline planes and consists in the reversal of the transverse component of the particle momentum. The measurements were collected with a high spatial resolution detector mainly based on Silicon strips. The proton beam was deviated in the direction opposite to that of channeling by ~12μrad, which is ~1.3 times the critical angle, with an efficiency larger than 97% in a range of the proton-to-crystal incident angle as large as the bending angle of crystallographic planes. This evidence opens new perspectives for manipulation of high-energy beams, e.g., for collimation and extraction in the new-generation of hadron colliders or as a method for high-energy experiments in the region near to the circulating beam.

* H8-RD22 collaboration: CERN, FNAL, INFN (Ferrara, Legnaro, Perugia, Roma, Milano, Trieste), IHEP, PNPI, JINR

• E. G. Stern
  
• J. F. Amundson, P. Spentzouris, A. Valishev
  Fermilab, Batavia, Illinois
• J. Qiang, R. D. Ryne
  LBNL, Berkeley, California

• S. H. Kim
  
• C. Doose
  ANL, Argonne, Illinois

Model superconducting helical undulators are under development for the proposed International Linear Collider (ILC) positron source. The undulator requires high-permeability steel poles and superconducting coils to meet the ILC parameters. A fabrication method for steel poles on a nonmagnetic beam chamber was developed. A model undulator with a period length of 14 mm and Nb3Sn coils was fabricated. Both ends of the model were designed to provide for continuous winding of a single conductor with 39 turns per helix. A 10-mm-period model was designed and is in the fabrication process. The 14-mm-period model may be used in the development of a cryogenic magnetic measurement system. Details of the fabrication and test results will be presented.

• C. Milardi
  
• D. Alesini, M. E. Biagini, C. Biscari, R. Boni, M. Boscolo, B. Buonomo, A. Clozza, G. O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, P. Iorio, C. Ligi, F. Marcellini, C. Marchetti, G. Mazzitelli, L. Pellegrino, M. A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov
  INFN/LNF, Frascati (Roma)
• J. D. Fox, D. Teytelman
  SLAC, Menlo Park, California
• E. Levichev, S. A. Nikitin, P. A. Piminov, D. N. Shatilov
  BINP SB RAS, Novosibirsk

• J. Seeman
  
• M. E. Biagini, P. Raimondi
  INFN/LNF, Frascati (Roma)
• Y. Cai, M. K. Sullivan, U. Wienands
  SLAC, Menlo Park, California

Submitted for the High Luminosity Study Group for an Asymmetric Super-B-Factory: Parameters are being studied for a high luminosity e⁺e^- collider operating at the Upsilon 4S that would deliver a luminosity of over 10³⁶/cm²/s. This collider would use a novel combination of linear collider and storage ring techniques. In this scheme an electron beam and a positron beam at 4 GeV x 7 GeV are stored in low-emittance damping rings similar to those designed for a Linear Collider (LC). A LC style interaction region is included in the ring to produce sub-millimeter vertical beta functions at the collision point. A large crossing angle (±30 mrad) is used at the collision point to allow beam separation and reduce the hourglass effect. Beam currents of about 3 A x 2 A in 1700 bunches can produce a luminosity of 10³⁶/cm²/s. Design parameters and beam dynamics effects are discussed.

• K. Foraz
  
• E. Barbero-Soto, H. Gaillard, C. Hauviller, S. Weisz
  CERN, Geneva

• Th. Weiler
  
• O. Aberle, R. W. Assmann, R. Chamizo, Y. Kadi, J. Lettry, S. Redaelli
  CERN, Geneva

• D. E. Johnson
  

• T. Sen
  
• V. E. Scarpine, R. Thurman-Keup
  Fermilab, Batavia, Illinois

• P. M. McIntyre
  
• R. Romero, A. Sattarov
  Texas A&M University, College Station, Texas

A conceptual design is presented for the 50 Tesla superconducting solenoids that are required for an optimized fast cooling ring in current designs for multi-TeV muon colliders. The solenoid utilizes high-performance multi-filament Bi-2212/Ag round strand. The conductor is a cable-in-conduit consisting of six such strands cabled around a thin-wall spring tube then drawn within an outer sheath. The spring tube and the sheath are made from high-strength superalloy Inconel. The solenoid coil comprises 5 concentric shells supported independently in the conventional manner. Each shell consists of a winding of the structured cable, impregnated in the voids between cables but empty inside so that the spring tubes decouple stress so that it cannot strain-degrade the fragile strands, and a high-modulus overband. An expansion bladder is located between the winding and the overband, and is pressurized and then frozen to provide hydraulic compressive preload to each shell. This approach makes it possible to accommodate ~10 T field contribution from each shell without degradation, and provides distributed refrigeration so that heat is removed throughout the windings.

• M. J. Hogan
  
• I. Blumenfeld, F.-J. Decker, R. Ischebeck, R. H. Iverson, N. A. Kirby, R. Siemann, D. R. Walz
  SLAC, Menlo Park, California
• C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
  UCLA, Los Angeles, California
• T. C. Katsouleas, P. Muggli, E. Oz
  USC, Los Angeles, California

The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam at the Stanford Linear Accelerator Center (SLAC). Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of ~52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a metre for a small fraction of the electrons in the injected bunch.

• V. Ptitsyn
  

• Y. Zhang
  
• S. A. Bogacz, P. B. Brindza, A. Bruell, L. S. Cardman, J. R. Delayen, Y. S. Derbenev, R. Ent, P. Evtushenko, J. M. Grames, A. Hutton, G. A. Krafft, R. Li, L. Merminga, J. Musson, M. Poelker, A. W. Thomas, B. Wojtsekhowski, B. C. Yunn
  Jefferson Lab, Newport News, Virginia
• V. P. Derenchuk
  IUCF, Bloomington, Indiana
• V. G. Dudnikov
  BTG, New York
• W. Fischer, C. Montag
  BNL, Upton, Long Island, New York
• P. N. Ostroumov
  ANL, Argonne, Illinois

Experiments on the study of fundamental quark-gluon structure of nucleons require an electron-light ion collider of a center of mass energy from 20 to 65 GeV at luminosity level of 10³⁵ cm^-2s-1 with both beams polarized. A CEBAF accelerator based ring-ring collider of 7 GeV electrons/positrons and 150 GeV light ions is envisioned as a possible next step after the 12 GeV CEBAF Upgrade. The developed ring-ring scheme takes advantage of the existing polarized continuous electron beam and SRF linac, the green-field design of the collider rings and the ion accelerator complex with electron cooling. We report results of our design studies of the ring-ring version of an electron-light ion collider of the required luminosity.

• C. M. Bhat
  
• B. Chase, C. Gattuso, P. W. Joireman
  Fermilab, Batavia, Illinois

The Recycler is the primary antiproton repository for the Tevatron collider at Fermilab. Stored antiproton beam intensity has been steadily increased to about 450·10¹⁰ over the last three years. We have used the technique of longitudinal momentum mining* in the Recycler to extract constant intensity and constant longitudinal emittance antiproton bunches for collider operation since early 2005. Since then, the Recycler has played a critical role in the luminosity performance of the Tevatron; the peak proton-antiproton luminosity has been raised by a factor of about three and a world record luminosity of 2.31·10³²cm^-2s^-1 has been achieved. Recently, many improvements have been implemented in the antiproton mining and stacking schemes used in the Recycler to handle higher intensity beam. In this paper we discuss morphing during antiproton stacking, reducing longitudinal emittance dilution, and use of soft mining buckets to maintain low peak density and control the beam instability during mining. In addition we present past and current performance of mining and beam stacking RF manipulations.

* C. M. Bhat, Phys. Letts. A Vol. 330 (2004), p 481

• T. O. Raubenheimer
  

• J. C. Smith
  

Polarized positron and electron beams are ideal for searching for new physics at the International Linear Collider (ILC). In order to properly orient and preserve the polarization of both beams at the Interaction Point (IP) the beam polarization must be manipulated by a series of spin rotators along the beam line. Furthermore, the polarization for both beams should be known with a relative uncertainty of about 0.5% or better, therefore, all sources of depolarization along the ILC should be identified. We report on a spin rotator design for the ILC and polarization studies between Damping Ring extraction and the Interaction Point.

• D. Proch
  

• R. Corsini
  

• J. Payet
  
• S. Auclair, A. Chance, O. Napoly, D. Uriot
  CEA, Gif-sur-Yvette

With the local chromaticity correction scheme, the luminosity optimisation of the beam delivery systems of the e⁺ e^- International Linear Collider (ILC) project is challenging. A manual optimization is a long and complex process and its automation becomes a necessity. Recent works have shown that it was possible to employ a simplex minimization method, applied to the beam size calculation at the Interaction Point (IP), to reach this objective automatically *. To achieve this goal in the ILC case, we have developed a minimization code which uses analytical computations of the IP beam sizes based on external code results, TRANSPORT** or MADX (with PTC extension)***. Two minimization algorithms can be employed. The maximum luminosity reached and the convergence time of the two codes and algorithms are compared. We also used the code TRACEWIN which tracks a particle cloud and minimise the rms beam spot sizes at IP to optimise the luminosity, and we compare with the previous results.

* Non-linear optimization of beam lines, R. Tomas, CLIC Note 659** Third-Order TRANSPORT with MAD Input, D. C. Carey, K. L. Brown and F. Rothacker, FERMILAB-Pub-98/310*** MADX User's Guide CERN

• K. Shirasawa
  
• H. Baba, H. Matsumoto
  KEK, Ibaraki
• T. Inagaki, H. Kitamura, T. Shintake
  RIKEN Spring-8 Harima, Hyogo
• S. Miura
  MHI, Hiroshima

• Z. G. Zong
  
• F. Furuta, H. Inoue, T. Saeki, K. Saito
  KEK, Ibaraki
• J. Gao, M. Q. Ge, Q. J. Xu, J. Y. Zhai
  IHEP Beijing, Beijing

• C.-F. Wu
  
• S. Dong, X. D. He, H. Lin, L. Wang
  USTC/NSRL, Hefei, Anhui

Some model cavities have been further developed and investigated for a X-band (f=9.37GHz) hybrid dielectric-iris-loaded accelerating structure based on the calculated results about the effect of the dimension tolerance on the RF properties. The dispersion curve fitted by using the measurement value is consistent with the one calculated. The r/Q values of the dipole modes have been calculated by the Mafia code. The theoretical results show that the r/Q values of dipole modes for the new accelerating structure are lower than those for the iris-load accelerating structure.

• P. V. Avrakhov
  
• A. Kanareykin
  Euclid TechLabs, LLC, Solon, Ohio
• S. Kazakov
  KEK, Ibaraki
• N. Solyak
  Fermilab, Batavia, Illinois
• V. P. Yakovlev
  Omega-P, Inc., New Haven, Connecticut

• M. Taborelli
  
• G. Arnau-Izquierdo, S. Calatroni, S. T. Heikkinen, T. Ramsvik, S. Sgobba, W. Wuensch
  CERN, Geneva

• M. A. Kempkes
  
• M. P.J. Gaudreau, I. Roth, R. P. Torti
  Diversified Technologies, Inc., Bedford, Massachusetts

• J. Z. Zhou
  
• C. Chen, B. M. Kardon
  MIT/PSFC, Cambridge, Massachusetts

A photonic band gap (PBG) higher-order-mode (HOM) coupler is proposed as an Alternative Configuration Design (ACD) for the HOM coupler for the International Linear Collider (ILC). The PBG HOM coupler uses a two-dimensional triangular PBG structure with good axial symmetry. Simulation studies of a PBG HOM coupler show that it maintains the operating mode at 1.3 GHz with . While a PBG HOM coupler provides superior damping for all the higher order modes in principle, detailed studies of the effectiveness of HOM damping are being carried out, and results will be discussed.

• P. M. McIntyre, P. M. McIntyre, N. Pogue, R. Romero, A. Sattarov
  Texas A&M University, College Station, Texas

A polyhedral superconducting cavity is being developed for possible use in linac colliders. In side view it has the contour of a Tesla-type multi-cell string. The surfaces of the cavity are formed by bonding flat foils to solid copper wedge-shaped segments, so that the end view is a polyhedron of such segments. Several features of this structure make it interesting for linac colliders: the cavity segments are totally open for cleaning, polishing, and inspection until the final assembly step; narrow slot gaps at the boundaries between segments strongly suppress all deflecting modes without penalty to the accelerating mode; the solid copper substrate accommodates cooling channels and eliminates the need for an immersion cryostat; and the open geometry makes it possible to utilize advanced superconductors (e.g. multi-layer Nb/Nb3Sn, YBCO, MgB2) on the cavity surface, opening the possibility of higher gradients.

• R. L. Geng
  
• G. V. Eremeev, H. Padamsee, V. D. Shemelin
  CLASSE, Ithaca

Based on the encouraging results of the first 1300 MHz 70 mm aperture single cell re-entrant cavities*, we continue the high gradient studies for ILC with new re-entrant cavities made of fine-grain as well as large-grain niobium. These new cavities have smaller aperture of 60 mm, providing a further reduced Hpk/Eacc or a further improved ultimate gradient. Four 1300 MHz 60 mm aperture re-entrant cavities are made, two out of fine grain niobium and the other two out of large-grain niobium. In addition, two elliptical shape 1500 MHz cavities are also made out of large-grain niobium. We present the testing results of these cavities.

* R. L. Geng et al., PAC2005, p.653.

• W. Reass
  
• R. F. Gribble
  LANL, Los Alamos, New Mexico

The converter-modulator is a resonant power conditioning configuration that is optimized for a particular load impedance or parameter space. Although traction motor IGBT's are typically used for hard-switching application in the 1 kHz regime, the present use of high-power (10 - 15 MW) converter-modulators have used a 20 kHz resonant switching topology. This presents design challenges to maintain efficient and reliable switching characteristics for the IGBT's. Improved tuning methods and circuit topological changes now offer a significant reduction in IGBT switching losses as compared to those used with the Spallation Neutron Source (SNS) design (perhaps by 10). These circuit and topology changes should also permit Pulse Width Modulation (PWM) of the modulator output voltage to provide a regulated voltage without anomalous IGBT switching characteristics. This paper will review the results of this investigation based on models developed from the SNS converter-modulator operational data.

• W. Reass
  
• C. Adolphsen, T. G. Beukers, C. Burkhart, R. L. Cassel, M. N. Nguyen, G. C. Pappas, R. Swent, A. C. de Lira
  SLAC, Menlo Park, California
• D. E. Anderson
  ORNL, Oak Ridge, Tennessee

To facilitate a rapid response to the International Linear Collider (ILC) L-Band development program at SLAC, a spare converter-modulator was shipped from Los Alamos. This modulator was to be a spare for the Spallation Neutron Source (SNS) accelerator at ORNL. The ILC application requires a 33% higher peak output power (15 MW) and output current (130 Amp). This presents significant design challenges to modify the existing hardware and yet maintain switching parameters and thermal cycling within the semiconductor component ratings. To minimize IGBT commutation and free-wheeling diode currents, a different set of optimizations, as compared to the SNS design, were used to tune the resonant switching networks. Additional complexities arose as nanocrystalline cores with different performance characteristics (as compared to SNS), were used to fabricate the resonant "boost" transformers. This paper will describe the electrical design, system modifications, modeling efforts, and resulting electrical performance as implemented for the ILC L-band test stand.

• A. Canabal
  
• J. D. Bowyer
  NMSU, Las Cruces, New Mexico
• P. Chacon, N. A. Gillespie, M. A. Madrid, T. Tajima
  LANL, Los Alamos, New Mexico

• C. D. Nantista
  
• C. Adolphsen, G. B. Bowden, B. D. McKee, R. Swent
  SLAC, Menlo Park, California

An ILC R&D facility is being constructed in the NML building at Fermilab which, in addition to an injector and beam dump with spectrometer, will contain up to three cryomodules worth of ILC-type superconducting 9-cell cavities, 24 in all. This linac will be powered by a single klystron. As part of SLAC?s contribution to this project, we will provide a distribution network in WR650 waveguide to the various cavity couplers. In addition to commercial waveguide components and circulators and loads developed for TESLA, this sytem will include adjustable tap-offs, and customized hybrids. In one configuration, the circulators will be removed to test pair-wise cancellation of cavity reflections through hybrids. The system will be pressurized with nitrogen to 3 bar absolute to avoid the need for SF6 at windows or circulator. The full distribution for the first cryomodule will be delivered and installed later this year. We describe the design of the system and completed RF testing.

• S. V. Kuzikov
  
• J. L. Hirshfield, V. P. Yakovlev
  Omega-P, Inc., New Haven, Connecticut
• M. E. Plotkin, D. Yu. Shegolkov, A. A. Vikharev
  IAP/RAS, Nizhny Novgorod

Basic studies of factors that limit RF fields in warm accelerator structures require experiments at RF power that can be produced using pulse compression. This approach is being implemented to compress output pulses from the Yale/Omega-P 34-GHz magnicon to produce ~100-200 MW, 100 ns pulses. A new approach for passive pulse compression is a SLED-II type circuit operating with axisymmetrical modes of the TE0n type that requires only a single channel instead of the usual double channel scheme. This allows avoidance of a 3-dB coupler and need for simultaneous fine tuning of two channels. A 30 GHz passive prototype was tested at low power level in order to demonstrate key principles. The prototype showed a power gain 3,8 at a compression ratio 6:1 for an efficiency 63%. An active version of the one-channel pulse compressor is also suggested. It is attractive due to a possibility to achieve higher power gain. The mentioned active version naturally requires an electrically controlled coupler. In particular, as active elements of the coupler we suggest to use gas filled discharge tubes or ferroelectrics which have well recommended itself at 11.4 GHz experiments.

• J. Haimson
  
• B. L. Mecklenburg
  HRC, Santa Clara, California

To avoid surface erosion damage and to assist in understanding RF breakdown limitations imposed on high gradient linac operation, a gradient hardened structure is being fabricated having high temperature brazed and machined stainless steel surfaces located in the high E-field region of the beam apertures and in the high H-field regions of the racetrack shaped coupling cavities. The microwave design parameters and physical dimensions of this 17GHz, 2pi/3 mode, 22-cavity structure were established specifically to allow comparison of its high gradient performance to that of a similar all-copper structure tested under identical conditions, using an existing 4X power amplifying, RF recirculating dual ring system. Use of the 6X thicker skin depth material, the resulting de-Q-ing effects and the minimal reduction of beam energy (2%) associated with the strategically located lossy surfaces are discussed; fabrication techniques are described; and design parameters of the gradient hardened linac and the 17GHz power amplifying system are presented.

• A. Kanareykin
  
• P. V. Avrakhov, Z. Liu
  Euclid TechLabs, LLC, Solon, Ohio
• W. Gai
  ANL, Argonne, Illinois
• S. Kazakov
  KEK, Ibaraki
• N. Solyak
  Fermilab, Batavia, Illinois
• V. P. Yakovlev
  Omega-P, Inc., New Haven, Connecticut

We describe a conceptual design for a superconducting traveling wave accelerator for the ILC. The RF feedback system plus phase shifter can redirect the accelerating wave that passed through the STWA section back to the input of the accelerating structure. In this paper, the STWA cell shape optimization, coupler cell design and rat race ring coupler in the feedback loop are presented. The STWA cell shape is similar to the LL cavity with a 60 mm disk diameter. A 9-cell STWA operates at the mode with group velocity as low as 0.0106 c. Both the ratio of peak electric field and magnetic field to the axial electric field are smaller than in the TESLA 9-cell cavity. The STWA structure has more cells per unit length than a TESLA structure but provides an accelerating gradient higher than a TESLA structure, consequently reducing the cost. The designed rat race directional coupler with four ports has ?3 dB direct coupling coefficients, 16.5 MHz bandwidth between ?30 dB isolations and 1.1 MHz bandwidth between ?30 dB reflection coefficients. Effects of the mechanical tolerances are also discussed.

• L. Lilje
  

• Y. Suetsugu
  
• K. Shibata
  KEK, Ibaraki

• M. A. Kempkes
  
• F. O. Arntz, J. A. Casey, M. P.J. Gaudreau, I. Roth
  Diversified Technologies, Inc., Bedford, Massachusetts

• J. Urbin
  
• R. D. Nolte
  Air Products & Chemicals, Inc., Allentown, Pennsylvania

• P. Dauguet
  

• Y. Iwashita
  
• H. Fujisawa, M. Ichikawa, Y. Tajima
  Kyoto ICR, Uji, Kyoto
• M. Kumada
  NIRS, Chiba-shi
• S. Kuroda, T. Okugi, T. Tauchi
  KEK, Ibaraki
• C. M. Spencer
  SLAC, Menlo Park, California

An adjustable permanent magnet quadrupole has been developed for the final focus in an electron-positron linear collider. The design has two concentric rings of permanent magnets. Recent activities include a newly fabricated inner ring that demonstrates the strongest field gradient at a small bore diameter of 15mm and a new magnetic field measurement system based on a rotating coil. The prospects of the R&D will be discussed.

• O. Dadoun
  
• P. Bambade
  LAL, Orsay

• C. Rimbault
  
• M. Alabau
  IFIC, Valencia
• P. Bambade, O. Dadoun, G. Le Meur, F. Touze
  LAL, Orsay
• D. Schulte
  CERN, Geneva

• F. Tecker
  
• C. Biscari, A. Ghigo
  INFN/LNF, Frascati (Roma)
• E. Bressi
  CNAO Foundation, Milan
• R. Corsini, S. Doebert, P. K. Skowronski, P. Urschutz
  CERN, Geneva
• A. Ferrari
  UU/ISV, Uppsala

• H. Aksakal
  
• A. K. Ciftci, Z. Nergiz
  Ankara University, Faculty of Sciences, Tandogan/Ankara
• D. Schulte, F. Zimmermann
  CERN, Geneva

• H. Aksakal
  
• J. Resta-Lopez
  IFIC, Valencia
• F. Zimmermann
  CERN, Geneva

• G. Ellwood
  
• R. J.S. Greenhalgh
  STFC/RAL, Chilton, Didcot, Oxon

Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts from each energetic electron or positron bunch of charged particles, in addition to maintaining low geometric and resistive wall wake fields. The transient shock wave resulting from rapid localised beam heating and its implications for spoiler design are studied using ANSYS. Shockwave propagation is modelled in 2 dimensions showing the effect of dilatational shockwaves striking free surfaces, producing reflected dilatational and distortional waves. The implication of these relflected waves on the damage of the collimators is also discussed.

• Y. Ivanyushenkov
  
• I. R. Bailey, J. A. Clarke, J. B. Dainton, O. B. Malyshev, L. I. Malysheva, G. A. Moortgat-Pick, D. J. Scott
  Cockcroft Institute, Warrington, Cheshire
• D. P. Barber
  DESY, Hamburg
• E. Baynham, T. W. Bradshaw, A. J. Brummitt, F. S. Carr, A. J. Lintern, J. Rochford
  STFC/RAL, Chilton, Didcot, Oxon
• P. Cooke
  Liverpool University, Science Faculty, Liverpool
• B. J.A. Shepherd
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

An undulator based positron source is a baseline for the International Linear Collider (ILC). The HeliCal collaboration in the UK is carrying out an R&D programme on a short period supercoducting helical undulator with the goal to develop manufacturing technique as well as modelling and measurement techniques. Several undulator prototypes have been built and successfully tested. This paper summarizes the results of the R&D phase of the project.

• A. F. Hartin
  

Incoherent background pair production processes are studied with respect to full polarizations of all states. Real initial photon polarizations are obtained via a QED calculation of the beamstrahlung process. Virtual photon polarizations are related to the electric field of the colliding bunches at the point of pair production. An explicit expression for the virtual photon polarization vector is developed and found to have no circular polarization component. Pair polarization states are highly dependent on initial state circular polarization and are consequently produced almost unpolarized. The Breit-Wheeler cross-section with full polarizations is calculated and coded into the CAIN pair generator program. Numerical evaluations of the ILC operating in the seven proposed collider parameter sets shows that there are 10-20% less low energy pairs than previously thought. Collider luminosity as calculated by CAIN remains the same.

• I. Konkashbaev
  
• P. F. Fisher, A. Hassanein
  ANL, Argonne, Illinois
• N. V. Mokhov
  Fermilab, Batavia, Illinois

• R. P. Johnson
  
• C. M. Ankenbrandt, C. M. Bhat, M. Popovic
  Fermilab, Batavia, Illinois
• S. A. Bogacz, Y. S. Derbenev
  Jefferson Lab, Newport News, Virginia

The idea of coalescing multiple muon bunches at high energy to enhance the luminosity of a muon collider provides many advantages. It circumvents space-charge, beam loading, and wakefield problems of intense low-energy bunches while restoring the synergy between muon colliders and neutrino factories based on muon storage rings. A sampling of initial conceptual design work for a coalescing ring is presented here.

• M. A.C. Cummings
  
• C. M. Ankenbrandt, K. Yonehara
  Fermilab, Batavia, Illinois
• R. P. Johnson
  Muons, Inc, Batavia

The study of rare processes using stopping muon beams provides access to new physics that cannot be addressed at energy frontier machines. The flux of muons into a small stopping target is limited by the kinematics of the production process and by stochastic processes in the material used to slow the particles. Innovative muon beam cooling techniques are being applied to the design of stopping muon beams in order to increase the event rates in such experiments. Such intense stopping beams will also aid the development of applications such as muon spin resonance and muon-catalyzed fusion.

• D. V. Neuffer
  
• R. P. Johnson
  Muons, Inc, Batavia
• C. Y. Yoshikawa
  Fermilab, Batavia, Illinois

Common to various front end designs for a muon collider or neutrino factory are costly low frequency RF cavities used to bunch muons. In this paper we show that adding higher harmonic RF cavities to the bunching section of a muon capture channel can provide as good or better bunching efficiency than the case where only the fundamental is used. Since higher harmonic cavities are less expensive to build and operate, this approach implies significant cost savings.

• K. Yonehara
  
• R. J. Abrams, M. A.C. Cummings, R. P. Johnson, S. A. Kahn, T. J. Roberts
  Muons, Inc, Batavia
• D. R. Broemmelsiek, M. Hu, A. Jansson, V. D. Shiltsev
  Fermilab, Batavia, Illinois

MANX is an experiment to prove that effective six-dimensional (6D) muon beam cooling can be achieved a Helical Cooling Channel (HCC) using ionization-cooling with helical and solenoidal magnets in a novel configuration. The aim is to demonstrate that 6D muon beam cooling is understood well enough to plan intense neutrino factories and high-luminosity muon colliders. The experiment consists of the HCC magnets that envelop a liquid helium energy absorber, upstream and downstream instrumentation to measure the particle or beam parameters before and after cooling, and emittance matching sections between the detectors and the HCC. We describe and compare the experimental configuration for both single particle and beam profile measurement techniques based on G4Beamline simulations.

• M. A. Kempkes
  
• F. O. Arntz, M. P.J. Gaudreau
  Diversified Technologies, Inc., Bedford, Massachusetts
• A. Kardo-Sysoev
  IOFFE, St. Petersburg
• A. Krasnykh
  SLAC, Menlo Park, California

• C. Toth
  
• D. L. Bruhwiler, J. R. Cary
  Tech-X, Boulder, Colorado
• E. Esarey, C. G.R. Geddes, W. Leemans, K. Nakamura, D. Panasenko, C. B. Schroeder
  LBNL, Berkeley, California

Colliding laser pulses* have been proposed as a method for controlling injection of electrons into a laser wakefield accelerator (LWFA) and hence producing high quality relativistic electron beams with energy spread below 1% and normalized emittances below 1 micron. The original proposal relied on three coaxial pulsesI. One pulse excites a plasma wake, and a collinear pulse following behind it collides with a counterpropagating pulse forming a beat pattern that boosts background electrons into accelerating phase. A variation of this method uses only two laser pulses** which may be non-collinear. The first pulse drives the wake, and beating of the trailing edge of this pulse with the colliding pulse injects electrons. Non-collinear injection avoids optical elements on the electron beam path (avoiding emittance growth). We report on progress of non-collinear experiments at LBNL, using the Ti:Sapphire laser at the LOASIS facility of LBNL. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiment will be presented.

* E. Esarey, et al, Phys. Rev. Lett 79, 2682 (1997).** G. Fubiani, Phys. Rev. E 70, 016402 (2004).

• J. A. Crittenden
  
• M. A. Palmer, J. T. Urban
  CLASSE, Ithaca

The ILC damping rings require wiggler magnets with large physical aperture and with excellent field quality to maintain the dynamic aperture of the rings. We consider two possible designs derived from the wigglers presently in operation at the Cornell Electron Storage Ring. Design optimization has been performed based on detailed tracking calculations of dynamic aperture and tune footprint in a full model of the damping ring. Results of finite-element modeling, transfer functions, and the accuracy of analytic models of the wiggler field will be discussed.

• D. B. Cline
  
• Y. Fukui
  SLAC, Menlo Park, California
• A. A. Garren
  LBNL, Berkeley, California

• R. Arnold
  
• V. N. Duginov, S. A. Kostromin, N. A. Morozov
  JINR, Dubna, Moscow Region
• A. Fisher, C. Hast, Z. Szalata, M. Woods
  SLAC, Menlo Park, California
• H. J. Schreiber, M. Viti
  DESY Zeuthen, Zeuthen

• G. R. Bower
  
• R. Arnold, M. Woods
  SLAC, Menlo Park, California
• N. Sinev
  University of Oregon, Eugene, Oregon
• Y. Sugimoto
  KEK, Ibaraki

• R. B. Palmer
  
• Y. Alexahin, D. V. Neuffer
  Fermilab, Batavia, Illinois
• J. S. Berg, R. C. Fernow, J. C. Gallardo, H. G. Kirk
  BNL, Upton, Long Island, New York
• S. A. Kahn
  Muons, Inc, Batavia
• D. J. Summers
  UMiss, University, Mississippi

We propose a complete scheme for cooling a muon beam for a muon collider. We first outline the parameters required for a multi-TeV muon collider. The cooling scheme starts with the front end of the Study 2a proposed Neutrino Factory. This yields bunch trains of both muon signs. Emittance exchange cooling in upward climbing helical lattices then reduces the longitudinal emittance until it becomes possible to combine the trains into single bunches, one of each sign. Further cooling is now possible in emittance exchange cooling rings. Final cooling to the required parameters is achieved in 50 T solenoids that use high temperature superconductor. Preliminary simulations of each element will be presented.

• F. W. Jones
  
• W. Herr
  CERN, Geneva
• T. Pieloni
  EPFL, Lausanne

• A. Bungau
  
• R. J. Barlow
  UMAN, Manchester

• T. J. Roberts
  
• D. M. Kaplan
  Illinois Institute of Technology, Chicago, Illinois

G4beamline is a single-particle simulation program optimized for the design and evaluation of beam lines. It is based on the Geant4 toolkit, and can implement accurate and realistic simulations of particle transport in both EM fields and in matter. This makes it particularly well suited for studies of muon collider and neutrino factory design concepts. G4beamline includes a rich repertoire of beamline elements and is intended to be used directly without C++ programming by accelerator physicists. The program has been enhanced to handle a larger class of beamline and detector systems, and to run on Linux, Windows, and Macintosh platforms.

• P. Snopok
  
• M. Berz
  MSU, East Lansing, Michigan
• C. Johnstone
  Fermilab, Batavia, Illinois

• W. Wittmer
  

The PEP II lattices are unique in their detector solenoid field compensation scheme by utilizing a set of skew quadrupoles in the IR region and the adjacent arcs left and right from the IP. Additionally the design orbit through this region is nonzero. This combined with the strong local coupling wave makes it very difficult to calculate IP tuning knobs which are orthogonal and closed. The usual approach results either in non-closure, not being orthogonal or the change in magnet strength being too big. To find a solution the set of tuning quads had to be extended which resulted having more degrees of freedom than constrains. To find the optimal set of quadrupoles which creates a linear, orthogonal and closed knob and simultaneously minimizing the changes in magnet strength, the method using Singular Value Decomposition, Response Matrices and an Adapted Moore Penrose Method had to be extended. The results of these simulations are discussed below and the results of first implementation in the machine are shown.

• M. Mangano
  

• E. Metral
  
• B. Salvant
  EPFL, Lausanne
• B. Zotter
  Honorary CERN Staff Member, Grand-Saconnex

• F. Zimmermann
  

• A. Lyapin
  
• C. Adolphsen, R. Arnold, C. Hast, D. J. McCormick, Z. Szalata, M. Woods
  SLAC, Menlo Park, California
• S. T. Boogert, G. E. Boorman
  Royal Holloway, University of London, Surrey
• M. V. Chistiakova, Yu. G. Kolomensky, E. Petigura, M. Sadre-Bazzaz
  UCB, Berkeley, California
• V. N. Duginov, S. A. Kostromin, N. A. Morozov
  JINR, Dubna, Moscow Region
• F. Gournaris, B. Maiheu, D. J. Miller, M. Wing
  UCL, London
• M. Hildreth
  Notre Dame University, Notre Dame, Iowa
• H. J. Schreiber, M. Viti
  DESY Zeuthen, Zeuthen
• M. Slater, M. Thomson, D. R. Ward
  University of Cambridge, Cambridge

• J.-P. Carneiro
  
• V. Kamerdzhiev, A. Semenov, R. C. Webber
  Fermilab, Batavia, Illinois