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linear-collider

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MOYBGM01 Global R&D Effort for the ILC Linac Technology linac, cryogenics, acceleration, collider 12
 
  • A. Yamamoto
    KEK, Ibaraki
  The presentation will cover the ongoing ILC R&D program in the field of superconducting accelerating structures, accelerator modules and rf systems. In addition to technical/scientific aspects, a view of the organisational challenges of this global R&D programme and how they are addressed will be described.  
slides icon Slides  
 
MOPD003 ILC Cavity Fabrication Optimization for High Production factory, vacuum, electron, radio-frequency 451
 
  • A. J. Favale, M. Calderaro, E. Peterson, J. J. Sredniawski
    AES, Medford, NY
  In 2006, AES performed a US based industrial Cost Study of RF units in production quantities sufficient for the ILC. During this study detailed costs were estimated for the fabrication steps of the SRF cavities in high production quantities. In late 2007, AES carried out a more detailed study specifically oriented toward optimizing the high production methods of only the SRF cavities to arrive at a best estimate of cost. We have found that the revised estimate shows a 34% reduction in cavity fabrication cost. We have optimized many of the machining and welding steps to take advantage of automated operations were possible. Our high production cost estimates were based upon actual machining, welding and parts handling times derived during the prototype fabrication of ILC type cavities at AES. These values were then applied with learning as appropriate to more automated operations to reduce labor costs. In addition, the type and size of e-beam welding machines was optimized. We found that the use of all single chamber welders covering three specific sizes was most cost effective. Details of steps leading to the stated conclusions are presented herein.  
 
MOPD014 First Test Results of ILC/STF Cryogenic System at KEK cryogenics, superconducting-RF, booster, vacuum 472
 
  • S. Kaneda, T. Ichitani
    Taiyo Nippon Sanso Corporation, Kawasaki-city Kanagawa Pref.
  • K. Hara, K. Hosoyama, A. Kabe, Y. Kojima, H. Nakai, K. Nakanishi
    KEK, Ibaraki
  • T. Kanekiyo
    Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura
  • M. Noguchi
    Mayekawa MFG. Co., Ltd., Moriya
  • S. Sakuma, K. Suzuki
    Taiyo Nippon Sanso Higashikanto Corporation, Hitachi-city, Ibaraki-Pref
  • J. Yoshida
    Hitachi Plant Technologies, Ltd., Tokyo
  The STF (Superconducting RF Test Facility) cryogenic system, of which capacity is 30W at 2.0K, has been constructed and commissioned for testing STF cryomodule. In the first operation phase, the STF cryogenic system was successfully cooled down to maintain a superconducting RF cavity at the working temperature of 2.0K. Presented in this session will be the results of the first operation of the cryogenic system and the future collaboration plan among KEK and Japanese cryogenic industrial members.  
 
MOPP005 The 2 mrad Crossing Angle Scheme for the International Linear Collider extraction, quadrupole, optics, multipole 556
 
  • R. Appleby
    UMAN, Manchester
  • D. Angal-Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P. Bambade, S. Cavalier, G. Le Meur, F. Touze
    LAL, Orsay
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  The present baseline configuration of the ILC has a 14 mrad crossing angle between the beams at the interaction point. This allows easier extraction of the beams after collisions, but imposes on the other hand more constraints on the control of the beams prior to colliding them. Moreover, some limitations to physics capabilities arise, in particular because of the degraded very forward electromagnetic detector hermeticity and because calibration procedures for (gaseous) tracking detectors become more complex. To mitigate these problems, alternative configurations with very small crossing angles are studied. A new version of the 2 mrad layout was designed last year, based on simpler concepts and assumptions. The emphasis of this new scheme was to satisfy specifications with as few and feasible magnets as possible, in order to reduce costs. Recent progress designing several of the magnets involved and the particular vacuum chamber needed in the shared part of the beam line is reported.  
 
MOPP012 DC Breakdown Experiments for CLIC collider, RF-structure, cathode, vacuum 577
 
  • A. Descoeudres, S. Calatroni, M. Taborelli
    CERN, Geneva
  For the production of the Compact Linear Collider (CLIC) RF structures, a material capable of sustaining high electric field, with a low breakdown rate and showing low damages after breakdowns is needed. A DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and also to have a better understanding of the breakdown mechanism. The saturated breakdown fields of several metals and alloys have been measured, ranging from 100MV/m for Al to 900MV/m for stainless steel, being around 150MV/m for Cu, CuZr and Glidcop, 300MV/m for W, 400MV/m for Mo, Nb and Cr, 650MV/m for V, and 750MV/m for Ti for example. Titanium shows a strong material displacement after breakdowns, while Cu, Mo and stainless steel are more stable. The conditioning speed of Mo can be significantly improved by removing oxides at the surface with a heat treatment, typically at 875°C for 2 hours. DC breakdown rate measurements have been done with Cu and Mo electrodes, showing similar results as in RF experiments: the breakdown probability seems to exponentially increase with the applied field.  
 
MOPP016 Collimation Aperture for the Beam Delivery System of the International Linear Collider collimation, quadrupole, extraction, emittance 586
 
  • F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The beam delivery sytem (BDS) of the international linear collider (ILC) must provide efficient removal of beam halo particles which would cause unacceptable detector background. The collimation aperture or 'collimation depth' is designed such that synchrotron radiation from the halo emitted in the final doublet passes cleanly through the detector interaction region. The ILC BDS collimation depth for several different detector scenarios is evaluated using a semi-analytical technique.  
 
MOPP017 A Kicker Driver Exploiting Drift Step Recovery Diodes for the International Linear Collider kicker, damping, instrumentation, collider 589
 
  • F. O. Arntz, M. P.J. Gaudreau, A. Kardo-Sysoev, M. K. Kempkes, A. Krasnykh
    Diversified Technologies, Inc., Bedford, Massachusetts
  Diversified Technologies, Inc. (DTI) is developing a driver for a kicker strip-line deflector which inserts and extracts charge bunches to and from the electron and positron damping rings of the International Linear Collider. The kicker driver must drive a 50 Ω terminated TEM deflector blade at 10 kV with 2 ns flat-topped pulses, which according to the ILC pulsing protocol, bursts pulses at a 3 MHz rate within one-millisecond bursts occurring at a 5 Hz rate. The driver must also effectively absorb high-order mode signals emerging from the deflector. In this paper, DTI will describe current progress utilizing a combination of high voltage DSRDs (Drift Step Recovery Diodes) and high voltage MOSFETs. The MOSFET array switch, without the DSRDs, is itself suitable for many accelerator systems with 10 – 100 ns kicker requirements. DTI has designed and demonstrated the key elements of a solid state kicker driver which both meets the ILC requirements, is suitable for a wide range of kicker driver applications. Full scale development and test are exptected to occur in Phase II of this DOE SBIR effort, with a full scale demonstration scheduled in 2009.  
 
MOPP024 Depolarization and Beam-beam Effects at the Linear Collider polarization, photon, positron, background 598
 
  • G. A. Moortgat-Pick, S. Hesselbach
    Durham University, Durham
  • I. R. Bailey, G. A. Moortgat-Pick, B. J.A. Shepherd
    Cockcroft Institute, Warrington, Cheshire
  • D. P. Barber
    DESY, Hamburg
  • E. Baynham, T. W. Bradshaw, F. S. Carr, J. Rochford
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A. J. Brummitt, A. J. Lintern
    STFC/RAL, Chilton, Didcot, Oxon
  • A. Bungau
    UMAN, Manchester
  • J. A. Clarke, O. B. Malyshev, N. C. Ryder, D. J. Scott
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva, L. Zang
    Liverpool University, Science Faculty, Liverpool
  • A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  The clean environment at the interaction point of a lepton linear collider allows high-precision measurements for physics analyses. In order to exploit this potential, precise knowledge about the polarization state of the beams is also required. In this paper we concentrate on depolarization effects caused by the intense beam-beam interaction, which is expected to be the dominant source of depolarization. Higher-order effects, as well as critical analyses of the theoretical assumptions used in the past and theoretical improvements in the derivation of suitable equations, are given. Updates on existing simulation programs are reported. Numerical results for the design of the International Linear Collider (ILC) are discussed.  
 
MOPP030 ATF2 Final Focus Orbit Correction and Tuning Optimisation sextupole, quadrupole, collider, dipole 613
 
  • A. Scarfe, R. Appleby
    UMAN, Manchester
  • D. Angal-Kalinin, J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  ATF2 is an upgrade to the ATF facility at KEK, Japan consisting of a replacement to the current ATF extraction line and the addition of a final focus section. The final focus system has been designed, and is aiming to test, the local chromaticity correction scheme as proposed for future linear colliders. The final focus system focuses the ultra-low emittance beams at the collision point in the linear collider. To provide the required small beam sizes and to maintain the beam sizes to nanometer level requires optimised orbit correction and tuning procedures. In this paper, the optimisation of the orbit correction using a global SVD method is discussed, along with the progress on final focus tuning knob analysis. The tuning algorithms used at ATF2 will provide an important feedback for future linear colliders (including the ILC and CLIC).  
 
MOPP035 ILC Siting in Dubna Region (Russia) and ILC activity in JINR site, collider, diagnostics, laser 622
 
  • G. Shirkov, Ju. Boudagov, Yu. N. Denisov, I. N. Meshkov, A. N. Sissakian, G. V. Trubnikov
    JINR, Dubna, Moscow Region
  The report presents the development of investigations on ILC siting in the Dubna region and ILC technical activity at JINR. Russia is one of candidates now for ILC hosting in the Dubna region. International intergovernmental status of JINR, stable geological and plain relief conditions comfortable location, well developed infrastructure create powerful advantages of JINR among other possible sites. Shallow layout of tunnels and experimental halls could significantly reduce the cost of conventional facilities and siting. Besides JINR physicists take part in several fields of activity in ILC: works on photo injector prototype, participation in design and construction of cryomodules, laser metrology, etc.  
 
MOPP043 Transverse Wake Field Simulations for the ILC Acceleration Structure emittance, simulation, acceleration, linac 640
 
  • V. P. Yakovlev, A. Lunin, N. Solyak
    Fermilab, Batavia, Illinois
  Details of wake potential simulation in the acceleration structure of ILC, including the RF cavities and input/HOM couplers are presented. Transverse wake potential dependence is described versus the bunch length. Beam emittance dilution caused by main and HOM couplers is estimated, followed by a discussion of possible structural modifications allowing a reduction of transverse wake potential.  
 
MOPP144 The First Cool-down Tests of the 6 Meter-Long-Cryomodules for Superconducting RF Test Facility (STF) at KEK superconducting-RF, cryogenics, vacuum, collider 892
 
  • N. Ohuchi, F. Furuta, K. Hara, H. Hayano, N. Higashi, Y. Higashi, H. Hisamatsu, K. Hosoyama, E. Kako, Y. Kojima, M. Masuzawa, H. Matsumoto, H. Nakai, S. Noguchi, T. Saeki, K. Saito, T. Shishido, A. Terashima, N. Toge, K. Tsuchiya, K. Yokoya
    KEK, Ibaraki
  • M. H. Tsai
    NSRRC, Hsinchu
  • Q. J. Xu
    IHEP Beijing, Beijing
  KEK is presently constructing the Superconducting RF Test Facility (STF) as the center of the ILC-R&D in Asia from 2005. In this project, KEK aims to get the manufacturing and operational experiences of the RF cavity and cryomodule toward the ILC, and two cryomodules have been developed. These cryomodules are 6 meter long and have 4 nine-cell cavities in each cryostat. The basic cross section designs of the cryomodules are almost same as the design of TESLA type-III, however, each cryostat has the different type of cavities, TESLA type and Low-Loss type. The tests for the cryomodules are planed to be performed at three steps. In the first test, measurements of the cryogenic performances of these cryomodules are the main objective. One nine-cell cavity was assembled in each cryostat and the cool-down of the two cryomodules was performed. In the following tests, the four nine-cell cavities will be assembled in each cryostat as the complete integration and the beam test will be performed. In this paper, we will report the design of the cryomodules and the cryogenic performances at the first cold test.  
 
MOPP146 The Coaxial Tuner for ILCTA_NML at Fermilab cryogenics, superconductivity, vacuum, collider 895
 
  • A. Bosotti, C. Pagani, N. Panzeri, R. Paparella
    INFN/LASA, Segrate (MI)
  The piezo Blade Tuner prototype has been successfully tested inside the horizontal cryostat, CHECHIA, at DESY and extensive tests at BESSY are planned. As suggested by the cold test results, a few minor modifications have been implemented and a set of 8 improved devices is under construction for the installation in the second module of ILCTA at Fermilab. This reviewed design, together with a simplified helium tank in prototyping, should hopefully fulfill also the XFEL requests in term of performances and cost. In particular the use of thicker blades and their slightly different distribution along the circumference produces the increase of the tuner strength and stiffness that is needed in order to fulfill the pressure vessel regulations for qualification. As in the past, two equivalent devices, respectively in titanium and stainless steel, have been designed to maintain open the possibility of the use of a SS helium vessel once the required technology were developed. The results of the extensive mechanical tests performed to validate the estimated performances and life time are also presented.  
 
MOPP154 Study of the High Pressure Rinsing Water Jet Interactions target, controls, collider, superconducting-RF 910
 
  • D. Sertore, M. Fusetti, P. M. Michelato, C. Pagani
    INFN/LASA, Segrate (MI)
  High Pressure Rinsing (HPR) is an important step in the cleaning of Superconducting Cavities (SC). The understanding of the interaction of the high pressure water jet on the cavity wall is of primary importance for the optimization of this process for upcoming SC based projects like XFEL and ILC. In this paper, we extend our results obtained so far in different labs and present our studies on water jet interaction on oblique surfaces and the possible induced damages.  
 
MOPP158 Conceptual Design of Automated Systems for SRF Cavity Optical Inspection and Assembly radio-frequency, collider, electron 922
 
  • T. Tajima, A. Canabal, T. A. Harden, R. J. Roybal
    LANL, Los Alamos, New Mexico
  The International Linear Collider (ILC) will require ~16,000 Superconducting Radio-Frequency (SRF) cavities at an accelerating gradient of 31.5 MV/m. One of the critical issues that needs to be addressed is the insufficient yield of high-gradient cavities that meet the requirement. This paper describes the design and initial tests of a cavity inner surface optical inspection system. Combined with a full-featured 9-cell cavity temperature mapping system being developed at LANL, we hope to be able to correlate the cavity heating and the surface condition causing it.  
 
MOPP168 Tests on the 1.3 GHz Low Loss Single-Cell RF Superconducting Large Grain Cavities of IHEP cryogenics, linac, vacuum, collider 943
 
  • Z. G. Zong, J. Gao, M. Q. Ge, J. Gu, H. Sun, D. Wang, Q. J. Xu, J. Y. Zhai, F. C. Zhao
    IHEP Beijing, Beijing
  • F. Furuta, T. Saeki, K. Saito
    KEK, Ibaraki
  • L. Q. Liu
    Technical Institute of Physics and Chemistry, Beijing
  • L.-Y. Xiong, L. Zhang, T. X. Zhao, Z. G. Zong
    TIPC, BeiJing
  To contribute to the International Linear Collider (ILC) R&D on the 1.3 GHz low loss cavities has been carried out at IHEP since 2005. Six cavities had been fabricated by the standard technology and treated by some procedures of surface treatments, such as centrifugal barrel polishing, barrel chemical polishing, annealing, high pressure rinsing and baking at in-house IHEP. Because of the shortage of liquid helium in Beijing two large grain cavities with a fine grain one were sent to KEK for vertical tests. The large grain cavities was tested and treated at KEk and finally both reached the accelerating gradients of more than 35 MV/m with the maximum of 40.27 MV/m. This paper presents the testing and results of the large grain cavities.  
 
TUOCM01 First Measurements of the Longitudinal Bunch Profile at SLAC Using Coherent Smith-Purcell Radiation at 28GeV radiation, background, diagnostics, collider 1026
 
  • V. Blackmore, G. Doucas, B. Ottewell, C. Perry
    OXFORDphysics, Oxford, Oxon
  • R. Arnold, S. Molloy, M. Woods
    SLAC, Menlo Park, California
  • M. F. Kimmitt
    University of Essex, Physics Centre, Colchester
  Coherent Smith-Purcell radiation has been demonstrated as a technique for measuring the longitudinal profile of charged particles bunches in the low to intermediate energy range. However, with the advent of the International Linear Collider, the need has arisen for a non-invasive method of measuring the bunch profile at extremely high energies. Smith-Purcell radiation has been used for the first time in the multi-GeV regime to measure the longitudinal profile of the 28GeV SLAC beam. The experiment has both successfully determined the bunch length, and has also demonstrated its sensitivity to bunch profile changes. The challenges associated with this technique, and its prospects as a diagnostic tool are reported here.  
slides icon Slides  
 
TUPC115 Vibration Stabilization for a Cantilever Magnet Prototype at the Subnanometer Scale controls, collider, ground-motion, instrumentation 1335
 
  • L. Brunetti, B. Bolzon, N. Geffroy, A. Jeremie
    IN2P3-LAPP, Annecy-le-Vieux
  • A. Badel, B. Caron, J. Lottin
    SYMME, Annecy-le-Vieux
  In the future linear colliders, the size of the beams is in the nanometer range, which requires stabilization of the final magnets before the interaction point. In order to guarantee the desired luminosity, an absolute displacement lower than 1/3 of the beam size, above a few hertz, has to be obtained. This paper describes an adapted instrumentation, the developed feedback loops dedicated to the active compensation and an adapted modelling able to simulate the behaviour of the structure. The obtained results at the subnanometer scale at the free end of a cantilever magnet prototype with a combination of the developed active compensation method and a commercial active isolation system are described.  
 
TUPC118 First Data from the Linear Collider Alignment and Survey Project (LiCAS) survey, laser, alignment, collider 1344
 
  • A. Reichold, T. Handford, L. A. Rainbow, M. Tacon, C. Uribe Estrada, D. Urner, S. Q. Yang
    OXFORDphysics, Oxford, Oxon
  • P. J. Brockill, S. Cohen, J. Dale, M. Dawson, M. Jones, G. Moss, R. Wastie
    JAI, Oxford
  • G. Grzelak
    Warsaw University, Warsaw
  • J. Prenting, M. Schloesser
    DESY, Hamburg
  The LiCAS project has developed a prototype robotic survey system for rapid and highly accurate surveying of long linear accelerator tunnel networks. It is aimed at the survey of the reference network for the International Linear Collider (ILC). This Rapid Tunnel Reference Surveyor (RTRS) is designed to be an R\&D instrument for evaluating the potential performance of the RTRS concept and its survey technology. The prototype has been commissioned in a test tunnel at DESY with initial calibrations and measurements ongoing. We will report on the results obtained so far and present conclusions for the design of an RTRS suitable for the ILC.  
 
TUPC121 Nanometre Precision Interferometric Stability Monitoring Systems for Key Accelerator Components laser, quadrupole, monitoring, alignment 1350
 
  • P. A. Coe, A. Reichold, D. Urner
    OXFORDphysics, Oxford, Oxon
  • M. S. Warden
    JAI, Oxford
  The MONALISA group develops novel, accurate, nanometre resolution, interferometric systems to monitor relative motions between key accelerator components. We use cost-effective technology developed for the telecommunications market, providing readily scalable, adaptable solutions. Key magnets and diagnostics in the beam-delivery section of the International Linear Collider (ILC) will need to maintain stable relative positions. In particular, the final focus quadrupole magnets require nanometre level stability. Even greater stability requirements will be placed on components for the Compact Linear Accelerator (CLIC). Interferometers provide the only means of monitoring relative positions over long timescales, at the nanometre and sub-nanometre level. We are working to improve our measurement resolution using an optical frequency reference obtained by locking the second harmonic of an ultra-narrow linewidth 1560 nm fibre laser to a D2 transition in Rubidium-87. The latest results from this system tested on novel design, fibre-coupled, evacuated interferometers will be presented.  
 
TUPC124 Development of a High Power Fibre Laser for Laser Based Electron Beam Diagnostics laser, collider, electron, scattering 1359
 
  • L. Corner, N. Delerue, M. Newman, R. Walczak
    OXFORDphysics, Oxford, Oxon
  • G. A. Blair, S. T. Boogert
    Royal Holloway, University of London, Surrey
  • L. Corner, D. F. Howell, L. J. Nevay
    JAI, Oxford
  We present the latest results on the development of a high power fibre laser system for the laserwire project on ILC-like laser based electron beam diagnostics. The laser consists of a solid state oscillator which can be synchronised to an external frequency reference, and two amplification stages in double clad doped fibre, giving 1uJ pulses in a burst mode suitable for the ATF2 laserwire project. This output is amplified in large mode area photonic crystal fibre to generate the high pulse energy necessary for Compton scattering without any deleterious nonlinear effects, whilst maintaining the high spatial mode quality and beam pointing stability of a fibre laser. These properties are essential for producing the sub-micron spot sizes required for the measurement of small particle beam sizes.  
 
TUPD008 Marx Bank Technology for Accelerators and Colliders controls, collider, impedance, diagnostics 1449
 
  • J. A. Casey, F. O. Arntz, M. P.J. Gaudreau, M. K. Kempkes, I. Roth
    Diversified Technologies, Inc., Bedford, Massachusetts
  Diversified Technologies, Inc. (DTI) has developed high power, solid-state Marx Bank designs for a range of accelerator and collider designs. We estimate the Marx topology can deliver equivalent performance to conventional designs, while reducing acquisition costs by 25-50%. In this paper DTI will describe the application of Marx based technology to two different designs: a long-pulse ILC focused design (140 kV, 160 A, 1.5 ms), and a short-pulse design (500 kV, 265 A, 3 us). These designs span the known requirements for future accelerator modulators. For the ILC design, the primary challenge is minimizing the overall size and cost of the storage capacitors in the modulator. For the short-pulse design, the primary challenge is high speed operation, to limit the energy lost in the pulse rise-time while providing a very tight (± 3%) voltage flattop. Each design demands unique choices in components and controls, including the use of electrolytic capacitors in the ILC Marx design. This paper will review recent progress in the development and testing of both of these prototype Marx designs, being built under two separate DOE Phase II SBIR grants.  
 
TUPP047 Simulation Studies on Coupler Wakefield and RF Kicks for the International Linear Collider with MERLIN linac, emittance, simulation, higher-order-mode 1649
 
  • D. Kruecker, I. Melzer-Pellmann, F. Poirier, N. J. Walker
    DESY, Hamburg
  One of the critical issues in the design of the superconducting cavities or the International Linear Collider (ILC) is the influence of the RF and higher order mode (HOM) couplers on the beam dynamics. Both types of couplers break the rotational symmetry of the cavity and introduce non vanishing transverse wakefields even on the cavity axis. Furthermore the RF input coupler introduces an asymmetry into the accelerating RF field and thereby additional transverse field components. We have implemented both effects following the calculations presented previously* into the MERLIN C++ library**. This allows us to study the influence of wakefield and RF kicks on the beam dynamics, the bunch shape and the overall performance of the ILC for different proposed coupler designs.

*I. Zagorodnov and M. Dohlus, ILC Workshop, DESY 2007; K. Bane and I. Zagorodnov, Wake Fest 07, SLAC 2007.
**Merlin - A C++ Class Library for Accelerator Simulations; http://www.desy.de/~merlin.

 
 
TUPP095 Computation of Resistive Wall Wakefields with the PBCI Code simulation, impedance, resonance, collider 1753
 
  • T. Lau, E. Gjonaj, T. Weiland
    TEMF, Darmstadt
  • R. Maekinen
    TUT, Tampere
  Both geometric disturbances and resistive wall loss of accelerator cavities contribute to the impedance causing the beam to lose energy. Impedance due to arbitrary three-dimensional (3-D) geometries can be computed with the Parallel Beam Cavity Interaction (PBCI), a parallelized, 3D-wakefield code. However, the contribution of wall loss is often significant. The contribution of this work is to incorporate resistive wall loss into 3-D time-domain simulation. Surface-impedance concept is used to consider wide-band skin-effect loss of metal. In theory, the proposed approach can be extended to consider high-frequency phenomena such as frequency-dependent conductivity of metal and anomalous skin effect.  
 
WEPD003 Manufacture and Test of a Small Ceramic-insulated Nb3Sn Split Solenoid collider, damping, vacuum, undulator 2404
 
  • B. Bordini, R. Maccaferri, L. Rossi, D. Tommasini
    CERN, Geneva
  A small split solenoid wound with high Jc Nb3Sn conductor, constituted by a 0.8 mm Rod Re-stack Process (RRP) strand, was built and tested at CERN in order to study the applicability of:
  1. ceramic wet glass braid insulation without epoxy impregnation of the magnet;
  2. a new heat treatment devised at CERN and particularly suitable for reacting RRP Nb3Sn strands.
This paper briefly describes the solenoid and the experimental results obtained during 4.4 K and 1.9 K tests. The split solenoid consists of two coils (25 mm inner diameter, 51.1 mm outer diameter, 12.9 mm height). The coils were initially separately tested, in an iron mirror configuration, and then tested together in split solenoid configuration. In all the tests at 4.4 K the coils reached a current higher than 97% of their short sample limits at the first quench; in split solenoid configuration the maximum field in the coils and in the aperture were respectively 10.7 T and 12.5 T. At 1.9 K the coils had premature quenches due to self field instability despite the rather high RRR of the two coils (190 and 270). This phenomenon at 1.9 K, expected by our theory* and also confirmed by strand measurements, is discussed.

*B. Bordini, E. Barzi, S. Feher, L. Rossi, and A. V. Zlobin. "Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands," to be published in IEEE Trans. Appl. Supercond. 2008.

 
 
WEPD036 Radiation and Thermal Analysis of Superconducting Quadrupoles in the Interaction Region of Linear Collider quadrupole, radiation, extraction, shielding 2488
 
  • A. V. Zlobin, A. I. Drozhdin, V. Kashikhin, V. S. Kashikhin, M. L. Lopes, N. V. Mokhov
    Fermilab, Batavia, Illinois
  • A. Seryi
    SLAC, Menlo Park, California
  The upcoming and disrupted electron and positron beams in the baseline design of ILC interaction region are focused by compact FD doublets each consisting of two small-aperture superconducting quadrupoles and multipole correctors. These magnets will work in a severe radiation environment generated primarily by incoherent pairs and radiative Bhabhas. This paper analyzes the radial, azimuthal and longitudinal distributions of radiation heat deposition in incoming and disrupted beam doublets. Operation margins of baseline quadrupoles based on NbTi superconductor and direct wind technology as well as alternative designs based on NbTi or Nb3Sn Rutherford cables are calculated and compared. The possibilities of reducing the heat deposition in magnet coils using internal absorbers are discussed.  
 
WEPP084 Fabrication of a Quadrant-type Accelerator Structure for CLIC collider, feedback, acceleration, background 2716
 
  • T. Higo, Y. Higashi, H. Kawamata, T. T. Takatomi, K. Ueno, Y. Watanabe, K. Yokoyama
    KEK, Ibaraki
  • A. Grudiev, G. Riddone, M. Taborelli, W. Wuensch, R. Zennaro
    CERN, Geneva
  In order to heavily damp the higher order modes of an accelerator structure for CLIC, two kind of damping mechanisms are implemented in one of the designs. Here each cell is equipped with electrically coupled damping channels in addition to the magnetically coupled waveguides. This design requires an assembly of longitudinally cut four quadrants to form a structure and the parts are necessarily made with milling. Since KEK has developed a high-precision machining of X-band accelerator cells with milling and turning at the same time, the experience was extended to the milling of this quadrant. Firstly, the fabrication test of a short quadrant was performed with multiple vendors to taste the present-day engineering level of milling. Following this, a full-size quadrant is also made. In this course, some of the key features are addressed, such as flatness of the reference mating surfaces, alignment grooves, 3D profile shape of the cells, surface roughness and edge treatment. In this paper, these issues are discussed from both fabrication and evaluation point of views.  
 
WEPP096 Nextef: The 100MW X-band Test Facility in KEK klystron, collider, controls, linac 2740
 
  • S. Matsumoto, M. Akemoto, S. Fukuda, T. Higo, N. Kudoh, H. Matsushita, H. Nakajima, T. Shidara, K. Yokoyama, M. Yoshida
    KEK, Ibaraki
  Nextef is a new X-band test facility in KEK. By combining the power from two klystrons, 100MW-class X-band RF power will be available. The facility is for researches on future high gradient linear accelerators. The commissioning operation of the whole facility was started in November 2007. It is planed to conduct high power testing of X-band accelerator structures as well as the fundamental researches such as the RF breakdown experiment with specially designed waveguides.  
 
WEPP133 High-gradient Multi-mode Two-beam Accelerating Structure acceleration, simulation, collider, coupling 2806
 
  • S. V. Kuzikov, M. E. Plotkin
    IAP/RAS, Nizhny Novgorod
  • J. L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  • S. Kazakov
    Omega-P, Inc., New Haven, Connecticut
  A new accelerating structure which is aimed to provide gradient >150 MV/m for next generation of multi-TeV linear colliders is suggested. The structure is based on periodic system of quasi-optical cavities*. Each of these cavities is excited in several equidistantly-spaced eigen modes by the drive beam in such a way that the RF fields reach peak values only during the short time intervals when an accelerating bunch is resident in the cavities, thus exposing the cavity surfaces to strong fields for only a small fraction of time. This feature is expected to raise the breakdown and pulse heating thresholds. The proposed structure embodies most of additional attractive properties: the cavity is an all metallic structure, no transfer or coupling structures are needed between the drive and acceleration channels, the cavity fields are symmetric around the axes of the drive beam and the accelerated beam, the cavity can exhibit high transformer ratio. Calculations of single quasi-optical rectangular cavity with parameters of drive and accelerating beams close to ones adopted for the CLIC project show that high gradient as well as high efficiency are achievable.

*S. V. Kuzikov et al. "Quasi-optical accelerating structure operated with a superposition of synchronized modes," Conf. Digest of Joint 32nd IRMMW Conf., Cardiff, UK, 2007, Vol.2, p.797-798.

 
 
WEPP163 Measurements of Collimator Wakefields at End Station A simulation, radiation, feedback, collider 2868
 
  • J.-L. Fernandez-Hernando
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S. Molloy
    SLAC, Menlo Park, California
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  • N. K. Watson
    Birmingham University, Birmingham
  The angular kicks imparted to an electron beam with energy of 28.5 GeV when it passes through a collimator jaw with a certain offset, generating a wakefield, were measured in End Station A (ESA) in SLAC for fifteen different collimator configurations of geometry and material. Some configurations were chosen in order to compare with previous measurements while others served to study the effect of geometry and taper angles (geometrical contribution to the wakefield) and the effect of the material resistivity (resistive contribution) to the kick. This paper summarises the final experimental results. The reconstructed kick factor is compared to analytical calculations and simulations.  
 
WEPP165 GdfidL Simulations of International Linear Collider Candidate Collimator Assemblies simulation, collider, insertion, vacuum 2874
 
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  Collimator performance is critical to the successful operation of any collider. Building on previous GdfidL simulations of collimator jaws, this paper describes simulations where STL files of the complete assembly are investigated and wakefield performance is determined and optimised.  
 
WEPP167 Effect of Collimator Wakefields in the Beam Delivery System of the International Linear Collider emittance, lattice, simulation, collimation 2880
 
  • A. M. Toader, R. J. Barlow
    UMAN, Manchester
  • D. Angal-Kalinin, F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The collimators in the design of the International Linear Collider (ILC) Beam Delivery System (BDS) may be a significant source of wakefields and significantly degrade luminosity. New simulations are used to predict the effect of BDS collimator wakefields, and compared with previous analytical methods. BDS lattices optimised for improved collimation performance are also examined.  
 
WEPP168 Mechanical Design of Collimators for the ILC radiation, vacuum, collider, photon 2883
 
  • B. D. Fell, D. Angal-Kalinin, S. C. Appleton, J.-L. Fernandez-Hernando, F. Jackson, O. B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. Bliss
    STFC/DL, Daresbury, Warrington, Cheshire
  • G. Ellwood, R. J.S. Greenhalgh
    STFC/RAL, Chilton, Didcot, Oxon
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  • N. K. Watson
    Birmingham University, Birmingham
  Much attention has been paid to the optimisation of the geometry and material of collimators in the ILC to mitigate the effects of both short-range transverse wakefields and errant beam impacts. We discuss the competing demands imposed by realistic engineering constraints and present a preliminary engineering design for adjustable jaw spoilers for the ILC.  
 
THYG01 The ILC Beam Delivery System Design and R&D Programme collimation, extraction, collider, instrumentation 2907
 
  • T. Tauchi
    KEK, Ibaraki
  The presentation will describe recent developments for the ILC beam delivery system. Special emphasis will be given to the R&D programme at existing and planned test facilities.  
slides icon Slides  
 
THPC114 Design and Performance of a Prototype Digital Feedback System for the International Linear Collider Interaction Point feedback, kicker, collider, extraction 3245
 
  • P. Burrows, B. Constance, H. Dabiri Khah, J. Resta-López
    JAI, Oxford
  • R. Apsimon, P. Burrows, C. I. Clarke, A. F. Hartin, C. Perry, C. Swinson
    OXFORDphysics, Oxford, Oxon
  • G. B. Christian
    ATOMKI, Debrecen
  • A. Kalinin
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  We present the design and preliminary results of a prototype beam-based digital feedback system for the Interaction Point of the International Linear Collider. A custom analogue front-end processor, FPGA-based digital signal processing board, and kicker drive amplifier have been designed, built, and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The system was measured to have a base latency of approximately 140 ns, increasing to approximately 148 ns with the inclusion of real-time charge normalisation.