CLIC

Paper	Title	Other Keywords	Page
MOPLS056	QCD Explorer Proposal: E-linac versus E-ring	LHC, collider, electron, LEP	673
	H. Karadeniz TAEK, Ankara S. Sultansoy Gazi University, Faculty of Science and Arts, Ankara
	TeV center of mass energy lepton-hadron collider is necessary both to clarify fundamental aspects of strong interactions and for adequate interpretation of the LHC data. Recently proposed QCD Explorer utilizes the energy advantage of the LHC proton and ion beams, which allows the usage of relatively low energy electron beam. Two options for the LHC based ep collider are possible: construction of a new electron ring in the LHC tunnel or construction of an e-linac tangentially to the LHC. In the latter case, which seems more acceptable for a number of reasons, two options are under consideration for electron linac: the CLIC technology allows shorter linac length, whereas TESLA technology gives higher luminosity.
MOPLS059	The Probe Beam Linac in CTF3	linac, CTF3, gun, emittance	679
	A. Mosnier, M. Authier, D. Bogard, A. Curtoni, O. Delferriere, G. Dispau, R. Duperrier, W. Farabolini, P. Girardot, M. Jablonka, J.L. Jannin, M. Luong, F. Peauger CEA, Gif-sur-Yvette N. Rouvière IPN, Orsay R. Roux LAL, Orsay
	The test facility CTF3, presently under construction at CERN within an international collaboration, is aimed at demonstrating the key feasibility issues of the multi-TeV linear collider CLIC. The objective of the probe beam linac is to "mimic" the main beam of CLIC in order to measure precisely the performances of the 30 GHz CLIC accelerating structures. In order to meet the required parameters of this 200 MeV probe beam, in terms of emittance, energy spread and bunch-length, the most advanced techniques have been considered: laser triggered photo-injector, velocity bunching, beam-loading compensation, RF pulse compression … The final layout is described, and the selection criteria and the beam dynamics results are reviewed.
MOPLS091	First Design of a Post Collision Line for CLIC at 3 TeV	photon, extraction, dipole, beam-losses	765
	V.G. Ziemann, T. J. C. Ekelof, A. Ferrari UU/ISV, Uppsala P. Eliasson CERN, Geneva
	As part of the Post collision diagnostic task of the ILPS work-package of EuroTeV we discuss a design of the beam line between the interaction point and the beam dump for CLIC with a center-of-mass energy of 3 TeV. The design is driven by the requirement to transport the beam and all secondaries such as beamstrahlung and coherent pairs to the beam dump with minimal losses. Moreover, we discuss the integration of novel diagnostic methods into the post collision beam line based on the detection of coherent pairs and monitoring the beam profile of the primary beam.
MOPLS092	Efficient Collimation and Machine Protection for the Compact Linear Collider	collimation, linac, kicker, luminosity	768
	R.W. Assmann, F. Zimmermann CERN, Geneva
	We present a new approach to machine protection and collimation in CLIC, separating these two functions: If emergency dumps in the linac protect the downstream beam line against drive-beam failures, the energy collimation only needs to clean the beam tails and can be compact. Overall, the length of the beam delivery system is significantly reduced.
MOPLS093	Commissioning Status of the CTF3 Delay Loop	CTF3, linac, CERN, wiggler	771
	R. Corsini, S. Doebert, F. Tecker, P. Urschütz CERN, Geneva D. Alesini, C. Biscari, B. Buonomo, A. Ghigo, F. Marcellini, B. Preger, M. Serio, A. Stella INFN/LNF, Frascati (Roma)
	The CLIC Test Facility CTF3, built at CERN by an international collaboration, aims at demonstrating the feasibility of the CLIC scheme by 2010. In particular, one of the main goals is to study the generation of high-current electron pulses by interleaving bunch trains in delay lines and rings using transverse RF deflectors. This will be done in the 42 m long delay loop, built under the responsibility of INFN/LNF, and in the 84 m long combiner ring that will be installed in 2006. The delay loop installation was completed, and its commissioning started at the end of 2005. In this paper the commissioning results are presented, including the first tests of beam recombination.
MOPLS095	Investigations of DC Breakdown Fields	cathode, vacuum, CERN, ion	777
	T. Ramsvik, S. Calatroni, A. Reginelli, M. Taborelli CERN, Geneva
	The need for high accelerating gradients for the future 30 GHz multi-TeV e+e- Compact Linear Collider (CLIC) at CERN has triggered a comprehensive study of DC breakdown fields of metals in UHV. The experimental setup is based on a capacitor discharge across a gap junction. The simple design and fully automated computer control enable breakdown fields and dark current of numerous materials to be measured. The study shows that Mo, W and Ti reach high breakdown fields, and are thus good candidates for the iris material of CLIC structures. For untreated Mo the breakdown field is higher than Cu but the conditioning speed is slower. Ti, on the other hand, shows acceptable conditioning speeds, but material erosion makes this solution problematic. Feasible solutions to increase the spark conditioning speed for the case of Mo are presented together with attempts to prevent Ti erosion. For some of the materials studied a significant reduction in the saturated breakdown field was observed upon gas exposure during intensive spark conditioning. As an example, a 50% decrease of the breakdown field of Mo is recorded when spark conditioning is carried out in an environment of 10-5 mbar air.
MOPLS096	Effects of Wake Fields in the CLIC BDS	luminosity, quadrupole, emittance, betatron	780
	G. Rumolo, A. Latina, D. Schulte CERN, Geneva
	The wake fields due to collimators in the Beam Delivery System of CLIC are modeled using a conventional approach. According to the chosen ranges of parameters, differences in the transverse kicks due to both the geometric and resistive wall components for different regimes are highlighted (inductive or diffractive for the geometric wake fields, short- or long-range, ac or dc for the resistive wall wake fields). A module for particle tracking along the BDS including the effect of wake fields has been introduced in PLACET, and the first tracking results are shown.
MOPLS097	Progress on the CTF3 Test Beam Line	CTF3, lattice, quadrupole, extraction	783
	D. Schulte, S. Doebert, G. Rumolo, I. Syratchev CERN, Geneva D. Carrillo CIEMAT, Madrid
	In CLIC, the RF power to accelerate the main beam is produced by decelerating a drive beam. The test beamline (TBL) of the CLIC test facility (CTF3) is designed to study and validate the stability of the drive beam during deceleration. This is one of the R&D items required from the International Linear Collider Technical Review Committee to demonstrate feasibility of CLIC. It will produce 30 GHz rf power in the GW range and allow to benchmark computer codes used for the CLIC decelerator design. Different options of this experimental beam line are discussed.
MOPLS100	CLIC Final Focus Studies	luminosity, octupole, sextupole, quadrupole	792
	R. Tomas, H.-H. Braun, D. Schulte, F. Zimmermann CERN, Geneva
	The design of the CLIC final focus system is based on the local compensation scheme proposed by P. Raimondi and A. Seryi. However, there exist important chromatic aberrations that deteriorate the performance of the system. This paper studies the optimization of the final focus based on the computation of the high orders of these aberrations using MAD-X and PTC. The use of octupole doublets to reduce the size of the halo in the locations with aperture limitations is also discussed.
MOPLS103	A High-gradient Test of a 30 GHz Molybdenum-iris Structure	CTF3, electron, vacuum, diagnostics	801
	W. Wuensch, C. Achard, H.-H. Braun, G. Carron, R. Corsini, S. Doebert, R. Fandos, A. Grudiev, E. Jensen, T. Ramsvik, J.A. Rodriguez, J.P.H. Sladen, I. Syratchev, M. Taborelli, F. Tecker, P. Urschütz, I. Wilson CERN, Geneva H. Aksakal Ankara University, Faculty of Sciences, Tandogan/Ankara Ö.M. Mete Ankara University, Faculty of Engineering, Tandogan, Ankara
	The CLIC study is investigating a number of different materials as part of an effort to find ways to increase achievable accelerating gradient. So far, a series of rf tests have been made with a set of identical-geometry structures: a tungsten-iris 30 GHz structure, a molybdenum-iris 30 GHz structure and a scaled molybdenum-iris X-band structure. A second molybdenum-iris 30 GHz structure of the same geometry has now been tested in CTF3 with pulse lengths up to 350 ns. The new results are presented and compared to those of the previous structures to determine dependencies of quantities such as accelerating gradient, material, frequency, pulse length, power flow, conditioning rate and breakdown rate.
MOPLS123	Performance of the FONT3 Fast Analogue Intra-train Beam-based Feedback System at ATF	feedback, kicker, linear-collider, SLAC	852
	P. Burrows Queen Mary University of London, London G.B. Christian, A.F. Hartin, H.D. Khah, G.R. White JAI, Oxford C.C. Clarke, C. Perry OXFORDphysics, Oxford, Oxon A. Kalinin CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire D.J. McCormick, S. Molloy, M.C. Ross SLAC, Menlo Park, California
	We report on the design and testing of the 3rd generation Feedback On Nanosecond Timescales (FONT) prototype intra-train beam-based feedback system for beam control and luminosity optimisation at the International Linear Collider (ILC). The all-analogue FONT3 electronics was designed to have an ultra-short latency of c. 10ns. We describe the design of the BPM signal processor, feedback circuit and kicker-driver amplifier. We report on deployment of FONT3 at the Accelerator Test Facility (ATF) at KEK, where it was tested with the 56ns-long electron bunchtrain extracted from the ATF damping ring. Feedback, with delay-loop operation, on the beam was demonstrated with a latency close to design. We comment on the applicability of this technology to ILC, as well as future warm-RF based linear colliders, such as CLIC.
MOPLS128	Status of the Fatigue Studies of the CLIC Accelerating Structures	laser, CERN, target, radio-frequency	858
	S.T. Heikkinen, S.T. Heikkinen HUT, Espoo S. Calatroni, H. Neupert, W. Wuensch CERN, Geneva
	The need for high accelerating gradients for the future Compact Linear Collider imposes considerable constraints on the materials of the accelerating structures. The surfaces exposed to high pulsed RF currents are subjected to cyclic thermal stresses possibly resulting in surface break up by fatigue. Since no fatigue data exists in the literature up to very large numbers of cycles, a comprehensive study has been initiated. Low cycle fatigue data (up to 108 cycles) has been collected by means of a pulsed laser surface heating apparatus. The surface damage has been characterized by SEM observations and roughness measurements. High cycle fatigue data (up to 1011 cycles) at various stress ratios have been collected in high frequency bulk fatigue tests using an ultrasonic apparatus. It is found that the appearance of surface fatigue damage in the laser experiments, and of fatigue cracks in the bulk specimen, happen at similar stress levels for similar numbers of cycles. This allows the two experimental techniques to be connected and to predict the surface damage at a high number of cycles. Up-to-date fatigue data for selected high conductivity, high strength Cu alloys are presented.
MOPLS130	Implications of a Curved Tunnel for the Main Linac of CLIC	linac, emittance, quadrupole, laser	864
	A. Latina, D. Schulte CERN, Geneva P. Eliasson Uppsala University, Uppsala
	Preliminary studies of a linac that follows the earth's curvature are presented for the CLIC main linac. The curvature of the tunnel is modeled in a realistic way by use of geometry changing elements. The emittance preservation is studied for a perfect machine as well as taking into account imperfections. Results for a curved linac are compared with those for a laser-straight machine.
MOPLS134	Minimizing Emittance for the CLIC Damping Ring	wiggler, damping, emittance, permanent-magnet	870
	H.-H. Braun, M. Korostelev, D. Schulte, F. Zimmermann CERN, Geneva E.B. Levitchev, P.A. Piminov, S.V. Sinyatkin, P. Vobly, K. Zolotarev BINP SB RAS, Novosibirsk
	The CLIC damping rings aim at unprecedented small normalized equilibrium emittances of 3.3 nm vertical and 550 nm horizontal, for a bunch charge of 2.6 109 particles and an energy of 2.4 GeV. In this parameter regime the dominant emittance growth mechanism is intra-beam scattering. Intense synchrotron radiation damping from wigglers is required to counteract its effect. Here the overall optimization of the wiggler parameters is described, taking into account state-of-the-art wiggler technologies, wiggler effects on dynamic aperture, and problems of wiggler radiation absorption. Two technical solutions, one based on superconducting magnet technology and the other on permanent magnets, are presented. Although dynamic aperture and tolerances of this ring design remain challenging, benefits are obtained from the strong damping. Only bunches for a single machine pulse need to be stored, making injection/extraction particularly simple and limiting the synchrotron-radiation power. With a 360 m circumference, the ring remains comparatively small.
MOPLS136	Ion Effects in the Damping Rings of ILC and CLIC	ion, damping, wiggler, vacuum	876
	F. Zimmermann, W. Bruns, D. Schulte CERN, Geneva
	We discuss ion trapping, rise time of the fast beam-ion instability, and ion-induced incoherent tune shift for various incarnations of the ILC damping rings and for CLIC, taking into account the different regions of each ring. Analytical calculations for ion trapping are compared with results from a new simulation code.
TUPCH086	Precision Beam Timing Measurement System for CLIC Synchronization	CTF3, linac, pick-up, CERN	1211
	J.P.H. Sladen, A. Andersson CERN, Geneva
	Very precise synchronization between main and drive beams is required in CLIC to avoid excessive luminosity loss due to energy variations. One possibility to accomplish this would be to measure and correct the drive beam phase. The timing reference for the correction could be the beam in the transfer line between the injector complex and the main linac. The timing of both main and drive beams will have to be measured to a precision in the region of 10 fs. The aim is to achieve this by means of a beam measurement at 30 GHz with the signal mixed down to an intermediate frequency (IF) for precise phase detection. The RF and IF electronics are being developed and tests will be carried out in CTF3.
TUPCH088	High Dynamic Range Beam Profile Measurements	CTF3, beam-losses, injection, site	1217
	C.P. Welsch, E. Bravin, B. Burel, T. Lefevre CERN, Geneva T. Chapman, M.J. Pilon Thermo, Liverpool, New York
	In future high intensity, high energy accelerators, beam loss has to be minimized to maximize performance and minimize activation of accelerator components. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for high resolution measurements of the transverse beam profile. In order to be applicable for measurements within the beam halo region, it is of utmost importance that a high dynamic range is covered by the image acquisition system. The existing camera system as it is installed in the CLIC Test Facility (CTF3) is compared to a step-by-step measurement with a photo multiplier tube (PMT) and measurements with a cooled charge injection device (CID) camera. The latter acquisition technique provides an innovative and highly flexible approach to high dynamic range measurements and is presented in some detail.
TUPCH142	Development of a Novel RF Waveguide Vacuum Valve	vacuum, CTF3, coupling, electromagnetic-fields	1349
	A. Grudiev CERN, Geneva
	The development of a novel rf waveguide vacuum valve is presented. The rf design is based on the use of TE0n modes of circular waveguides. In the device, the T·1001 mode at the input is converted into a mixture of several TE0n modes which provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the T·1001 mode at the output. There are a number of advantages associated with the absence of surface fields in the region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·1001 mode and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3 (CTF3) are presented showing in particular that the rf power transmission losses are below 1%.
TUPCH163	Status of 30 GHz High Power RF Pulse Compressor for CTF3	CTF3, laser, vacuum, linac	1405
	I. Syratchev CERN, Geneva
	A 70 ns 30 GHz pulse compressor with resonant delay lines has been built and installed in the CTF3 test area to obtain the high peak power of 150 MW necessary to demonstrate the full performance of the new CLIC accelerating structure. This pulse compressor will be commissioned at high power in 2006. Different methods to provide fast RF phase switching are discussed. The current status of the CTF3 RF pulse compressor commissioning and first results are presented.
TUPCH164	Ka-band Test Facility for High-gradient Accelerator R&D	vacuum, SLAC, cathode, DIAMOND	1408
	M.A. LaPointe, J.L. Hirshfield, E.V. Kozyrev Yale University, Physics Department, New Haven, CT A.A. Bogdashov, A.V. Chirkov, G.G. Denisov, A.S. Fix, D.A. Lukovnikov, V.I. Malygin, Yu.V. Rodin, M.Y. Shmelyov IAP/RAS, Nizhny Novgorod S.V. Kuzikov, A.G. Litvak, O.A. Nezhevenko, M.I. Petelin, A.A. Vikharev, V.P. Yakovlev Omega-P, Inc., New Haven, Connecticut G.V. Serdobintsev BINP SB RAS, Novosibirsk S.V. Shchelkunov Columbia University, New York
	Achievement of high acceleration gradients in room-temperature structures requires basic studies of electric and magnetic RF field limits at surfaces of conductors and dielectrics. Facilities for such studies at 11.4 GHz have been in use at KEK and SLAC; facilities for studies at 17.1 GHz are being developed at MIT and UMd; and studies at 30 GHz are being conducted at CERN using the CLIC drive beam to generate short intense RF pulses. Longer pulse studies at 34 GHz are to be carried out at a new test facility being established at the Yale Beam Physics Laboratory, built around the Yale/Omega-P 34-GHz magnicon. This high-power amplifier, together with an available ensemble of components, should enable tests to be carried at up to about 9 MW in 1 mcs wide pulses at up to four output stations or, using a power combiner, at up to about 35 MW in 1 mcs wide pulses at a single station. RF pulse compression is planned to be used to produce 100-200 MW, 100 ns pulses; or GW-level, 1 mcs wide pulses in a resonant ring. A number of experiments have been prepared to utilize multi-MW 34-GHz power for accelerator R&D, and users for future experiments are encouraged to express their interest.
TUPCH165	Compact Single-channel Ka-band SLED-II Pulse Compressor	coupling, scattering, LEFT, linac	1411
	S.V. Kuzikov, S.V. Kuzikov, M.E. Plotkin, A.A. Vikharev Omega-P, Inc., New Haven, Connecticut J.L. Hirshfield Yale University, Physics Department, New Haven, CT
	Basic studies of factors that limit RF fields in warm accelerator structures require experiments at RF power levels that can only be produced from an intense drive beam, as with CLIC studies, or using pulse compression of output pulses from the RF source. This latter 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 described that uses 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. Calculations show that with this device at 34 GHz one can anticipate a power gain of 3.3:1, and an efficiency of 66% for a 100 ns wide output pulse, taking into account losses and a realistic 50-ns long 180 degrees phase flip.
WEYPA03	CLIC Feasibility Study in CTF3	CTF3, linac, collider, CERN	1862
	A. Ghigo INFN/LNF, Frascati (Roma)
	After a reminder of the CLIC scheme towards multi-TeV Linear Collider and of the main challenges of this novel technology, the presentation will focus on the CTF3 test facility presently under construction at CERN to address all key issues in a multi-lateral collaboration. It will present the status of the facility and of the technological developments, especially the high field accelerating structures and the RF power production, the performances already achieved as well as the plans and schedule for the future. It will finally compare the CTF3 results with those foreseen by the theory and the corresponding benchmarking of CLIC simulations.
	Transparencies
WEOAPA02	Optimum Frequency and Gradient for the CLIC Main Linac	linac, luminosity, emittance, damping	1867
	A. Grudiev, D. Schulte, W. Wuensch CERN, Geneva
	A novel procedure for the optimization of the operating frequency, the accelerating gradient, and many other parameters of the CLIC main linac is presented. Based on the new accelerating structure design HDS (Hybrid Damped Structure), the optimization procedure takes into account both beam dynamics (BD) and RF constraints. BD constraints are related to emittance growth due to short- and long-range transverse wakefields. RF constraints are related to RF breakdown and pulsed surface heating limitations of the accelerating structure. Interpolation of beam and structure parameters in a wide range allows hundreds of millions of structures to be analyzed. Only those structures which satisfy BD and RF constraints are evaluated further in terms of ratio of luminosity to main linac input power, which is used as the figure of merit. The frequency and gradient have been varied in the range 12-30 GHz and 90-150 MV/m, respectively. It is shown that the optimum frequency varies in the range from 16 to 20 GHz depending on the accelerating gradient and that the optimum gradient is below 100 MV/m and that changing frequency and gradient can double the luminosity for the same main linac input power.
	Transparencies
WEPCH124	BDSIM - Beamline Simulation Toolkit Based on Geant4	simulation, quadrupole, electron, scattering	2212
	I.V. Agapov, G.A. Blair, J. Carter Royal Holloway, University of London, Surrey O. Dadoun LAL, Orsay
	BDSIM is a code that combines accelerator-style particle tracking with traditional Geant-style tracking based on Runge-Kutta techniques. This approach means that particle beams can be tracked efficiently when inside the beampipe, while also enabling full Geant4 processes when beam-particles interact with beamline apertures. Tracking of the resulting secondary particles is automatic. The code is described, including a new MAD-style interface and new geometry description, and key performance parameters are listed.
WEPCH137	FAKTOR2: A Code to Simulate the Collective Effects of Electrons and Ions	electron, ion, simulation, LEFT	2242
	W. Bruns, D. Schulte, F. Zimmermann CERN, Geneva
	A new code for computing the multiple effects of slowly moving charges is being developed. The basic method is electrostatic particle in cell. The underlying grid is rectangular and locally homogeneous. At regions of interest, e.g., where the beam is, or near material boundaries, the mesh is refined recursively. The motion of the macroparticles is integrated with an adapted timestep. Fast particles are treated with a smaller timestep, and particles in regions of fine grids are also treated with a fine timestep. The position of collision of particles with material boundaries is accurately resolved. Secondary particles are then created according to user-specified yield functions.
WEPCH140	Recent Improvements of PLACET	linac, simulation, ground-motion, luminosity	2251
	A. Latina, H. Burkhardt, L. Neukermans, G. Rumolo, D. Schulte, R. Tomas CERN, Geneva P. Eliasson Uppsala University, Uppsala J. Resta-López IFIC, Valencia
	The tracking code PLACET is used to simulate the beam transport in linear colliders from the damping ring to the interaction point and beyond. Recent improvements of the code are presented. They include the possibility to simulate bunch compressors and to use parallel computer systems.
WEPLS023	The Two-beam Test-stand in CTF3	CTF3, diagnostics, linac, dipole	2445
	V.G. Ziemann, T. J. C. Ekelof, M. A. Johnson UU/ISV, Uppsala H.-H. Braun, S. Doebert, G. Geschonke, J.P.H. Sladen, W. Wuensch CERN, Geneva
	The acceleration concept for CLIC, based on the two-beam acceleration scheme, where the 30 GHz RF power needed to accelerate the high energy beam is generated by a high-intensity but rather low energy drive beam, will be tested in the two-beam test-stand in CTF3. There RF-structures will be tested at full pulse length. The extreme power levels of up to 640 MW warrant a careful diagnostic system to analyze RF breakdown by observing the effect on both probe- and drive-beam but also the RF signals and secondary effects such as emitted light, vibrations, vacuum, temperatures. We describe the experimental setup and the diagnostic system planned to be installed in CTF3 for 2007.
WEPLS038	Design of Diamond-lined Accelerator Structure Test Cavity	DIAMOND, collider, linear-collider, acceleration	2457
	C. Wang, V.P. Yakovlev Omega-P, Inc., New Haven, Connecticut J.L. Hirshfield, M.A. LaPointe Yale University, Physics Department, New Haven, CT
	For a high-gradient normal-conducting accelerator structure for a future multi-TeV linear collider, the main limitation to achievement of high acceleration gradient is RF breakdown. In an attempt to increase the gradient beyond limits that are acceptable for metallic structures, a diamond-lined structure is suggested. The published DC breakdown limit for CVD diamond is ~2 GV/m, but the limit has never been determined for RF fields. Here we present a design for a 34-GHz diamond-lined rectangular test cavity, operating in the symmetric LSM-1,1,6 mode with symmetric side input couplers. The goal is to produce as high electric fields as possible (approaching 1 GV/m) at the diamond surfaces with ~10 MW of input power supplied by the Omega-P/Yale 34-GHz magnicon for experiment test of dielectric strength.
WEPLS060	CLIC Polarized Positron Source Based on Laser Compton Scattering	laser, positron, damping, photon	2520
	F. Zimmermann, H.-H. Braun, M. Korostelev, L. Rinolfi, D. Schulte CERN, Geneva S. Araki, Y. Higashi, Y. Honda, Y. Kurihara, M. Kuriki, T. Okugi, T. Omori, T. Taniguchi, N. Terunuma, J. Urakawa KEK, Ibaraki X. Artru, R. Chehab, M. Chevallier IN2P3 IPNL, Villeurbanne E.V. Bulyak, P. Gladkikh NSC/KIPT, Kharkov M.K. Fukuda, K. Hirano, M. Takano NIRS, Chiba-shi J. Gao IHEP Beijing, Beijing S. Guiducci, P. Raimondi INFN/LNF, Frascati (Roma) T. Hirose, K. Sakaue, M. Washio RISE, Tokyo K. Moenig DESY Zeuthen, Zeuthen H.D. Sato HU/AdSM, Higashi-Hiroshima V. Soskov LPI, Moscow V.M. Strakhovenko BINP SB RAS, Novosibirsk T. Takahashi Hiroshima University, Higashi-Hiroshima A. Tsunemi SHI, Tokyo V. Variola, Z.F. Zomer LAL, Orsay
	We describe the possible layout and parameters of a polarized positron source for CLIC, where the positrons are produced from polarized gamma rays created by Compton scattering of a 1.3-GeV electron beam off a YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. We point out the differences with respect to a similar system proposed for the ILC.
THPCH019	Halo and Tail Generation Studies for Linear Colliders	scattering, simulation, linac, collimation	2823
	L. Neukermans, H. Burkhardt CERN, Geneva J. Resta-López IFIC, Valencia
	Halo particles in linear colliders can result in significant losses and serious background which may reduce the overall performances. We present a study of various halo generation processes with numerical estimates. The aim is to allow to predict and minimize the halo throughout the accelerator chain including the final focus up to the experimental detectors. We include estimates for the planned CLIC beam line.