EPAC08 - Classification:03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques/A03 Linear Colliders

03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques

A03 Linear Colliders

Paper	Title	Page
MOYBGM01	Global R&D Effort for the ILC Linac Technology	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
MOPP001	Beam-Based Alignment for the CLIC Decelerator	547
	E. Adli, D. Schulte CERN, Geneva
	The CLIC Drive Beam decelerator requires the beam to be transported with very small losses. Beam-based alignment is necessary in order to achieve this, and various beam-based alignment schemes have been tested for the decelerator lattice. The decelerator beam has an energy spread of up to 90%, which impacts the performance of the alignment schemes. We have shown that Dispersion-Free-Steering works well for the decelerator lattice. However, because of the transverse focusing approach, modifications of the normal DFS schemes must be applied. Tune-up scenarios for the CLIC decelerator using beam-based alignment are also discussed.
MOPP002	A Study of Failure Modes in the CLIC Decelerator	550
	E. Adli, D. Schulte, I. Syratchev CERN, Geneva
	The CLIC Drive Beam decelerator is responsible for producing the RF power for the main linacs, using Power Extraction and Transfer Structures (PETS). To provide uniform power production, the beam must be transported with very small losses. In the paper failure modes for the operation of the decelerator are investigated, and the impact on beam stability, loss level and machine protection issues is presented. Quadrupole failure, PETS inhibition and PETS break down scenarios are being considered.
MOPP003	Study of Abnormal Vertical Emittance Growth in ATF Extraction Line	553
	M. Alabau, A. Faus-Golfe IFIC (CSIC-UV), Valencia M. Alabau, P. Bambade, J. Brossard, G. Le Meur, C. Rimbault, F. Touze LAL, Orsay D. Angal-Kalinin, J. K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire R. Appleby, A. Scarfe UMAN, Manchester S. Kuroda KEK, Ibaraki G. R. White, M. Woodley SLAC, Menlo Park, California F. Zimmermann CERN, Geneva
	Since several years, the vertical emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This long-standing problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experienced by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.
MOPP005	The 2 mrad Crossing Angle Scheme for the International Linear Collider	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.
MOPP007	Wakefield Calculations - Comparison between Simulations and Experimental Data	562
	A. Bungau, R. J. Barlow UMAN, Manchester
	In linear colliders the collimator wakefields have a significant effect on emittance growth, beam jitter and background estimates. Each simulation code models the collimator wakefields using a different approach and a discussion of the formalism for incorporating wakefields into the particle tracking code Merlin is included in this paper. Using simple collimator types we present the different predictions for bunch shape effects, and also for the wakefield kicks. These kicks are also compared with experimental results from SLAC End Station A.
MOPP008	Design of the Photon Collimators for the ILC Positron Helical Undulator	565
	A. Bungau UMAN, Manchester I. R. Bailey, J. B. Dainton, K. M. Hock, L. J. Jenner, L. I. Malysheva Liverpool University, Science Faculty, Liverpool 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 J. A. Clarke, O. B. Malyshev, N. C. Ryder, D. J. Scott STFC/DL/ASTeC, Daresbury, Warrington, Cheshire N. A. Collomb STFC/DL, Daresbury, Warrington, Cheshire A. F. Hartin OXFORDphysics, Oxford, Oxon S. Hesselbach, G. A. Moortgat-Pick Durham University, Durham L. Zang Cockcroft Institute, Warrington, Cheshire
	A number of photon collimators are placed inside the helical undulator to protect the cold surfaces of the vacuum vessel from being hit by the photons and thus achieving the baseline pressure requirement. Computer simulations were run in order to determine the energy deposition and instantaneous temperature rise in these collimators and various material candidates were studied. This paper presents the status of the simulation.
MOPP009	Copper Prototype Measurements of the HOM, LOM and SOM Couplers for the ILC Crab Cavity	568
	G. Burt, P. K. Ambattu, A. C. Dexter Cockcroft Institute, Lancaster University, Lancaster L. Bellantoni Fermilab, Batavia, Illinois P. Goudket, P. A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire Z. Li, L. Xiao SLAC, Menlo Park, California
	The ILC Crab Cavity is positioned close to the IP and hence is very sensitive to the wakefields induced by the beam. A set of couplers were designed to couple to and hence damp the spurious modes of the crab cavity. As the crab cavity is a deflecting mode cavity, it operates using a dipole mode and has different damping requirements than an accelerating mode cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz, known as the LOMs, the opposite polarization of the operating mode, the SOM, and the modes above the operating frequency, the HOMs. Each of these couplers have been manufactured out of copper and measured attached to an aluminium nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.
MOPP010	Experimental Studies on Drive Beam Generation in CTF3	571
	R. Corsini, S. Bettoni, S. Doebert, P. K. Skowronski, F. Tecker CERN, Geneva C. Biscari, A. Ghigo INFN/LNF, Frascati (Roma) Y.-C. Chao Jefferson Lab, Newport News, Virginia
	The objective of the CLIC Test Facility CTF3, built at CERN by an international collaboration, is to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. CTF3 consists of a 150 MeV electron linac followed by a 42 m long delay loop, an 84 m combiner ring and a two-beam test area. One key-issue studied in CTF3 is the efficient generation of a very high current drive beam, used in CLIC as the power source for the acceleration of the main beam to multi-TeV energies. The beam current is first doubled in the delay loop and then multiplied again by a factor four in the combiner ring by interleaving bunches using transverse deflecting RF cavities. The combiner ring and the connecting transfer line have been installed and put into operation in 2007. In this paper we give the status of the commissioning, illustrate the beam optics measurements, discuss the main issues and present the results of the combination tests.
MOPP011	Fast Vertical Beam Instability in the CTF3 Combiner Ring	574
	R. Corsini, D. Schulte, P. K. Skowronski, F. Tecker CERN, Geneva D. Alesini, C. Biscari, A. Ghigo INFN/LNF, Frascati (Roma)
	The CLIC Test Facility CTF3 is being built at CERN by an international collaboration, in order to demonstrate the main feasibility issues of the CLIC two-beam technology by 2010. The facility includes an 84 m combiner ring, which was installed and put into operation in 2007. High-current operation has shown a vertical beam break-up instability, leading to high beam losses over the four turns required for nominal operation of the CTF3 ring. Such instability is most likely due to the vertically polarized transverse mode in the RF deflectors used for beam injection and combination. In this paper we report the experimental data and compare them with simulations. Possible methods to eliminate the instability are also outlined.
MOPP012	DC Breakdown Experiments for CLIC	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.
MOPP013	Coupler Kick for Very Short Bunches and its Compensation	580
	M. Dohlus, I. Zagorodnov DESY, Hamburg E. Gjonaj, T. Weiland TEMF, Darmstadt
	In this contribution we estimate two different effects: the kick due to asymmetry of the external accelerating field (coupler RF kick) and the kick due to electromagnetic field of the bunch scattered by the couplers (coupler wake kick). We take into acoount the cavities and calculate the periodic solution for bunch with an rms width of 300 mkm. The different possibilities for compensation of the kick are considered.
MOPP015	Continuously Adjustable Permanent Magnet Quadrupole for a Final Focus	583
	T. Sugimoto, M. Ichikawa, Y. Iwashita, M. Yamada Kyoto ICR, Uji, Kyoto M. Kumada NIRS, Chiba-shi S. Kuroda, T. Tauchi KEK, Ibaraki
	A permanent magnet quadrupole with continuous strength adjustability has been fabricated. It has a five-ring-singlet structure, which was proposed by R. L.Gluckstern. Its small overall diameter allows an outgoing beamline to pass closeby. Since the permanent magnet pieces do not have any vibration source in themselves, this magnet could be used as a quadrupole in a final focus doublet. Such a quadrupole system is described.
MOPP016	Collimation Aperture for the Beam Delivery System of the International Linear Collider	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	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.
MOPP022	Transatlantic Transport of Fermilab 3.9 GHZ Cryomodule for TTF/FLASH to DESY	592
	M. McGee, V. T. Bocean, J. Grimm, W. Schappert Fermilab, Batavia, Illinois
	In an exchange of technology agreement, Fermilab built and will deliver a 3.9 GHz (3rd harmonic) cryomodule to DESY to be installed in the TTF/FLASH beamline. This cryomodule delivery will involve a combination of flatbed air ride truck and commercial aircraft transport to Hamburg Germany. A description of the isolation and damping systems that maintain alignment during transport and protect fragile components is provided. Initially, transport and corresponding alignment stability studies were performed in order to assess the risk associated with transatlantic travel of a fully assembled cryomodule. Shock loads were applied to the cryomodule by using a coldmass mockup to prevent subjecting actual critical components (such as the cavities and input couplers) to excessive forces. Accumulative and peak shock loads were applied through over-the-road testing and using a pendulum hammer apparatus, respectively. Finite Element Analysis (FEA) studies were implemented to define location of instrumentation for transport studies and provide modal frequencies and shapes. Shock and vibration measurement results of transport studies and stabilization techniques are discussed.
MOPP023	Test of Short Period SC Undulator	595
	A. A. Mikhailichenko Cornell University, Department of Physics, Ithaca, New York
	We represent details of design and results of test of 4-m long undulator in cryostat having period 12mm and aperture ~6.35 mm allowing K=1.0. This undulator can be used in ILC positron conversion system as well as insertion device for developing FEL systems.
MOPP024	Depolarization and Beam-beam Effects at the Linear Collider	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.
MOPP025	Design of the Beam Extraction by Using Strip-line Kicker at KEK-ATF	601
	T. Naito, H. Hayano, K. Kubo, S. Kuroda, T. Okugi, N. Terunuma, J. Urakawa KEK, Ibaraki
	The developing work of the strip-line kicker system for International linear collider(ILC) is carrying out at KEK. To confirm the performance of the kicker system, the beam extraction test by using strip-line kicker is in progress at KEK-ATF. The multi-bunch beam, which has 2.8ns bunch spacing in the damping ring, is extracted from the damping ring to the extraction line with 308ns duration. The scheme is the same as the kicker of the ILC. The bump orbit and the auxiliary septum magnet will be used with the kicker to clear the geometrical restriction. The detail of the hardware design and the basic performance of each component are presented in this paper. T. Naito et al. Development of the Strip-line Kicker System for ILC Damping Ring, Proceedings of PAC07, Albuquerque, New Mexico, USA, pp2772-2274.
MOPP027	Placet Based Start-to-end Simulations of the ILC with Intra-train Fast Feedback System	604
	J. Resta-López, P. Burrows, A. F. Hartin JAI, Oxford A. Latina, D. Schulte CERN, Geneva
	Integrated simulations are important to assess the reliability of the luminosity performance of the future linear colliders. In this paper we present multi-bunch tracking simulation results for the International Linear Collider (ILC) from the start of the LINAC to the interaction point. The tracking along the LINAC and the beam delivery system is done using the code Placet. This code allows us to introduce cavity wakefield effects, element misalignment errors and ground motion. Static beam based alignment of the LINAC are also considered. The luminosity and beam-beam parameters are calculated using the code Guinea-Pig. In the framework of the Feedback On Nano-second Timescales (FONT) project, we describe and simulate an updated fast intra-train feedback system in order to correct for luminosity degradation mainly due to high frequency ground motion.
MOPP028	Technical Specification for the CLIC Two-Beam Module	607
	G. Riddone, H. Mainaud Durand, D. Schulte, I. Syratchev, W. Wuensch, R. Zennaro CERN, Geneva R. Nousiainen HIP, University of Helsinki A. Samoshkin JINR, Dubna, Moscow Region
	The 2-m long CLIC module comprises four decelerating structures and two quadrupoles forming a FODO cell. Each decelerating structure powers two accelerating structures. Some accelerating structures are removed at regular intervals to liberate space for a quadrupole of a FODO lattice. The present layout of the standard and special modules is presented as well as the status of the system integration. The main requirements for the different sub-systems (alignment, supporting, stabilization, cooling and vacuum) are introduced together with the major integration constraints. For the key components the specification on pre-alignment and beam-based alignment tolerances is also recalled as well as their influence on the requirements of other sub-systems. For example the required stable thermal behavior and the tight tolerances of accelerating structure (the requirements for the accelerating structure pre-alignment is 0.014 mm at 1? ) in the CLIC linac largely directly the sizing and integration of the cooling system. The paper also covers the main issues related to the module integration in the tunnel. In the last part, the critical issues and future activities are summarized.
MOPP029	The First Measurement of Low-loss 9-cell Cavity in a Cryomodule at STF	610
	T. Saeki, M. Akemoto, S. Fukuda, F. Furuta, K. Hara, Y. Higashi, T. Higo, K. Hosoyama, H. Inoue, A. Kabe, H. Katagiri, S. Kazakov, Y. Kojima, H. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, Y. Morozumi, H. Nakai, K. Nakanishi, N. Ohuchi, K. Saito, M. Satoh, T. Takenaka, K. Tsuchiya, H. Yamaoka, Y. Yano KEK, Ibaraki T. Kanekiyo Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura J. Y. Zhai IHEP Beijing, Beijing
	We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of International Linear Collider (ILC) accelerator. In the beginning of year 2008, we installed one high-gradient Low-Loss (LL) type 9-cell cavity into a cryomodule at STF, where we assembled an input coupler and peripherals with the cavity in a clean room, and the assembled cavity packages were dressed with thermal shields and installed into a cryomodule. At the room-temperature, we performed the processing of capacitive-coupling input-coupler upto the RF power of 250 kW. At the temperature of 4 K, we measured the loaded Q of the cavity and the tuner was tested. At the temperature of 2 K, high-power RF was supplied from a klystron to the cavity and the performance of the cavity packeage was tested. This article presents the results of the first test of the Low-Loss (LL) 9-cell cavity package at 2 K in a cryomodule.
MOPP030	ATF2 Final Focus Orbit Correction and Tuning Optimisation	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).
MOPP031	Challenges and Concepts for Design of an Interaction Region with Push-pull Arrangement of Detectors - an Interface Document	616
	A. Seryi, T. W. Markiewicz, M. Oriunno, M. K. Sullivan SLAC, Menlo Park, California D. Angal-Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire B. Ashmanskas, V. R. Kuchler, N. V. Mokhov Fermilab, Batavia, Illinois K. Buesser DESY, Hamburg P. Burrows OXFORDphysics, Oxford, Oxon A. Enomoto, Y. Sugimoto, T. Tauchi, K. Tsuchiya KEK, Ibaraki A. Herve, J. A. Osborne CERN, Geneva A. A. Mikhailichenko Cornell University, Department of Physics, Ithaca, New York B. Parker BNL, Upton, Long Island, New York T. Sanuki Tohoku University, School of Scinece, Sendai J. Weisend NSF, Arlington H. Y. Yamamoto Tohoku University, Sendai
	Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics system, for alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent.
MOPP034	Large Scale Linac Simulations Using a Globalised Scattering Matrix Approach	619
	I. R.R. Shinton, R. M. Jones UMAN, Manchester
	A globalised cascaded scattering matrix scheme serves as practical method to simulate the electromagnetic (e.m.) fields in the groups of cavities which constitute the main accelerating structures of a linac. The cascaded scattering matrix technique is a well-proven method which allows realistic fabrication errors to be incorporated in an efficient manner without the necessity to re-mesh the entire geometry. Once the unit cell structures have been determined using a numerical scheme, such as finite element method utilized here, the overall cascaded scattering matrix calculation requires little in the way of computational resources or time and is consequently an efficient means of characterizing the e.m. field. Details of the e.m. field, shunt impedance and trapped modes for large scale linac simulations applied to the baseline and alternate high gradient cavities for the ILC and applications to XFEL are presented.
MOPP035	ILC Siting in Dubna Region (Russia) and ILC activity in JINR	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.
MOPP036	Dark Current Model for ILC Main Linac	625
	N. Solyak, N. V. Mokhov, G. V. Romanov Fermilab, Batavia, Illinois Y. I. Eidelman BINP SB RAS, Novosibirsk W. M. Tam IUCF, Bloomington, Indiana
	In the ILC Main Linac the dark current electrons, generated in SRF cavity can be accelerated to hundreds of MeV before being kicked out by quadrupoles and thus will originate electromagnetic cascade showers in the surrounding materials. Some of the shower secondaries can return back into vacuum and re-accelerated again. The results of simulation of the dark current dynamics and energy deposition along the linac are discussed in paper.
MOPP037	Alignment of the CLIC BDS	628
	A. Latina, D. Schulte, R. Tomas CERN, Geneva
	Aligning the CLIC Beam Delivery System faces two major challenges, the tight tolerances for the emittance preservation and its strong non-linear beam dynamics. For these reasons conventional beam-based alignment techniques, like dispersion free steering, are only partially successful and need to be followed by optimization algorithms based on other observables, like beam sizes.
MOPP038	Optimizing the CLIC Beam Delivery System	631
	R. Tomas BNL, Upton, Long Island, New York H.-H. Braun, M. Jorgensen, D. Schulte CERN, Geneva
	The optimization of the new CLIC Final Focus System (FFS) with L*=3.5m is presented for a collection of CLIC beam parameters. The final performance is computed for the full Beam Delivery System including the new diagnostics section. A comparison to previous designs is also presented.
MOPP039	Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System	634
	G. R. White, S. Molloy, M. Woodley SLAC, Menlo Park, California
	Using a new extraction line currently under construction, the ATF2 experiment plans to test the novel compact final focus optics design with local chromaticity correction intended for use in future linear colliders. With a 1.3 GeV design beam of 30nm normalised vertical emittance extracted from the ATF damping ring, the primary goal is to achieve a vertical spot-size at the IP waist of 37nm. We discuss our planned strategy for tuning the ATF2 beam to meet the primary goal. Simulation studies have been performed to asses the effectiveness of the strategy, including “static” (installation) errors and dynamical effects (ground-motion, mechanical vibration, ring extraction jitter etc.). We have simulated all steps in the tuning procedure, from initial orbit establishment to final IP spot-size tuning. Through a Monte Carlo study of 100's of simulation seeds we find we can achieve a spot-size within ~10% of the design optics value in at least 75% of cases. We also ran a simulation to study the long-term performance with the use of beam-based feedbacks.
MOPP042	RF Kick in the ILC Acceleration Structure	637
	V. P. Yakovlev, I. G. Gonin, A. Latina, A. Lunin, K. Ranjan, N. Solyak Fermilab, Batavia, Illinois
	Detailed results of estimations and simulations for the RF kick caused by input and HOM couplers of the ILC acceleration structure are presented. Results of possible beam emittance dilution caused by RF kick are discussed for the main LINAC acceleration structure, and the RF structures of the ILC bunch compressors BC1 and BC2. Methods of the RF kick reduction are discussed.
MOPP043	Transverse Wake Field Simulations for the ILC Acceleration Structure	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.
MOPP044	Cavity Diagnostic System for the Vertical Test of the STF Baseline 9-cell Cavity at KEK	643
	Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, M. Satoh, T. Shishido, K. Umemori, K. Watanabe KEK, Ibaraki S.-I. Moon POSTECH, Pohang, Kyungbuk H. Sakai, K. Shinoe ISSP/SRL, Chiba Q. J. Xu IHEP Beijing, Beijing
	Four 9-cell cavities, which are TESLA-type 9-cell cavities, were developed and tested in KEK for the future ILC project. A simple cavity diagnostic system was introduced to search the heating spot and to detect the x-ray emission. It is composed of the carbon resistors and the PIN photo diodes. They were attached on the equator of the cell, around the HOM couplers and on the end flanges. They were very effective to search the heating spot and to detect the x-ray emission during the vertical tests. All cavities eventually had the heating spot around the equator in the final state of the vertical test. It is conceivable that the quality of the electron beam welding was somewhat poor, when the dumbbells were connected. On this February, a new vertical test facility will be completed in STF (Superconducting RF Test Facility). Six 9-cell cavities will be tested by using the new system for S0 plan, which goal is the higher accelerating gradient for ILC. The new temperature and x-ray mapping system and new DAQ system will be introduced. This paper reports the recent status in the new vertical test facility in KEK-STF.
MOPP045	Study of the Validity of K. Bane's Formulae for the CLIC Accelerating Structure	646
	R. Zennaro CERN, Geneva
	The comprehension of short range wake is essential for the design of CLIC. Useful tools are the Karl Bane's formulae which predict the short range wake for periodic 2D symmetry structures. The comparison of 2D computations based on ABCI with predicted results and the study of the range of validity of these formulae are the subjects of this paper. A new fitting of the computational results is proposed for structures with very small aperture. A model for rounded iris structures is also proposed.
MOPP046	Collimation Optimizations, Capture Efficiency, and Primary-Beam Power Loss in the ILC Positron Source	649
	F. Zhou, Y. Nosochkov, J. Sheppard SLAC, Menlo Park, California W. Liu ANL, Argonne, Illinois
	The ILC positron beam generated from a thin Ti target has a wide energy spread and large transverse divergence. With the collection optics immediately downstream of the target and pre-acceleration to 125 MeV, the collected positron beam still has a long tail of positrons with low energies and large transverse divergence, which will be lost in the rest of the ILC positron source beamline. A collimation system is proposed and optimized for the case of a shielded target with quarter-wave transformation collection optics so that the power loss in the magnets and RF structures is effectively controlled within the acceptable level and in the damping ring (DR) within 640 W, assuming 3× 10¹⁰ of the captured positrons per bunch in the DR. In this case, the capture efficiency and DR injection efficiency are 13% and 99.8%, respectively. The lower capture efficiency is expected to result in higher injection efficiency and therefore, a lower power loss in the DR. The capture efficiency for the cases of a shielded target with flux concentrator and 5-T immersed target with flux concentrator is 20% and 30%, respectively, with the collimation system.
MOPP047	Simulation Studies on the Vertical Emittance Growth at the Existing ATF Extraction Beamline	652
	F. Zhou, J. W. Amann, S. Seletskiy, A. Seryi, C. M. Spencer, M. Woodley SLAC, Menlo Park, California
	Significant dependence of the vertical emittance growth on the beam intensity was experimentally observed at the Accelerator Test Facility (ATF) at KEK extraction beamline. This technical note describes the simulations of possible vertical emittance growth sources, particularly in the extraction channel, where the magnets are shared by both the ATF extraction beamline and its damping ring. The vertical emittance growth is observed in the simulations by changing the beam orbit in the extraction channel, even with all optics corrections. The possible reasons for the experimentally observed dependence of the vertical emittance growth on the beam intensity are discussed. An experiment to measure the emittance versus beam orbit at the existing ATF extraction beamline is underway. M. Alabau et al. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line, this proceeding.
MOPP048	Fast Ion Instability in the CLIC Transfer Line and Main Linac	655
	G. Rumolo, D. Schulte CERN, Geneva
	The Fast Ion Instability is believed to be a serious danger for bunch trains propagating in the CLIC electron transfer line and main linac, since it may strongly affect the bunches in the tail of the train if the vacuum pressure is not below a certain threshold. We have developed the FASTION code, which can track electrons through a FODO cell line and takes into account their interactions with the produced (and possibly trapped) ions. We describe how this tool can be used for setting tolerances on the vacuum pressure and for giving specifications for the design of a feedback system.
WEOBG01	CLIC RF High Power Production Testing Program	1909
	I. Syratchev, G. Riddone CERN, Geneva S. G. Tantawi SLAC, Menlo Park, California
	The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and generate RF power for the main linac accelerating structure. The demands on the high power production (~ 150 MW) and the needs to transport the 100 A drive beam for about 1 km without losses make the PETS design rather unique and the operation very challenging. In coming years the intensive PETS testing program will be implemented. The target is to demonstrate full performance of the PETS operation. The testing program overview and test results available to date will be presented.
	Slides
THYG01	The ILC Beam Delivery System Design and R&D Programme	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
THYG02	Results from the CLIC Test Facility CTF3 and Update on the CLIC Design	2912
	G. Geschonke CERN, Geneva
	The CLIC Test Facility CTF3 is being built and commissioned in stages. Up to now the facility consists of an electron linac, a magnetic chicane for changing bunch length, the Delay Loop and the Combiner Ring. Recent experience and commissioning results will be presented together with plans for the next steps which should lead to feasibility demonstration of CLIC technology by the year 2010. The CLIC design has been reviewed in detail. The resulting changes in parameters will be presented.
	Slides