03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques
A03 Linear Colliders

Paper	Title	Page
MOYBA01	Present Status of the ILC Project and Developments	16
	M.C. Ross Fermilab, Batavia, USA N.J. Walker DESY, Hamburg, Germany A. Yamamoto KEK, Ibaraki, Japan
	Funding: FNAL is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The Technical Design of the ILC Project will be finished in late 2012. The Technical Design Report will include a description of the updated design, with a cost estimate and a project plan, and the results of R & D done in support of the ILC. Results from directed ILC R & D are used to reduce the cost and risk associated with the ILC design. We present a summary of key challenges and show how the global R & D effort has addressed them. The most important activity has been in pursuit of very high gradient superconducting RF linac technology. There has been excellent progress toward the goal of practical industrial production of niobium sheet-metal cavities with gradient performance in excess of 35 MV/m. In addition, three purpose-built beam test facilities have been constructed and used to study and demonstrate high current linac performance, electron-cloud beam dynamics and precision beam control. The report also includes a summary of component design studies and conventional facilities cost optimization design studies.
	Slides MOYBA01 [9.755 MB]
MOOCA02	Two Beam Test Stand Experiments in the CTF3 Facility	29
	W. Farabolini, F. Peauger CEA/DSM/IRFU, France J. Barranco, S. Bettoni, B. Constance, R. Corsini, M. Csatari, S. Döbert, A. Dubrovskiy, C. Heßler, T. Persson, G. Riddone, P.K. Skowroński, F. Tecker CERN, Geneva, Switzerland D. Gudkov, A. Solodko JINR, Dubna, Moscow Region, Russia M. Jacewicz, T. Muranaka, A. Palaia, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden
	The CLEX building in the CTF3 facility is the place where essential experiments are performed to validate the Two-Beam Acceleration scheme upon which the CLIC project relies. The Drive Beam enters the CLEX after being recombined in the Delay loop and the Combiner Ring in intense beam trains of 24 A – 150 MeV lasting 140 ns and bunched at 12 GHz, although other beam parameters are also accessible. This beam is then decelerated in dedicated structures installed in the Test Beam Line (TBL) and in the Two-Beam Test Stand (TBTS) aimed at delivering bursts of 12 GHz RF power. In the TBTS this power is used to generate a high accelerating gradient of 100 MV/m in specially designed accelerating structures. To assess the performances of these structures a probe beam is used, produced by a small Linac. We reported here the various experiences conducted in the TBTS making use of the versatility the probe beam and of dedicated diagnostics.
	Slides MOOCA02 [3.003 MB]
TUYB01	First Results from the EMMA Experiment	951
	S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Report on first commissioning results and operational experience with EMMA, the world's first nonscaling FFAG. In particular review the effect of resonance crossing, and the efficiency of serpentine acceleration.
	Slides TUYB01 [9.201 MB]
TUYB03	CLIC Conceptual Design and CTF3 Results	961
	D. Schulte CERN, Geneva, Switzerland
	An international collaboration is carrying out an extensive R&D programme to prepare CLIC, a multi-TeV electron-positron collider. In this concept, the colliding beams will be accelerated in very high gradient normal conducting 12 GHz accelerating structures. The necessary RF power is extracted from a high-current, low-energy drive beam that runs parallel to the colliding beams and is generated in a central complex. This year the collaboration will produce a conceptual design report to establish the feasibility of the technology. The CLIC concept will be introduced and the status of key studies of critical issues will be reviewed. A focus will be on the CLIC Test Facility 3 (CTF3), which is a test facility to produce and use high current a drive beam.
	Slides TUYB03 [13.204 MB]
TUPC001	Simulations of the Interaction Point for TeV-scale e+ e− Colliders	985
	J. Esberg Aarhus University, Aarhus, Denmark
	The design of a detector and post collisional line of a future linear collider calls for detailed knowledge of the beam-beam dynamics at the interaction point. We here describe the implementation and results of new simulation tools in the program GUINEA-PIG. The subjects are direct trident production relevant in the deep quantum-regime, incoherent muon generation, synchrotron radiation from secondary particles and depolarization effects. We choose beam parameters in the range relevant for CLIC and comment on the implications for the design of such a machine.
TUPC002	Study of a Large Piwinski’s Angle Configuration for Linear Colliders	988
	R. Versteegen, O. Napoly CEA/DSM/IRFU, France
	The application of a Large Piwinski’s Angle configuration to the interaction region of a linear collider is studied. The calculation of the equivalent disruption parameter and beamstrahlung parameter in the presence of a crossing angle are necessary to estimate the beam-beam effects in such a configuration. The reduction of the beam-beam interaction effects, based on these parameters, while keeping same luminosity is presented for both ILC and CLIC parameters.
TUPC004	The Luminosity for the ILC Travelling Focus Regime with Offsets and Angle Scans*	991
	L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, A. Ushakov University of Hamburg, Hamburg, Germany K. Buesser, A.F. Hartin, G.A. Moortgat-Pick, N.J. Walker DESY, Hamburg, Germany S. Riemann, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	One of the crucial challenges of a future linear collider is to provide high luminosity. In the current ILC design a luminosity of 2x1034 is foreseen. In order to enhance the luminosity, use of the “travelling focus” scheme is under discussion. Within this regime the hourglass effect at the interaction point can be effectively overcome by judiciously arranging for the head and tail of the bunches to be focused at a proportionally displaced longitudinal position. The effect is further enhanced by the strong beam-beam interaction which continuously focuses the bunches during collision. In principle travelling focus could provide an additional 30% luminosity. Nevertheless the regime is highly sensitive to beam-beam transverse and angular offsets at the collision point. The study of the luminosity stability for various ILC parameters using traveling focus will be presented.
TUPC005	Evolution of Pressure in Positron Source for Future Linear e+e− Collider	994
	O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva University of Hamburg, Hamburg, Germany A.F. Hartin, G.A. Moortgat-Pick, S. Riemann, A. Ushakov DESY, Hamburg, Germany A. Schälicke, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE Energy deposition in the conversion targets of positron sources for future linear colliders induces an immense thermal load and create pressure waves in the material. This stress could substantially reduce the lifetime of the target or other target materials impinged by the incident intense photon or electron beam. We have studied the evolution of acoustic pressure waves in target materials based on the parameter assumptions for the International Linear Collider (ILC) baseline source. The fluid model is employed by taking into account the target and the incident photon beam parameters. Initial results of these new simulations are presented and compared with earlier studies. Prospects for further studies are outlined.
TUPC007	Kicker and Monitor for CTF3 Phase Feed Forward	1000
	F. Marcellini, D. Alesini, A. Ghigo INFN/LNF, Frascati (Roma), Italy
	Funding: Work partially supported by the EuCARD research programme, Grant Agreement 227579, within the 'Assessment of Novel Accelerator Concepts'. In the Compact LInear Collider (CLIC) the synchronization of the Drive Beam and the Main Beam has to be assured in the femtosecond range to avoid luminosity reduction of the collider. The Drive and Main Beams arrival time is measured with longitudinal monitors and the correction is applied changing the path length of one beam respect to the other in a magnetic chicane by means of two transverse fast stripline kicker. The performance of the feed forward system will be tested in the CLIC Test Facility (CTF3) measuring the phase at the linac exit, correcting in the chicane after the combination rings and comparing the longitudinal position change before the power RF production system. The developed phase monitors and kicker magnets for the test in CTF3 are described.
TUPC008	CLIC Two-Beam Module for the CLIC Conceptual Design and Related Experimental Program	1003
	A. Samoshkin, D. Gudkov, A. Solodko JINR, Dubna, Moscow Region, Russia G. Riddone CERN, Geneva, Switzerland
	The Compact LInear Collider (CLIC), being studied at CERN, involves the design and integration of many different technical systems, tightly bound and influencing each other. For the construction of two main linacs it has been decided to proceed with a modular design, and repetitive two-beam modules of a few types were defined. The modules consist of micro-precision components operating under ultra-high vacuum as required by the beam physics. For the CLIC Conceptual Design Report, the development and system integration is mainly focused on the most complex module type containing the highest number of components and technical systems. For proving the proper functioning of the needed technical systems and confirming their feasibility it has been decided to build four prototype modules and test them without beam. In addition, three modules have to be produced in parallel for tests in the CLIC Experimental Area with beam. This paper is focused on the design of the different technical systems and integration issues of the two-beam module. The experimental program for the prototype modules is also recalled.
TUPC009	The Recent JINR Advances in Technology Development on Linear Accelerators	1006
	G. Shirkov, N. Balalykin, A. Dudarev, E. Syresin, G.V. Trubnikov, Yu.A. Yulian JINR, Dubna, Moscow Region, Russia E. Khazanov IAP/RAS, Nizhny Novgorod, Russia
	JINR experts take part in a few ILC related projects including photo injector prototype, participation in design and construction of cryomodules, RND on design of a new version of superconducting niobium resonator, laser metrology, etc. Some new results of this activity as well as recent data of ILC siting investigations in the Dubna region are presented.
TUPC010	Status of the Manufacturing of Accelerating Structures for LINACs	1009
	F.M. Mirapeix, J. Añel, J. Castillo, A. Ortiz HTS, Mendaro, Spain X. Aldalur, J. Amores, A. Urzainki DMP, Mendaro, Spain
	Funding: HTS, DMP, ZEHATZ, CERN Particle accelerators need ongoing development in the state of the art of the field: high-quality manufacturing of accelerating structures, PETS, but also drift tubes, bunchers, high-power couplers, alignment systems, precision test stands, etc. They also require engineering projects in the range of mechatronics, thermodynamics, microwaves, ultra high vacuum, cryogenics, joining techniques, high precision manufacturing, 3D high precision scanning, etc. HTS together with DMP are actually working on all this fronts. In this paper, the actual status of the manufacturing capabilities concerning some accelerating structures will be described.
TUPC011	Striplines for CLIC Pre-Damping and Damping Rings*	1012
	C. Belver-Aguilar, A. Faus-Golfe IFIC, Valencia, Spain M.J. Barnes, G. Rumolo CERN, Geneva, Switzerland F. Toral CIEMAT, Madrid, Spain C. Zannini EPFL, Lausanne, Switzerland
	The Compact Linear Collider (CLIC) study explores the scheme for an electron-positron collider with high luminosity and a nominal center-of-mass energy of 3 TeV: CLIC would complement LHC physics in the multi-TeV range. The CLIC design relies on the presence of Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve, through synchrotron radiation, the very low emittance needed to fulfil the luminosity requirements. The specifications for the kicker systems are very challenging and include very low beam coupling impedance and excellent field homogeneity: striplines have been chosen for the kicker elements. Analytical calculations have been carried out to determine the effect of tapering upon the high frequency beam coupling impedance. In addition detailed numerical modeling of the field homogeneity has been performed and the sensitivity of the homogeneity to various parameters, including stripline cross-section, has been studied. This paper presents the main conclusions of the beam impedance calculations and field homogeneity predictions.
TUPC012	Fabrication and Validation of the Prototype Supporting System for the CLIC Two-beam Modules	1015
	N. Gazis, G. Riddone, S. griffet CERN, Geneva, Switzerland A. Samoshkin JINR, Dubna, Moscow Region, Russia
	The Compact LInear Collider (CLIC), currently under study at CERN, aims at the development of a Multi-TeV e+ e- collider and relies upon a novel two-beam acceleration concept. In the two-beam acceleration, the Radio Frequency (RF) power is extracted from a low energy but high-intensity particle beam, and it is transferred to a parallel high energy main beam. The two-beam modules are the smallest repetitive units which compose the two linacs. The RF structures are the most precise components and they are mounted and aligned on specially developed supporting system, which provides stability and quick re-positioning. The supporting girders have stringent stiffness and damping requirements, imposed by beam physics requirements. In addition, several constraints, such as allocated space and weight limitation have to be taken into consideration. This paper describes different girder configurations following various fabrication techniques and materials. Extensive qualification measurements have been performed on the first prototype units, and the main results are also presented.
TUPC013	Simulation of Phase Stability at the Flat Top of the CLIC Drive Beam	1018
	A. Gerbershagen, D. Schulte CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Funding: University of Oxford The drive beam phase stability is one of the critical issues of the Compact Linear Collider (CLIC). In this paper the generation and propagation of drive beam phase errors is studied for effects that vary during the drive beam pulse. This includes the influence of drive beam current and phase errors as well as of drive beam accelerator RF phase and amplitude errors on the drive beam phase after the compressor chicanes and the analysis of the propagation of these errors through the drive beam combination scheme. The impact of the imperfections on the main beam is studied including the possible correction with help of a feedforward system.
TUPC014	System Control for the CLIC Main Beam Quadrupole Stabilization and Nano-positioning*	1021
	S.M. Janssens, K. Artoos, C.G.R.L. Collette, M. Esposito, P. Fernandez Carmona, M. Guinchard, C. Hauviller, A.M. Kuzmin, R. Leuxe, J. Pfingstner, D. Schulte, J. Snuverink CERN, Geneva, Switzerland
	The conceptual design of the active stabilization and nano-positioning of the CLIC main beam quadrupoles was validated in models and experimentally demonstrated on test benches. Although the mechanical vibrations were reduced to within the specification of 1.5 nm at 1 Hz, additional input for the stabilization system control was received from integrated luminosity simulations that included the measured stabilization transfer functions. Studies are ongoing to obtain a transfer function which is more compatible with beam based orbit feedback; it concerns the controller layout, new sensors and their combination. In addition, the gain margin must be increased in order to reach the requirements from a higher vibration background. For this purpose, the mechanical support is adapted to raise the frequency of some resonances in the system and the implementation of force sensors is considered. Furthermore, this will increase the speed of repositioning the magnets between beam pulses. This paper describes the improvements and their implementation from a controls perspective.
TUPC015	Comparative Wakefield Analysis of a First Prototype of a DDS Structure for CLIC Main Linac	1024
	A. D'Elia, A. Grudiev, V.F. Khan, W. Wuensch CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom
	A Damped Detuned Structure (DDS) for CLIC main linac has been proposed as an alternative to the present baseline design which is based on heavy damping. A first prototype, CLICDDSA, for high power tests has been already designed and is under construction. It is also foreseen to design a further prototype, CLICDDSB, to test both the wakefield suppression and high power performances. Wakefield calculations for DDS are, in the early design stage, based on single infinitely periodic cells. Though cell-to-cell interaction is taken into account to calculate the wakefields, it is important to study full structure properties using computational tools. In particular this is fundamental for defining the input parameters for the HOM coupler that is crucial for the performances of DDS. In the following a full analysis of wakefields and impedances based on simulations conducted with finite difference based electromagnetic computer code GdfidL will be presented.
TUPC016	Status of the ATF2 Lattices	1027
	E. Marin, R. Tomás CERN, Geneva, Switzerland P. Bambade LAL, Orsay, France T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan A. Seryi JAI, Oxford, United Kingdom G.R. White, M. Woodley SLAC, Menlo Park, California, USA
	The latest status for the ATF2 Nominal and Ultra-low beta lattices designs obtained to minimize the detrimental effect of the measured multipoles are presented in this paper. A set of correction knobs for the most important aberrations at the IP have been obtained for both lattices in order to perform the tuning under realistic imperfections. Starting from the tuned ATF2 Nominal lattice a squeeze sequence reducing betay is performed to reach the ultra-low beta lattice. Tuning results are shown for both options.
TUPC017	Civil Engineering Studies for Major Projects after LHC	1030
	J.A. Osborne, F.J. Magnin, E. Perez-Duenas CERN, Geneva, Switzerland
	CERN civil engineers are heavily involved in studying several major projects to succeed/complement the LHC. Infrastructure works typically represent one third of the cost of major physics projects, so it's critical that the construction costs are well understood from the conceptual stage. For example, CERN are studying infrastructure requirements for the Linear Collider (CLIC & ILC) and the LHeC projects. This poster presents some of the key civil engineering challenges faced in such large scale projects.
TUPC018	Progress on Modelling of the Thermo-Mechanical Behavior of the CLIC Two-Beam Module	1033
	R.J. Raatikainen, K. Osterberg HIP, University of Helsinki, Finland T.O. Niinikoski, G. Riddone CERN, Geneva, Switzerland
	The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module will be tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the FEA model developed for CLIC prototype module is described. The thermal and structural results for the new module configuration are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done during 2011 and 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behaviour and they will be propagated back to the present thermo-mechanical model.
TUPC019	Beam-based Alignment of CLIC Drive Beam Decelerator using Girders Movers	1036
	G. Sterbini, D. Schulte CERN, Geneva, Switzerland
	The CLIC drive beams will provide the rf power to accelerate the colliding beams: in order to reach the design performance, an efficient transport of the drive beam has to be ensured in spite of its challenging energy spread and large current intensity. As shown in previous studies, the specifications can be met by coupling a convenient optics design with the state-of-the-art of pre-alignment and beam-based alignment techniques. In this paper we consider a novel beam-based alignment scheme that does not require quadrupole movers or dipole correctors but uses the motors already foreseen for the pre-alignment system. This implies potential savings in terms of complexity and cost at the expense of the alignment flexibility: the performance, limitations and sensitivity to pre-alignment tolerances of this method are discussed.
TUPC020	Alignment and Wake Field Issues in the CLIC RTML	1039
	F. Stulle, S. Döbert, A. Latina, D. Schulte CERN, Geneva, Switzerland
	At main linac injection the particle beams need to stay within tight tolerances for the transverse emittances and the pointing stability. We study how these tolerances influence alignment requirements for the RTML components and the stability of the beams entering the RTML. An emphasize is put on the booster linac and the RF cavities of the second bunch compression stage since short and long range wake fields might strongly influence beam dynamics in these parts of the RTML.
TUPC021	The CLIC Feasibility Demonstration in CTF3	1042
	P.K. Skowroński, J. Barranco, S. Bettoni, B. Constance, R. Corsini, A.E. Dabrowski, M. Divall Csatari, S. Döbert, A. Dubrovskiy, O. Kononenko, M. Olvegård, T. Persson, A. Rabiller, F. Tecker CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway W. Farabolini CEA/DSM/IRFU, France R.L. Lillestol NTNU, Trondheim, Norway T. Muranaka, A. Palaia, R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden
	The objective of the CLIC Test Facility CTF3 is to demonstrate the feasibility issues of the CLIC two-beam technology: the efficient generation of a very high current drive beam, used as the power source to accelerate the main beam to multi-TeV energies with gradient over 100MeV/m, stable drive beam deceleration over long distances. Results on successful beam acceleration with over 100 MeV/m energy gain are shown. Measurements of drive beam deceleration over a chain of Power Extraction Structures are presented. The achieved RF power levels, the stability of the power production and of the deceleration are discussed. Finally, we overview the remaining issues to be shown until the end of 2011.
TUPC022	Design of the CLIC Drive Beam Recombination Complex	1045
	J. Barranco, P.K. Skowroński, F. Tecker CERN, Geneva, Switzerland C. Biscari INFN/LNF, Frascati (Roma), Italy
	The CLIC Drive Beam Recombination Complex (DBRC) is designed to compress beam pulses from a current of 4.1 A to 100 A before using them to produce RF power in the deceleration lines. The beam is transported isochronously through a complex system consisting of a delay loop, two combiner rings and final turn around. The system is designed to preserve transverse and longitudinal emittances. During the optics design, chromaticity and non-linear dispersion were identified as the main single particle dynamics causes for transverse emittance increase. Different sextupole families are used to compensate these chromatic effects while keeping isochronicity. The bunch length is also adjusted to minimize coherent synchrotron radiation effects on bunch length, energy spread and transverse emittance. Finally, the injection scheme of the combiner rings was improved making the time variable bump created with help of the RF deflectors truly achromatic.
TUPC023	Status of Ground Motion Mitigation Techniques for CLIC	1048
	J. Snuverink, K. Artoos, C.G.R.L. Collette, F. Duarte Ramos, A. Gaddi, H. Gerwig, S.M. Janssens, J. Pfingstner, D. Schulte CERN, Geneva, Switzerland G. Balik, L. Brunetti, A. Jeremie IN2P3-LAPP, Annecy-le-Vieux, France P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom B. Caron SYMME, Annecy-le-Vieux, France J. Resta-López IFIC, Valencia, Spain
	The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion. A number of mitigation techniques are proposed - quadrupole stabilisation and positioning, final doublet stabilisation as well as beam based orbit and interaction point (IP) feedback. Integrated studies of the impact of the ground motion on the CLIC Main Linac (ML) and Beam Delivery System (BDS) have been performed, which model the hardware and beam performance in detail. Based on the results future improvements of the mitigation techniques are suggested and simulated. It is shown that with the current design the tight luminosity budget for ground motion effects is fulfilled and accordingly, an essential feasibility issue of CLIC has been addressed.
TUPC025	Calibration Errors in the Cavity Beam Position Monitor System at the ATF2	1051
	F.J. Cullinan, S.T. Boogert, N.Y. Joshi, A. Lyapin JAI, Egham, Surrey, United Kingdom
	It has been shown at the Accelerator Test Facility at KEK, that it is possible to run a system of 37 cavity beam position monitors (BPMs) and achieve high working resolution. However, stability of the calibration constants (position scale and radio frequency (RF) phase) over a three/four week running period is yet to be demonstrated. During the calibration procedure, random beam jitter gives rise to a statistical error in the position scale and slow orbit drift in position and tilt causes systematic errors in both the position scale and RF phase. These errors are dominant and have been evaluated for each BPM. The results are compared with the errors expected after a tested method of beam jitter subtraction has been applied.
TUPC026	Status of the Crab Cavity Design for the CLIC	1054
	P.K. Ambattu, G. Burt, A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom V.A. Dolgashev SLAC, Menlo Park, California, USA A. Grudiev CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	RF design of a crab cavity (2π/3, 11.9942 GHz) for the Compact Linear Collide (CLIC) is presented. As part of the UK-CLIC collaboration, CERN is building two copper prototypes, designed by Lancaster University / Cockcroft Institute. The first prototype to be made will be a 12 cell undamped cavity and the second will be waveguide damped cavity. The RF test at CERN will help characterisation of the dipole mode with X-band RF pulses of 15 MW peak power and pulse length of ~242 ns. Since the cavity frequency and phase advance per cell are identical to those of the CLIC main linac, the first prototype could exploit CERN’s X-band cavity characterisation facilities. A fully damped cavity will be required for the actual machine in order to meet the luminosity specs. The damped prototype will use an identical coupler type as the undamped one, but the cells will have damping waveguides with / without dielectric material.
TUPC027	CLIC Post-Collision Line Luminosity Monitoring	1057
	R. Appleby UMAN, Manchester, United Kingdom A. Apyan, L.C. Deacon, E. Gschwendtner CERN, Geneva, Switzerland
	The CLIC post collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14 MW to the main beam dump. Full Monte Carlo simulation has been done for the description of the Compact Linear Collider (CLIC) luminosity monitoring at the post collision line. One method of the luminosity diagnostic is based on the detection of high energy muons produced by the beamsstrahlung photons in the main beam dump. The disrupted beam and the beamsstrahlung photons produce at the order of 106 muons per bunch crossing, with energies greater than 10 GeV. Currently threshold Cherenkov counters are considered after the beam dump for the detection of these high energy muons. A second method using the direct detection of the beamsstrahlung photons is also considered.
TUPC028	Background and Energy Deposition Studies for the CLIC Post-Collision Line*	1060
	R. Appleby, M.D. Salt UMAN, Manchester, United Kingdom L.C. Deacon, E. Gschwendtner CERN, Geneva, Switzerland
	The CLIC post-collision line is designed to transport the spent-beam products of collision to their respective dumps, with minimal losses and thus minimal background contributions. With nanometre spot-sizes at TeV energies, large beam-beam effects induce divergence and dispersion of the outgoing beams, with a large production cross-section of Beamstrahlung photons and subsequently coherent pairs. The post-collision line should provide sufficient divergence of the beam to avoid damage to the vacuum exit and dump entrance windows. In this study, the beam losses are investigated, with the production of secondary particles from the interaction with matter simulated. The particle flux leakage from absorbers and dumps is modelled to determine the total energy deposited on magnets of the post-collision line. Finally, both electromagnetic and hadronic backgrounds at the CLIC experiment are considered.
TUPC030	Recommendation for Mitigations of the Electron Cloud Instability in the ILC	1063
	M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA L.E. Boon, K.C. Harkay ANL, Argonne, USA J.A. Crittenden, G. Dugan, M.A. Palmer CLASSE, Ithaca, New York, USA T. Demma, S. Guiducci INFN/LNF, Frascati (Roma), Italy M.A. Furman LBNL, Berkeley, California, USA K. Ohmi, K. Shibata, Y. Suetsugu, J. Urakawa KEK, Ibaraki, Japan C. Yin Vallgren Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden
	Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515. Electron cloud has been identified as one of the highest priority issues for the ILC Damping Rings (DR). A working group has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions for the electron cloud mitigation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2km design. Detailed studies of a range of mitigation options including coatings, clearing electrodes, grooves and novel concepts, were carried out over the previous several years by nearly 50 researchers, and the results of the studies form the basis for the recommendation. The assessments of the benefits or risks associated with the various options were based on a systematic ranking scheme. The recommendations are the result of the working group discussions held at numerous meetings and during a dedicated workshop. The mitigation choices will be also presented in a more detailed report later in 2012. In addition, a number of items requiring further investigation were identified and studies will be carried out at CesrTA and other institutions.
TUPC053	Superconducting Positron Stacking Ring for CLIC	1117
	F. Zimmermann, L. Rinolfi CERN, Geneva, Switzerland E.V. Bulyak, P. Gladkikh NSC/KIPT, Kharkov, Ukraine T. Omori, J. Urakawa, K. Yokoya KEK, Ibaraki, Japan
	The generation of polarized positrons for future colliders based on Compton storage rings is a promising method. A challenging key ingredient of this method is the necessary quasi-continuous positron injection into a stacking ring. The ordinary methods of multi-turn injection are not appropriate for this purpose, because the required number of injection-turns is a few hundred, and the emittance of the injected positron bunches is large. This paper describes a possible solution based on 5 GeV superconducting stacking ring, where a novel method of the combined longitudinal and transverse injection process is used to stack positrons. The ring dynamic aperture allows to inject the positron beam with normalized emittance up to 2000 micrometers during a few hundred turns. The injection efficiency is larger than 90% in simulation. The number of the injection turns is only limited by the synchrotron radiation power. The ring lattice and the results of injection simulations are presented.