| Paper |
Title |
Page |
| MOPCH091 |
An Alternative Nonlinear Collimation System for the LHC
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246 |
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- J. Resta-López, R.W. Assmann, S. Redaelli, J. Resta-López, G. Robert-Demolaize, D. Schulte, F. Zimmermann
CERN, Geneva
- A. Faus-Golfe
IFIC, Valencia
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The optics design of an alternative nonlinear collimation system for the LHC is presented. We discuss an optics scheme based on a single spoiler located in between a pair of skew sextupoles for betatron collimation. The nonlinear system allows opening up the collimator gaps and, thereby reduces the collimator impedance, which presently limits the LHC beam intensity. After placing secondary absorbers at optimum locations behind the spoiler, we analyze the beam losses and calculate the cleaning efficiency from tracking studies. The results are compared with those of the conventional linear collimation system.
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| MOPLS027 |
Beam-beam Simulations for a Single Pass SuperB-factory
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601 |
| |
- M.E. Biagini
INFN/LNF, Frascati (Roma)
- P. Raimondi, J. Seeman
SLAC, Menlo Park, California
- D. Schulte
CERN, Geneva
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A study of beam-beam collisions for an asymmetric single pass SuperB-Factory is presented*. In this scheme an electron and a positron beam are first stored and damped in two damping rings, then extracted, compressed and focused to the IP. After collision the two beams are re-injected in the DR to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Very flat beams and round beams were compared in the simulations, with the GuineaPig code**, in order to optimize both luminosity performances and beam blow-up after collision. With such approach, luminosities of the order of 1036 /(cm2 sec) can be achieved.
*http://arxiv.org/abs/physics/0512235.**D. Schulte. “Study of electromagnetic and hadronic background in the Interaction Region of the TESLA Collider”, PhD Thesis, Hamburg, 1996.
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| MOPLS094 |
Luminosity Tuning at the Interaction Point
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774 |
| |
- P. Eliasson, M. Korostelev, D. Schulte, R. Tomas, F. Zimmermann
CERN, Geneva
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Minimisation of the emittance in a linear collider is not enough to achieve optimal performance. For optimisation of the luminosity, tuning of collision parameters such as angle, offset, waist, etc. is needed, and a fast and reliable tuning signal is required. In this paper tuning knobs are presented, and their optimisation using beamstrahlung as a tuning signal is studied.
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| MOPLS096 |
Effects of Wake Fields in the CLIC BDS
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780 |
| |
- G. Rumolo, A. Latina, D. Schulte
CERN, Geneva
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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.
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| MOPLS097 |
Progress on the CTF3 Test Beam Line
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783 |
| |
- D. Schulte, S. Doebert, G. Rumolo, I. Syratchev
CERN, Geneva
- D. Carrillo
CIEMAT, Madrid
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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.
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| MOPLS098 |
Study of an ILC Main Linac that Follows the Earth Curvature
|
786 |
| |
- D. Schulte, P. Eliasson, A. Latina
CERN, Geneva
- F. Poirier, N.J. Walker
DESY, Hamburg
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In the base line configuration, the tunnel of the ILC will follow the earth curvature. The emittance growth in a curved main linac has been studied, including static and dynamic imperfections. These include effects due to current ripples in the power supplies of the steering coils, the impact of the beam position monitor scale errors.
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| MOPLS099 |
A Study of Failure Modes in the ILC Main Linac
|
789 |
| |
- D. Schulte, P. Eliasson, A. Latina
CERN, Geneva
- Eckhard. Elsen, D. Kruecker, F. Poirier, N.J. Walker, G.X. Xia
DESY, Hamburg
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Failures in the ILC can lead to beam loss or even damage the machine. Also failures that do not lead to beam loss can affect the luminosity performance, in particular since some time is required to recover from them. In the paper a number of different failures is being investigated and the impact on the machine performance is being studied.
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| MOPLS100 |
CLIC Final Focus Studies
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792 |
| |
- R. Tomas, H.-H. Braun, D. Schulte, F. Zimmermann
CERN, Geneva
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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.
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| MOPLS130 |
Implications of a Curved Tunnel for the Main Linac of CLIC
|
864 |
| |
- A. Latina, D. Schulte
CERN, Geneva
- P. Eliasson
Uppsala University, Uppsala
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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.
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| MOPLS134 |
Minimizing Emittance for the CLIC Damping Ring
|
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
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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.
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| MOPLS136 |
Ion Effects in the Damping Rings of ILC and CLIC
|
876 |
| |
- F. Zimmermann, W. Bruns, D. Schulte
CERN, Geneva
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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.
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| WEOAPA02 |
Optimum Frequency and Gradient for the CLIC Main Linac
|
1867 |
| |
- A. Grudiev, D. Schulte, W. Wuensch
CERN, Geneva
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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.
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Transparencies
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| WEPCH137 |
FAKTOR2: A Code to Simulate the Collective Effects of Electrons and Ions
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2242 |
| |
- W. Bruns, D. Schulte, F. Zimmermann
CERN, Geneva
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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.
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| WEPCH140 |
Recent Improvements of PLACET
|
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
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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.
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| WEPLS060 |
CLIC Polarized Positron Source Based on Laser Compton Scattering
|
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
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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.
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| THPCH104 |
Design and Simulation of the ILC Intra-train Orbit and Luminosity Feedback Systems
|
3041 |
| |
- G.R. White, G.R. White
JAI, Oxford
- D. Schulte
CERN, Geneva
- N.J. Walker
DESY, Hamburg
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To maintain luminosity to within a few percent of the design at the International Linear Collider (ILC), beam stability at the IP needs to be maintained at the sub-nanometre level. To achieve the beam stability required in the presence of ground motion, multiple feedback systems are required. The baseline design calls for a 5-Hz system to control the orbit in the Linac and Beam Delivery System (BDS) and an intra-train system to address high-frequency ground motion and mechanical disturbances which cause orbit distortions at the IP between pulses enough to completely destroy the luminosity. Details of the slower feedback systems have been addressed elsewhere*. The detailed design and simulation of the intra-train feedback systems are described here. This system controls the vertical position and angle at the IP such that luminosity is maximised. The system brings the beams into collision based on BPM-derived information from the initial bunches of the train. It then tunes the IP collision parameters (both position and angle) based on a fast (bunch-by-bunch) luminosity signal from the BeamCal. The system is implemented in fast digital FPGA logic, designed using Matlab's Simulink.
*A. Seryi et al. "Issues of Stability and Ground Motion in ILC", Nanobeam 2005.**G. White et al. "Multi-Bunch Simulations of the ILC for Luminosity Performance Studies", PAC2005.
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