Paper |
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WEOAG02 |
Measurements of Heavy Ion Beam Losses from Collimation
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1906 |
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- R. Bruce, R. W. Assmann, G. Bellodi, C. Bracco, H.-H. Braun, S. S. Gilardoni, E. B. Holzer, J. M. Jowett, S. Redaelli, Th. Weiler, C. Zamantzas
CERN, Geneva
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The collimation efficiency for Pb82+ ion beams in the LHC is predicted to be much lower than for protons. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements of loss patterns caused by a prototype LHC collimator in the CERN SPS. The loss maps show a qualitative difference between Pb82+ ions and protons, with the maximum loss rate observed at different places in the ring. This behaviour was predicted by simulations and provides a valuable benchmark of the simulations done for the LHC.
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Slides
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WEPP064 |
Apertures in the LHC Beam Dump System and Beam Losses during Beam Abort
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2665 |
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- T. Kramer, B. Goddard, M. Gyr, A. Koschik, J. A. Uythoven, Th. Weiler
CERN, Geneva
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The LHC beam dump system is used to dispose accelerated protons and ions in a wide energy range from 450 GeV up to 7 TeV. An abort gap of 3 microseconds is foreseen to avoid sweeping particles through the ring aperture. This paper gives a brief overview of the critical apertures in the extraction region and the two beam dump lines, and presents MAD-X tracking studies made to investigate the impact of particles swept through the aperture due to extraction kicker failures or spurious particles within the abort gap.
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WEPP009 |
Collimator Integration and Installation Example of One Object to be Installed in the LHC
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2542 |
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- K. Foraz, O. Aberle, R. W. Assmann, C. Bertone, R. Chamizo, S. Chemli, J.-P. Corso, F. Delsaux, J. L. Grenard, J. M. Jimenez, Y. Kadi, K. Kershaw, M. Lazzaroni, R. Perret, Th. Weiler
CERN, Geneva
- J. Coupard
IN2P3-CNRS, Orsay
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The collimation system is a vital part of the LHC project, protecting the accelerator against unavoidable regular and irregular beam loss. About 80 collimators will be installed in the machine before the first run. Two insertion regions are dedicated to collimation and these regions will be among the most radioactive in the LHC. The space available in the collimation regions is very restricted. It was therefore important to ensure that the 3-D integration of these areas of the LHC tunnel would allow straightforward installation of collimators and also exchange of collimators under the remote handling constraints imposed by high radiation levels. The paper describes the 3-D integration studies and verifications of the collimation regions combining the restricted space available, the dimensions of the different types of collimators and the space needed for transport and handling. The paper explains how installation has been planned and carried out taking into account the handling system and component availability.
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WEPP072 |
Evaluation of Beam Losses and Energy Deposition for A Possible Phase II Design for LHC Collimation
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2686 |
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- L. Lari, R. W. Assmann, C. Bracco, M. Brugger, F. Cerutti, A. Ferrari, M. Mauri, S. Redaelli, L. Sarchiapone, V. Vlachoudis, Th. Weiler
CERN, Geneva
- J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith
SLAC, Menlo Park, California
- L. Lari
EPFL, Lausanne
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The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.
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