| Paper |
Title |
Page |
| MOPLT005 |
An Improved Collimation System for the LHC
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536 |
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- R.W. Assmann, O. Aberle, A. Bertarelli, H.-H. Braun, M. Brugger, L. Bruno, O.S. Brüning, S. Calatroni, E. Chiaveri, B. Dehning, A. Ferrari, B. Goddard, E.B. Holzer, J.-B. Jeanneret, J.M. Jimenez, V. Kain, M. Lamont, M. Mayer, E. Métral, R. Perret, S. Redaelli, T. Risselada, G. Robert-Demolaize, S. Roesler, F. Ruggiero, R. Schmidt, D. Schulte, P. Sievers, V. Vlachoudis, L. Vos, G. Vossenberg, J. Wenninger
CERN, Geneva
- I.L. Ajguirei, I. Baishev, I.L. Kurochkin
IHEP Protvino, Protvino, Moscow Region
- D. Kaltchev
TRIUMF, Vancouver
- H. Tsutsui
SHI, Tokyo
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The LHC design parameters extend the maximum stored beam energy 2-3 orders of magnitude beyond present experience. The handling of the high-intensity LHC beams in a super-conducting environment requires a high-robustness collimation system with unprecedented cleaning efficiency. For gap closures down to 2mm no beam instabilities may be induced from the collimator impedance. A difficult trade-off between collimator robustness, cleaning efficiency and collimator impedance is encountered. The conflicting LHC requirements are resolved with a phased approach, relying on low Z collimators for maximum robustness and hybrid metallic collimators for maximum performance. Efficiency is further enhanced with an additional cleaning close to the insertion triplets. The machine layouts have been adapted to the new requirements. The LHC collimation hardware is presently under design and has entered into the prototyping and early testing phase. Plans for collimator tests with beam are presented.
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| WEPLT006 |
Expected Performance and Beam-based Optimization of the LHC Collimation System
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1825 |
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- R.W. Assmann, E.B. Holzer, J.-B. Jeanneret, V. Kain, S. Redaelli, G. Robert-Demolaize, J. Wenninger
CERN, Geneva
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The cleaning efficiency requirements in the LHC are 2-3 orders of magnitude beyond the requirements at other super-conducting circular colliders. The achievable ideal cleaning efficiency in the LHC is presented and the deteriorating effects of various physics processes and imperfections are discussed in detail for the improved LHC collimation system. The longitudinal distribution of proton losses downstream of the betatron cleaning system are evaluated with a realistic aperture model of the LHC. The results from simplified tracking studies are compared to simulations with complete physics and error models. Possibilities for beam-based optimization of collimator settings are described.
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| THPLT011 |
Longitudinal Loss Distribution along the LHC
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2481 |
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- E.B. Holzer, B. Dehning
CERN, Geneva
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For the design and calibration of the LHC beam loss monitoring system it is essential to have good predictions of the expected longitudinal loss distributions. For this purpose a complete and detailed aperture model of one LHC sector was compiled and included with the tracking code MAD. The positions of all beam pipe bellows are included in the model as well. Therefore, it allows investigating the loss pattern due to misalignment effects, in addition to steady beam losses (beam halo, beam-beam and beam-rest gas interactions) and orbit errors. Loss maps of halo particles originating from the betatron cleaning insertion have been created for proton and ion beams. The distribution of particle losses along the beam pipe is folded with the result of GEANT simulations of the shower development through the magnets and cold masses. They link the loss of a beam particle on the aperture to particle fluencies outside of the cryostats, where the beam loss monitors will be installed. These simulations determine the positioning of the loss monitors, the longitudinal distance one detector has to cover to achieve the required resolution as well as all calibration factors for the individual detectors. The model also serves to identify hot spots, which can limit the performance of the LHC.
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| THPLT012 |
Design of the Beam Loss Monitoring System for the LHC Ring
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2484 |
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- E.B. Holzer, B. Dehning, E. Effinger, G. Ferioli, J.L. Gonzalez, E. Gschwendtner, G. Guaglio, M. Hodgson, V. Prieto, C. Zamantzas
CERN, Geneva
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The beam loss monitoring (BLM) system of the LHC is one of the most critical elements for the protection of the LHC. It must prevent the super conducting magnets from quenches and the machine components from damages, caused by beam losses. It helps in the identification of the loss mechanism by measuring the loss pattern. Special detectors will be used for the setup and control of the collimators. Furthermore, it will be an important tool during machine setup and studies. The specification requirements of the BLM system include a very high reliability
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