| Paper |
Title |
Page |
| MOPLT010 |
Collimation of Heavy Ion Beams in LHC
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551 |
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- H.-H. Braun, R.W. Assmann, A. Ferrari, J.-B. Jeanneret, J.M. Jowett
CERN, Geneva
- I.A. Pshenichnov
RAS/INR, Moscow
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The LHC collimation system is designed to cope with requirements of proton beams having 100 times higher beam power than the nominal LHC heavy ion beam. In spite of this, specific problems occur for ion collimation, due to different particle-collimator interaction mechanism for ions and protons. Ions are subject to hadronic fragmentation and electromagnetic dissociation, resulting in a non-negligible flux of secondary particles of small angle divergence and Z/A ratios slightly different from the primary beam. These particles are difficult to intercept by the collimation system and can produce significant heat-load in the superconducting magnets when they hit the magnet vacuum chamber. A computer program has been developed to obtain quantitative estimates of the magnitude and location of the particle losses. Hadronic fragmentation and electromagnetic dissociation of ions in the collimators were considered within the frameworks of abrasion-ablation and RELDIS models, respectively. Trajectories of the secondary particles in the ring magnet lattice and the distribution of intercept points of these trajectories with the vacuum chamber are computed. Results are given for the present collimation system design and potential improvements are discussed.
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| MOPLT020 |
Limits to the Performance of the LHC with Ion Beams
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578 |
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- J.M. Jowett, H.-H. Braun, M.I. Gresham, E. Mahner, A.N. Nicholson, E.N. Shaposhnikova
CERN, Geneva
- I.A. Pshenichnov
RAS/INR, Moscow
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The performance of the LHC as a heavy-ion collider will be limited by a diverse range of phenomena that are often qualitatively different from those limiting the performance with protons. We summarise the latest understanding and results concerning the consequences of nuclear electromagnetic processes in lead ion collisions, the interactions of ions with the residual gas and the effects of lost ions on the beam environment and vacuum. Besides these limitations on beam intensity, lifetime and luminosity, performance will be governed by the evolution of the beam emittances under the influences of synchrotron radiation damping, intra-beam scattering, RF noise and multiple scattering on residual gas. These effects constrain beam parameters in the LHC ring throughout the operational cycle with lead ions.
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