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Jimenez, J.M.

Paper Title Page
MOPLT006 The New Layout of the LHC Cleaning Insertions 539
 
  • R.W. Assmann, O. Aberle, O.S. Brüning, S. Chemli, D. Gasser, J.-B. Jeanneret, J.M. Jimenez, V. Kain, E. Métral, G. Peon, S. Ramberger, C. Rathjen, T. Risselada, F. Ruggiero, L. Vos
    CERN, Geneva
  • D. Kaltchev
    TRIUMF, Vancouver
  
  The improved LHC collimation system required significant changes in the layout and design of the warm insertion IR7. Requirements for collimation, optics, impedance, vacuum, and additional infrastructure are described and the adopted layout is discussed. Various design principles have been explored during the re-design, ranging from a regular 90 degree lattice and special low impedance lattices to an option with additional warm quadrupole units that could have extended the usable space for collimator installations in the insertion. The various constraints for the optics and cleaning design in the LHC cleaning insertions are summarized. Magnet positions and collimators were moved significantly, such that a good cleaning efficiency was maintained while impedance was reduced by a factor of two. Metallic phase 2 collimators allow a better efficiency than originally achievable and additional scrapers were allocated. The required infrastructure was specified, including a powerful cooling system for the collimators.  
MOPLT005 An Improved Collimation System for the LHC 536
 
  • 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
  
  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.  
WEPLT044 Electron-cloud Build-up Simulations and Experiments at CERN 1930
 
  • F. Zimmermann, G. Arduini, V. Baglin, T. Bohl, B.J. Jenninger, J.M. Jimenez, J.-M. Laurent, F. Ruggiero, D. Schulte
    CERN, Geneva
  
  We compare the predications of electron-cloud build-up simulations with measurements at the CERN SPS. Specifically, we compare the electron flux at the wall, electron-energy spectra, heat loads, and the spatial distribution of the electrons for two different bunch spacings, with variable magnetic fields, and for several chamber temperatures and associated surface conditions. The simulations employ a modified, improved version of the ECLOUD code. The main changes are briefly described. We finally present updated simulation results for the heat load in the cold LHC arcs.