Author: Crouch, M.P.
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TUPVA025 Observations of Beam Losses at the LHC During Reduction of Crossing Angle 2105
 
  • B. Salvachua, X. Buffat, A.A. Gorzawski, T. Pieloni, S. Redaelli, C. Tambasco, J. Wenninger
    CERN, Geneva, Switzerland
  • J. Barranco García, A.A. Gorzawski
    EPFL, Lausanne, Switzerland
  • M.P. Crouch
    UMAN, Manchester, United Kingdom
 
  Several machine development studies have been performed in 2016 at the LHC in order to evaluate the effects of reducing the crossing angles in favor of defining the maximum achievable luminosity in the ATLAS and CMS experiments. At the end of the LHC proton-proton run at 6.5TeV the reduction of the crossing angle from 185urad to 140urad was operationally implemented. The observation of beam losses and lifetimes during this process are analysed and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA025  
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THPAB056 Dynamic Aperture Studies of the Long-Range Beam-Beam Interaction at the LHC 3840
 
  • M.P. Crouch, R.B. Appleby
    UMAN, Manchester, United Kingdom
  • J. Barranco García, T. Pieloni, C. Tambasco
    EPFL, Lausanne, Switzerland
  • X. Buffat, M. Giovannozzi, E.H. Maclean
    CERN, Geneva, Switzerland
  • B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Long-range beam-beam interactions dictate the choice of operational parameters for the LHC, such as the crossing angle and β* and therefore the luminosity reach for the collider. These effects can lead to particle losses, closed orbit effects and emittance growth. Defining how these effects depend on the beam-beam separation will determine the minimum crossing angle and the β* the LHC can operate. In this article, analysis from a dedicated machine study is presented in which the crossing angle was reduced in steps and the impact on beam intensity and luminosity lifetimes were observed. Based on the observations during the machine study, the intensity decays are compared to expectations from models. Estimates of the luminosity reach in the LHC are also computed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB056  
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