Author: Gorzawski, A.A.
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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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THPAB042 Long-Range Beam-Beam Orbit Effects in LHC, Simulations and Observations From Machine Operation in 2016 3799
 
  • A.A. Gorzawski, K. Fuchsberger, M. Hostettler, T. Pieloni, J. Wenninger
    CERN, Geneva, Switzerland
 
  To limit the number of head on collisions to only one at the interaction point in the Large Hadron Collider (LHC), two beams are colliding with a non zero crossing angle. Under the presence of such angle the closed orbits of the individual bunches in the bunch train varies due to the long-range beam-beam effects. These variations leave a signature as a non zero transverse offset at the collision points visible in the front and trail of the bunch train. When operation team aims for the optimised beam orbit and therefore maximised luminosity, those front and tail bunches due to the overall offset experience reduced luminosity. This paper describes an overview of the existing tool for simulating these effects and compares to operational data. The effects of different operational scenarios (i.e. beam brightness, reduced or asymmetric crossing angles between the interaction points etc.) are simulated and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB042  
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