Author: Giovannozzi, M.
Paper Title Page
TUOAB1 First LHC Transverse Beam Size Measurements With the Beam Gas Vertex Detector 1240
SUSPSIK078   use link to see paper's listing under its alternate paper code  
 
  • A. Alexopoulos, C. Barschel, E. Bravin, G. Bregliozzi, N. Chritin, B. Dehning, M. Ferro-Luzzi, M. Giovannozzi, R. Jacobsson, L.K. Jensen, O.R. Jones, V. Kain, R. Matev, M.N. Rihl, V. Salustino Guimaraes, R. Veness, S. Vlachos, B. Würkner
    CERN, Geneva, Switzerland
  • A. Bay, F. Blanc, S. Gianì, O. Girard, G.J. Haefeli, P. Hopchev, A. Kuonen, T. Nakada, O. Schneider, M. Tobin, Q.D. Veyrat, Z. Xu
    EPFL, Lausanne, Switzerland
  • R. Greim, W. Karpinski, T. Kirn, S. Schael, A. Schultz von Dratzig, G. Schwering, M. Wlochal
    RWTH, Aachen, Germany
 
  The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor based on the reconstruction of beam-gas interaction vertices which is being developed as part of the High Luminosity LHC project. Tracks are identified using several planes of scintillating fibres, located outside the beam vacuum chamber and perpendicular to the beam axis. The gas pressure in the interaction volume is adjusted such as to provide an adequate trigger rate, without disturbing the beam. A BGV demonstrator monitoring one of the two LHC beams was fully installed and commissioned in 2016. First data and beam size measurements show that the complete detector and data acquisition system is operating as expected. The BGV operating parameters are now being optimised and the reconstruction algorithms developed to produce accurate and fast reconstruction on a CPU farm in order to provide real time beam profile measurements to the LHC operators.  
slides icon Slides TUOAB1 [3.456 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOAB1  
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WEPIK088 Analysis of Performance Fluctuations for the CERN Proton Synchrotron Multi-Turn Extraction 3135
 
  • M. Giovannozzi, A. Huschauer, O. Michels, A. Nicoletti, G. Sterbini
    CERN, Geneva, Switzerland
 
  After the successful beam commissioning and tests in 2015, the Multi-Turn Extraction (MTE) has been put in operation in 2016. In this paper, the remaining issues related with fluctuation of the MTE performance are evaluated and correlation studies are presented in view of estimating the impact of planned improvements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK088  
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WEPIK092 Effect of Linear Coupling on Nonlinear Observables at the LHC 3151
 
  • E.H. Maclean, F.S. Carlier, M. Giovannozzi, T. Persson, R. Tomás
    CERN, Geneva, Switzerland
 
  Simulation work during LHC Run 1 established that linear coupling had a large impact on nonlinear observables such amplitude detuning and dynamic aperture. It is generally taken to be the largest single source of uncertainty in the modelling of the LHC's nonlinear single particle dynamics. Measurements in 2016 sought to confirm this impact of linear coupling with beam. This paper summarizes the observed influence of linear coupling on various nonlinear observables in the LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK092  
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WEPIK093 New Methods for Measurement of Nonlinear Errors in LHC Experimental IRs and Their Application in the HL-LHC 3155
 
  • E.H. Maclean, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, M. Giovannozzi, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
    CERN, Geneva, Switzerland
 
  Studies of nonlinear errors in LHC experimental insertions (IRs) during Run 1 were based upon feed-down to tune and coupling from the crossing angle orbit bumps. Useful for validating the magnetic model, this method alone is of limited use to understand discrepancies between magnetic and beam-based measurement. Feed-down from high-order multipoles is also difficult to observe. During Run 2 several alternative methods were tested in the LHC. This paper summarizes the results of these tests, and comments on their potential application to the High-Luminosity LHC upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK093  
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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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