Author: Steinhagen, R.J.
Paper Title Page
TUPPR068 The Achromatic Telescopic Squeezing Scheme: Basic Principles and First Demonstration at the LHC 1978
  • S.D. Fartoukh, R. De Maria, B. Goddard, W. Höfle, M. Lamont, G.J. Müller, L. Ponce, S. Redaelli, R.J. Steinhagen, M. Strzelczyk, R. Tomás, G. Vanbavinckhove, J. Wenninger
    CERN, Geneva, Switzerland
  • R. Miyamoto
    ESS, Lund, Sweden
  The Achromatic Telescopic Squeezing (ATS) scheme [1] is a novel squeezing mechanism enabling the production of very low β* in circular colliders. The basic principles of the ATS scheme will be reviewed together with its strong justification for the High-Luminosity LHC Project. In this context, a few dedicated beam experiments were meticulously prepared and took place at the LHC in 2011. The results obtained will be highlighted, demonstrating already the potential of the ATS scheme for any upgrade project relying on a strong reduction of β*.
[1] S. Fartoukh, "An Achromatic Telescopic Squeezing (ATS) Scheme For The LHC Upgrade," IPAC'11, WEPC037, p. 2088 (2001).
TUPPR077 Simulation Studies for the LHC Long-Range Beam-Beam Compensators 2002
  • T.L. Rijoff, R.J. Steinhagen, F. Zimmermann
    CERN, Geneva, Switzerland
  The LHC performance and the minimum crossing angle are limited by long-range beam-beam collisions. Wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, smaller β*, or higher beam intensity. A prototype long-range wire compensator should be installed in the LHC by 2014/15. We report simulation studies examining and comparing the efficiency of the wire compensation, in terms of tune footprint or dynamic aperture, at various candidate locations, with different wire shapes, and for varying transverse distance from the beam.  
WEEPPB014 The Magnetic Model of the LHC during the 3.5 TeV Run 2194
  • E. Todesco, N. Aquilina, M. Giovannozzi, M. Lamont, F. Schmidt, R.J. Steinhagen, M. Strzelczyk, R. Tomás
    CERN, Geneva, Switzerland
  • N.J. Sammut
    University of Malta, Information and Communication Technology, Msida, Malta
  The magnetic model of the LHC is based on a fit of the magnetic measurements through equations that model the field components (geometric, saturation, persistent) at different currents. In this paper we will review the main results related to the magnetic model during the run of the LHC in 2010-2011: with a top energy of 3.5 TeV, all components of the model but the saturation are visible. We first give an estimate of the reproducibility of the main components and multipolar errors as they can be deduced from beam measurements, i.e. orbit, tune, chromaticity, beta beating and coupling. We then review the main results relative to the decay at injection plateau, dependence on powering history, and snapback at the beginning of the ramp for both tune and chromaticity. We discuss the precision obtained in tracking the magnets during the ramp, where the persistent current components gradually disappear. We conclude by presenting the behaviour of the quadrupoles model during the squeeze. A list of the major changes implemented during the operation together with what are considered as the main open issues is given.  
TUPPC081 First Experimental Observations from the LHC Dynamic Aperture Experiment 1362
  • M. Giovannozzi, M. Albert, G.E. Crockford, S.D. Fartoukh, W. Höfle, E.H. Maclean, A. Macpherson, L. Ponce, S. Redaelli, H. Renshall, F. Roncarolo, R.J. Steinhagen, E. Todesco, R. Tomás, W. Venturini Delsolaro
    CERN, Geneva, Switzerland
  • R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  Following intensive numerical simulations to compute the dynamic aperture for the LHC in the design phase, the successful beam commissioning and the ensuing beam operations opened the possibility of performing beam measurements of the dynamics aperture. In this paper the experimental set-up and the first observations based on the few experimental sessions performed will be presented and discussed in detail.