MC4: Hadron Accelerators
T19 Collimation
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MOPRB058 Collimation of Partially Stripped Ion Beams in the LHC 700
 
  • A. Abramov, L.J. Nevay
    JAI, Egham, Surrey, United Kingdom
  • R. Bruce, N. Fuster-Martínez, A.A. Gorzawski, M.W. Krasny, J. Molson, S. Redaelli, M. Schaumann
    CERN, Meyrin, Switzerland
 
  In the scope of the Physics Beyond Colliders studies, the Gamma Factory initiative proposes the use of partially stripped ions as a driver of a new type, high intensity photon source in CERN’s Large Hadron Collider (LHC). In 2018, the LHC accelerated and stored partially stripped 208-Pb-81+ ions for the first time. The collimation system efficiency recorded during this test was found to be prohibitively low. The worst losses were localised in the dispersion suppressor (DS) of the betatron-cleaning insertion. Analytic arguments and simulations show that the large losses are driven by the stripping of the remaining electron from the Pb nucleus by the primary collimators. The rising dispersion in the DS pushes the resulting off-rigidity, fully-stripped ions into the aperture of the superconducting magnets. In this study the measured loss maps are compared against results from simulations. Different mitigation strategies are outlined, including a dispersion suppressor (DS) collimator, crystal collimation or an orbit bump.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB058  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB059 Collimation of Heavy-Ion Beams in the HE-LHC 704
SUSPFO111   use link to see paper's listing under its alternate paper code  
 
  • A. Abramov, L.J. Nevay
    JAI, Egham, Surrey, United Kingdom
  • R. Bruce, M.P. Crouch, N. Fuster-Martínez, A. Mereghetti, J. Molson, S. Redaelli
    CERN, Meyrin, Switzerland
 
  A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (Pb-82-208) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB059  
About • paper received ※ 18 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPRB060 Simulating Novel Collimation Schemes for High-Luminosity LHC With Merlin++ 708
 
  • S.C. Tygier, R.B. Appleby
    UMAN, Manchester, United Kingdom
  • R.J. Barlow, S. Rowan
    IIAA, Huddersfield, United Kingdom
 
  Due to the large stored beam energy in the HL-LHC new collimation technologies must be used to protect the machine. Active halo control of the proton beam halo with a Hollow Electron Lens can give a kick to protons at the edge of the beam without effecting the core. Various modes of operation are possible for example the electron lens can have a continuous current or it can be pulsed to different amplitudes for each passage of the proton beam. In this article we use Merlin++ simulations to show the performance of these modes for HL-LHC parameters. We also present recent simulations comparing scattering models in Merlin++.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB060  
About • paper received ※ 08 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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