• Open Access

Beam diffusion measurements using collimator scans in the LHC

Gianluca Valentino, Ralph Aßmann, Roderik Bruce, Florian Burkart, Valentina Previtali, Stefano Redaelli, Belen Salvachua, Giulio Stancari, and Alexander Valishev
Phys. Rev. ST Accel. Beams 16, 021003 – Published 19 February 2013

Abstract

The time evolution of beam losses during a collimator scan provides information on halo diffusion and population. This is an essential input for machine performance characterization and for the design of collimation systems. Beam halo measurements in the CERN Large Hadron Collider were conducted through collimator scrapings in a dedicated beam study for the first time at 4 TeV. Four scans were performed with two collimators, in the vertical plane for beam 1 and horizontally for beam 2, before and after bringing the beams into collisions. Inward and outward steps were performed. A diffusion model was used to interpret the observed loss rate evolution in response to the collimator steps. With this technique, diffusion coefficients were estimated as a function of betatron oscillation amplitude from approximately 3 to 7 standard deviations of the transverse beam distribution. A comparison of halo diffusion and core emittance growth rates is also presented.

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  • Received 6 December 2012

DOI:https://doi.org/10.1103/PhysRevSTAB.16.021003

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Authors & Affiliations

Gianluca Valentino1,2,*, Ralph Aßmann3,†, Roderik Bruce1, Florian Burkart1, Valentina Previtali4, Stefano Redaelli1, Belen Salvachua1, Giulio Stancari4,‡, and Alexander Valishev4

  • 1CERN, Geneva, Switzerland
  • 2University of Malta, Msida, Malta
  • 3DESY, Hamburg, Germany
  • 4Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois 60510, USA

  • *gianluca.valentino@cern.ch
  • On leave from CERN, Geneva, Switzerland.
  • stancari@fnal.gov

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Vol. 16, Iss. 2 — February 2013

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