Physical Review Accelerators and Beams (Sep 2017)

4-twist helix snake to maintain polarization in multi-GeV proton rings

  • F. Antoulinakis,
  • Y. Chen,
  • A. Dutton,
  • E. Rossi De La Fuente,
  • S. Haupert,
  • E. A. Ljungman,
  • P. D. Myers,
  • J. K. Thompson,
  • A. Tai,
  • C. A. Aidala,
  • E. D. Courant,
  • A. D. Krisch,
  • M. A. Leonova,
  • W. Lorenzon,
  • R. S. Raymond,
  • D. W. Sivers,
  • V. K. Wong,
  • T. Yang,
  • Y. S. Derbenev,
  • V. S. Morozov,
  • A. M. Kondratenko

DOI
https://doi.org/10.1103/PhysRevAccelBeams.20.091003
Journal volume & issue
Vol. 20, no. 9
p. 091003

Abstract

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Solenoid Siberian snakes have successfully maintained polarization in particle rings below 1 GeV, but never in multi-GeV rings, because the spin rotation by a solenoid is inversely proportional to the beam momentum. High energy rings, such as Brookhaven’s 255 GeV Relativistic Heavy Ion Collider (RHIC), use only odd multiples of pairs of transverse B-field Siberian snakes directly opposite each other. When it became impractical to use a pair of Siberian Snakes in Fermilab’s 120 GeV/c Main Injector, we searched for a new type of single Siberian snake that could overcome all depolarizing resonances in the 8.9–120 GeV/c range. We found that a snake made of one 4-twist helix and 2 dipoles could maintain the polarization. This snake design could solve the long-standing problem of significant polarization loss during acceleration of polarized protons from a few GeV to tens of GeV, such as in the AGS, before injecting them into multi-hundred GeV rings, such as RHIC.