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Lin, F.

Paper Title Page
TPAP044 Observations of Snake Resonance in RHIC 2839
 
  • M. Bai, H. Huang, W. Mac Kay, V. Ptitsyn, T. Roser, S. Tepikian
    BNL, Upton, Long Island, New York
  • S.-Y. Lee, F. Lin
    IUCF, Bloomington, Indiana
  
  Funding: The work was performed under the auspices of the U.S. Department of Energy.

Siberian snakes now become essential in the polarized proton acceleration. With proper configuration of Siberian snakes, the spin precession tune of the beam becomes $\frac{1}{2}$ which avoids all the spin depolarizing resonance. However, the enhancement of the perturbations on the spin motion can still occur when the betatron tune is near some low order fractional numbers, called snake resonances, and the beam can be depolarized when passing through the resonance. The snake resonances have been confirmed in the spin tracking calculations, and observed in RHIC with polarized proton beam. Equipped with two full Siberian snakes in each ring, RHIC provides us a perfect facility for snake resonance studies. This paper presents latest experimental results. New insights are also discussed.

 
FPAE014 Acceleration of Polarized Protons in the AGS with Two Helical Partial Snakes 1404
 
  • H. Huang, L. Ahrens, M. Bai, A. Bravar, K.A. Brown, G. Bunce, E.D. Courant, C.J. Gardner, J. Glenn, R.C. Gupta, A.U. Luccio, W.W. MacKay, V. Ptitsyn, T. Roser, S. Tepikian, N. Tsoupas, E. Willen, A. Zelenski, K. Zeno
    BNL, Upton, Long Island, New York
  • F. Lin
    IUCF, Bloomington, Indiana
  • M. Okamura
    RIKEN/RARF/CC, Saitama
  • J. Takano
    RIKEN, Saitama
  • D.G. Underwood
    ANL, Argonne, Illinois
  • J. Wood
    UCLA, Los Angeles, California
  
  Funding: Work supported by U.S. DOE and RIKEN of Japan.

The RHIC spin program requires 2*1011 proton/bunch with 70% polarization. As the injector to RHIC, AGS is the bottleneck for preserving polarization: there is not enough space in the ring to install a full snake to overcome the numerous depolarizing resonances. An ac dipole and a partial Siberian snake have been used to preserve beam polarization in the past. The correction with this scheme is not 100% since not all depolarizing resonances can be overcome. Recently, two helical snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate all depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.