Author: Schoefer, V.
Paper Title Page
MOPPC024 Modelling of the AGS Using Zgoubi - Status 181
  • F. Méot, L. A. Ahrens, Y. Dutheil, J.W. Glenn, H. Huang, T. Roser, V. Schoefer, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  A computer model, based on the ray-tracing code Zgoubi, is being developed in view of on-line simulation of the RHIC injector AGS, and of beam and spin dynamics simulations and studies in the presence of the cold and warm helical partial snakes. A status of this work is given here.  
MOPPC025 RHIC Polarized Proton Operation in Run 12 184
  • V. Schoefer, L. A. Ahrens, A. Anders, E.C. Aschenauer, G. Atoian, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, A. Dion, K.A. Drees, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, R.L. Hulsart, A. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
    BNL, Upton, Long Island, New York, USA
  Successful RHIC operation with polarized protons requires meeting demanding and sometimes competing goals for maximizing both luminosity and beam polarization. In Run 12 we sought to fully integrate into operation the many systems that were newly commissioned in Run 11 as well as to enhance collider performance with incremental improvements throughout the acceleration cycle. For luminosity maximization special attention was paid to several possible source of emittance dilution along the injector chain, in particular to optical matching during transfer between accelerators. Possible sources of depolarization in the AGS and RHIC were also investigated including the effects of local coupling and low frequency (10 Hz) oscillations in the vertical equilibrium orbit during the RHIC ramp. The results of a fine storage energy scan made in an effort to improve store polarization lifetime are also reported in this note.  
TUXA03 Increasing the AGS Beam Polarization with 80 Tune Jumps 1015
  • V. Schoefer, L. A. Ahrens, M. Bai, E.D. Courant, W. Fu, C.J. Gardner, J.W. Glenn, H. Huang, F. Lin, A.U. Luccio, J.-L. Mi, J. Morris, P.J. Rosas, T. Roser, P. Thieberger, N. Tsoupas, A. Zelenski, K. Zeno
    BNL, Upton, Long Island, New York, USA
  Vertical depolarizing resonances in the AGS are removed by partial Siberian snakes. These magnets move the stable spin direction and lead to horizontal depolarizing resonances. The tune jump quadrupole system increases the crossing rate for horizontal resonances by a factor of six. This presentation will review the fundamental mechanism of depolarizing resonances, the partial Siberian snake solution and describe recent experimental evidence at the AGS demonstrating improvements to beam polarization and the beam dynamics challenges posed by the tune jump.  
slides icon Slides TUXA03 [5.199 MB]  
THPPP030 Near Integer Tune for Polarization Preservation in the AGS 3797
  • N. Tsoupas, L. A. Ahrens, M. Bai, K.A. Brown, J.W. Glenn, H. Huang, W.W. MacKay, T. Roser, V. Schoefer, K. Zeno
    BNL, Upton, Long Island, New York, USA
  Funding: *Work supported by the US Department of Energy.
The high energy (T=250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, two partial helical magnets* have been installed in AGS. In order to minimize the loss of the beam polarization due to the various intrinsic spin resonances occurring during the proton acceleration, we constrain the value of the vertical tune to be higher than 8.97. With the AGS running at near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads** in AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices.
* H. Huang, et al., Proc. EPAC06, p. 273, (2006).
** N. Tsoupas et al., Proc. PAC07, p. 3723 (2007).