• M. Bai, W.C. Dawson, Y. Makdisi, W. Meng, S. Nayak, P. Oddo, C. Pai, P.H. Pile, T. Roser
  BNL, Upton, Long Island, New York
• F. Méot
  CEA, Gif-sur-Yvette

Commissioning of spin flipper in the RHIC (Relativistic Heavy Ion Collider) Blue ring during the 2009 RHIC polarized proton run showed significant global vertical coherent betatron oscillations induced by a two AC dipole plus four DC dipole configuration. These global orbital coherent oscillations affected collision rates and Yellow beam polarization when beams were in collision. The measured depolarizing strength of of the two AC dipoles at a phase difference of 180 degrees at injection with a different spin tune also confirmed that a single isolated spin resonance can not be induced in the presence of this global vertical coherent betatron oscillation. Hence, a new design was proposed to eliminate the coherent orbital oscillation outside the spin flipper with three additional AC dipoles. This paper presents the new design and supporting numerical simulations. In the RHIC 2010 Au run, only one AC dipole was inserted between the two original AC dipoles; and the measured closure of this AC dipole bump is also presented.

This work is under the auspices of the US Department of Energy

• C. Montag, L. Ahrens, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, G. Ganetis, C.J. Gardner, J.W. Glenn, H. Hahn, M. Harvey, T. Hayes, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, A. Kayran, J. Kewisch, R.C. Lee, D.I. Lowenstein, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, N. Malitsky, G.J. Marr, A. Marusic, M.P. Menga, R.J. Michnoff, M.G. Minty, J. Morris, B. Oerter, F.C. Pilat, P.H. Pile, E. Pozdeyev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, T. Satogata, V. Schoefer, C. Schultheiss, F. Severino, M. Sivertz, K. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
  BNL, Upton, Long Island, New York

During the second half of Run-9, the Relativistic Heavy Ion Collider (RHIC) provided polarized proton collisions at two interaction points with both longitudinal and vertical spin direction. Despite an increase in the peak luminosity by up to 40%, the average store luminosity did not increase compared to previous runs. We discuss the luminosity limitations and polarization performance during Run-9.