• M.G. Minty, A.J. Curcio, W.C. Dawson, C. Degen, Y. Luo, G.J. Marr, B. Martin, A. Marusic, K. Mernick, P. Oddo, T. Russo, V. Schoefer, R. Schroeder, C. Schultheiss, M. Wilinski
  BNL, Upton, Long Island, New York

Precision measurement and control of the betatron tunes and betatron coupling in the Relativistic Heavy Ion Collider (RHIC) are required for establishing and maintaining both good operating conditions and, particularly during the ramp to high beam energies, high proton beam polarization. While the proof-of-principle for simultaneous tune and coupling feedback was successfully demonstrated earlier, routine application of these systems has only become possible recently. Following numerous modifications for improved measurement resolution and feedback control, the time required to establish full-energy beams with the betatron tunes and coupling regulated by feedback was reduced from several weeks to a few hours. A summary of these improvements, select measurements benefitting from the improved resolution and a review of system performance are the subject of this report.

• K.A. Brown, L. Ahrens, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, D. Bruno, C. Carlson, R. Connolly, T. D'Ottavio, R. De Maria, K.A. Drees, W. Fischer, W. Fu, C.J. Gardner, D.M. Gassner, J.W. Glenn, Y. Hao, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, J.S. Laster, R.C. Lee, V. Litvinenko, Y. Luo, W.W. MacKay, M. Mapes, G.J. Marr, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, B. Oerter, F.C. Pilat, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, P. Sampson, J. Sandberg, T. Satogata, V. Schoefer, C. Schultheiss, F. Severino, K. Smith, D. Steski, S. Tepikian, C. Theisen, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang
  BNL, Upton, Long Island, New York

Since the last successful RHIC Au+Au run in 2007 (Run7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run7 RHIC achieved an average store luminosity of <L>=12x10²⁶ cm^-2 s^-1 by operating with 103 bunches (out of 110 possible), and by squeezing to β*=0.8 m. Our goal for this year's run, Run10, was to achieve an average of <L>=27x10²⁶ cm^-2 s^-1. The measures taken were decreasing β* to 0.6 m, and reducing longitudinal and transverse emittances by means of bunched-beam stochastic cooling. In addition we introduced a lattice to suppress intra-beam scattering (IBS) in both RHIC rings, upgraded the RF system, and separated transition crossings in both rings while ramping. We present an overview of the changes and the results in terms of Run10 increased instantaneous luminosity, luminosity lifetime, and integrated luminosity.

• 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.