• M. Bai, L. A. Ahrens, J.G. Alessi, G. Atonian, A. Bazilevsky, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, G. Ganetis, C.J. Gardner, R.L. Gill, J.W. Glenn, Y. Hao, T. Hayes, H. Huang, R.L. Hulsart, A. Kayran, J.S. Laster, R.C. Lee, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, G.J. Marr, A. Marusic, G.T. McIntyre, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, B. Morozov, J. Morris, P. Oddo, B. Oerter, F.C. Pilat, V. Ptitsyn, D. Raparia, G. Robert-Demolaize, T. Roser, T. Russo, T. Satogata, V. Schoefer, K. Smith, D. Svirida, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

After having provided collisions of polarized protons at a beam energy of 100 GeV since 2001, the Relativistic Heavy Ion Collider~(RHIC) at BNL reached its design energy of polarized proton collision at 250 GeV. With the help of the two full Siberian snakes in each ring as well as careful orbit correction and working point control, polarization was preserved during acceleration from injection to 250~GeV. During the course of the Physics data taking, the spin rotators on either side of the experiments of STAR and PHENIX were set up to provide collisions with longitudinal polarization at both experiments. Various techniques to increase luminosity like further beta star squeeze and RF system upgrades as well as gymnastics to shorten the bunch length at store were also explored during the run. This paper reports the performance of the run as well as the plan for future performance improvement in RHIC.

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• F. Lin, H. Huang, A.U. Luccio, T. Roser
  BNL, Upton, Long Island, New York

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

A new horizontal tune jump mechanism has been proposed to overcome the horizontal intrinsic resonances and preserve the polarization of the proton beam in the AGS during the energy ramp. An adiabatic change of the AGS lattice is needed to avoid the emittance growth in both horizontal and vertical motion, as the emittance growth can deteriorate the polarization of the proton beam. Two critical questions are necessary to be answered: how fast can the lattice be changed and how much emittance growth can be tolerated from both optics and polarization points of view? Preliminary simulations, using a realistic AGS lattice and acceleration rate, have been carried out to give a first glance of this mechanism. Several different conditions are presented in this paper.

• H. Huang, L. A. Ahrens, M. Bai, K.A. Brown, C.J. Gardner, J.W. Glenn, F. Lin, A.U. Luccio, W.W. MacKay, T. Roser, V. Schoefer, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno
  BNL, Upton, Long Island, New York
• H.M. Spinka, D.G. Underwood
  ANL, Argonne

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

After installation of two partial snakes in the Brookhaven Alternating Gradient Synchrotron (AGS), a polarized proton beam with 1.5*10¹¹ intensity and 65% polarization has been achieved. There are residual polarization losses due to horizontal resonances over the whole energy ramp and some polarization loss due to vertical intrinsic resonances. Many efforts have been put in to reduce the emittances coming into the AGS and to consequently reduce polarization loss. This paper presents the accelerator setup and preliminary results from run-9 operations.

Slides