• 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.

Slides

• T. Satogata, L. A. Ahrens, M. Bai, J.M. Brennan, D. Bruno, J.J. Butler, K.A. Drees, A.V. Fedotov, W. Fischer, M. Harvey, T. Hayes, W. Jappe, R.C. Lee, W.W. MacKay, N. Malitsky, G.J. Marr, R.J. Michnoff, B. Oerter, E. Pozdeyev, T. Roser, F. Severino, K. Smith, S. Tepikian, N. Tsoupas
  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.

There is significant interest in RHIC heavy ion collisions at center of mass energies of 5-50 GeV/u, motivated by a search for the QCD phase transition critical point. The low end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of 19.6 GeV/u. There are several operational challenges in the low-energy regime, including harmonic number changes, longitudinal acceptance, magnet field quality, lattice control, and luminosity monitoring. We report on the results of beam tests with protons and gold in 2007–9, including first RHIC operations at √{(s_NN)=9.2} GeV and low-energy nonlinear field corrections at √{(s_NN)=5} GeV.

• R.J. Michnoff, P. Cerniglia, C. Degen, R.L. Hulsart, M.G. Minty, R.H. Olsen, T. Roser, T. Satogata
  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.

RHIC BPM system average orbit was originally calculated by averaging positions of 10000 consecutive turns for a single selected bunch. Known perturbations in RHIC particle trajectories, with multiple frequencies around 10 Hz, contribute to observed average orbit fluctuations. In 2006, the number of turns for average orbit calculations was made programmable; this was used to explore averaging over single periods near 10 Hz. Although this has provided an average orbit signal quality improvement, an average over many periods would further improve the accuracy of the measured closed orbit. A new continuous average orbit calculation is currently under development and planned for use in the 2009 RHIC run. This paper will discuss the algorithm, performance with a simulated beam signal, and beam measurements.