• Y. Luo, P. Cameron, A. Della Penna, W. Fischer, J.S. Laster, A. Marusic, F.C. Pilat, T. Roser, D. Trbojevic
  BNL, Upton, Long Island, New York

The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). In the polarized proton run, the betatron tunes are required to keep almost constant on the ramp to avoid spin resonance line crossing and the beam polarization loss. Some possible correction schemes on the ramp, like three-ramp correction, the coupling amplitude modulation and the coupling phase modulaxtion, have been found. The principles of these schemes are shortly reviewed and compared. Operational results of their applications on the RHIC ramps are given.

• M. Bai, L. Ahrens, J.G. Alessi, J. Beebe-Wang, M. Blaskiewicz, A. Bravar, J.M. Brennan, D. Bruno, G. Bunce, J.J. Butler, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, W. Fischer, G. Ganetis, C.J. Gardner, J. Glenn, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, U. Iriso, J.S. Laster, R.C. Lee, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, G.J. Marr, A. Marusic, G.T. McIntyre, R.J. Michnoff, C. Montag, J. Morris, T. Nicoletti, P. Oddo, B. Oerter, O. Osamu, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, K. Smith, S. Tepikian, R. Tomas, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, K. Vetter, M. Wilinski, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
  BNL, Upton, Long Island, New York
• I.G. Alekseev, D. Svirida
  ITEP, Moscow

The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limited conditions are reported.

• Y. Luo, P. Cameron, A. Della Penna, A. Marusic, S. Peggs, T. Roser, D. Trbojevic
  BNL, Upton, Long Island, New York
• O.R. Jones
  CERN, Geneva

Besides two eigentunes Q1 and Q2 , two amplitude ratios r1 and r2 and two phase differences ∆ φ₁ and ∆ φ₂ are introduced for the global coupling observation. Simulations are carried out to check their behaviors in the process of the skew quadrupole strength scans. Some attractive features of the phase differences ∆ φ_1,2 have been found, which are possibly useful for the global decoupling phase loop, or future global decoupling feedback. Analytical descriptions to these 6 quantities are described in the Twiss parameters through the linear coupling's action-angle parameterization, or in coupling coefficient through the linear coupling's Hamiltonian perturbation theory. Dedicated beam experiments are carried out at the Relativistic Heavy Ion Collider (RHIC) to check the global coupling observables from the phase lock loop (PLL) system. The six observables are measured under PLL driving oscillations during the 1-D and 2-D skew quadrupole scans. The experimental results are reported and discussions are given.

• C. Montag, A. Marusic, R.J. Michnoff, T. Roser, T. Satogata, C. Schultheiss
  BNL, Upton, Long Island, New York

Mechanical low-beta triplet vibrations lead to horizontal jitter of RHIC beams at frequencies around 10 Hz. The resulting beam offsets at the interaction points are considered detrimental to RHIC luminosity performance. To stabilize beam orbits at the interaction points, installation of a fast orbit feedback is foreseen. A prototype of this system is being developed and tested. Recent results are presented.

• F.C. Pilat, L. Ahrens, M. Bai, D.S. Barton, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, D. Bruno, P. Cameron, R. Connolly, T. D'Ottavio, J. DeLong, K.A. Drees, W. Fischer, G. Ganetis, C.J. Gardner, J. Glenn, M. Harvey, T. Hayes, H.-C. Hseuh, H. Huang, P. Ingrassia, U. Iriso, R.C. Lee, V. Litvinenko, Y. Luo, W.W. MacKay, G.J. Marr, A. Marusic, R.J. Michnoff, C. Montag, J. Morris, T. Nicoletti, B. Oerter, V. Ptitsyn, T. Roser, T. Russo, J. Sandberg, T. Satogata, C. Schultheiss, S. Tepikian, R. Tomas, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, K. Vetter, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang
  BNL, Upton, Long Island, New York

The 5th year of RHIC operations, started in November 2004 and expected to last till June 2005, consists of a physics run with Cu-Cu collisions at 100 GeV/u followed by one with polarized protons at 100 GeV. We will address here overall performance of the RHIC complex used for the first time as a Cu-Cu collider, and compare it with previous operational experience with Au, PP and asymmetric d-Au collisions. We will also discuss operational improvements, such as a ?* squeeze to 85cm in the high luminosity interaction regions from the design value of 1m, system improvements and machine performance limitations, such as vacuum pressure rise, intra-beam scattering, and beam beam interaction.