RHIC PERFORMANCE FOR FY’10 200 GeV Au+Au HEAVY ION RUN ∗

Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous de-tector 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 in-crease in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of < L> = 12 × 1026 cm−2 s−1 by operating with 103 bunches (out of 111 possible), and by squeezing to β ∗ = 0.85 m. This year, Run-10, we achieved < L> = 20 × 1026 cm−2 s−1, which put us an order of magnitude above the RHIC design luminosity. To reach these luminosity levels we decreased β ∗ to 0.75 m, operated with 111 bunches per ring, and reduced longitudi-nal 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 control system, and separated transition crossing times in the two rings. We present an overview of the changes and the results of Run-10 performance