BNL, Upton, Long Island, New York, USA
In the 2012 RHIC heavy ion run, we collided uranium-uranium (U-U) ions at 96.4~GeV/nucleon and copper-gold (Cu-Au) ions at 100~GeV/nucleon for the first time in RHIC. The new Electron-Beam Ion Source (EBIS) was used for the first time to provide ions for the RHIC physics program. After adding the horizontal cooling, 3-D stochastic cooling became operational in RHIC for the first time, which greatly enhanced the luminosity. In this article, we first review the improvements and performances in the 2012 RHIC ion runs. Then we discuss the conditions and approaches to achieve the burn-off dominated Uranium beam lifetime at physics stores. And we discuss the asymmetric copper-gold collision due to different IBS and stochastic cooling rates, and the operational solutions to maximize the integrated luminosity.
