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.
BNL, Upton, Long Island, New York, USA
A future electron ion collider "QCD test facility" is designed in the present Relativistic Heavy Ion Collider (RHIC) tunnel. Electron acceleration and de-acceleration is preformed with energy recovery linac with multiple passes. We report on a combination of a multi-pass linac with the Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) arcs. A single NS-FFAG arc allow electrons to pass through the same structure with an energy range between 1.425 and 10 GeV. The NS-FFAG is placed in the existing RHIC tunnel. The 200 MeV injector bring the polarized electrons to the 1.225 GeV GeV superconducting linac. After one pass through the linac 1.425 GeV electrons enter NS-FFAG arc and after 7 passes reach the energy of 10 GeV. After collisions the beam is brought back by the NS-FFAG and decelerated to the initial energy and directed to the dump.
BNL, Upton, Long Island, New York, USA
For the RHIC spin flipper to achieve a rotating field, it requires operating five AC dipoles as a pair of closed orbit bumps. One key requirement is to minimize the remnant AC dipole driven betatron oscillation outside of the spin flipper by 50dB. In the past, due to its inherent sensitivity, a single pickup with a direct-diode detector (3D) and dynamic signal analyzer (DSA) were used to measure bump closure by measuring the remnant oscillations. This however proved to be inadequate, as the betatron phase advance between the AC dipoles is non-zero. A method of combining multiple BPMs into a sensitive measure of bump closure has been developed and will be tested during RHIC polarized proton operation in 2013. This technique as well as the experimental results will be presented.
BNL, Upton, Long Island, New York, USA
Mechanical analysis of the RHIC beam dump window has shown that present heavy ion beam intensities are close to the tolerable limit, and will likely exceed that limit in future runs. Different approaches to upgrade the abort system for those projected higher intensities have been studied, namely replacing the existing window, and adding a vertical kicker that distributes the individual bunches more evenly across the window, thus reducing the heat load. We present the results of these studies and the present status of the upgrade project.