BNL, Upton, Long Island, New York, USA
Over the past several years, the installation of the full 3-dimensional stochastic cooling system in RHIC has been completed. The FY12 U-U and Cu-Au collider runs were the first to benefit from the full installation. In the U-U run, stochastic cooling improved the integrated luminosity by a factor of 5. This presentation provides an overview of the design of the stochastic cooling system and reviews the performance of the system during the FY12 heavy ion runs.
BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
RHIC operations with heavy ion beams at energies below 10 GeV/nucleon are motivated by a search for the QCD Critical Point. An electron cooler is proposed as a means to increase RHIC luminosity for collider operations at these low energies. The electron cooling system should be able to deliver an electron beam of adequate quality over a wide range of electron beam energies (0.9-5 MeV). It also should provide optimum 3-D cooling for both hadron beams in the collider. A method based on bunched electron beam, which is also a natural approach for high-energy electron cooling, is being developed. In this paper, we describe the requirements for this system, its design aspects, as well as the associated challenges.
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
Deviation of the optical functions from the model may result in reduced dynamic aperture, luminosity and beam polarization all of which are of particular interest in the polarized proton program at RHIC. Peak to peak beta-beats as large as ± 80% have been observed. In run-13, we demonstrated that the optical functions can be corrected globally by two different approaches, beta-beat and phase-beat corrections. The optics measurement, correction algorithm and beta-beat measurements before and after correction will be presented.
BNL, Upton, Long Island, New York, USA
A semi-numerical method of integrating the Vlasov equation to obtain beam transfer functions directly as a function of frequency is presented. The results are compared with beam transfer functions calculated via particle tracking and excellent agreement is shown. The technique works well with both transverse wakes and detuning wakes from space charge.