BNL, Upton, Long Island, New York
Operational experience on crossing RHIC transition as well as observed beam dynamics effects are described. The techniques to provide the successful transition crossing without beam losses and deterioration of the beam quality in both transverse and longitudinal plane are reviewed. Presently the ion beam intensity is limited by the transverse instability happenning at the transition region. It was observed that the threshold of the instability was significantly affected by the presence of the electron cloud. The results of recent studies of the intensity limiting instability are presented.
Fermilab, Batavia, Illinois
BNL, Upton, Long Island, New York
Beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and the principle is now being experimentally investigated at RHIC. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, we do simulations to study the effect of wire compensator based on diffusive apertures, beam loss rates, and beam transfer function using a parallel weak-strong beam simulation code (bbsimc) without parasitic collisions. The simulation results are compared with measurements.