BNL, Upton, Long Island, New York
There is a strong interest in heavy-ion collisions at the center of mass energies of 5-20 GeV/nucleon. This physics program is motivated by a search of the QCD phase transition critical point. Such low-energy operations started at Relativistic Heavy Ion Collider (RHIC) in 2010. The defining limitation in luminosity improvement for this program is expected to be due to the space charge. For RHIC, we are interested in rather long beam lifetime, which sets limitation on an allowable space-charge tune shift. An additional complication comes from the fact that ion beams are colliding, which requires careful consideration of the interplay of direct space-charge and beam-beam effects. We started to explore these beam dynamics effects in RHIC Accelerator Physics Experiments (APEX) in 2009 with proton beams. The experiments continued in 2010 with Au ion beams. This paper summarizes our findings and observations.
