Burn-off dominated uranium and asymmetric copper-gold operation in RHIC

Abstract

In 2012 the Relativistic Heavy Ion Collider collided uranium-uranium ions with a particle energy of 96.4 GeV/nucleon and copper-gold (Cu-Au) ions at 100 GeV/nucleon for the first time. 3-dimensional stochastic cooling became operational for the first time and greatly enhanced the luminosity. Together with a new lattice configuration, we achieved a burn-off dominated uranium beam lifetime at physics stores. In the asymmetric Cu-Au collision, we observed an increased Cu beam loss stemming from different intrabeam-scattering and cooling rates between the Au and Cu ion bunches. By intentionally slowing down the cooling rate for the Au beam at the beginning of store, we reduced the Cu beam loss and maximized the integrated luminosity.