MEDIUM ENERGY HEAVY ION OPERATIONS AT RHIC∗

As part of the search for a phase transition or critical point on the QCD phase diagram, an energy scan includ-ing 5 different energy settings was performed during the 2010 RHIC heavy ion run. While the top beam energy for heavy ions is at 100 GeV/n and the lowest achieved energy setpoint was significantly below RHICs injection energy of approximately 10 GeV/n, we also provided beams for data taking in a medium energy range above injection en-ergy and below top beam energy. This paper reviews RHIC experience and challenges for RHIC medium energy op-erations that produced full experimental data sets at beam energies of 31.2 GeV/n and 19.5 GeV/n.