Collisions between relativistic heavy-ions (gold or lead) are energetic enough to vaporize the participating neutrons and protons creating an equilibrated plasma of quarks and gluons. This plasma is thought to be similar to the state of the universe about one microsecond after the big bang. An important open question is how QCD matter undergoes the transition between a quark-gluon plasma and a hot hadronic gas. If the plasma has an equal mix of quarks and anti-quarks, lattice QCD calculations now tell us that there will be a crossover transition. However, in QCD matter with excess of quarks, we expect a first order phase transition, the termination will be a critical point. RHIC has performed a survey of several beam energies in order to study the QCD matter phase diagram. The results of that program have been used propose a more discriminating and focused second beam energy scan. This talk will report on the conclusions drawn from the first energy scan program and outline what remains to be done.
Host: Saehanseul Oh