Speakers
Description
The RHIC beam energy scan program allows for the investigation of the phase diagram of QCD matter by varying the beam energy in the region where the change from crossover to first order phase transition is expected to occur. The nature of the quark-hadron transition can be studied through analyzing the space-time structure of the hadron emission source. One of the best tools to gain information about the source is the measurement of Bose-Einstein or HBT correlations of identical bosons. In recent measurements, we utilize Levy-type sources to describe the measured correlation functions. In this presentation we report the detailed measurement of the Levy source parameters as a function of transverse mass in Au+Au collisions at $\sqrt{s_{NN}}$ = 39, 62 and 200 GeV. In particular we discuss the observation of a new scaling parameter, Rhat, as well as the shape of the correlation strength versus transverse mass (lambda(mT)) and its relation to the eta' mass.
