The STAR experiment at RHIC has completed its first phase of the Beam Energy Scan (BES-I) program to understand the phase structure of the quantum chromodynamics (QCD). The bulk properties of the system formed in Au+Au collisions at different center of mass energy $\sqrt{ s_{ NN}} = $ 7.7, 11.5, 19.6, 27, and 39 GeV have been studied from the data collected in the year 2010 and 2011. The centrality and energy dependence of mid-rapidity ($|y|$ < 0.1) particle yields, and ratios are presented here. The chemical freeze-out parameters are extracted using measured particle ratios within the framework of a statistical model.
Categories: nucl-ex hep-ex hep-ph