The PHENIX experiment at RHIC has measured transverse energy and charged particle multiplicity at mid-rapidity in Au + Au collisions at $\sqrt{ s_{ NN}}$ = 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented results are compared to measurements from other RHIC experiments, and experiments at lower energies. The $\sqrt{ s_{ NN}}$ dependence of $dE_{ T}/d\eta$ and $dN_{ ch}/d\eta$ per pair of participants is consistent with logarithmic scaling for the most central events. The centrality dependence of $dE_{ T}/d\eta$ and $dN_{ ch}/d\eta$ is similar at all measured incident energies. At RHIC energies the ratio of transverse energy per charged particle was found independent of centrality and growing slowly with $\sqrt{ s_{ NN}}$. A survey of comparisons between the data and available theoretical models is also presented.
Categories: nucl-ex