Centrality and $\sqrt{s_{NN}}Dependenceofthe$dE_{T}/d\eta$and$dN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity

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 $d{E}_T\mathrm{/}d\eta$ and $d{N}_{ch}\mathrm{/}d\eta$ per pair of participants is consistent with logarithmic scaling for the most central events. The centrality dependence of $d{E}_T\mathrm{/}d\eta$ and $d{N}_{ch}\mathrm{/}d\eta$ 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.