Transverse energy measurement in Au+Au collisions by the STAR experiment

Transverse energy (ET) has been measured with both of its components, namely hadronic (EThad) and electromagnetic (ETem) in a common phase space at mid-rapidity for 62.4 GeV Au+Au collisions by the STAR experiment. ET production with centrality and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sqrt {s_{NN} } $\end{document} is studied with similar measurements from SPS to RHIC and is compared with a final state gluon saturation model (EKRT). The most striking feature is the observation of a nearly constant value of ET /Nch ∼ 0.8 GeV from AGS, SPS to RHIC. The initial energy density estimated by the boost-invariant Bjorken hydrodynamic model, is well above the critical density for a deconfined matter of quarks and gluons predicted by lattice QCD calculations.