Transverse Energy Measurements from the Beam Energy Scan in PHENIX

Abstract

Transverse energy distributions at midrapidity have been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) for Au+Au, U+U, Cu+Au, Cu+Cu, He+Au, d+Au, and p+p collisions over a wide energy range from $\sqrt{s_{NN}}$ = 7.7 GeV to $\sqrt{s_{NN}}$ = 200 GeV as a function of centrality. For central Au+Au collisions, it is observed that the midrapidity Bjorken energy density demonstrates a power law behavior from $\sqrt{s_{NN}}$ = 7.7 GeV to $\sqrt{s_{NN}}$ = 2.76 TeV. At a given collision energy, the data presented as a function of $N_{part}$ are independent of the size of the collision system. For Au+Au, Cu+Au, and Cu+Cu collisions, the centrality-dependent data are better described by scaling with the number of constituent quark participants than scaling with the number of nucleon participants.