Transverse energy production and charged-particle multiplicity at midrapidity in various systems from √sNN = 7.7 to 200 GeV

Abstract

Measurements of midrapidity charged-particle multiplicity distributions, dNch/dη, and midrapidity transverseenergy distributions, dET /dη, are presented for a variety of collision systems and energies. Included are distributions for Au + Au collisions at √sNN = 200, 130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, Cu + Cu collisions at √sNN = 200 and 62.4 GeV, Cu + Au collisions at √sNN = 200 GeV, U + U collisions at √sNN = 193 GeV, d + Au collisions at √sNN = 200 GeV, 3 He + Au collisions at √sNN = 200 GeV, and p + p collisions at √sNN = 200 GeV. Centrality-dependent distributions at midrapidity are presented in terms of the number of nucleon participants, Npart, and the number of constituent quark participants, Nqp. For all A + A collisions down to √sNN = 7.7 GeV, it is observed that the midrapidity data are better described by scaling with Nqp than scaling with Npart. Also presented are estimates of the Bjorken energy density, εBJ, and the ratio of dET /dη to dNch/dη, the latter of which is seen to be constant as a function of centrality for all systems.