Abstract
Measurements of midrapidity charged-particle multiplicity distributions, dN(ch)/d eta, and midrapidity transverse-energy distributions, dE(T)/d eta, are presented for a variety of collision systems and energies. Included are distributions for Au + Au collisions at root s(NN) = 200, 130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, Cu + Cu collisions at root s(NN) = 200 and 62.4 GeV, Cu + Au collisions at root s(NN) = 200 GeV, U + U collisions at root s(NN) = 193 GeV, d + Au collisions at root s(NN) = 200 GeV, He-3 + Au collisions at root s(NN) = 200 GeV, and p + p collisions at root s(NN) = 200 GeV. Centrality-dependent distributions at midrapidity are presented in terms of the number of nucleon participants, N-part, and the number of constituent quark participants, N-qp. For all A + A collisions down to root s(NN) = 7.7 GeV, it is observed that the midrapidity data are better described by scaling with N-qp than scaling with N-part. Also presented are estimates of the Bjorken energy density, epsilon(BJ), and the ratio of dE(T)/d eta to dN(ch)/d eta, the latter of which is seen to be constant as a function of centrality for all systems.
