Transverse energy production and charged-particle multiplicity at midrapidity in various systems from $\sqrt{s_{NN}}=7.7$ to 200 GeV

Abstract

Measurements of midrapidity charged particle multiplicity distributions, $d{N}_{\mathrm{ch}}/d\hat{I}\cdot$, and midrapidity transverse-energy distributions, $d{E}_T/d\hat{I}\cdot$, are presented for a variety of collision systems and energies. Included are distributions for Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$, 130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, Cu$+$Cu collisions at $\sqrt{s_{{}_{NN}}}=200$ and 62.4 GeV, Cu$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV, U$+$U collisions at $\sqrt{s_{{}_{NN}}}=193$ GeV, $d$$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV, ${}^3$He$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV, and $p$$+$$p$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV. Centrality-dependent distributions at midrapidity are presented in terms of the number of nucleon participants, $N_{\mathrm{part}}$, and the number of constituent quark participants, $N_{q\mathrm{p}}$. For all $A$$+$$A$ collisions down to $\sqrt{s_{{}_{NN}}}=7.7$ GeV, it is observed that the midrapidity data are better described by scaling with $N_{q\mathrm{p}}$ than scaling with $N_{\mathrm{part}}$. Also presented are estimates of the Bjorken energy density, ${\epsilon }_{\mathrm{BJ}}$, and the ratio of $d{E}_T/d\hat{I}\cdot$ to $d{N}_{\mathrm{ch}}/d\hat{I}\cdot$, the latter of which is seen to be constant as a function of centrality for all systems.

706 authors, 32 pages, 20 figures, 34 tables, 2004, 2005, 2008, 2010, 2011, and 2012 data. v2 is version accepted for publication in Phys. Rev. C