Pseudorapidity Distributions of Charged Particles fromAu+AuCollisions at the Maximum RHIC Energy,sNN=200GeV

We present charged-particle multiplicities as a function of pseudorapidity and collision centrality for the ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ reaction at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{}\mathrm{GeV}$. For the $5\%$ most central events we obtain ${\mathrm{dN}}_{\mathrm{ch}}/d\eta {|}_{\eta =0\mathrm{}}=625\mathrm{}\pm 55$ and $N_{\mathrm{ch}}{|}_{-4.7\mathrm{}\le \eta \le 4.7}=4630\mathrm{}\pm 370$, i.e., $14\%$ and $21\%$ increases, respectively, relative to $\sqrt{s_{\mathrm{NN}}}=130\mathrm{}\mathrm{GeV}$ collisions. Charged-particle production per pair of participant nucleons is found to increase from peripheral to central collisions around midrapidity. These results constrain current models of particle production at the highest RHIC energy.