The charged-particle pseudorapidity density ${\mathrm{dN}}_{\mathrm{ch}}/d\eta$ has been measured for $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=130\mathrm{}\mathrm{GeV}$ at RHIC, using the PHOBOS apparatus. The total number of charged particles produced for the $3\%$ most-central $\mathrm{Au}+\mathrm{Au}$ collisions for $|\eta |\le 5.4$ is found to be $4200\pm 470$. The evolution of ${\mathrm{dN}}_{\mathrm{ch}}/d\eta$ with centrality is discussed, and compared to model calculations and to data from proton-induced collisions. The data show an enhancement in charged-particle production at midrapidity, while in the fragmentation regions, the results are consistent with expectations from $\mathrm{pp}$ and $\mathrm{pA}$ scattering.

• Received 6 June 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.102303