Charged particle multiplicity and transverse energy in Au - Au collisions at $\sqrt{s_{{}_{NN}}}=130$ GeV

This paper presents the results for the charged-particle multiplicity and transverse energy distributions at mid-rapidity in Au - Au collisions at $\sqrt{s_{{}_{NN}}}=130$ GeV measured with the PHENIX detector at RHIC. The values of $d{N}_{ch}\mathrm{/}d{\eta }_{\mathrm{\mid }\eta =0}$ and $d{E}_T\mathrm{/}d{\eta }_{\mathrm{\mid }\eta =0}$, analyzed as a function of centrality, show a consistent steady rise. For the 5% most central collisions they are $\sim 70$% larger compared to the SPS results for Pb-Pb collisions at $\sqrt{s_{{}_{NN}}}=17.2$ GeV. The ratio of $<E_T>\mathrm{/}<N_{ch}>$ remains constant as a function of centrality at 0.8 GeV, as also observed at the SPS at CERN and at the AGS at BNL.