The centrality dependence of transverse momentum distributions and yields for ± , K ± , p, and p in Au + Au collisions at ͱ s NN = 200 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. We observe a clear particle mass dependence of the shapes of transverse momentum spectra in central collisions below ϳ2 GeV/ c in p T. Both mean transverse momenta and particle yields per participant pair increase from peripheral to midcentral and saturate at the most central collisions for all particle species. We also measure particle ratios of − / + , K − / K + , p / p, K / , p / , and p / as a function of p T and collision centrality. The ratios of equal mass particle yields are independent of p T and centrality within the experimental uncertainties. In central collisions at intermediate transverse momenta ϳ1.5-4.5 GeV/ c, proton and antiproton yields constitute a significant fraction of the charged hadron production and show a scaling behavior different from that of pions.

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The PHENIX experiment at RHIC has measured transverse energy and charged particle multiplicity at mid-rapidity in Au + Au collisions at √ s N N = 19.6, 130 and 200 GeV as a function of centrality. The presented results are compared to measurements from other RHIC experiments, and experiments at lower energies. The √ s N N dependence of dET /dη and dN ch /dη per pair of participants is consistent with logarithmic scaling for the most central events. The centrality dependence of dET /dη and dN ch /dη is similar at all measured incident energies. At RHIC energies the ratio of transverse energy per charged particle was found independent of centrality and growing slowly with √ s N N . A survey of comparisons between the data and available theoretical models is also presented.