Centrality Dependence of Inclusive Identified Hadrons in PHENIX

Abstract

Results of identified charged hadrons produced in Au+Au collisions at ${\sqrt{s_{NN}}} = 130$ GeV as a function of centrality are discussed. The $<{p_{T}}>$ of protons and antiprotons is significantly larger than in p--p collisions at the same center of mass energy. Its scaling with the number of participant nucleons, an increase of $20 \pm 5%$ from peripheral to central, may be due to radial expansion. In a hydrodynamical picture a simultaneous fit of pions, kaons and protons is consistent with a radial flow velocity of $\beta_{\rm{Tsurface}} = 0.72 \pm 0.01$ and a temperature of $T = 122 \pm 4$ MeV for the 5% most central collisions. Dominant proton yields at ${p_{T}} > 1.5$ GeV/c and antiproton yields at ${p_{T}} > 1.8$ GeV/c may be explained by a combination of suppression of pion yields at high ${p_{T}}$ and the boost of low ${p_{T}}$ protons to high ${p_{T}}$ from radial flow.