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 ${\beta }_{\mathrm{Tsurface}}=0.72\pm 0.01$ 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.