Hadron production in heavy relativistic systems

We investigate particle production in heavy-ion collisions at RHIC energies as a function of incident energy, and centrality in a three-sources Relativistic Diffusion Model. Pseudorapidity distributions of produced charged hadrons in Au + Au and Cu + Cu collisions at $\sqrt{s_{NN}} = 19.6 $ GeV, 62.4 GeV, 130 GeV and 200 GeV show an almost equilibrated midrapidity source that tends to increase in size towards higher incident energy, and more central collisions. It may indicate quark-gluon plasma formation prior to hadronization