Energy and System Size Dependence of Charged Hadron Transverse Momentum Spectra from Cu+Cu and Au+Au Collisions at √ s NN = 62.4 and 200 GeV

The PHOBOS Collaboration has measured transverse momentum distributions of charged hadrons produced in Cu+Cu collisions at √sNN=200 and 62.4 GeV. The nuclear modification factor RAANpart is calculated relative to p+p data at both collision energies as a function of collision centrality. For the same number of participating nucleons, RAANpart is essentially the same in both systems over the full range of pTthat is measured. In addition, we observe that within experimental uncertainties, the ratio of 200 GeV to 62.4 GeV Cu+Cu yields has only a moderate centrality dependence and is consistent with the value previously measured in Au+Au collisions for a broad range of pT.