We have measured transverse momentum distributions of charged hadrons produced in $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{s_{NN}}=62.4\mathrm{G}\mathrm{e}\mathrm{V}$. The spectra are presented for transverse momenta $0.25<p_T<4.5\mathrm{G}\mathrm{e}\mathrm{V}/c$, in a pseudorapidity range of $0.2<\eta <1.4$. The nuclear modification factor $R_{AA}$ is calculated relative to $p+p$ data at the same collision energy as a function of collision centrality. For $2<p_T<4.5\mathrm{G}\mathrm{e}\mathrm{V}/c$, $R_{AA}$ is found to be significantly larger than in $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{s_{NN}}=$ 130 and 200 GeV. In contrast to the large change in $R_{AA}$, we observe a very similar centrality evolution of the $p_T$ spectra at $\sqrt{s_{NN}}=62.4$ and 200 GeV. The dynamical origin of this surprising factorization of energy and centrality dependence of particle production in heavy-ion collisions remains to be understood.

• Received 5 May 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.082304