Abstract

We report measurements of the nuclear modification factor R-CP for charged hadrons as well as identified pi (+(-)) K+(-), and p((p) over bar) for Au + Au collision energies of root s(NN) = 7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV. We observe a clear high-p(T) net suppression in central collisions at 62.4 GeV for charged hadrons which evolves smoothly to a large net enhancement at lower energies. This trend is driven by the evolution of the pion spectra but is also very similar for the kaon spectra. While the magnitude of the proton R-CP at high p(T) does depend on the collision energy, neither the proton nor the antiproton R-CP at high p(T) exhibit net suppression at any energy. A study of how the binary collision-scaled high-p(T) yield evolves with centrality reveals a nonmonotonic shape that is consistent with the idea that jet quenching is increasing faster than the combined phenomena that lead to enhancement.