Very Energetic Heavy Fragments from Relativistic Heavy-Ion Reactions

In bombardments of Au with 25-GeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions we have studied the energy and angular distribution of fragments with $5<~Z<~9$ emitted at energies up to ∼ 1000 MeV. Beyond ∼ 150 MeV the spectra change from roughly exponential in energy and isotropic in some forward-moving frame to roughly inverse power law in energy (steepening with increasing $Z$) and strongly forward peaked in direction. Possible bumps in the angular and energy distributions suggest hydrodynamic effects.