Relative velocities between fragments. A key quantity in multifragmentation

Relative velocities between fragments are discussed as a tool to study different fragmentation mechanisms in the intermediate energy regime. Comparing data of the reaction α-Au at 800 MeV/u with calculations, we exclude for the subgroup of light-light coincidences a sequential evaporation-type emission. The data agree with a simultaneous break-up. Within the presented model multifragmentation dominates at excitation energies above 800 MeV and likely these energies are just reached in the experiment. (orig.)