Fragment excitation energies at freeze-out in84Kr+93Nbcollisions at 45 MeV/nucleon

Abstract

The emission of light charged particles and intermediate-mass fragments (IMF’s) from central collisions of 45 MeV/nucleon 84Kr with 93Nb has been studied. Violent collisions have been selected using the total collected charge condition. The analysis of the primary IMF excitation energies has been performed for four bins of the detected IMF charge (2<ZIMF<20). We find evidence that (a) the mean excitation energy per nucleon for these fragments is independent of fragment charge and approximately equal to 2.5 MeV, (b) the primary fragments at freeze-out preserve the entrance channel (combined system) N/Z ratio, and (c) the freeze-out volume itself is far from spherical.