ENTRANCE CHANNEL DEPENDENCE OF FRAGMENTATION DYNAMICS IN HEAVY-ION COLLISIONS

We study the mechanism of intermediate energy heavy-ion collisions in a picture of tripartition of the total system, using the framework of statistical simultaneous multifragmentation model taking into account the entrance channel characteristics, with no other parameter except d ensity. The relative excitations of the three parts and their contribu tions to the physical observables such as mean multiplicity for differ ent fragments and total fragment multiplicity are shown as functions o f entrance channel properties; namely, the impact parameter, the bomba rding energy, and the mass of projectile and target nuclei. As an appl ication we apply the model to describe the data on Ar-40+Ca-40 and Ar- 40+Au-197 reaction with incident energy varying from 42 to 137 MeV/nuc leon, and the intermediate mass fragment production in the Au-197+Au-1 97 reaction with incident energies 100 and 400 MeV/nucleon. The import ance of the contributions from the spectator parts is clearly demonstr ated. It is also shown that the role of the interfragment interaction is important up to bombarding energy 100 MeV/nucleon and a temperature of about 10 MeV.