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 density. The relative excitations of the three parts and their contributions to the physical observables such as mean multiplicity for different fragments and total fragment multiplicity are shown as functions of entrance channel properties; namely, the impact parameter, the bombarding energy, and the mass of projectile and target nuclei. As an application we apply the model to describe the data on 40Ar+40Ca and 40Ar+197Au reaction with incident energy varying from 42 to 137 MeV/nucleon, and the intermediate mass fragment production in the 197Au+197Au reaction with incident energies 100 and 400 MeV/nucleon. The importance of the contributions from the spectator parts is clearly demonstrated. 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. copyright 1997 The American Physical Society