INTERMEDIATE-MASS FRAGMENT EMISSION IN BOLTZMANN MASTER EQUATION THEORY OF PREEQUILIBRIUM REACTIONS

A coalescence model originally proposed to account for the emission of nucleons and light particles in nuclear reactions is extended to acco unt for intermediate mass fragment (IMF) emission. This theory uses a set of Boltzmann master equations to evaluate the time evolution of th e occupation probability of nucleon states in the course of the de-exc itation cascade during which the IMF are emitted. The internal structu re of the IMF and the depletion of nucleon states due to IMF emission are explicitly considered. The theoretical predictions reproduce satis factorily the experimental multiplicity spectra measured in central co llisions of Ar-36 ions with Au-197 at incident energies of 35 MeV/nucl eon.