Intermediate mass fragment emission in Boltzmann master equation theory of pre–equilibrium reactions

A coalescence model originally proposed to account for the emission of nucleons and light particles in nuclear reactions is extended to account for intermediate mass fragment (IMF) emission. This theory uses a set of Boltzmann master equations to evaluate the time evolution of the occupation probability of nucleon states in the course of the de-excitation cascade during which the IMF are emitted. The internal structure of the IMF and the depletion of nucleon states due to IMF emission are explicitly considered. The theoretical predictions reproduce satisfactorily the experimental multiplicity spectra measured in central collisions of36Ar ions with197Au at incident energies of 35 MeV/nucleon.