Configuration mixing in nucleon-induced pre-equilibrium reactions

Abstract
We present a unified semiclassical model of nucleon-induced pre-equilibrium reactions that permits the simulation of varying degrees of internal configuration mixing. We can reproduce the limits of no intraclass transitions, assumed in the hybrid Monte Carlo simulation (HMS) model, or of intraclass equilibrium, assumed in exciton models. We compare the two limiting cases with a natural model, in which the intraclass transitions are treated on an equal footing with the others. Monte Carlo simulations of the models with no intraclass transitions and with the natural ones yield very similar emission spectra, which are quite different from the exciton model ones. To reproduce standard exciton model spectra, the model simulations require an intraclass transition rate a thousand times larger than the natural one. Calculations using simple shell-model interactions show the average squared interclass and intraclass matrix elements to be similar in magnitude, as assumed in the natural model.