Emission of direct particles in heavy ion collisions

This paper presents a theoretical model for the emission of fast light particles derived from the PEP (Promptly Emitted Particles) model. This model is extended to the emission of fast alpha particles. With some restrictions, analytical formulae are derived for the production rate and the mean angular momentum associated with fast particles. Most of the qualitative features predicted by the analytical formulae are confirmed by the numerical results obtained from a more realistic calculation where the trajectories of the particles are followed during the whole collision. It is argued that PEP alpha particles emitted preferentially in low angular momentum collisions, could represent the major part of the fast alpha particles observed in incomplete fusion reactions. (orig.)