Transport description of intermediate processes in heavy ion collisions

An extension of the diffusion model is proposed in order to describe the intermediate processes and the compound nucleus formation in heavy ion collisions. The model describes the intermediate processes and fusion in terms of the formation and the evolution of a long-lived dinuclear molecular complex (DMC) and its subsequent decay by fragmentation. The colliding ions can be trapped into the pocket of the entrance channel nucleus-nucleus potential and a DMC is formed. This DMC acts as a doorway state towards formation of a completely equilibrated compound nucleus (CN). It evolves through the exchange of nucleons to different dinuclear configurations. At each stage of its evolution, there is a finite probability for direct fragmentation into outgoing channels by thermal penetration over the barrier. The doorway states that do not fragment relax into a CN configuration and are identified as the fusion yield. 8 refs