DISSIPATIVE COLLISION AND COMPOUND-NUCLEUS FORMATION

Abstract
The successes, limitations and generalizations of transport theories for dissipative heavy-ion collisions are reviewed. The evolution of the collision complex can be divided roughly into three stages : mutual approach of the nuclei, local equilibration and slow relaxation of macroscopic degrees of freedom. In particular, the last stage has been thoroughly investigated within the framework of transport theories. The main steps in the derivation of transport equations is discussed and applications of Fokker-Planck equations are presented. Recent developments try to bridge the gap between the initial stage and the third stage of the process. An important feature of the mutual approach is due to the initial correlations imposed by the ground-state, configurations (doorway) of the colliding nuclei. These correlations give rise to an explicity time-dependent dynamical potential in the relative motion. The resulting modified Fokker-Planck equation is applied to compound-nucleus formation and dissipative collisions. The possible existence and some characteristic features of a slow component of dissipative collisions (besides the familiar fast component) are studied.