Nuclear Physics A378 (1982) 37396 © North-Holland Publishing Company THE INTERPLAY BETWEEN COHERENT AND STOCHASTIC EFFECTS IN DEEPLY INELASTIC COLLISIONS OF HEAVY IONS (II). Fluctuations in the collective dynamics

Abstract: We extend the work developed in paper I of this series, by discussing the dynamics in the collec-tive phase space in terms of a generalized Fokker-Planck equation. We are thus able to discuss fluctuations in the collective motion which were neglected in the mean field theory of paper I. In contrast with the standard derivations of Fokker-Planck equations, we do not assume quasi-equi-librium for the internal system, but rather, describe its evolution in time as it is coupled to the collec-tive system. The transport ccefTcients appearing in the Fokker-Planck equation are expressed as functionals ofthe internal density matrix. We use a coarse-grained description to study the devel-opment of the internal system as the reaction progresses, and we express the transport coefïicients in terms ofthe above-mentioned coarse-grained variables. Finally, we analyze the balance of energy between the collective and the internal systems. 1. Introductiou In a previous publication in this series of articles [ref. '), to be referred to as I], we presented a self-consistent mean-field approximation Z) for the treatment of dissipative heavy-ion collisions (DIC). The macroscopic degrees of freedom were described by means of classical trajectories. Using a coarse-grained description