Neutron and gamma emission from highly excited states and states with high spin. Annual progress report. [Summaries of research activities at Rensselaer Polytechnic Institute

Abstract

Both classical and quantum models for the collision between heavy ions were studied. Classical models were used to account for the possibility of strong damping. Two models which account for side peaking and considerable energy loss were proposed. According to the first, the ions clutch at the distance of closest approach and the radial energy is dissipated fast in the entrance channel. This is followed by a slow motion in the exit channel up to the snapping point. According to the second model, there is an asymmetry in the conservative potential between the entrance and exit channels. The exit channel potential includes deformations. A dynamical model including transfer was developed. The trajectories are determined dynamically whereas the transfer is considered as a random process. Semi-classical calculations (first order quantum calculation) were performed to test the validity of the classical model or the sharp cut-off approximation. The main conclusion is that for energies high above the Coulomb barrier, the classical approximation is adequate but close to the barrier, it is insufficient, and quantum effects are important. It was shown that a quantum mechanical model using time dependent perturbation accounts very well for the angular distribution in strongly damped collisions. A list of publications is included. (JFP)