Transitional dissipative mechanisms in the fission-like fragmentation of medium-mass nuclear systems

Transitional dissipative mechanisms in the fissionlike decay of medium mass composite systems have been studied systematically. Fragments produced in the collision of 4--7 MeV/nucleon, A = 19--37 projectiles, with A = 59--89 target nuclei, were identified by time-of-flight spectrometers. Mass, energy, and angular distributions of the fissionlike fragments have been reproduced by dynamical model calculations based on the transport theory. Systematics of lifetimes of the intermediate complex systems are given, indicating a clear dependence on the bombarding energy and entrance channel mass asymmetry.