Possible Mechanism in Heavy Ion Induced Reactions: Fast Fission Process

摘要

The influence of the orbital angular momentum 1 on the mass distribution of fission fragments is studied, both on previously available data on heavy ion induced fission and in new specifically planned experiments: systems Ar-40 + Ho-165 and Mg-24 + Ta-81 at bombarding energies ranging from 180 up to 391 MeV and leading to the same fissioning nucleus At-205 with different 1 distributions. When 1 values corresponding to a vanished fission barrier are reached, the mass distribution broadens. This suggest the existence of a specific process, fast fission, at 1-values leading to compound nucleus formation and deep inelastic collisions, respectively. This process and its conditions of occurrence are discussed; of special interest are the correlated differences between the limitations to the fission cross-section and the fission mass distributions broadenings, respectively, for the Ar + Ho and Mg + Ta systems.