A possible mechanism in heavy ion induced reactions: "Fast fission process"

The influence of the orbital angular momentum l 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: systems40Ar+165Ho and24Mg+181Ta at bombarding energies ranging from 180 up to 391 MeV and leading to the same fissioning nucleus205At with different l distributions. When l values corresponding to a vanished fission barrier are reached, the mass distribution broadens. This suggest the existence of a specific process, "fast fission", at l-values intermediate between l-values leading to compound nucleus formation and deep inelastic collisions, respectively. This process and its conditions of occurence are discussed; of special interest are the correlated differences between the limitations to the fusion cross-section and the fission mass distributions broadenings, respectively, for the Ar+Ho and Mg+Ta systems. © 1981 Springer-Verlag.SCOPUS: ar.j