Fast Fission Phenomenon: An Intermediate Mechanism Between Compound Nucleus Formation and Deep Inelastic Reactions.

摘要

We review some experimental results which cannot be understood within the usual framework of dissipative collisions: the critical angular momentum for fusion which can be larger than the value of the angular momentum for which the fission barrier of the compound nucleus vanishes and the large increase of the FWHM of the symmetric fragmentation mass distribution which strongly increases with angular momentum. We present a dynamical model which treats both dissipation and fluctuations for the collective motions. This model allows to compute deep inelastic properties and the fusion cross section. For some systems, and under certain conditions, a new type of dissipative collision appears: the fast fission phenomenon. This process turns out to be intermediate between deep inelastic reactions and compound nucleus formation. The condition under which fast fission can be observed are discussed. (Atomindex citation 12:634129)