Intermediate Energy Reactions Versus Heavy-Ion Fusion: Light Particle Emission and Post-Saddle Friction in the Presence of Deformation Effects

摘要

A decaying nucleus undergoes a change in deformation when it fissions.This affects the particle emission in the fission process.Using the dynamical Langevin model,we investigate the role of deformation in the sensitivity of post-saddle neutrons and light charged particles (LCPs) to the post-saddle friction strength (β) for heavy nuclei 240Am produced with different initial conditions:(i) a low excitation energy E* and a large spin l (provided via a fusion mechanism) and (ii) a high E* and a large l as well as a higher E* but a small l (provided in peripheral and near-central intermediate energy heavy-ion reactions,respectively).It is shown that deformation obviously enhances the sensitivity of post-saddle neutrons toβ at intermediate-energy peripheral collisions and that for case (i),the drop of LCPs emission due to deformation makes post-saddle LCPs to be almost insensitive toβ,but for case (ii) LCPs still have a significant change with β.Furthermore,we find that post-saddle LCPs display a greater sensitivity to β for near-central collisions than for peripheral collisions.These results suggest that given the deformation effects,to better probe post-saddle dissipation properties with neutrons (LCPs) in experiments,it is best to choose those excited heavy nuclear systems populated in peripheral (near-central) collisions at intermediate energies.