Fission Decay Widths for Heavy-Ion Fusion-Fission Reactions

TL;DR

This paper demonstrates that heavy-ion fusion-fission reaction data align with a Kramers-modified statistical model incorporating collective motion, temperature effects, and orientation, without requiring modifications to nuclear viscosity models.

Contribution

It shows that existing data are consistent with a comprehensive statistical model, challenging claims of temperature-dependent nuclear viscosity changes.

Findings

Data fit well with the Kramers-modified statistical model.

No evidence for departure from surface-plus-window dissipation model.

Temperature dependence of fission transition points is confirmed.

Abstract

Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state; the temperature dependence of the location of fission transition points; and the orientation degree of freedom. We see no evidence to suggest that the nuclear viscosity departs from the surface-plus-window dissipation model. The strong increase in the nuclear viscosity above a temperature of ~1 MeV deduced by others is an artifact generated by an inadequate fission model.