Pre-neutron-emission mass distributions for low-energy neutron-induced actinide fission

Abstract

According to the driving potential of a fissile system, we propose a phenomenological fission potential for a description of the pre-neutron emission mass distributions of neutron-induced actinide fission. Based on the nucleus-nucleus potential with the Skyrme energy-density functional, the driving potential of the fissile system is studied considering the deformations of nuclei. The energy dependence of the potential parameters is investigated based on the experimental data for the heights of the peak and valley of the mass distributions. The pre-neutron emission mass distributions for reactions 238 U(n, f), 237 Np(n, f), 235 U(n, f), 232 Th(n, f) and 239 Pu(n, f) can be reasonably well reproduced. Some predictions for these reactions at unmeasured incident energies are also presented.

Pre-neutron-emission Mass Distributions for Reaction 232 Th( n, f ) up to 60 MeV

“…The red solid curve denotes the calculated results at E n =10 MeV, and the blue dash curve does the results using the parameters of Ref. [1] at the same incident energy. (n, 2nf).…”

“…(1) will be simplified as the three harmonic-oscillator functions [1]. The positions A 1 and A 2 are obtained from the nucleus-nucleus driving potential of the fissile nucleus 233 Th [1,15,16]. With increasing the incident neutron energy, the excitation energy of the compound nucleus will become higher, and a few neutrons will be evaporated before scission.…”

“…For reaction 232 Th(n, f) at low incident energies (E n < 6.0 MeV), the pre-neutron-emission mass distributions show a double-damped shape, and the fission potential Eq. (1) will be simplified as the three harmonic-oscillator functions [1]. The positions A 1 and A 2 are obtained from the nucleus-nucleus driving potential of the fissile nucleus 233 Th [1,15,16].…”

“…It is necessary to accurately describe and predict fission yields at different energies for a successful nuclear fission model. Due to the complex of fission process, it is still difficult to microscopically describe the mass splitting for neutroninduced fission at low and intermediate energies [1,2,3], though it is believed that the formation of the fission fragment-mass distribution is closely connected with the potential energy surface in deformation space [4,5]. Nowadays, there is an increasing interest in studying neutroninduced fission of actinides at intermediate energies.…”

“…≃ 140 denotes the lowest position of the driving potential derived from the ground state of the fissile nucleus [1].…”