A microscopic analysis of sub-barrier photo-induced fission in $^{236}$U$(\gamma,f)$ based on the non-equilibrium Green function method

Abstract

Sub-barrier photo-induced fission in $^{236}$U$(\gamma,f)$ is investigated within the non-equilibrium Green function (NEGF) method. A model space for the fission process is constructed by superposing Skyrme-Hartree-Fock wave functions along the fission path allowing the particle-hole excitation. Then, the transition from the photo-absorption channel to the fission channel is described by the non-equilibrium Green-function formalism. The calculated fission cross section in the incident gamma-ray energy range $5 ~ {\rm MeV} \leq E_\gamma \leq 6 ~ {\rm MeV}$ reproduces the overall behavior of the experimental data, including the suppression below the fission barrier. An eigenchannel analysis of the wave propagation in the present fission model space is also performed, and the first eigenchannel is found to dominate the fission probability. This result supports the Bohr-Wheeler transition-state picture from a microscopic viewpoint.