Photonuclear reactions of actinide and pre-actinide nuclei at intermediate energies

摘要

Photonuclear reaction is described with an approach based on thequasideuteron nuclear photoabsorption model followed by the process ofcompetition between light particle evaporation and fission for the excitednucleus. Thus fission process is considered as a decay mode. Theevaporation-fission process of the compound nucleus is simulated in aMonte-Carlo framework. Photofission reaction cross sections are analysed in asystematic manner in the energy range $\sim$~50-70 MeV for the actinides$^{232}$Th, $^{233}$U, $^{235}$U, $^{238}$U and $^{237}$Np and the pre-actinidenuclei $^{208}$Pb and $^{209}$Bi. The study reproduces satisfactorily well theavailable experimental data of photofission cross sections at energies$\sim$~50-70 MeV and the increasing trend of nuclear fissility with thefissility parameter $Z^2/A$ for the actinides and pre-actinides at intermediateenergies [$\sim$~20-140 MeV].