Description of cross sections for photonuclear reactions in the energy range between 7 and 140 MeV

Abstract

A combination of the exciton and evaporation models is used to describe photonuclear reactions induced in light, medium-mass, and heavy nuclei by photons of energy in the range 7 ≤ Eγ ≤ 140 MeV. Two mechanisms of the photoexcitation of nuclei are considered. These are the formation of a giant dipole resonance at energies in the range Eγ ≲ 30 MeV and quasideuteron photoabsorption, which is dominant at energies in the region Eγ ≳ 40 MeV. The density of particle-hole states, which appears in the exciton model, is calculated on the basis of the Fermi gas model. The emission of two preequilibrium particles is taken into account in describing the quasideuteron reaction channel. The effect of isospin conservation on giant-dipole-resonance decay accompanied by photonucleon emission is examined. The model in question is used to describe cross sections for photon-induced reactions on 26Mg, 54Fe, 112,118,119,124Sn, and 181Ta nuclei.