Pre-equilibrium and direct-semi-direct model calculations of nucleon radiative capture excitation functions on heavy nuclei

Abstract

Excitation functions of activation cross section (cascades over continuum states included) for proton capture in heavy nuclei, namely 52130Te(p, gamma )53131I, 58142Ce(p, gamma )59143Pr, 70176Yb(p, gamma )71177Lu, 83209Bi(p, gamma )84210Po, and integrated cross sections (direct transitions to the bound states) for neutron capture in 3989Y(n, gamma )3990Y, 58140Ce(n, gamma )58141Ce, 82208Pb(n, gamma )82209Pb, were calculated within a preequilibrium-equilibrium exciton model, using the ground-state binding energy of the even nucleon reduced for pairing, as well as within the direct-semidirect capture model. The integrated cross sections calculated within both the approaches agree reasonably well with the available experimental data, though the models differ in many aspects. As the direct-semidirect model does not treat the transitions to the continuum states, only the preequilibrium-equilibrium model is applied to the activation data. It reproduces them rather successfully.