Unified formalism to study nonstatistical effects in radiative capture reactions.

Abstract

Based upon a consistent description of the wave functions of the captured state and the final state, a unified formalism has been established to investigate the nonstatistical effects in radiative nucleon capture reactions at energies ranging from 0.1 to 20 MeV. This model includes the direct-semidirect capture and radiative capture in the compound elastic and inelastic channels. By applying this model theory and including also the statistical contributions of the compound-nucleus process, the radiative neutron capture cross sections in $^{27}\mathrm{Al}$, $^{55}\mathrm{Mn}$, $^{89}\mathrm{Y}$, and $^{208}\mathrm{Pb}$ have been calculated and the results are compared with the measured data. We have also investigated the relative importance of the operation for each nonstatistical mechanism in the total capture cross sections.