Pure-resonance model, direct-semidirect model and pure-semidirect model for radiative nucleon capture in the giant resonance region

The direct-semidirect and the pure-resonance model for radiative capture of fast nucleons are comparatively discussed. It is shown that criticism recently directed toward the direct-semidirect model does not apply. The acceptability of an approximation used in the pure-resonance model is examined. An improved and a new version of the model are proposed (the pure-semidirect model) and a possible relative test of particular model calculations suggested. (orig.)