Effects of finite ground-state spin on fission fragment angular distributions following collisions with spherical or deformed nuclei

The influence of the ground-state spin of fusing nuclei on the subsequent fission fragment angular distributions has been investigated through realistic quantum-mechanical calculations. The domain of applicability of an approximate formula is found for spherical nuclei. For deformed nuclei, a generalization of the standard transition state model expression for the fission fragment angular distribution is presented. This predicts dramatic changes in the shape and anisotropy of the distribution, for reactions of deformed nuclei with large ground-state spin.