Statistical theory of the angular distribution of fission fragments

Abstract

The angular distribution of fragments is considered in the case where fission takes place at an excitation energy high enough for the momentum to be distributed among a large number of nucleons, so that the statistical theory of the nucleus applies. The distribution of the states of the “transitional” nucleus over K, the projection of the angular momentum of the compound nucleus along the fission axis, is calculated. The most probable state is that with K = 0, which in the case of neutron-induced fission leads to maxima at 0° and 180° in the angular distribution of the fragments. These results are compared with experiment, and the moment of inertia of the “transitional” nucleus about the symmetry axis (the direction of fission) determined thereby. Consideration is also given to the angular distributions resulting from fission induced by charged particles and γ-quanta.