Fission fragment angular distributions for the systems ¹⁴N+²³²Th and ¹¹B+²³⁵U at near and sub-barrier energies

Abstract

Fission fragment angular distributions have been measured for the systems ¹¹B+²³⁵U and ¹⁴N+²³²Th, at sub and near-barrier energies. Complete and incomplete momentum transfer fission components have been separated around 90° c.m. for ¹⁴N+²³²Th. The contribution of incomplete momentum transfer events is found to be about 8% over the present energy range of investigation. In the ¹⁴N+²³²Th case, anisotropy data are found to be anomalous throughout the energy range, where as corresponding data for ¹¹B+²³⁵U are found to be normal, with respect to the saddle-point statistical model predictions. The large ground state spin values of ¹¹B and ²³⁵U are found to play a major role at the sub-barrier region in influencing the anisotropy values.