Decay of 246Bk* formed in similar entrance channel reactions of 11B+235U and 14N+232Th at low energies using the dynamical cluster-decay model

The decay of the Bk-246* nucleus, formed in entrance channel reactions B-11+U-235 and N-14+Th-232 at different incident energies, is studied by using the dynamical cluster-decay model (DCM) extended to include the deformations and orientations of nuclei. The main decay mode here is fission. The other (weaker) decay channels are the light particles evaporation (A <= 4) and intermediate mass fragments (5 <= A <= 20). All decay products are calculated as emissions of preformed clusters through the interaction barriers. The calculated fission cross sections sigma(fiss), taken as a sum of the energetically favored symmetric and near symmetric fragments (A(CN)/2 +/- 7 and A = 106-110 plus complementary fragments) show an excellent agreement with experimental data at all experimental incident c.m. energies for both reactions, except for the top three energies in the case of the B-11+U-235 reaction. The disagreement between the DCM calculations and data at higher incident c.m. energies for the B-11+U-235 entrance channel is associated with the presence of additional effects of noncompound, quasifission (qf) components, in contradiction with the measured anisotropy effects which indicate the other entrance channel N-14+Th-232 to contain the noncompound nucleus contribution. The prediction of two fission windows, the symmetric fission (SF) and near symmetric or heavy mass fragments (HMFs), suggests the presence of a fine structure of fission fragments, which also need an experimental verification. The only parameter of the model is the neck length parameter Delta R whose value is shown to depend strongly on limiting angular momentum, which in turn depends on the use of sticking or nonsticking moment of inertia for angular momentum effects.