Entrance-channel effect in fission fragment anisotropies from 11B+235U and 14N+232Th systems -: art. no. 041602

Fission fragment angular distributions have been measured for B-11 + U-235 and N-14 + Th-232, both leading to the same compound nucleus Bk-246 and lying on either side of the Businaro-Galtone critical asymmetry parameter. At comparable excitation energies, even though of the compound nucleus for N-14 + Th-232 are smaller than that of B-11 + U-235, the anisotropies measured for the former are found to be significantly larger than that from the latter. Further, while the measured anisotropies in the case of B-11 + U-235 are found to be consistent with the statistical saddle-point model, the corresponding data for N-14 + Th-232 are found to be anomalous indicating the presence of entrance, channel dependent noncompound nuclear contributions.