The recoil catcher technique and gamma spectrometric assay of fission products were used to measure angular distribution of 17 fission products in ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ induced fission of ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ at near barrier energies. The observed mass dependence of anisotropies of fission products in these systems are very different from that of p and α induced fission of ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ at similar excitation energies. It has been suggested that the difference in the rotational energy for the symmetric and asymmetric modes for large compound nucleus spins could be responsible for the observed variation. No systematic change in the mass dependence of anisotropies across the Bussinaro-Gallone point was observed. For ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ induced fission of ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$, sharp variation in anisotropies have been observed in the mass region 120–135. This has been attributed to transfer induced fission.

• Received 4 April 1994

DOI:https://doi.org/10.1103/PhysRevC.51.165