Fission fragment mass distributions have been measured from the decay of the compound nucleus ${}^{246}\mathrm{Bk}$ that has been populated via two entrance channels. These entrance channels have a slight difference in their mass asymmetries that puts them on either side of the Businaro Gallone mass asymmetry parameter. Both target nuclei were deformed. Near the Coulomb barrier, at similar excitation energies, the width of the fission fragment mass distribution was found to be drastically different for the ${}^{14}\mathrm{N}+{}^{232}\mathrm{Th}$ reaction compared to the ${}^{11}\mathrm{B}+{}^{235}\mathrm{U}$ reaction. The entrance channel mass asymmetry was found to affect the fusion process sharply.

• Received 20 June 2008

DOI:https://doi.org/10.1103/PhysRevC.79.054607