Disappearance of entrance channel dependence of fission fragment anisotropies at well-above-barrier energies

Abstract

Fission fragment anisotropies have been measured to energies extending well above the barrier for three entrance channels leading to the same compound nucleus $^{248}\mathrm{Cf}$. For the $^{12}\mathrm{C}$ + $^{236}\mathrm{U}$ and $^{16}\mathrm{O}$ + $^{232}\mathrm{Th}$ systems, lying on either side of the Businaro-Gallone critical asymmetry, the mean square angular momentum is matched at an excitation energy of 62 MeV. The anisotropies, although different at lower energies, are in agreement within experimental errors at this excitation energy and thus show no entrance channel dependence.