Signature of non-compound-nucleus fission at sub-barrier energies.

Abstract

We have extracted the experimental ${\mathit{J}}_{\mathrm{eff}}$ values from fission fragment angular distributions for the systems of $^{16}\mathrm{O}$${+}^{232}$Th, $^{19}\mathrm{F}$${+}^{232}$Th, and $^{16}\mathrm{O}$${+}^{238}$U at near- and sub-barrier energies. The ${\mathit{J}}_{0}$/${\mathit{J}}_{\mathrm{eff}}$ values for the cases of the above reactions and the heavy-ion reactions with projectiles heavier than A=24 show same systematic trend when plotted as a function of mean-square angular momentum of the fissioning nucleus. This observation leads us to the conjecture that the systematic trend of ${\mathit{J}}_{0}$/${\mathit{J}}_{\mathrm{eff}}$ bears the signature of non-compound-nucleus fission for the heavy-ion reactions with lighter projectiles at near- and sub-barrier energies.