Fission probability calculations for heavy-ion induced reactions

The Bohr-Wheeler formalism for nuclear fission has been included in a nuclear evaporation code. The added parameters are the saddle-point level density $a_f$ and the fission barrier for $J=0, B_f$. Effects of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ evaporation are explored by variation of the relevant level density parameter $a_{\alpha }$. Good fits to fission excitation functions could be achieved but ambiguity remains due to the entrance channel, i.e., the estimated critical angular momentum and the $\alpha$ evaporation probability. Three different systems have been investigated: ${}_{}{}^{182}{}_{}{}^{}\mathrm{W}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$→${}_{}{}^{194}{}_{}{}^{}\mathrm{Hg}$, ${}_{}{}^{175}{}_{}{}^{}\mathrm{Lu}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$→${}_{}{}^{187}{}_{}{}^{}\mathrm{Ir}$, and ${}_{}{}^{174}{}_{}{}^{}\mathrm{Yb}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$→${}_{}{}^{186}{}_{}{}^{}\mathrm{Os}$. In this framework the measurement of cross sections for $\alpha$ emission and evaporation residues, as well as that for fission, would suffice to fix the important parameters.