Investigation of the Influence of Angular Momentum on Fission Probability

A nuclear emulsion technique has been used to determine total fission cross sections in the following heavy-ion bombardments: (${\mathrm{C}}^{12}$+${\mathrm{Tm}}^{169}$; ${\mathrm{O}}^{16}$+${\mathrm{Ho}}^{165}$), (${\mathrm{O}}^{16}$+${\mathrm{Tm}}^{169}$; ${\mathrm{Ne}}^{20}$+${\mathrm{Ho}}^{165}$), (${\mathrm{C}}^{12}$+${\mathrm{Re}}^{185}$; ${\mathrm{O}}^{16}$+${\mathrm{Ta}}^{181}$), (${\mathrm{O}}^{16}$+${\mathrm{Re}}^{185}$; ${\mathrm{Ne}}^{20}$+${\mathrm{Ta}}^{181}$). Each pair of bombardments resulted in the same compound nucleus, and excitation energies could be made equal in the two cases by adjustment of bombarding energies. The ratio of the fission cross section to a calculated compound-nucleus-formation cross section, $\frac{{\sigma }_f}{{\sigma }_c}$, was taken as a measure of fission probability in each bombardment. Larger fission probabilities were observed to occur for the systems having greater angular momenta.