The independent yields of ${}_{}{}^{96}{}_{}{}^{}\mathrm{Nb}$, 51 min ${}_{}{}^{98}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{130}{}_{}{}^{}\mathrm{I}_{}^{\mathrm{g}}{}_{}{}^{}$, ${}_{}{}^{136}{}_{}{}^{}\mathrm{Cs}$, and the fractional cumulative yield of ${}_{}{}^{135}{}_{}{}^{}\mathrm{I}$ were determined in the thermal-neutron-induced fission of ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cf}$. They were found to be [(4.4 ± 0.6) × ${10}^{-3\mathrm{}}$]%, (0.15 ± 0.03)%, [(3.1 ± 0.3) × ${10}^{-2\mathrm{}}$]%, (0.34 ± 0.02)%, and (3.3 ± 0.2)%, respectively; these values correspond to empirical $Z_p$ values of 38.92, > 39.41, > 51.04, 53.64, and 53.30, respectively, if a Gaussian charge dispersion function with a $\sigma$ of 0.56 is used. No odd-even nuclide corrections were applied in the calculation of $Z_p$. A mean value for $\Delta Z (=Z_p-Z_{\mathrm{UCD}})$ of 0.45 ± 0.24 is obtained from all $Z_p$ values presently available in the thermal-neutron-induced fission of ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cf}$. The $Z_p$ values suggest a larger deviation from unchanged charge distribution for very asymmetric splits of the compound nucleus.

[RADIOACTIVITY, FISSION ${}_{}{}^{249}{}_{}{}^{}\mathrm{Cf}\mathrm{}(n,f)\mathrm{}$; measured $\gamma$ activity of fission products ${}_{}{}^{96}{}_{}{}^{}\mathrm{Nb}$, 51 min ${}_{}{}^{98}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{130}{}_{}{}^{}I_{}^g{}_{}{}^{}$, ${}_{}{}^{135}{}_{}{}^{}\mathrm{I}$, and ${}_{}{}^{136}{}_{}{}^{}\mathrm{Cs}$. Ge(Li) detector, Radiochemical separations.]

• Received 11 July 1977

DOI:https://doi.org/10.1103/PhysRevC.17.172