Yields of In and Sn products from thermal- and 14-MeV-neutron-induced fission ofU235

The fractions of tin fission products formed independently and by decay of indium isotopes were determined for $A=121, 123, 125, 127, \mathrm{and} 128$ from thermal-neutron-induced fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$, and for $A=121, 123, 127, \mathrm{and} 128$ from 14-MeV-neutron-induced fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. The procedure involved on-line chemical separation of indium and tin fission products by use of a continuous-extraction method during irradiation and beta-activity measurements of purified tin samples after decay of indium precursors. Measured fractions of tin isotopes formed directly or by beta decay combined with their cumulative yields and mass-number (chain) yields allowed calculation of independent and/or cumulative yields for the nuclides studied. The yields of indium isotopes agree with complementary technetium yields measured radiochemically, but they are lower than most indium yields measured mass spectrometrically and most complementary technetium yields measured with recoil separators. The yield data were used to determine mass- and charge-distribution parameters ${\sigma }_{A^{\prime }}$, $\Delta A^{\prime }$, $Y\left(Z\right)\mathrm{}$, ${\sigma }_Z$, and $\Delta Z$ for thermal-neutron-induced fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. The values of ${\sigma }_{A^{\prime }}$ and ${\sigma }_Z$ are similar to the averages of values derived for other elements and mass numbers. $\Delta A^{\prime }$ has a pronounced peak at $Z=50\mathrm{}$, and the elemental yield decreases sharply from $Y(Z=50\mathrm{})=4.0\%$ to $Y(Z=49\mathrm{})=0.1\%$. The $\Delta Z$ function increases abruptly near $Z=50\mathrm{}$, changing from ∼-0.45 to positive values, as indicated by earlier experimental data, but inconsistent with the scission-point theoretical predictions. These effects, associated with the fifty-proton shell, diminish at higher excitation energy.