Identification and Yield of 5.0-secPd117in the Thermal-Neutron Fission ofU235

As part of a study of nuclear charge distribution in the region of symmetric fission, evidence for the existence and cumulative fission yield of ${}_{}{}^{117}{}_{}{}^{}\mathrm{Pd}$ was sought. Palladium was isolated free from silver and cadmium at different times after fission, and the quantity of descendant ${}_{}{}^{117}{}_{}{}^{}\mathrm{Cd}$ activity produced was measured. A half-life for ${}_{}{}^{117}{}_{}{}^{}\mathrm{Pd}$ of $5.0_{0.7}^{}{}_{}{}^{+0.5\mathrm{}}$ sec was derived from these data. Through a comparison of ${}_{}{}^{117}{}_{}{}^{}\mathrm{Cd}$ activity produced by ${}_{}{}^{117}{}_{}{}^{}\mathrm{Pd}$ with the total ${}_{}{}^{117}{}_{}{}^{}\mathrm{Cd}$ activity produced by all isobars, a cumulative fractional chain yield of 0.669 was computed for ${}_{}{}^{117}{}_{}{}^{}\mathrm{Pd}$. From this yield the most probable nuclear charge $Z_p$ for the 117-mass chain was estimated.