Identification of 5.3-secAg118as a Product ofU235Fission

A search for ${}_{}{}^{118}{}_{}{}^{}\mathrm{Ag}$ was carried out as part of a study on the distribution of nuclear charge in symmetric fission. A method was developed for the separation of silver from its palladium precursor and cadmium descendant, based upon the rapid reduction and retention of silver by finely divided copper. Silver was separated at various times after thermal-neutron fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. The copper powder with affixed silver was dissolved in concentrated nitric acid and radiochemically purified for the analysis of ${}_{}{}^{118}{}_{}{}^{}\mathrm{Cd}$ derived from its silver precursor. The linear relationship between the logarithm of ${}_{}{}^{118}{}_{}{}^{}\mathrm{Cd}$ activity and separation time led to the identification of ${}_{}{}^{118}{}_{}{}^{}\mathrm{Ag}$. The half-life of this radionuclide was determined to be $5.3_{-0.7\mathrm{}}^{}{}_{}{}^{+0.9\mathrm{}}$ sec.