FRACTIONAL INDEPENDENT YIELDS OF SILVER-121 AND CADMIUM-121 FROM THERMAL-NEUTRON FISSION OF URANIUM-235

The fractional cumulative yield of ('121)Ag and the fractional inde-pendent yield of ('121)Cd were determined from thermal-neutron induced fission of ('235)U. The SISAK continuous solvent extraction system was used to operate Ag and Cd rapidly during irradiation of an aqueous solution containing 93% enriched ('235)U. After allowing sufficient time for decay of all precursors, Sn was chemically separated and its beta decay followed on proportional counters.

To utilize the SISAK system fully, it was first necessary to inves-tigate rapid (<1sec) solvent extraction systems, and methods were developed which allowed the separation of silver from cadmium and cadmium from indium.

The fractional yields obtained were used to determine the charge dispersion parameters (sigma)(,Z) and (DELTA)Z for A=121. The value of (sigma)(,Z) = 0.55 (+OR-) 0.02 is about the same as (sigma)(,Z) for most fission products. The positive value of (DELTA)Z = 0.42 (+OR-) 0.03 is very different from the negative values found for most heavy fission products and supports with other data a zig-zag (DELTA)Z function as symmetry is approached.