Radiochemical studies of pine structure in chain yields from neutron-induced fission

Abstract

The cumulative fission yields of several mass chains have been determined radiochemically relative to those of mass-99 and -97 for fission of uranium- 238 and thorlam-232 induced by both 3- and 14.8-MeV neutrons. The yields of mass chains 133 and 135 produced in these fissioning systems were calculated from measurements of xenon-133 and -135. Yields of mass chains 131 to 13k resulting from 14.8-MeV neutron-Induced fission of uranlum-238 were calculated from measurements of the iodine isotopes in the decay chains. An end-window gas-flow (β-proportional counter was used to count the solid sources; gas Geiger-counters were used to count the xenon samples. Computer techniques were employed to analyse the decay data. Fine structure was observed in the mass-yield curves around masses 133-135 for fission of uranlum-238 at both neutron bombarding energies; it was also observed for fission of thorlum-232 at the lower but not at the higher excitation energy. The results are discussed In relation to other relevant experimental data and theoretical models.