Relative yields of stable cadmium isotopes in neutron induced fission

The relative fission yields of the five stable isotopes of cadmium ( 111 Cd, 112 Cd, 113 Cd, 114 Cd, and 116 Cd) produced in the thermal and epicadmium fission of 233 U and 235 U and the epicadmium fission of 238 U have been measured by solid source mass spectrometry. Nanogram sized samples of fission product cadmium were analyzed to give a range of yields on the low mass side of symmetric fission. The results indicate that the mass yield distribution for thermal induced fission is relatively flat within five mass units of the valley of symmetry. The epicadmium induced fission results show enhanced yields at mass 111, the degree of enrichment depending on the mass of the fissioning nucleus. The only significant fine structure occurs at mass 113 for the epicadmium induced fission of 235 U. Although less certain, there is also a suggestion of a depressed yield at mass 113 for thermal neutron induced fission of 235 U as well. No evidence of a symmetric peak was observed in any of the data. The absence of significant fine structure in this mass range suggests that the average number of neutrons emitted per fission event varies fairly smoothly with mass.