Cumulative fission product yields of fast-neutron fission of 232Th

The cumulative yields of 33 fission products in fast-neutron induced fission of 232Th have been determined using direct gamma ray spectroscopic method. To obtain the absolute yields of fission products having half-lives ranging from 13 s to 32 days, a total of 66 multi-scaling gamma ray spectra with various irradiation and cooling periods were collected. Gamma rays and photopeak areas of interest were assigned to the fission products by their energies and half-lives. Fission product activities were evaluated from spectral data using growth and decay calculation, and fission yields were determined by normalizing the 140Ba yield to the average value from reported data. Results of the cumulative fission yields, among which 22 were measured for the first time, are compared with previous measurements and with recommended yields in recent evaluations. The agreements and some discrepancies of the comparisons are discussed, with the odd-even pairing effect emphasized. (orig.)