Abstract
The emission of prompt fission rays within a few nanoseconds to a few microseconds following the scission point is studied in the Hauser-Feshbach formalism applied to the deexcitation of primary excited fission fragments. Neutron and -ray evaporations from fully accelerated fission fragments are calculated in competition at each stage of the decay, and the role of isomers in the fission products, before decay, is analyzed. The time evolution of the average total -ray energy, the average total -ray multiplicity, and the fragment-specific -ray spectra is presented in the case of neutron-induced fission reactions of and , as well as spontaneous fission of . The production of specific isomeric states is calculated and compared to available experimental data. About 7% of all prompt fission rays are predicted to be emitted between 10 ns and 5 following fission, in the case of and reactions, and up to 3% in the case of spontaneous fission. The cumulative average total -ray energy increases by 2% to 5% in the same time interval. Finally, those results are shown to be robust against significant changes in the model input parameters.
7 More- Received 1 July 2016
DOI:https://doi.org/10.1103/PhysRevC.94.064613
©2016 American Physical Society