The Use of Beta-Strength-Function Data to Obtain Average Decay Energy Values for Short-Lived Fission Product Nuclides

In this paper, we point out that data from earlier experiments carried out to measure beta-strength functions for short-lived fission products can also be used to provide average beta- and gamma-decay energy values for these nuclides. In our evaluation of decay data for the ENDF/B-V fission product file, we have used this approach as a means of deducing average decay energy values for a number of these isotopes for which experimentally based average values would otherwise not have been available. The methods employed are discussed, and the results for the average beta-decay energies per decay, <E_β>, are presented. Where available, <E_β> values deduced from decay scheme studies and from direct beta-spectrum measurements are given for purposes of comparison. Evidence is presented that suggests that the conventional decay scheme studies may not be a reliable source of average decay energy data for nuclides with large Q_β values. We propose that different types of experimental measurements, possibly involving total absorption techniques (of which the beta-strength work treated here might be considered as one example), may provide a better means of producing this important information.