Decay spectroscopy of the blocked fission product I130

Abstract

Numerous applications rely on the identification and quantification of fission products with the activation technique, where $\ensuremath{\gamma}$ rays emitted in the decay are used to estimate the initial activity of the radionuclide of interest. $^{130}\mathrm{I}$ is a so-called blocked fission product, which can be produced only directly through fission, a property that makes it particularly attractive for nuclear forensics. A source of $^{130}\mathrm{I}$ was produced using a $(p,n)$ reaction on enriched $^{130}\mathrm{Te}$ at the Brookhaven Tandem Van de Graaff, and its decay was studied with the Gammasphere at Argonne National Laboratory. Two new levels were identified, and over 25 transitions were added, removed, or replaced in the level scheme with intensity measurements made down to ${I}_{\ensuremath{\gamma}}$ = 0.000 66 per 100 decays. The uncertainty on the intensities of the strongest transitions, those that are commonly used to quantify the activity of the radionuclide, was improved by a factor of 2 compared to the previous best assessment, and discrepancies in the literature values were resolved. A detailed angular correlation analysis further permitted the determination of a number of spin assignments for excited levels and mixing ratios for $\ensuremath{\gamma}$-ray transitions.