Gamma-ray spectroscopy in the decay of 83Se to levels of 83Br

High-resolution γ ray spectroscopy experiments have been done to study the emissions from the radioactive decay of 22-min 83gSe produced from neutron capture using samples of enriched 82Se. Energy and intensity values have been obtained to roughly an order of magnitude greater precision than in previous studies. Based on energy sums, 2 new levels are proposed in the daughter 83Br and one previously proposed level is shown to be doubtful. Some 25 new transitions appear to decay with the 83Se halflife, about half of which can be accommodated among the previous or newly proposed levels. Several previous γ ray placements are shown to be inconsistent with the new determinations of the 83Br energy levels, but cannot be accommodated anywhere else among the known levels. As a result of the missing γ ray placements, some of the β branchings in the decay to levels of 83Br appear to be negative. Gamma rays from the 2.4-h decay of the daughter 83Br to levels of 83Kr have also been observed, along with decays of 81g,mSe present as a small impurity in the enriched samples and also as a strong component in irradiated samples of natural Se.