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Hoff, D. E.M.

Publications and source records attributed to Hoff, D. E.M..

Report on branching ratios for 111 Ag

Our understanding on the distribution of fragment masses following fission, or fission yields is largely impacted by the quality of nuclear data. One of the most straightforward and reliable ways to determine the number of fissions that occurred in a chain reaction is done via detection of the characteristic γ-rays emitted during the β decay of the fission product. These γ rays are emitted in only a fraction of the decays, and this fraction (the γ-ray intensities) must be known accurately to determine the total number of fissions. Many long-lived fission products, such as 111 Ag, play an important role in science-based stockpile stewardship and nuclear forensics. The γ-ray intensities from the decay of 111 Ag are known to only 5%, leading to a 5% uncertainty in fission-chain yield. This work aims to improve the precision of these γ-ray intensities for the most intense emissions following the decay of 111 Ag, as seen in Figure 1.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Precise mass measurements of A = 133 isobars with the Canadian Penning Trap: Resolving the Q β − anomaly at 133Te

We report precision mass measurements of 133 Sb 133g,m Te, and 133g,m I, produced at CARIBU at Argonne National Laboratory's ATLAS facility and measured using the Canadian Penning Trap mass spectrometer. These masses clarify an anomaly in the 133 Te β-decay. The masses reported in the 2020 Atomic Mass Evaluation (M. Wang et al., 2021) produce Q B - ( 133 Te)=2920(6) keV; however, the highest-lying 133 I level populated in this decay is observed at E i = 2935.83(15) keV, resulting in an anomalous Q$^i_B-$ = -16(6)keV. Our new measurements give Q B - ( 133 Te)=2934.8(11) keV, a factor of five more precise, yielding Q$^i_B$ = -1.0(12) keV, a 3σ shift from the previous results. This resolves this anomaly, but indicates further anomalies in our understanding of the structure of this isotope.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗