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

We report precision mass measurements of ¹³³Sb, ${}^{133g,m}$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 ¹³³Te β-decay. The masses reported in the 2020 Atomic Mass Evaluation (M. Wang et al., 2021) produce $Q_{{\beta }^{-}}({}^{133}$Te)=2920(6) keV; however, the highest-lying ¹³³I level populated in this decay is observed at $E_i=2935.83\left(15\right)$ keV, resulting in an anomalous $Q_{{\beta }^{-}}^i=-16\left(6\right)$ keV. Our new measurements give $Q_{{\beta }^{-}}\left({}^{133}\text{Te}\right)=2934.8\left(11\right)$ keV, a factor of five more precise, yielding $Q_{\beta }^i=-1.0\left(12\right)$ 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.