Penning trap mass measurements of ${}^{149}\mathrm{La}$, ${}^{149}\mathrm{Ce}$, and ${}^{149}\mathrm{Pr}$ were performed with the Canadian Penning Trap at the Californium Rare Isotope Breeder Upgrade facility of Argonne National Laboratory using the phase-imaging ion-cyclotron-resonance technique. The resulting mass excess of ${}^{149}\mathrm{La}$ differs by 221.6(32) keV from a recent JYFLTRAP measurement, resulting in a significant change in the profile of the two-neutron separation energy for that isotopic chain. The mass excesses of ${}^{149}\mathrm{Ce}$ and ${}^{149}\mathrm{Pr}$ are determined with an eightfold improvement in precision compared to previous time-of-flight ion-cyclotron-resonance measurements; the ${}^{149}\mathrm{Ce}$ value is consistent with AME2020, while the ${}^{149}\mathrm{Pr}$ mass excess is lower by 17.5(100) keV. The mass excesses of ${}^{149}\mathrm{La}$ and ${}^{149}\mathrm{Pr}$ reported in this work have been confirmed recently by a measurement with a multireflection time-of-flight mass spectrometer coupled to a $\beta$-time-of-flight detector at RIKEN, providing further validation of the present results.

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• Binding energy & masses
• Nuclear structure & decays
• 90 ≤ A ≤ 149