High-precision measurements of the atomic mass and electron-capture decay Q value of 95Tc

Le résumé fourni par la source

A direct measurement of the ground-state-to-ground-state electron-capture decay Q value of 95 Tc has been performed utilizing the double Penning trap mass spectrometer JYFLTRAP. The Q value was determined to be 1695.92(13) keV by taking advantage of the high resolving power of the phase-imaging ion-cyclotron-resonance technique to resolve the low-lying isomeric state of 95 Tc (excitation energy of 38.910(40) keV) from the ground state. The mass excess of 95 Tc was measured to be −86015.95(18) keV/c 2 , exhibiting a precision of about 28 times higher and in agreement with the value from the newest Atomic Mass Evaluation (AME2020). Combined with the nuclear energy-level data for the decay-daughter 95 Mo, two potential ultra-low Q -value transitions are identified for future long-term neutrino-mass determination experiments. The atomic self-consistent many-electron Dirac–Hartree–Fock–Slater method and the nuclear shell model have been used to predict the partial half-lives and energy-release distributions for the two transitions. The dominant correction terms related to those processes are considered, including the exchange and overlap corrections, and the shake-up and shake-off effects. The normalized distribution of the released energy in the electron-capture decay of 95 Tc to excited states of 95 Mo is compared to that of 163 Ho currently being used for electron-neutrino-mass determination.

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