A direct measurement of the ground-state-to-ground-state electron-capture decay Q value of 95Tc 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 95Tc (excitation energy of 38.910(40) keV) from the ground state. The mass excess of 95Tc was measured to be −86015.95(18) keV/c2, 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 95Mo, 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 95Tc to excited states of 95Mo is compared to that of 163Ho currently being used for electron-neutrino-mass determination.

中文翻译：

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原子质量和电子捕获衰变 Q 值的高精度测量 95Tc


使用双 Penning 离子阱质谱仪 JYFLTRAP 直接测量了 95Tc 的基态到基态电子捕获衰减 Q 值。利用相位成像离子回旋共振技术的高分辨率，从基态分辨出 95Tc 的低位异构体（激发能量为 38.910（40） keV），确定 Q 值为 1695.92（13） keV。95Tc 的质量过剩测量为 −86015.95（18） keV/c2，精度高出约 28 倍，与最新的原子质量评估 （AME2020） 的值一致。结合衰变子 95Mo 的核能级数据，确定了两个潜在的超低 Q 值跃迁，用于未来的长期中微子质量测定实验。原子自洽多电子 Dirac-Hartree-Fock-Slater 方法和核壳模型已被用于预测两个跃迁的部分半衰期和能量释放分布。考虑了与这些过程相关的主要修正项，包括交换和重叠修正，以及 shake-up 和 shake-off 效应。将 95Tc 的电子捕获衰变为 95Mo 激发态中释放能量的归一化分布与目前用于电子-中微子质量测定的 163Ho 的分布进行了比较。