We report the first direct determination of the ground-state to ground-state electron-capture $Q$ value for the ${}^{72}\mathrm{As}$ to ${}^{72}\mathrm{Ge}$ decay by measuring their atomic mass difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The $Q$ value was measured to be 4343.596(75) keV, which is more than a fiftyfold improvement in precision compared to the value in the most recent Atomic Mass Evaluation 2020. Furthermore, the new $Q$ value was found to be 12.4(40) keV (3.1 $\sigma$) lower. With the significant reduction of the uncertainty of the ground-state to ground-state $Q$ value combined with the level scheme of ${}^{72}\mathrm{Ge}$ from $\gamma$-ray spectroscopy, we confirm that the five potential ultralow $Q$-value ${\beta }^{+}$ decay or electron capture transitions are energetically forbidden, thus precluding all the transitions as possible candidates for the electron neutrino mass determination. However, the discovery of small negative $Q$ values opens up the possibility to use ${}^{72}\mathrm{As}$ for the study of virtual $\beta \text{−}\gamma$ transitions.

中文翻译：

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直接测量 As72−Ge72 的质量差异排除了 As72 作为确定中微子质量的有希望的 β-衰变候选者

我们报告了第一次直接确定基态到基态电子捕获 $问$ 的价值 ${}^{72}\mathrm{作为}$ 至 ${}^{72}葛$通过使用双 Penning 阱质谱仪 JYFLTRAP 测量它们的原子质量差异来衰变。这$问$ 测量值为 4343.596(75) keV，与最近的 2020 年原子质量评估中的值相比，精度提高了 50 多倍。此外，新的 $问$ 发现值为 12.4(40) keV (3.1 $\sigma$） 降低。随着基态到基态的不确定性显着降低$问$ 值与级别方案相结合 ${}^{72}葛$ 从 $\gamma$射线光谱，我们确认五个潜在的超低 $问$-价值 ${\beta }^{+}$衰变或电子俘获跃迁在能量上被禁止，因此排除了所有跃迁作为电子中微子质量确定的可能候选者。然而，小负的发现$问$ 值开辟了使用的可能性 ${}^{72}\mathrm{作为}$ 用于研究虚拟 $\beta \text{-}\gamma$ 过渡。