1. Direct measurement of the mass difference of As72−Ge72 rules out As72 as a promising β -decay candidate to determine the neutrino mass
- Author
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J. Kotila, S. Geldhof, Á. Koszorús, Dmitrii Nesterenko, Jouni Suhonen, Ari Jokinen, Joel Kostensalo, R. P. de Groote, V. Virtanen, A. P. Weaver, A. Raggio, Sami Rinta-Antila, A. Zadvornaya, Iain Moore, M. Hukkanen, Anu Kankainen, O. Beliuskina, W. Gins, A. de Roubin, Z. Ge, and Tommi Eronen
- Subjects
Physics ,010308 nuclear & particles physics ,Electron capture ,Sigma ,Penning trap ,Mass spectrometry ,01 natural sciences ,Atomic mass ,0103 physical sciences ,Neutrino ,Atomic physics ,010306 general physics ,Spectroscopy ,Electron neutrino - Abstract
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 $\ensuremath{\sigma}$) 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 $\ensuremath{\gamma}$-ray spectroscopy, we confirm that the five potential ultralow $Q$-value ${\ensuremath{\beta}}^{+}$ 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 $\ensuremath{\beta}\text{\ensuremath{-}}\ensuremath{\gamma}$ transitions.
- Published
- 2021