The low-energy beam and ion trap Penning trap mass spectrometer was used for an improved determination of the ${}^{48}\mathrm{Ca}$ double-$\beta$ decay $Q$ value: $Q_{\beta \beta }=4268.121\left(79\right)\mathrm{keV}$. The new value is 1.2 keV greater than the value in the 2012 atomic mass evaluation [Chin. Phys. C 36, 1603 (2012)], a shift of three $\sigma$, and is a factor of 5 more precise. Accurate knowledge of this $Q$ value is important for experimental searches to observe neutrinoless double-$\beta$ decay (0$\nu \beta \beta$) in ${}^{48}\mathrm{Ca}$ and is essential for extracting the effective mass of the electron neutrino if the ${}^{48}\mathrm{Ca}$ half-life of 0$\nu \beta \beta$ was experimentally determined.

• Received 12 April 2013

DOI:https://doi.org/10.1103/PhysRevC.88.022501