Updated evaluation of potential ultralow <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Q</mml:mi></mml:math>-value <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math>-decay candidates
D. K. Keblbeck, Ramesh Bhandari, N. D. Gamage, M. Horana Gamage, K. G. Leach, X. Mougeot, Matthew Redshaw
Abstract
``Ultralow'' $Q$-value $\ensuremath{\beta}$ decays are referred to as such due to their low decay energies of less than $\ensuremath{\approx}1$ keV. Such a low energy decay is possible when the parent nucleus decays to an excited state in the daughter, with an energy close to that of the $Q$ value. These decays are of interest as potential new candidates for neutrino mass determination experiments and as a testing ground for studies of atomic interference effects in the nuclear decay process. In this paper, we provide an updated evaluation of atomic mass data and nuclear energy-level data to identify potential ultralow $Q$-value $\ensuremath{\beta}$-decay candidates. For many of these candidates, more precise and accurate atomic mass data is needed to determine if the $Q$ value of the potential ultralow decay branch is energetically allowed and in fact ultralow. The relevant precise atomic mass measurements can be achieved via Penning trap mass spectrometry.