Updated evaluation of potential ultra-low Q value $\beta$-decay candidates

Understand

"Ultra-low" Q value $\beta$ decays are referred to as such due to their low decay energies of less than $\sim$1 keV.

• Such a low energy decay is possible when the parent nucleus decays into 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 ultra-low Q value $\beta$ decay candidates.