Precise Penning trap Q value determinations for forbidden and low energy beta-decays

Nuclear β-decay has played a significant role in developing our understanding of the weak interaction. It continues to be relevant for tests of the standard model, searches for new physics, and investigations of neutrino properties. Penning trap mass spectrometry can provide a precise and independent determination of the β-decay Q value via a measurement of the mass difference between parent and daughter atoms. Q value measurements provide inputs for theoretical calculations of β-spectrum shape factors, electron branching ratios, and half-lives. They also enable the identification of β-decays with very low Q values that could be used in direct neutrino mass determination experiments, and they can be used to test systematics in precise β-spectroscopy measurements. In this presentation we will review recent measurements by our group of Q values for forbidden decays of long-lived primordial nuclides, searches for potential ultra-low Q value decay nuclides, and for evaluation of β-decay spectra.