New determination of double-β-decay properties in 48Ca: High-precision Qββ-value measurement and improved nuclear matrix element calculations

We report a direct measurement of the Qββ value of the neutrinoless double-β-decay candidate 48Ca at the TITAN Penning-trap mass spectrometer, with the result that Qββ=4267.98(32)keV. We measured the masses of both the mother and daughter nuclides, and in the latter case found a 1 keV deviation from the literature value. In addition to the Qββ value, we also present results of a new calculation of the neutrinoless double-β-decay nuclear matrix …