Abstract
We report a direct measurement of the value of the neutrinoless double--decay candidate at the TITAN Penning-trap mass spectrometer, with the result that . 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 value, we also present results of a new calculation of the neutrinoless double--decay nuclear matrix element of . Using diagrammatic many-body perturbation theory to second order to account for physics outside the valence space, we constructed an effective shell-model double--decay operator, which increased the nuclear matrix element by about 75% compared with that produced by the bare operator. The new value and matrix element strengthen the case for a double--decay experiment.
- Received 17 August 2013
DOI:https://doi.org/10.1103/PhysRevC.89.045502
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