High-precision Q-value measurement and nuclear matrix element calculations for the double-β decay of 98Mo

The 98Mo double-beta decay Q-value has been measured, and the corresponding nuclear matrix elements of neutrinoless double-beta (0νββ) decay and the standard two-neutrino double-beta (2νββ) decay have been provided by nuclear theory. The double-beta decay Q-value has been determined as Qββ=113.668(68) keV using the JYFLTRAP Penning trap mass spectrometer. It is in agreement with the literature value, Qββ=109(6) keV, but almost 90 times more precise. Based on the measured Q-value, precise phase-space factors for 2νββ decay and 0νββ decay, needed in the half-life predictions, have been calculated. Furthermore, the involved nuclear matrix elements have been computed in the proton–neutron quasiparticle random-phase approximation (pnQRPA) and the microscopic interacting boson model (IBM-2) frameworks. Finally, predictions for the 2νββ decay are given, suggesting a much longer half-life than for the currently observed cases.