High-precision Q-value measurement and nuclear matrix element calculations for the double-$$\beta $$ decay of $$^{98}$$Mo

Abstract

AbstractThe $$^{98}$$ 98 Mo double-beta decay Q-value has been measured, and the corresponding nuclear matrix elements of neutrinoless double-beta ($$0\nu \beta \beta $$ 0 ν β β ) decay and the standard two-neutrino double-beta ($$2\nu \beta \beta $$ 2 ν β β ) decay have been provided by nuclear theory. The double-beta decay Q-value has been determined as $$Q_{\beta \beta }=113.668(68)$$ Q β β = 113.668 ( 68 )  keV using the JYFLTRAP Penning trap mass spectrometer. It is in agreement with the literature value, $$Q_{\beta \beta }=109(6)$$ Q β β = 109 ( 6 )  keV, but almost 90 times more precise. Based on the measured Q-value, precise phase-space factors for $$2\nu \beta \beta $$ 2 ν β β decay and $$0\nu \beta \beta $$ 0 ν β β 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 $$2\nu \beta \beta $$ 2 ν β β decay are given, suggesting a much longer half-life than for the currently observed cases.