Eur. Phys. J. A (2025) 61: 33
https://doi.org/10.1140/epja/s10050-024-01481-6

Regular Article - Experimental Physics

Probing the double-beta decay of $_{}^{104}$Ru through precise Q-value measurements and nuclear matrix element calculations

¹ University of Jyväskylä, Department of Physics, Accelerator laboratory, P.O. Box 35 (YFL), FI-40014, Jyväskylä, Finland
² Finnish Institute for Educational Research, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
³ International Center for Advanced Training and Research in Physics (CIFRA), 409, Atomistilor Street, 077125, Bucharest-Magurele, Romania

^a jouni.k.a.ruotsalainen@jyu.fi
^b elina.k.kauppinen@jyu.fi

Received: 21 October 2024
Accepted: 25 December 2024
Published online: 16 February 2025

Abstract

The Q value of the double-beta (${\beta }^{-}{\beta }^{-}$) decay of $_{}^{104}$Ru ($Q_{{\beta }^{-}{\beta }^{-}}$-value) was determined using the JYFLTRAP double Penning trap mass spectrometer employing the Phase-Imaging Ion Cyclotron Resonance (PI-ICR) method. The obtained value of 1297.705(36) keV is in agreement with the current literature value of 1299.4(27) keV but is over 70 times more precise. As a consistency check on a 100 eV level, we also measured the precisely known $_{}^{102}$Pd double-electron capture Q value, $Q_{\text{ECEC}}=1203.531(92)$ keV, which agrees with the literature value of 1203.47(4) keV. The measured Q value of $_{}^{104}$Ru ${\beta }^{-}{\beta }^{-}$ decay was used in calculations of the phase-space factors of the double-beta decay. Also, the nuclear matrix elements were calculated using the microscopic interacting boson model (IBM-2) as a nuclear model and compared with other available results. With these theoretical calculations based on the measured Q value, the estimates for the two-neutrino and neutrinoless double-beta decay half-lives of $_{}^{104}$Ru were calculated to be $t_{1/2}^{2\nu \beta \beta }>5.449\times {10}^{21}$ years and $t_{1/2}^{0\nu \beta \beta }>5.775\times {10}^{26}$ years, respectively. The calculated $2\nu {\beta }^{-}{\beta }^{-}$ half-life is longer than the current experimental lower limit but short enough to be potentially within reach with future high precision experiments.