$Q$ Value and Half-Lives for the Double-$\beta$-Decay Nuclide ${}^{110}\mathrm{Pd}$

The ${}^{110}\mathrm{Pd}$ double-$\beta$ decay $Q$ value was measured with the Penning-trap mass spectrometer ISOLTRAP to be $Q=2017.85(64)\mathrm{keV}$. This value shifted by 14 keV compared with the literature value and is 17 times more precise, resulting in new phase-space factors for the two-neutrino and neutrinoless decay modes. In addition a new set of the relevant matrix elements has been calculated. The expected half-life of the two-neutrino mode was reevaluated as $1.5(6)\times {10}^{20}\mathrm{yr}$. With its high natural abundance, the new results reveal ${}^{110}\mathrm{Pd}$ to be an excellent candidate for double-$\beta$ decay studies.

Figure 1

Scheme of ISOLTRAP as used for the present measurements. The atoms are ionized with the ablation ion source, trapped in the first trap for purification and transferred to the second trap to measure their cyclotron frequency.

Figure 2

Time-of-flight resonance as a function of the excitation frequency for ${}^{110}\mathrm{Pd}^{+}$ for the Ramsey excitation scheme 50-600-50 ms with a fit of the expected theoretical line shape (solid line) [29].

Figure 3

Cyclotron frequencies of ${}^{110}\mathrm{Cd}^{+}$ (circles, top) and of ${}^{110}\mathrm{Pd}^{+}$ (squares, bottom) using the Ramsey excitation pattern 50-600-50 ms. The solid lines are simultaneous fits to both isobars (see text).