The investigation of the absolute scale of the effective neutrino mass remains challenging due to the exclusively weak interaction of neutrinos with all known particles in the standard model of particle physics. Currently, the most precise and least model-dependent upper limit on the electron antineutrino mass is set by the KATRIN experiment from the analysis of the tritium \b{eta}-decay. Another promising approach is the electron capture in 163Ho, which is under investigation using microcalorimetry within the ECHo and HOLMES collab orations. An independently measured Q-value of this process is vital for the assessment of systematic uncertainties in the neutrino mass determination. Here, we report a direct, independent determination of this Q-value by measuring the free-space cyclotron frequency ratio of highly charged ions of 163Ho and 163Dy in the Penning trap experiment \textsc{Pentatrap}. Combining this ratio with atomic physics calculations of the electronic binding energies yields a Q-value of 2863.2(0.6)eV/c2 – a more than 50-fold improvement over the state-of-the-art. This will enable the determination of the electron neutrino mass on a sub-eV level from the analysis of the electron capture in 163Ho.

M. W. Haverkort, C. H. Keitel, K. Blaum et al., „Penning-trap measurement of the Q-value
of the electron capture in 163Ho for the determination of the electron neutrino mass“, 9. Feb.
2024, arXiv:2402.06464 (2024).


Related to Project B01, B02, C01