Direct Measurement of the Mass Difference of Ho163 and Dy163 Solves the Q-Value Puzzle for the Neutrino Mass Determination

TL;DR

This study directly measured the atomic mass difference between 163Ho and 163Dy using advanced Penning trap techniques, resolving discrepancies in the Q value crucial for neutrino mass experiments.

Contribution

The paper presents the first direct measurement of the 163Ho-163Dy mass difference, clarifying the Q value for electron capture and improving neutrino mass sensitivity.

Findings

Measured mass difference shifts Q value by over 7 sigma

New Q value enables neutrino mass sensitivity below 10 eV in ECHo

Resolves longstanding discrepancies in previous measurements

Abstract

The atomic mass difference of 163Ho and 163Dy has been directly measured with the Penning trap mass spectrometer SHIPTRAP applying the novel phase imaging ion cyclotron resonance technique. Our measurement has solved the long standing problem of large discrepancies in the Q value of the electron capture in 163Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 [G. Audi et al., Chin. Phys. C 36, 1157 (2012)] by more than 7 sigma to 2833(30stat)(15sys) eV/c2. With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude.