Measurement of the mass of the electron neutrino using electron capture in 163Ho

Abstract

Using an M X-ray spectrum from electron capture in 163Ho together with M X-ray fluorescence spectra of the Dy atom, the partial decay constants of 163Ho, λM1 and λM2 were measured. With λM1, λM2 and λt (total decay constant) as three constraints, the mass of the electron neutrino, mVe, the Q-value, and log(ft) of the 163Ho decay were simultaneously determined. Results obtained are mVe=110−110+350eV, Q=2.710−0.500+0.100keV, and log(ft)=4.993−0.001+0.030.