Evidence for the emission of a 17-keV neutrino in the β decay ofC14

Abstract
We have studied the β spectrum of C14 using a germanium detector containing a crystal with C14 dissolved in it. We find a feature in the β spectrum 17 keV below the end point which can be explained by the hypothesis that there is a heavy neutrino emitted in the β decay of C14 with a mass of 17±2 keV and an emission probability of (1.40±0.45±0.14)%.