Report on determination of the rest mass of electron neutrino with 3H β ray spectroscopy

Abstract

With an iron free double focusing β ray spectrometer and Bergkvist electrostatic compensated Ti-3H and implantated tritium source, we studied β ray spectrum of 3H near the end point. We found that if the rest mass of electron neutrino is positive, the value must be less than the experimental uncertainty now attainable.