REPORT ON DETERMINATION OF THE REST MASS OF ELECTRON NEUTRINO WITH 3H β RAY SPECTROSCOPY

With an iron free double focusing β ray spectrometer and Bergkvist electrostatic compensated Ti³H 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.