An experiment to determine the mass of the electron antineutrino

The fact that neutrinos may have mass has attracted considerable attention in recent years both on the theoretical and experimental forefronts. The advent of Grand Unified Theories, the candidacy of neutrinos as dark matter, the proposed neutrino oscillation (and MSW effect) solution to the Solar Neutrino Puzzle and the observance of neutrinos from Supernova 1987A have further stimulated experimental efforts to directly probe neutrino masses by looking for dynamical effects. The technique of examining the end-point spectrum of Tritium β-decay has long been used in this vein. The recent report of a positive electron antineutrino mass of 30 ± 2 eV by the ITEP group in Moscow and the subsequent results from Los Alamos, Zurich and Japan which are in conflict with this value have stirred some controversy in this field. The present experiment uses a technique which is different from the usual magnetic-electrostatic analysis of the β-spectrum employed by most groups-that of spherical electrostatic retarding field analysis. This method yields an integrated spectrum of the source and became of this and the large solid angle of acceptance of the spectrometer, the experiment yields very good statistics. Also the proposed source in this case is frozen T2 for which the various correction factors can be estimated very accurately. The design, construction and testing of the spectrometer is described in detail in this dissertation as is the procedure used for fitting the data and calculating the correction factors to be applied to it