04/20/2010

Searching for Neutrino Mass at the sub-eV scale with the Enriched Xenon Observatory

Lisa Kaufman, University of Maryland

Neutrinos are the most mysterious and elusive particles known to particle physicists. The neutrino was first theorized in 1930 to be a neutral and massless particle needed to preserve conservation of energy in the radioactive process of nuclear beta decay. Since its discovery in 1956, physicists have actively sought to understand more about the neutrino’s physical properties and behavior. In the past 10 years, one of the most interesting discoveries about neutrinos has been that there are three different types, or flavors, of neutrinos and that those flavors can mix into one another. The experimental evidence for mixing has led physicists to conclude that neutrinos have mass. While the relative masses between the flavors is known, the absolute mass scale is still unknown. Studying beta decay allowed for the discovery of the neutrino, and studying the process of double beta decay will allow the determination of the neutrino mass. The Enriched Xenon Observatory (EXO) for double beta decay will measure this process for the nucleus of 136Xe. The first phase of the experiment uses 200 kg of xenon isotopically enriched to 80% in 136Xe and is currently the largest double beta decay experiment in the world. EXO has recently been installed at the WIPP site in Carlsbad, NM. A description of the EXO experiment, installation, and current status will be presented.