The International Germanium Experiment (IGEX) is an intense search for an exotic nuclear decay mode, nutrionless double-beta decay, the existence of which would definitely prove that neutrinos are their own anti-particles, and have non-zero mass. Presently the experiment is being operated in the Canfranc Underground Laboratory operated by the University of Zaragoza in Spain, and includes three large germanium detectors fabricated with isotopically enriched germanium from the former Soviet Union. At present a forth detector is being fabricated with funding from the US Department of Energy. This experiment, and its competitor the Heidelburg-Moscow experiment, have produced the most sensitive search for this type of exotic process thus far. IGEX has recently developed very high quality pulse shape electronics techniques that allow the elimination of much of the interfering background which will further increase its sensitivity. This grant supports the technical leader and spokesman of the experiment and three graduate students. The spokesman's institute, the University of South Carolina, also supports travel and subsistence of Russian participants. The IGEX collaboration is composed of twenty-six researchers from the United States, Spain, and the former Soviet Union. The grant also provides partial support for the Principle Investigator to participate in the development of next generation, significantly enlarged double-beta decay experiments using newly development cryogenic techniques. Since these techniques have not yet demonstrated their ability to reduce interfering background to the necessary levels, the germanium-76 experiments still represent the most sensitive technique for searching for this important exotic nuclear decay mode and its implications for the existence of neutrino mass. These experiments represent very sensitive tests of the standard model of elementary particle physics, and have the potential for a significant impact in particle physics, astrophysics, and cosmology.
