| The goal of searching for 0νββ-decay is to probe an absolute neutrino mass scale suggested by the mass-splitting parameters observed by neutrino oscillation experiments. Furthermore, observation of 0νββ-decay is an explicit instance of lepton-number non-conservation. To detect the rare events such as 0νββ-decay, half-lives of the order of 10 25-1027 years have to be probed. Using an active detector with a large volume, such as hundreds of kilograms of HPGe in the case of MAJORANA, and taking efficient measures to mitigate background of cosmic and primordial origins are necessary for the success of a sensitive 0νββ-decay experiment.;One focus of the present research is the analysis of data from Cascades, a HPGe crystal array developed at Pacific Northwest National Laboratory in Richland, WA, to determine an upper bound on primordial radiation levels in the cryostat constructed with electroformed copper similar to that electroformed for MAJORANA. It will be shown, however, that there are sources of background much more serious than cryostats in 76Ge experiments. Additionally, experimental applications of the Cascades detector were studied by predicting the sensitivity for a 0νBB-decay experiment using GEANT4 simulations. Tellurium-130, an even-even nucleus that can undergo 0νββ-decay to either the ground state or first 01+ excited state of 130Xe, was used as an example. The present work developed techniques that will be used for a number of measurements of ββ-decay half-lives for decays to excited states of the daughter isotopes. |
