Optimization Studies for the COBRA Neutrinoless Double-Beta Decay Experiment and Results from a Prototype

The COBRA experiment uses Cadmium Zinc Telluride (CZT) room-temperature semiconductor detectors to search for the neutrinoless double-beta decay of cadmium-116. While the experiment has produced globally competitive half-life limits with data from coplanar-grid CZT detectors, a future ton-scale iteration could set limits constraining the effective Majorana neutrino mass to less than 100 meV. The aim of this work is to determine the optimal CZT detector type for such an experiment. First, an overview of the relevant neutrino physics as well as an introduction to the COBRA experiment is presented. The performance characteristics and design criteria for CZT detectors are then covered, both in general and as they relate to COBRA. Simulations and prototype experiments have been performed using two of the detector design candidates. The method and results are discussed in detail. Finally, the prototype is compared with other CZT detector designs in the context of performance and scalability for a 420 kg COBRA experiment.