Development of noble gas/liquid detectors for neutrinoless double beta decay and dark matter searches

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Some of the most compelling questions in present-day physics, such as discovering dark matter particles ordetermining the neutrino mass scale via neutrinoless double beta decay, can only be answered via large-mass, low-background detectors sensitive to rare processes at the level of tens of events/year.  Such detectors must be constructed from ultra-pure materials to minimize internally generated backgrounds, properly shielded from backgrounds local to the experimental environment, and located deep underground to minimize contamination from cosmic-ray induced backgrounds.Efforts are currently underway to develop noble gas/liquid detectors utilizing ionization induced charge and/or scintillation light as the detection mechanism.  The central target for such detectors, typically Argon or Xenon in liquid or gaseous form, can be readily purified to reduce most backgrounds to the parts per billion level.  The detector signals can provide good energy resolution and position reconstruction enabling significant suppression of background levels and efficient identification of signal events.  The proposed research will focus on the development of noble gas/liquid detector technology with the  aim of designing and constructing large-scale detectors for dark matter particle and neutrinoless double beta decay searches.  A large-scale gaseous Xenon time projection chamber (TPC) with scintillation light readout is being developed at Carleton with the Enriched Xenon Observatory (EXO) collaboration.  The goal here is to measure the double beta decay spectrum of 136Xe and search for a neutrinoless double beta decay signal. Development of a liquid argon scintillation detector for a dark matter search will be carried out in conjunction with the Dark Matter Experiment using Argon Pulse shapes (DEAP). The SNOLAB facility, providing 6000 meters water equivalent of cosmic-ray shielding, is the ideal site to host both of these experiments.