Date of Award

2018

Document Type

Open Access Dissertation

Department

Physics and Astronomy

First Advisor

Vincente Guiseppe

Abstract

The Majorana Demonstrator is an array of P-type point contact (PPC) germanium detectors enclosed in a multi-layered shield at the 4850’ level of the Sanford Underground Research Facility. Its primary goal is to search for the neutrinoless double beta decay of 76Ge. The initial 10 kg-y dataset, taken over a two year period, has energy thresholds as low as 1 keV. This allows concurrent rare event searches for the signatures of dark matter and solar axions in the low energy spectrum. Though the detectors are routinely operated with sub-keV energy thresholds, changing noise conditions in the array have made it challenging to reliably discriminate true physics signals from noise at the lowest energies. New pulse shape analysis (PSA) techniques have been developed to remove electronics noise, and reject energy-degraded “slow” events in the data. A novel training set of low energy small-angle Compton scatter events is used to determine the efficiency of the PSA cuts to 1 keV, the lowest energy threshold analyzed to date by Majorana. This dissertation gives an overview of the neutrino and axion physics relevant to the Demonstrator, presents the PSA techniques and their application to the low energy data set, and gives results from a search for solar axions.

Available for download on Tuesday, February 11, 2020

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