Doctoral Dissertations
Date of Award
8-2021
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Physics
Major Professor
Yuri V. Efremenko
Committee Members
Nadia Fomin, Eric D. Lukosi, Lucas Platter, Andrew W. Steiner
Abstract
Neutrino-less double-beta decay is a proposed type of radioactive decay that, if observed, could answer several outstanding physics questions, such as "Is the neutrino its own antiparticle otherwise known as a Majorana particle?", "What is the mass of the neutrino?", and "What is the neutrino mass hierarchy?" As technology and experimental techniques improve, the sensitivity of experiments looking for rare events becomes more dependent on the backgrounds. Some of these backgrounds can be reduced using shielding techniques such as implementing a veto system, selecting radiopure components, and conducting the experiment deep underground. However some amount of cosmogenically induced backgrounds remain as an irreducible background. By understanding how these processes occur within the experimental setup, the effect of these backgrounds on the experimental analysis can be mitigated. The Majorana Demonstrator, located at the Sanford Underground Research Facility in Lead, South Dakota, is currently searching for neutrinoless double-beta decay using two arrays of germanium-76 P-Type Point Contact detectors. In this work, for the first time, actual data from the Majorana Demonstrator is being used to benchmark popular simulation packages to better understand in situ production of radioactive isotopes and provide tools for future low background experiments. The simulation packages FLUKA and GEANT4 are used to estimate the irreducible prompt muon-induced background rate in the Majorana Demonstrator, and the measurement of five muon-induced background signals is conducted. In addition, the University of Tennessee group was responsible for construction, commissioning, maintaining, and data analysis for one of the key Majorana Demonstrator subsystems: The Active Muon Veto System. We will discuss related activities as well.
Recommended Citation
Lopez, Andrew, "In Situ Cosmogenic Backgrounds in the MAJORANA DEMONSTRATOR. " PhD diss., University of Tennessee, 2021.
https://trace.tennessee.edu/utk_graddiss/6540