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Dissertation
Radon injection for light response calibration of the nEXO detector
Doctor of Philosophy (Ph.D.), Drexel University
Dec 2019
DOI:
https://doi.org/10.17918/tzwj-ka27
Abstract
Neutrinoless double beta decay (0vbb) is a second-order process that occurs in isotopes for which single beta decay is energetically forbidden. Observation of 0vbb would demonstrate that the neutrino is a Majorana particle and would violate total lepton number conservation. The nEXO experiment will search for 0vbb of 136-Xe using 5 tonnes of enriched liquid xenon in a low-background single-phase time projection chamber. nEXO is expected to reach a 10 year sensitivity to the 0vbb halflife of 136-Xe of approximately 10^28 years. This dissertation presents a novel technique for calibrating the response of the nEXO detector to scintillation signals using an injection of radon into the xenon recirculation loop. The baseline calibration plan for nEXO is a series of external gamma-ray sources which suffer from xenon's self-shielding properties. Dissolved calibration sources, on the other hand, are capable of characterizing the center of nEXO's large drift chamber, especially when complemented by liquid xenon fluid simulations. Better characterization of the detector response to light improves the energy resolution of the detector and therefore its sensitivity to the halflife of 0vbb. I present results from an end-of run calibration campaign on nEXO's predecessor experiment, EXO-200, using two candidate isotopes: 220-Rn and 222-Rn. I report observed alpha populations, efficiency corrections, and validation of EXO-200 fluid simulations using these data. This work also presents a new framework that combines fluid simulations with nEXO Monte Carlo to produce position-dependent functions of the detector response to light. Finally, I propose possible calibration schemes for radon injection for the nEXO detector.
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Details
- Title
- Radon injection for light response calibration of the nEXO detector
- Creators
- Erin V. Hansen - DU
- Contributors
- Michelle Dolinski (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xii, 110 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Arts and Sciences; Physics; Drexel University
- Other Identifier
- 11384; 991014632510504721