- 140 views
- 186 downloads
Electron Antineutrinos in the Water Phase of the SNO+ Experiment
-
- Author / Creator
- Mekarski, Pawel
-
The SNO+ experiment will soon complete its commissioning and begin searching for the neutrinoless double beta decay of tellurium, loaded within its liquid scintillator. As a large-scale (780 tonne) liquid scintillator detector, SNO+ will also be well positioned to make a precision measurement of antineutrinos, produced from nearby nuclear reactors. Measuring these antineutrinos would provide direct information about the cores of these reactors and enable a study of neutrino properties. In anticipation, a first search for antineutrinos was performed over 69.7 live days of data collected while the SNO+ detector was filled with water, an intermediate commissioning phase. A combination of Monte Carlo simulations and measurements with radioactive calibration sources were used to determine what the antineutrino signal (characterized by a coincident positron and neutron) would look like in the detector.
The neutron modeling was first validated by performing a series of measurements of an americium-beryllium (AmBe) neutron source at the University of Alberta. The neutron interactions were detected by irradiating various targets and measuring the gamma rays of the resulting reactions using a High Purity Germanium detector. Following Monte Carlo simulations of antineutrinos in the SNO+ detector, a search algorithm was developed to distinguish this signal from naturally occurring backgrounds. Lastly, another AmBe source was placed within the SNO+ detector to exactly characterize its neutron detection capabilities. Searching the detector-collected data yielded a total of 5 antineutrino candidate events in the region of interest. This was in agreement with expectations from another Monte Carlo simulation that was developed to model the detector backgrounds for this specific signal. From this, an upper limit at 90% confidence was determined for the flux of antineutrinos from nuclear reactors passing through the SNO+ detector of (1.45 +/- 0.23)E7 neutrinos/(cm2 s).
-
- Subjects / Keywords
-
- Graduation date
- Fall 2018
-
- Type of Item
- Thesis
-
- Degree
- Doctor of Philosophy
-
- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.