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The Development of the SNO+ Experiment: Scintillator Timing, Pulse Shape Discrimination, and Sterile Neutrinos

The SNO+ experiment is a multi-purpose neutrino detector which is under construction in the SNOLAB facility in Sudbury, Ontario. SNO+ will search for neutrinoless double beta decay, and will measure low energy solar neutrinos.

This thesis will describe three main development activities for the SNO+ experiment: the measurement of the timing parameters for the liquid scintillator cocktail, using those timing parameters to estimate the ability of SNO+ to discriminate
alpha and beta events in the detector, and a sensitivity study that examines how solar neutrino data can constrain a light sterile neutrino model.

Characterizing the timing parameters of the emission light due to charged-particle excitation in the scintillator is necessary for proper reconstruction of events in the detector. Using data obtained from a bench-top setup, the timing profile was modelled as three exponential components with distinct timing coefficients. Also investigated was the feasibility of using the timing profiles as a means to separate alpha and beta excitation events in the scintillator. The bench-top study suggested that using the peak-to-total method of analyzing the timing profiles could remove >$99.9% of alpha events while retaining >$99.9% of beta events. The timing parameters measured in the test set-up were then implemented in a Monte Carlo code which simulated the SNO+ detector conditions. The
simulation results suggested that detector effects reduce the effectiveness of discriminating between alpha and beta events using the peak-to-total method. Using a more optimal method of analyzing the timing profile differences, specifically using a Gatti filter, improved the discrimination capability back to the levels determined
in the bench-top setup.

One of the physics goals of SNO+ is the first precision measurement of the pep solar neutrino flux at the level of about 5% uncertainty. A study was performed to investigate how current solar neutrino data constrains the allowed parameters of a light 3+1 sterile neutrino model. The impact of adding a SNO+ pep solar neutrino measurement on the allowed parameters of the sterile model was then examined. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2014-04-28 20:52:42.41

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/12133
Date29 April 2014
CreatorsO'Sullivan, ERIN
ContributorsQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish, English
Detected LanguageEnglish
TypeThesis
RightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
RelationCanadian theses

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