Sensitivity of SNO+ to supernova neutrinos

Stringer, Mark (2019) Sensitivity of SNO+ to supernova neutrinos. Doctoral thesis (PhD), University of Sussex.

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Abstract

The Super-K experiment determined that neutrinos are massive particles by observing the oscillation of atmospheric neutrinos. The SNO experiment confirmed this measurement by observing neutrinos from the Sun. The SNO+ experiment is intended to study the nature of neutrino masses by replacing the heavy water used in SNO with scintillator. The main goal of the experiment is to search for neutrinoless double-beta decay within 130Te. The SNO+ detector is much more sensitive to radioactive contamination than the SNO experiment. For this reason an external LED calibration system has been developed so the detector can be calibrated without risking contamination of the scintillator volume. This thesis describes the commissioning of this calibration system and its performance during the water phase of SNO+. The scintillator volume is separated from the surrounding detector via an acrylic vessel. As scintillator is less dense than water the position of the vessel is expected to shift throughout the lifetime of SNO+. A method to determine the position of the vessel using the external LED system is detailed as well as its performance. A measurement of the scattering length of the water surrounding the acrylic vessel using the same LED system is also presented. Calibration of the detector will also be performed using sources deployed within the vessel, and a study on the angular distribution of light from these sources and the effect of hardware upgrades is also presented. During the lifetime of the SNO+ experiment, the detector will be sensitive to neutrinos emitted from a supernovae within the Milky Way. A software framework was developed to accurately simulate the main interaction channels for supernova neutrinos within SNO+. The software was used to determine the burst trigger effciency during the water phase as well as a procedure to follow in the case of the burst. One outstanding problem in the field of neutrino physics is the neutrino mass hierarchy; whether there are two heavy and one light or two light and one heavy neutrino mass eigenstates. Neutrinos from a supernova burst may be able to solve this problem. A simple study is performed to determine the sensitivity of various detectors. The same analysis is performed using the aforementioned software to explore any systematic effects which may alter the sensitivity.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QC Physics > QC0170 Atomic physics. Constitution and properties of matter Including molecular physics, relativity, quantum theory, and solid state physics
Depositing User: Library Cataloguing
Date Deposited: 18 Jan 2019 12:42
Last Modified: 18 Jan 2019 12:42
URI: http://srodev.sussex.ac.uk/id/eprint/81233

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