{"id":{"repo_id":"queens","oai_identifier":"oai:queensu.scholaris.ca:1974/27931"},"canonical_url":"https://search.dev.ndltd.org/etd/queens/oai:queensu.scholaris.ca:1974/27931","repository":{"repo_id":"queens","name":"Queens University","base_url":"https://qspace.library.queensu.ca/server/oai/request"},"display":{"title":"Neutron Measurements and Reactor Antineutrino Search with the SNO+ Detector in the Water Phase","abstract":"The SNO+ experiment is a large-scale liquid scintillator neutrino experiment with a wide range of physics objectives. SNO+ has adopted a staged approach where the detector was first filled with ultra-pure water before substituting with liquid scintillator and the target isotope $^{130}$Te for neutrinoless double beta decay. During the SNO+ water phase, an $^{241}$Am$^{9}$Be source is deployed across the detector volume to calibrate the detector's energy response and its response to neutrons. The $^{241}$Am$^{9}$Be source emits a unique coincidence signal with the prompt event being a 4.4 MeV $\\gamma$ and the delayed a neutron capture signal (2.2 MeV $\\gamma$). A novel, minimalistic, statistical analysis of the $^{241}$Am$^{9}$Be calibration data was designed and used to measure the capture time constant $\\tau$, capture cross-section $\\sigma_{H,t}$, and the neutron detection efficiency $E_{\\textrm{center}}$ at the center of the detector: \\begin{equation} \\begin{aligned} &\\tau = 202.35 \\pm 0.42\\ (stat.)\\ ^{+0.38}_{-0.31}\\ (syst.)~\\mu\\textrm{s}, \\\\ &\\sigma_{H,t} = 336.3 ^{+1.2}_{-1.5}~\\textrm{mb}, \\\\ &E_{\\textrm{center}} = (50.8 \\pm 0.6)\\%. \\end{aligned} \\end{equation} Additionally, with the help of Monte Carlo simulations, a volume-weighted neutron detection efficiency across the detector is evaluated to be $E_{\\textrm{detector}} = (46.5 \\pm 0.5\\ (stat.\\ only))\\%$. The simulation is also central to an energy calibration using the 4.4 MeV $\\gamma$ to measure the energy resolution and energy scale of the detector. Finally, with $\\sim$115 days of early water data, an upper limit, $\\hat{\\Phi}_{\\bar{\\nu}_e, \\textrm{ult}}$ = $(1.76 \\pm 0.29) \\times 10^6 \\bar{\\nu}/(\\textrm{cm}^2\\cdot\\textrm{s})$, on the reactor antineutrino flux for SNO+ is obtained using a maximum likelihood approach. The limit is about a factor of 9 higher than the expected signal in SNO+, which can be calculated using available reactor output power data.","abstract_html":"The SNO+ experiment is a large-scale liquid scintillator neutrino experiment with a wide range of physics objectives. SNO+ has adopted a staged approach where the detector was first filled with ultra-pure water before substituting with liquid scintillator and the target isotope <span class=\"etd-inline-math\"><sup>130</sup></span>Te for neutrinoless double beta decay. During the SNO+ water phase, an <span class=\"etd-inline-math\"><sup>241</sup></span>Am<span class=\"etd-inline-math\"><sup>9</sup></span>Be source is deployed across the detector volume to calibrate the detector&#x27;s energy response and its response to neutrons. The <span class=\"etd-inline-math\"><sup>241</sup></span>Am<span class=\"etd-inline-math\"><sup>9</sup></span>Be source emits a unique coincidence signal with the prompt event being a 4.4 MeV <span class=\"etd-inline-math\">&gamma;</span> and the delayed a neutron capture signal (2.2 MeV <span class=\"etd-inline-math\">&gamma;</span>). A novel, minimalistic, statistical analysis of the <span class=\"etd-inline-math\"><sup>241</sup></span>Am<span class=\"etd-inline-math\"><sup>9</sup></span>Be calibration data was designed and used to measure the capture time constant $\\tau$, capture cross-section <span class=\"etd-inline-math\">&sigma;<sub>H,t</sub></span>, and the neutron detection efficiency <span class=\"etd-inline-math\">E<sub>\\textrm{center}</sub></span> at the center of the detector: \\begin{equation} \\begin{aligned} &amp;\\tau = 202.35 \\pm 0.42\\ (stat.)\\ ^{+0.38}_{-0.31}\\ (syst.)~\\mu\\textrm{s}, \\\\ &amp;\\sigma_{H,t} = 336.3 ^{+1.2}_{-1.5}~\\textrm{mb}, \\\\ &amp;E_{\\textrm{center}} = (50.8 \\pm 0.6)\\%. \\end{aligned} \\end{equation} Additionally, with the help of Monte Carlo simulations, a volume-weighted neutron detection efficiency across the detector is evaluated to be <span class=\"etd-inline-math\">E<sub>\\textrm{detector}</sub> = (46.5 \\pm 0.5 (stat. only))\\%</span>. The simulation is also central to an energy calibration using the 4.4 MeV <span class=\"etd-inline-math\">&gamma;</span> to measure the energy resolution and energy scale of the detector. Finally, with $\\sim$115 days of early water data, an upper limit, <span class=\"etd-inline-math\">\\hat{\\Phi}<sub>\\bar{\\nu}<sub>e</sub>, \\textrm{ult}</sub></span> = <span class=\"etd-inline-math\">(1.76 \\pm 0.29) \\times 10<sup>6</sup> \\bar{\\nu}/(\\textrm{cm}<sup>2</sup>\\cdot\\textrm{s})</span>, on the reactor antineutrino flux for SNO+ is obtained using a maximum likelihood approach. The limit is about a factor of 9 higher than the expected signal in SNO+, which can be calculated using available reactor output power data.","abstract_has_math":true,"creators":["Liu, Yan"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Physics, Engineering Physics and Astronomy","school":null,"contributors":[],"advisors":["Chen, Mark"],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-27T20:35:25Z","subjects":["SNO+","Neutrino Physics","Reactor Antineutrinos","Neutron Capture"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1974/27931","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Physics, Engineering Physics and Astronomy"]},{"key":"dc:contributor.supervisor","label":"Supervisor","values":["Chen, Mark"]},{"key":"dc:creator","label":"Author","values":["Liu, Yan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-06-30T16:32:25Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-06-30T16:32:25Z"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["SNO+","Neutrino Physics","Reactor Antineutrinos","Neutron Capture"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1974/27931"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The SNO+ experiment is a large-scale liquid scintillator neutrino experiment with a wide range of physics objectives. SNO+ has adopted a staged approach where the detector was first filled with ultra-pure water before substituting with liquid scintillator and the target isotope $^{130}$Te for neutrinoless double beta decay. During the SNO+ water phase, an $^{241}$Am$^{9}$Be source is deployed across the detector volume to calibrate the detector's energy response and its response to neutrons. The $^{241}$Am$^{9}$Be source emits a unique coincidence signal with the prompt event being a 4.4 MeV $\\gamma$ and the delayed a neutron capture signal (2.2 MeV $\\gamma$). A novel, minimalistic, statistical analysis of the $^{241}$Am$^{9}$Be calibration data was designed and used to measure the capture time constant $\\tau$, capture cross-section $\\sigma_{H,t}$, and the neutron detection efficiency $E_{\\textrm{center}}$ at the center of the detector: \\begin{equation} \\begin{aligned} &\\tau = 202.35 \\pm 0.42\\ (stat.)\\ ^{+0.38}_{-0.31}\\ (syst.)~\\mu\\textrm{s}, \\\\ &\\sigma_{H,t} = 336.3 ^{+1.2}_{-1.5}~\\textrm{mb}, \\\\ &E_{\\textrm{center}} = (50.8 \\pm 0.6)\\%. \\end{aligned} \\end{equation} Additionally, with the help of Monte Carlo simulations, a volume-weighted neutron detection efficiency across the detector is evaluated to be $E_{\\textrm{detector}} = (46.5 \\pm 0.5\\ (stat.\\ only))\\%$. The simulation is also central to an energy calibration using the 4.4 MeV $\\gamma$ to measure the energy resolution and energy scale of the detector. Finally, with $\\sim$115 days of early water data, an upper limit, $\\hat{\\Phi}_{\\bar{\\nu}_e, \\textrm{ult}}$ = $(1.76 \\pm 0.29) \\times 10^6 \\bar{\\nu}/(\\textrm{cm}^2\\cdot\\textrm{s})$, on the reactor antineutrino flux for SNO+ is obtained using a maximum likelihood approach. The limit is about a factor of 9 higher than the expected signal in SNO+, which can be calculated using available reactor output power data."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["PhD"]},{"key":"dc:title","label":"Title","values":["Neutron Measurements and Reactor Antineutrino Search with the SNO+ Detector in the Water Phase"]}]}],"canonical_facts":{"dc:contributor.department":["Physics, Engineering Physics and Astronomy"],"dc:contributor.supervisor":["Chen, Mark"],"dc:creator":["Liu, Yan"],"dc:date.accessioned":["2020-06-30T16:32:25Z"],"dc:date.available":["2020-06-30T16:32:25Z"],"dc:description.abstract":["The SNO+ experiment is a large-scale liquid scintillator neutrino experiment with a wide range of physics objectives. SNO+ has adopted a staged approach where the detector was first filled with ultra-pure water before substituting with liquid scintillator and the target isotope $^{130}$Te for neutrinoless double beta decay. During the SNO+ water phase, an $^{241}$Am$^{9}$Be source is deployed across the detector volume to calibrate the detector's energy response and its response to neutrons. The $^{241}$Am$^{9}$Be source emits a unique coincidence signal with the prompt event being a 4.4 MeV $\\gamma$ and the delayed a neutron capture signal (2.2 MeV $\\gamma$). A novel, minimalistic, statistical analysis of the $^{241}$Am$^{9}$Be calibration data was designed and used to measure the capture time constant $\\tau$, capture cross-section $\\sigma_{H,t}$, and the neutron detection efficiency $E_{\\textrm{center}}$ at the center of the detector: \\begin{equation} \\begin{aligned} &\\tau = 202.35 \\pm 0.42\\ (stat.)\\ ^{+0.38}_{-0.31}\\ (syst.)~\\mu\\textrm{s}, \\\\ &\\sigma_{H,t} = 336.3 ^{+1.2}_{-1.5}~\\textrm{mb}, \\\\ &E_{\\textrm{center}} = (50.8 \\pm 0.6)\\%. \\end{aligned} \\end{equation} Additionally, with the help of Monte Carlo simulations, a volume-weighted neutron detection efficiency across the detector is evaluated to be $E_{\\textrm{detector}} = (46.5 \\pm 0.5\\ (stat.\\ only))\\%$. The simulation is also central to an energy calibration using the 4.4 MeV $\\gamma$ to measure the energy resolution and energy scale of the detector. Finally, with $\\sim$115 days of early water data, an upper limit, $\\hat{\\Phi}_{\\bar{\\nu}_e, \\textrm{ult}}$ = $(1.76 \\pm 0.29) \\times 10^6 \\bar{\\nu}/(\\textrm{cm}^2\\cdot\\textrm{s})$, on the reactor antineutrino flux for SNO+ is obtained using a maximum likelihood approach. The limit is about a factor of 9 higher than the expected signal in SNO+, which can be calculated using available reactor output power data."],"dc:description.degree":["PhD"],"dc:identifier.uri":["http://hdl.handle.net/1974/27931"],"dc:language.iso":["eng"],"dc:subject":["SNO+","Neutrino Physics","Reactor Antineutrinos","Neutron Capture"],"dc:title":["Neutron Measurements and Reactor Antineutrino Search with the SNO+ Detector in the Water Phase"],"dc:type":["thesis"]},"updated_at":"2026-07-27T20:35:25Z"}