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Measurement of Neutrino Mixing Angle thetas13 Using Neutron Captured on Hydrogen in Daya Bay

Posted on:2016-05-03Degree:Ph.DType:Thesis
University:The Chinese University of Hong Kong (Hong Kong)Candidate:Xu, JianyiFull Text:PDF
GTID:2470390017977085Subject:High Energy Physics
Abstract/Summary:
The Daya Bay Reactor Neutrino Experiment aims to measure the last unknown neutrino mixing angle theta13, by measuring the disappearance of electron anti-neutrinos produced by the six nuclear reactors of the Daya Bay Nuclear Power Plant. In total eight functionally identical anti-neutrino detectors are deployed underground, with two detectors distributed at each of the two near sites close to the reactor cores and four detectors placed at a far site ∼2 km away from the reactor cores.;The number of observed electron anti-neutrinos are measured via inverse-beta decay reaction, v¯e+ p+ → e+ + n. The positrons deposit energy in the liquid scintillator and annihilate with electrons, emitting gammas, which is the prompt signals for detection. The neutrons are captured on either gadolinium or hydrogen atoms and emit gammas with total energy ∼8 MeV or ∼2 MeV, respectively, producing the delayed signals. The ratio between the numbers of anti-neutrinos from far site and near site detectors is used to measure the oscillation parameters.;With 55 calendar days of data, the Daya Bay experiment first published its result using neutron-captured-on-gadolinium signals in March 2012, with best-fit sin2 2theta13 = 0.092&;In this thesis, an independent oscillation analysis using the neutron-captured-on- hydrogen signals is presented, which could cross-check the neutron-captured-on-gadolinium analysis result with independent anti-neutrino samples and different systematic uncertainty. With 190 live days of data and 6 detectors, the rate-only analysis gives best-fit sin2 2theta13 = 0.078 +/- 0.02.
Keywords/Search Tags:Daya, Neutrino, Detectors, Using, Hydrogen
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