Looking for matter enhanced neutrino oscillations via day v. night asymmetries in the NCD phase of the Sudbury Neutrino Observatory

Abstract

To measure the regeneration of electron neutrinos during passage through the Earth via the MSW effect, the difference in electron neutrino flux between day and night is measured at the Sudbury Neutrino Observatory (SNO). To be able to distinguish an actual discrepancy from an artifact, the detector properties and backgrounds are studied in regard to both a diurnal difference and a difference in the detector for upgoing v. downgoing neutrinos. This thesis focuses on the signal extraction part of this process, by which the neutrino fluxes are determined from the processed data by means of a Markov Chain Monte Carlo method. Recognizing that this effect is expected to have an energy dependence, the asymmetry is modeled as an affine function of energy. This measurement yields an asymmetry in the neutrino flux of ... measured in MeV.