Extraction of active and sterile neutrino mixing parameters with the Sudbury Neutrino Observatory

Abstract

The Sudbury Neutrino Observatory (SNO) is a 1 kilotonne heavy-water Cerenkov detector designed to study fundamental properties of neutrinos produced by thermonuclear fusion reactions in the core of the Sun. The uniqueness of SNO resides in its capability to distinctively measure the total flux of all active neutrino flavours as well as the flux of electron neutrinos, through the Neutral-Current (NC) and Charged-Current (CC) interactions of neutrinos on deuterium, respectively. The measurements of the NC and CC fluxes for neutrinos originated from B disintegration inside the Sun unambiguously proved that neutrinos change their flavour while traveling to the Earth. These results are consistent with predictions from a neutrino oscillation hypothesis on neutrino flavour transitions due to the mixing of massive neutrino states. The NC measurement from SNO also solved the long-standing Solar Neutrino Problem (SNP). In this dissertation, the measurements of the fundamental properties of neutrinos, in particular their mixing parameters, are presented. Data samples from SNO and other experiments are used to extract the mixing parameters of active and sterile neutrino states. Under the assumption on the two-neutrino oscillation hypothesis, the mixing parameters for active neutrinos (the squared-mass difference ∆m and the mixing angle θ) are obtained from a global analysis of solar