A Measurement of νe Appearance and νμ Disappearance Neutrino Oscillations with the NOvA Experiment

Citation

Pershey, Daniel Stephen (2018) A Measurement of νe Appearance and νμ Disappearance Neutrino Oscillations with the NOvA Experiment. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/rc0w-zg32. https://resolver.caltech.edu/CaltechTHESIS:06012018-215047231

Abstract

NOvA is a two-detector, neutrino oscillation experiment on an 810 km baseline in the NuMI beam at Fermilab. NuMI is an off-axis, narrow-band beam centered near 1.8 GeV and is configurable to send a high-purity ν_μ or ^-ν_μ neutrino flux which passes through the NOvA far detector, sensitive to ν_μ and ^-ν_μ disappearance and ν_e and ^-ν_e appearance. The NOvA near and far detectors are functionally identical, liquid scintillator trackers. They are finely segmented relative to the radiation length in the detectors allowing for the detailed reconstruction of electromagnetic shower necessary to identify ν_e CC events.

Through a joint analysis of the appearance and disappearance oscillation channels using neutrino and anti-neutrino data, NOvA constrains the allowed parameter space in δ_CP, the neutrino mass hierarchy, sin²θ₂₃, and Δm²₃₂. We observe 58 and 18 appearance candidates on an expected background of 15.06 and 5.32 events in neutrino and anti-neutrino mode, respectively. This observation gives a 1.77σ preference for the normal mass hierarchy and 1.7σ preference for θ₂₃ in the upper octant. NOvA will maintain its position as a long-baseline oscillation experiment with leading sensitivity for several more years in which time analysis will further disambiguate the fundamental neutrino parameters that determine oscillation behavior.

Thesis Files