A Search for Anomalous Muon Neutrino Disappearance and Tau Neutrino Appearance using NOvA Near Detector
The NOvA experiment consists of two finely segmented, liquid scintillator detectors operating 14.6 mrad off-axis from the NuMI muon-neutrino beam. The Near Detector (ND) is located in the Fermilab campus, 1 km from the NuMI target, while the Far Detector (FD) is located at Ash River, MN, 810 km from the NuMI target. The NOvA experiment is primarily designed to measure electron-neutrino appearance at the FD using the ND to control systematic uncertainties. However, the ND is well suited to search for anomalous short-baseline (SBL) oscillations. The standard three-flavor neutrino oscillations have well explained by a wide range of neutrino experiments. The anomalous results, such as electron-antineutrino excess seen by LSND and MiniBooNE do not fit the three-flavor paradigm. This can be explained by an additional fourth flavor sterile neutrino at a larger mass scale than the existing three flavor neutrinos. This thesis presents a novel method for selecting tau neutrino interact ions with high purity at the ND using a convolutional neural network (CNN). Using this method, the preliminary sensitivities of anomalous SBL muon-neutrino disappearance and tau-neutrino appearance due to sterile neutrino oscillations in NOvA are shown.