Towards an Improved Neutrino Cross Section Landscape: First Measurements of ve-Argon and Monoenergetic v? Interactions

Knowledge of neutrino cross sections is critical for understanding neutrino oscillation experiments. Existing theoretical interaction models can be improved by data-driven constraints measured across a variety of neutrino-nucleus interaction mechanisms and energies. However, neutrino cross section measurements are complicated by a number of factors, including detector limitations and challenges to neutrino energy reconstruction. Improving neutrino flavor identification and reconstruction in now popular liquid argon time projection chamber (LArTPC) detectors operating with GeV-scale neutrino sources is critical for success in upcoming large-scale neutrino experiments like the Deep Underground Neutrino Experiment (DUNE), aiming to further illuminate our picture of the neutrino. Specifically, the value of the charge-parity violating phase governing neutrino mixing and the mass ordering of the neutrinos are yet unknown. In parallel, studies of unique known energy neutrinos from decays at rest can eliminate one source of uncertainty to improve our understanding of neutrino-nucleus interactions in the MeV range and aid detector energy calibration. The topics covered in this dissertation are broad. They traverse multiple collaborations, analysis, hardware tests, electron neutrinos, muon neutrinos, and photon detectors. Foremost are the two published results. The first is a measurement of the electron neutrino cross section on argon with ArgoNeuT (at the time the only measurement of its kind). This electron neutrino sample, albeit low in statistics, is unique as the only currently available GeV-scale neutrino beam electron neutrino data collected by a LArTPC. The GeV-scale energy region presents distinct challenges for electron neutrino identification and reconstruction driven by increased hadron multiplicities that obscure vertex information traditionally used to classify electron neutrinos. The ArgoNeuT analysis demonstrates novel strategies for GeV-scale electron neutrino searches. The second result is a measurement of monoenergetic muon neutrino interactions in MiniBooNE from kaon decay at rest in the NuMI neutrino beam dump. Neutrino energy reconstruction is famously difficult and this monoenergetic neutrino source is a valuable tool for probing neutrino-nucleus interactions. The distinct timing and direction information of these events make it possible to extract signal shape and rate above background and the resulting measurements can be used to constrain interaction models. Between these two bookends, we consider first MicroBooNE's low energy excess search and cross section program through the lens of the Wire-Cell tomographic reconstruction toolbox. And finally, we discuss photon detection in LArTPCs. The design and testing of the photon detection system for the Short Baseline Near Detector (SBND) and recent research and development efforts for DUNE are summarized.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169776/1/roryfitz_1.pd