Dissertation Defense: Brooke Russell, Yale University, “An Electron Neutrino Appearance Search in MicroBooNE with 5$\times$10$^{19}$ POT”

MicroBooNE is a single-phase liquid argon time projection chamber (LArTPC) short-baseline accelerator neutrino experiment located at Fermi National Accelerator Laboratory in the Booster Neutrino Beam. MicroBooNE’s foremost scientific objective is to definitively resolve the low-energy excess of single shower electromagnetic events seen by the precursor MiniBooNE experiment.
This thesis examines a small fraction of early MicroBooNE data.
By leveraging fine-grained drifted ionization charge signal from particle interactions, the LArTPC detector technology provides detailed topological and calorimetric information for neutrino-argon interaction analysis. The interplay of scintillation light and tomographic imaging of ionization charge signals is exploited for a charged current neutrino pre-selection. This pre-selection serves as the foundation for parallel inclusive charged current muon neutrino and electron neutrino selections. The charged current muon neutrino selection aims to constrain the expected intrinsic charged current electron neutrino events measured, such that an excess, if present, may be quantified. With approximately 5$\times$10$^{19}$ protons on target (POT) beam exposure, the low-energy excess of electron-like events is measured at 0.51$\sigma$.
Thesis Advisor: Bonnie Fleming (bonnie.fleming@yale.edu)