Brooke Russell defends graduate thesis “An Electron Neutrino Appearance Search in MicroBooNE with 5 x 10^19 POT”

The thesis committee (L-R): O. Keith Baker, Francesco Iachello, Brooke Russell, Bonnie Fleming, Steve Lamoreaux. Image courtesy of Brooke Russell.
December 16, 2019

On December 6, 2019, Brooke Russell successfully defended her thesis, “An Electron Neutrino Appearance Search in MicroBooNE with 5 x 1019 POT” (advisor Bonnie Fleming)

Russell explained, “One of the most pressing questions in neutrino physics is a simple one: how many neutrino species are there? The MicroBooNE experiment aims to shed light on this question by utilizing single-phase liquid argon time projection chamber detector technology. MicroBooNE’s primary physics objective is to definitively understand the nature of the low-energy excess of single-shower electromagnetic events measured by the precursor MiniBooNE experiment. My thesis aims to address the leading capability stipulations required to test the MiniBooNE measurement, namely (1) the ability to observe and reconstruct complicated topologies through robust noise filtering and signal processing and (2) a proficiency to trigger on low energy final states realized by a highly performant neutrino selection.”

Russell is the first black woman to earn a physics Ph.D. in the Yale Physics Department.

Russell will join the Neutrino Group in the Physics Division at Lawrence Berkeley National Laboratory as an Owen Chamberlain Postdoctoral Fellow, working on 3D pixelated charge readout devices to enable the single-phase LArTPC DUNE Near Detector physics program.

Thesis abstract:  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 x 1019protons on target (POT) beam exposure, the low-energy excess of electron-like events is measured at 0.51 s.