Constraining the Neutrino Flux for Oscillation Measurements at MicroBooNE and DUNE

Abstract

Neutrino physics requires a myriad of different complex aspects which need to come together precisely in order for accurate measurements to be accomplished in this meticulously detailed field. Some experiments are known best for one key measurement despite other physics also taking place, such as MicroBooNE, whereas some are well known for a wide range of tasks, such as DUNE. But in both types of experiment the hardware must first be constructed and extensively tested, to the same standards as the software that will be used to reconstruct and analyse data. This thesis explores both of these facets across the two experiments. This research covers a range of topics within the world of neutrino physics, helping to achieve some of the goals at both the MicroBooNE and DUNE experiments. Two elements of work were based around the pattern recognition reconstruction software, Pandora. A new tool to incorporate the Bragg peak information in order to help identify the neutrino slice was applied — once the tool was integrated, testing on MicroBooNE data showed a near 5% improvement in correct identifications. A new branch of the Pandora software was also introduced for the LAr module of the DUNE ND; it was developed to the level of basic testing on full spill samples before the author left the group. Hardware work was also undertaken for DUNE, in the form of the design and testing of a purity monitor system for one of the DUNE ND modules, demonstrating the system’s readiness to be moved into place for testing alongside other module systems. The remaining part of the thesis looks at a MicroBooNE νe /νµ CCNp0π ratio analysis using the NuMI beam, aiming to improve the uncertainties in the cross section measurement and to examine the form of the ratio. Both a full reconstructed study and a truth study were performed, including all systematic and statistical uncertainties. The truth study found that taking a ratio reduced the uncertainties by about a quarter, but the unfolded results of the full study did not see this improvement. A νe /νµ ratio value of ∼ 2:1 was found. Bringing all these contributions together will help to provide improvements in constraining the fluxes seen at MicroBooNE and DUNE.