Development Towards a Model-dependent Measurement of the Muon Neutrino Charged Current Single Pi-plus Pion Momentum Spectrum
Connolly, Kevin Thomas
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In this thesis the development and study of a method for a model-dependent measurement of the muon neutrino charged current (CC) single pion interaction's positive pion momentum spectrum is proposed. The measurement is part of the Tokai-to-Kamioka (T2K) experiment and was performed in Tokai at the near detector hall, using an event selection from a fine-grained detector (FGD) on a carbon target. The T2K neutrino beam has a peak energy of about 0.6 GeV, and the near detector is located 280 m downstream from the proton beam target. Data from 5.9 × 10^20 protons on target was collected and used in a CC-inclusive and CC-exclusive event selection. The inclusive event selection contains about 25,000 CC muon neutrino events, and was subdivided into a single positively charged pion production channel (CC-1-pion) and a CC multi-pion interaction channel (CC-other). The official event selection, applied to both data and Monte Carlo (MC), is presented. Amongst the systematic errors involved in this event selection, the development of a novel detector systematic, created by the author of this thesis and dubbed the "hybrid analysis" is presented in detail. The analysis of published CC muon interaction data from deuterium bubble chamber experiments is presented in detail and used to tune a model of charged pion multiplicities. Utilizing this model, a systematic error on the number of charged pions produced in CC multi-pion events is characterized for the first time and implemented. The official T2K MC corresponding to the presented event selection is used extensively in the development, study and validation of a fitting method proposed to extract the a model- dependent measurement of the CC-1-pion differential cross section with respect to true positive pion momentum. The studies to date suggest tuning of input cross section model parameters may need to be re-evaluated to ensure representative validation tests, and that the fit method may need to include a regularization method.
- Physics