Selection optimization of neutral current π⁰ production from an anti-neutrino interaction in the NOvA near detector
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The NOvA experiment (NuMI Off-Axis e Appearance) is a particle physics experiment that is designed to measure neutrino oscillation parameters of muon neutrino (ν μ) to electron neutrino (ν e), or muon anti-neutrino ( ̅ν μ ) to electron anti-neutrino ( ̅ν e). In order to get the best results, the signal, which is muon neutrino/anti-neutrino to electron neutrino/anti-neutrino, detection should be maximized, and the background (other interactions and factors that may mislead the detection result) should be minimized. One of the important backgrounds in neutrino oscillation is the neutral current (NC) π⁰ produced by neutrino or anti-neutrino. π⁰ decays and produces to two photons that can come together to look like an electron, which indicates ̅ν e signal. Also, if one of the photons escaped the detector the other one will mimic electron shower of the signal. In this thesis, neutral current π⁰ produced from anti-neutrino interactions and with > 0.5 GeV, will be the signal. The ultimate goal of this analysis to find the cross section of this interaction. Knowing the cross section helps in reducing backgrounds from this type of interaction when looking at ̅ν µ → ̅ν e oscillation, and hence get accurate oscillation parameters. The background in this analysis are charge current (CC) interactions with and without π⁰ and NC interactions without π⁰. It is important that in this thesis I found the fractional uncertainty on the cross section, and not cross section, due to time constraint. However, the result in this analysis could be used to find the interaction cross section and compare it with the value from GENIE Monte Carlo (MC) generator. This analysis was performed based on 6.90×10^20 POT (proton on target) simulated data (MC data), whereas the real POT in the near detector in is 3.54×10^20. The efficiency and purity of the signal based on used cuts (Quality, 2 prong, fiducial, containment, MuonID, prong 1 CVN Gamma ID, and prong 2 CVN Gamma ID) are 0.67% and 64% respectively.
Thesis (M.S.)-- Wichita State University, College of Liberal Arts and Sciences, Dept. of Mathematics, Statistics, and Physics