Measurement of Muon Neutrino Charged-Current High Q² Double Differential Cross-Section using the Pi-Zero Detector at T2K

Tokai-to-Kamioka (T2K) is a long baseline neutrino oscillation experiment. A high intensity beam of muon neutrinos is produced at the Japan Proton Accelerator Research Complex (J-PARC) and travels 295 km across Japan towards the Super-Kamiokande (SuperK) water Cerenkov detector. A suite of near detectors (ND280) is located 280 m downstream of the production point and contained within a 0.2 T dipole magnet. The Pi-Zero Detector (P0D) is a component of the near detector complex. The P0D is designed to constrain the π⁰ background at SuperK, and is optimized to detect electromagnetic showers. It is composed of alternating layers of plastic scintillator and water targets which can be drained or filled, allowing for measurements in both a ``water-in'' and ``water-out'' configuration. The neutrino beam is directed 2.5^o off-axis to produce a flux peaked at ~600 MeV at the near and far detectors. For this paper, the total beam used is 2.5 x 10²⁰ protons on target (p.o.t) for water-in running, and 3.6 x 10²⁰ p.o.t for water-out.

This thesis will present the selection for a P0D-contained charged-current 0-pion (CC-0π) single-track sample in both water-in and water-out modes. This selection is the first P0D-specific analysis to be implemented fully in the ND280 analysis framework, Highland2. Several tools were developed to determine the directionality of P0D tracks, and this selection is also the first P0D analysis to use the full angular phase-space of the out-going muon. A Bayesian unfolding engine is then used to calculate the double differential CC-0π cross-section on water. The results are presented in bins of the reconstructed muon momentum, p_μ, and angle from the neutrino direction, cos(θ_μ) for both data and Monte Carlo.