Initial study of the Neutral Current Single π⁰ production in muon anti-neutrino interaction on water with the P0D Detector at T2K

The T2K experiment is a long-baseline neutrino oscillation experiment in Japan. It measures ν_μ appearance in ν_e beam and aims to measure the last lepton sector mixing angle θ₁₃ and oscillation parameters θ₂₃ and Δm₂₃² . The experiment also search for sterile neutrino and measure neutrino cross section. The neutrino beam is generated at the J-PARC nuclear physics site in Tokai on the east coast of Japan and goes 295 km directly to Super-Kamiokande detector in Kamioka mine on the west coast. The Super-K is a water Cherenkov detector that can measure and distinguish ν_μ and ν_e. One of the main background in the Super-K when measuring neutrino is the Neutral Current Single π⁰ (NC1π⁰) interaction of the neutrino with water. The process is not well understood. In order to constrain this background, π⁰ Detector (P0D) is introduced in the near detector complex (ND280) located 280 meters downstream of the origin of beam. P0D has 50 water bags that can be filled and drained to give analyzers access to a mass subtraction to find on-water cross section. In this initial study, I will present the measurement of NC1π⁰ rate on-water with anti-ν_μ beam. The on-water rate will be obtained by comparing the interaction when the bags are filled with water and empty.