Electron Neutrinos in the Pi-Zero Detector of the T2K Experiment.

摘要

Starting in 1998 experiments began to show that neutrinos oscillate from one flavor to another over time, a phenomena that is explained by the existence of neutrino mass. The disappearance of muon and electron neutrinos over long distances, presumably from conversion into tau neutrinos, has been measured to great precision in many experiments. T2K is a long baseline experiment from Tokai to Kamioka in Japan that was designed to precisely measure a third type of oscillation by observing the conversion of muon neutrinos into electron neutrinos. A major background for oscillated electron neutrinos at the far detector comes from intrinsic electron neutrinos produced in the beam. To constrain this background, near detectors located 280m from the target are used to measure electron neutrino flux and cross sections. This work explains in detail the composition of the T2K beam, near and far detectors and how the components are calibrated to reduce errors. It focuses on the specific uncertainties that exist in the neutrino generators and in the beam models that affect the far detector measurement. Finally a detailed explanation of a measurement in the Pi-zero detector (P0D) of the intrinsic electron neutrino component and a constraint on the Q2 distribution of the charged current quasi-elastic like component of the sample is described.