Measurement of Single Positive Pion Production in Neutrino Neutral Current Interactions in the ND280 Detector and Particle Identification with the Fine Grained Detector at T2K

Licciardi, Caio Augusto Pelegrina Del Bianco
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Faculty of Graduate Studies and Research, University of Regina

In this thesis, I present a measurement of the absolute inclusive cross section of single

  • production induced by neutral current interactions ( (NCS +)). I also present a method to identify particles stopping in the Fine Grained Detectors (FGDs). An introductory description of neutrino physics, as well as of the T2K experiment and the ND280 tracker system are included for completeness. Other important contributions to the development of the FGDs, including the selection and characterization of the wavelength shifting bers used in these detectors, as well as their commissioning at JPARC, are also discussed in the thesis. The particle identi cation with the FGDs is based on the reconstructed deposited energy versus track length. It is primarily devoted to separate stopping protons from pions. In particular, this method can distinguish between exiting and stopping muons (or pions). In the measurement of (NCS +), the tracker system of the near detector (ND280) of the T2K experiment is used to reconstruct the particles and respective kinematics. It consists of two FGDs and three Time Projection Chambers (TPCs). One of the FGDs provides a target mass of 1 tonne for neutrino interactions, out of it 93% is composed of CH. The number of neutrino interactions used in this thesis corresponds to a total of 1:077 1020 protons on target at the Japan Proton Accelerator Research Complex (JPARC) facility in Tokai, collected during the T2K Run-1 and Run-2 data acquisition periods. Since the ND280 is 2:5 o the neutrino beam direction, its energy spectrum has a narrow width with peak at near 0.6 GeV. The analysis is based on NEUT Monte Carlo (MC) predictions for neutrino-nucleus interactions. The achieved e ciency and purity in the selection of forward-going + are 39% and 21%, respectively, for pions with momentum between 0.2 and 1.1 GeV/c. Systematic errors arising from neutrino ux uncertainties, event reconstruction and neutrino interaction models have been considered in the analysis. The ratio data to MC simulation is data= MC < 1:43 at 68% con dence level (CL). This is equivalent to an upper limit on the e ective cross section of (NCS +) < 0:043 10􀀀38 cm2=nucleus (68% CL).
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Physics, University of Regina. xxxviii, 268 p.