Calibrating the Electromagnetic Calorimeter of T2K

Abstract

In this thesis, I describe the first calibration of the T2K ND280 electromagnetic calorimeter using cosmic muons. T2K is a long baseline neutrino oscillation experiment whose main aim is to observe for the first time the νµ → νe oscillations. A complete understanding of the νµ disappearance or νµ → νx oscillations, x = µ or τ , and neutrino–nucleon interactions will complete the T2K physics programme. T2K produces an intense muon neutrino beam at the J-PARC facility on Japan’s East coast. This neutrino beam is then detected twice: once 280 m from its start by ND280—whose purpose is to characterise the beam—and then again 295 km away at the far detector SuperKamiokande on the West coast of Japan. One of the components of the ND280 detector is the electromagnetic calorimeter. A thorough understanding of the electromagnetic calorimeter is crucial. In this thesis I first describe the quality assurance of the photosensors used in the calorimeter. Then I describe the cosmic muon flux simulation, that I adapted from CORSIKA for the electromagnetic calorimeter studies, and now adopted by the whole T2K collaboration. This is followed by a description of calibration of the calorimeter using the cosmic muon flux, in particular the light yield attenuation, and fi- nally the comparison of the results obtained with cosmic muons taken at two different locations, CERN and Tokai. Moreover, I describe the ND280 Workbook, an online guide to the ND280 software, including tutorials and information for all the ND280 collaborators, that I developed in its entirety.