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Abstract

Measurements of neutrino interaction cross-sections are important for the study of neutrino oscillations. For the T2K experiment, which has a near detector with a primarily carbon target and a far detector with an oxygen target, the cross-section difference is important for correctly comparing the neutrino fluxes at the two detectors. This dissertation presents a first measurement of the ratio between oxygen and carbon of the muon neutrino charge-current inclusive cross-section using the T2K near detector, ND280. The design and construction methods of the water target system in the ND280 Fine-Grained Detector (FGD) will be discussed, as will a new algorithm for reconstructing particle tracks contained within the FGD. The data analysis leading to the cross-section ratio measurement will be described. It is based on a statistical subtraction method which extracts the contribution of the FGD water mass to the total interaction rate for the FGD with water targets. We find an oxygen/carbon ratio of 1.129 ± 0.114 (stat) ± 0.044 (syst) from the ND280 data, a 1.39σ difference from the Monte Carlo prediction of 0.954 ± 0.029.