Alexander Hyndman
Published: 2011
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This thesis measures the muon neutrino oscillation at T2K using the first data of the experiment. It concentrates on developing an original selection at Super-Kamionde, the T2K far detector, that improves the performance of the current standard selection. Anew, more precise measurement of the oscillation parameters sin22823 and ~m~2 is performed using this new selection. T2K is a long-baseline neutrino oscillation experiment located in Japan which began data taking in January 2010. It uses the world's most powerful ac- celerator generated beam of muon neutrinos intersected by two detectors. The near detector is located 280 m from the beam source while Super-Kamiokande lies 295 km away. Super-Kamiokande is a 50 kt water Cherenkov detector which measures the neutrino beam after oscillation. The determination of the oscillation pa- rameters comes from looking at the disappearance of muon neutrinos from the beam. For this purpose event selection at Super-Kamiokande is optimised for neutrino flavour identification and energy reconstruction, specifically, select- ing muon neutrino charged-current quasi-elastic events, primarily with single muon-like Cherenkov rings produced by the outgoing muon. This thesis eval- " uates two new methods of enhancing the selection to obtain a higher sensi- tivity from the data, firstly by exploring a multi-variate analysis approach to charged-current quasi-elastic selection, and secondly through the exploration of an additional charged-current single charged pion channel. Out of these only the multivariate based selection produced an improvement in the sensitivity to oscillation with respect to the standard selection. A first analysis of the data collected until March 11th 2011 using the above described improvement is presented in this thesis. A value of 2.68~~:ig x 10-3 eV2 was recorded for ~m~2 and 0.999~~:~~~ for sin22823.