Muon neutrino disappearance at T2K
Abstract
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. A new, more precise measurement of the oscillation
parameters sin2 2 23 and Δm2
32 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 accelerator
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 parameters
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, selecting
muon neutrino charged-current quasi-elastic events, primarily with single
muon-like Cherenkov rings produced by the outgoing muon. This thesis evaluates
two new methods of enhancing the selection to obtain a higher sensitivity
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+0:12
−0:18
×
10−3 eV2 was recorded for Δm2
32 and 0:999+0:001
−0:009 for sin2 2 23.
2
Authors
Hyndman, AlexanderCollections
- Theses [3702]