| This thesis describes a search for nue appearance in the two-detector long-baseline MINOS neutrino experiment at Fermilab, based on a data set representing an exposure of 8.2 x 10 20 protons on the NuMI target. The analysis detailed herein represents an increase in sensitivity to the theta13 mixing angle of approximately 25% over previous analyses, due to improvements in the event discriminant and fitting technique. Based on our observation, we constrain the value of theta 13 further, finding 2 sin2 theta23 sin 2 2theta13 < 0.12(0.20) at the 90% confidence level for deltaCP = 0 and the normal (inverted) neutrino mass hierarchy. The best-fit value is 2 sin2 theta23 sin 2 2theta13 = 0.041+0.047-0.0310.079 +0.071-0.053 under the same assumptions. We exclude the theta13 = 0 hypothesis at the 89% confidence level. |
