Background, sensitivity and directionality studies for the Double Chooz experiment

The goal of the Double Chooz experiment is the measurement of the neutrino oscillation angle θ13. So far, only an upper limit for its magnitude is known. Two reactors of a nuclear power plant at the French Chooz village provide a source of electron antineutrinos, whose flux is measured with a near and far detector. While the far detector is sensitive to neutrino oscillation, the near detector minimizes different systematic errors. In spring 2011 the far detector will start collecting data, while the near detector will follow roughly 18 months later. For the sensitivity of the experiment it is crucial to minimize the systematic error. Therefore, knowledge on background events is important. In this thesis the different sources of background are characterized and the efficiency of various rejection techniques is investigated. Furthermore, different options to determine the background rate from the experimental data are analyzed. The influence of different background rates on the sensitivity of Double Chooz is calculated. Another central aspect of this thesis is the directional reconstruction of neutrino events. It is demonstrated that the direction of the two reactors can be resolved with neutrino events within the first few months. This thesis designs a precise reconstruction of neutrino directions and thus provides an important benchmark for the applicability of future large scale scintillator experiments in both geo- and astrophysics.