The sensitivity of liquid scintillator detectorsfor the measurement of the neutrino masshierarchy with atmospheric neutrinosVeröffentlicht auf dem Publikationsserver der RWTH Aachen University

An unknown parameter for the description of neutrino oscillations is the ordering of the neutrino mass eigenstates where it is unknown whether the third or the first eigenstate is the lightest. This is called the mass hierarchy problem A measurement of the mass hierarchy is possible by measuring oscillations of atmospheric neutrinos crossing the Earth interior. Since this channel requires a large target volume, it is commonly used by detectors using several mega tons of water as target material. Detectors using a scintillating liquid as target can not be as big due to the higher cost pervolume but can achieve a higher resolution of the neutrino events. Future liquid scintillatordetectors are planned with target masses in the 10 kt scale. The goal of the first part of this thesis is to investigate the sensitivity of the planned LENA and JUNO liquid scintillator detectors to measure the neutrino mass hierarchy. For this, the expected atmospheric neutrino rate is estimated using Monte Carlo simulations. The resolution of the detectors is estimated in direction and energy, considering an optimistic andconservative scenario. It is found that in the optimistic case for a 10 year measurement thesensitivity for the JUNO detector reaches 1.15 σ. Here, the electron neutrino sample contributes most to the sensitivity. The second part of the thesis investigates a newly developed reconstruction method formuons in liquid scintillator detectors. It is implemented for the Double Chooz experimentwhich consists of two small detectors currently in operation. This implementation is usedto prove the algorithms feasibility under realistic conditions and for real muon data. For the used Monte Carlo data set, the reconstruction achieves an angular resolution of4.8° and a spatial resolution of 14.9 cm. To test the reconstruction of measured muons, thereconstructed data was compared to a Monte Carlo simulation of the directional distribution of muons. It was found that the two distributions agree with a probability of 77.85 %considering a systematic uncertainty of 15 %