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Abstract

The Karlsruhe Tritium Neutrino (KATRIN) experiment aims at measuring the neutrino mass with a sensitivity of 0.2 eV (90%C.L.) in a model independent way. To this end it uses electrons originating from tritium b-decay and investigates their spectrum close to the kinematic endpoint. In order to reach the desired sensitivity a low background and a good understanding of its properties is necessary. This thesis presents a data-driven Monte Carlo simulation of the background focusing on its non-Poissonian nature which originates from nuclear decays in the main spectrometer. The impact of a non-Poisson background on the neutrino mass under various model assumptions and measurement configurations is investigated. It could be shown that different scanning strategies and background treatments have minor impact on the neutrino mass result. Furthermore optimising the electromagnetic field configuration in the main spectrometer allows for an overall background reduction by a factor of 2. However this asymmetric setting requires precise measurements of the electromagnetic fields in the center of the spectrometer. In the scope of this thesis a new method of field calibrations with a gaseous krypton source has been established and the field input values for the third neutrino mass campaign were provided.