Search for Neutrinoless Double-Beta Decay in 136 Xe with EXO-200

Several properties of neutrinos, such as their absolute mass, their possible Majorana nature or the mechanisms that lead to small neutrino masses, are still unknown. The EXO-200 experiment is trying to answer some of these questions by searching for the hypothetical neutrinoless double beta decay of the isotope 136 Xe. This thesis describes an analysis of two years of detector data, which yields a lower limit on the half-life of neutrinoless double beta decay of 136 Xe of 1.1·10 25 years.