Search for neutrinoless double beta decay in ¹³⁶Xe 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 ¹³⁶Xe. 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 ¹³⁶Xe of 1.1 x 10²⁵ years.