Characterization and Minimization of Background Processes in the KATRIN Main Spectrometer

This thesis summarizes work performed in the context of the identification, characterization, and minimization of background sources in the large-scale main spectrometer of the Karlsruhe Tritium Neutrino (KATRIN) experiment. These works are of crucial importance to reach the nominal background level of 10 mcps which is an essential prerequisite for KATRIN to assess the absolute mass scale of neutrinos with an unsurpassed sensitivity of 200 meV (90% C.L.)