Systematics and background suppression in the KATRIN experiment

Recent neutrino mass experiments at Mainz and Troitsk using tritium β-decay have reached their sensitivity potential, yielding upper limits of about 2 eV/c for m(ν̄e). The KArlsruhe TRItium Neutrino experiment (KATRIN), designed to reach a sensitivity of m(ν̄e) = 0.2 eV/c 2 (90% C.L.), will improve the signal rate by a factor of about 100 with respect to previous experiments while maintaining the same low background level at an enhanced energy resolution of 0.93 eV of the spectrometer which is scaled up by a factor of 10 in linear dimensions. This low background rate can only be achieved by active and passive reduction of the background components induced by the spectrometer itself and in the detector region. Furthermore, sources of systematic errors such as energy losses inside the tritium source or fluctuations of the energy scale of the spectrometer need to be carefully controlled and analysed. An overview of KATRIN’s method to reduce the background rate and to determine the systematics as well as the sensitivity on the neutrino mass