First operation of the KATRIN experiment with tritium
  The determination of the neutrino mass is one of the major challenges in
astroparticle physics today. Direct neutrino mass experiments, based solely on
the kinematics of beta-decay, provide a largely model-independent probe to the
neutrino mass scale. The Karlsruhe Tritium Neutrino (KATRIN) experiment is
designed to directly measure the effective electron antineutrino mass with a
sensitivity of 0.2 eV 90% CL. In this work we report on the first operation of
KATRIN with tritium which took place in 2018. During this commissioning phase
of the tritium circulation system, excellent agreement of the theoretical
prediction with the recorded spectra was found and stable conditions over a
time period of 13 days could be established. These results are an essential
prerequisite for the subsequent neutrino mass measurements with KATRIN in 2019.
