The KATRIN experiment - a direct measurement of the electron antineutrino mass in the sub-eV region

With the evidence for massive neutrinos from recent ν-oscillation experiments, one of the most fundamental tasks of particle physics over the next years will be the determination of the absolute mass scale of neutrinos, which has crucial implications for cosmology, astrophysics and particle physics. The KArlsruhe TRItium Neutrino (KATRIN) experiment is the next-generation direct neutrino mass experiment with a sensitivity to sub-eV ν-masses. It combines an ultra-luminous windowless gaseous molecular tritium source with a high resolution electrostatic retarding spectrometer (MAC-E filter) to measure the spectral shape of β-decay electrons close to the endpoint at 18.6 keV with unprecedented precision. If no neutrino mass signal is found, the KATRIN sensitivity after 3 years of measurements is mν<0.2eV/c2 (90 % C.L.); a ν-mass signal of mν=0.35eV/c2 can be measured with 5 σ evidence.