KATRIN - direct measurement of a sub-eV neutrino mass

The KArlsruhe TRItium Neutrino (KATRIN) experiment is a next-generation direct neutrino mass experiment designed to investigate in a model-independent way the fundamental mass scale of neutrinos with sub-eV sensitivity. It combines an ultra-luminous molecular windowless gaseous tritium source with a high resolution electrostatic retarding spectrometer (MAC-E filter system) to measure the spectral shape of β-decay electrons close to the T2 end point at 18.6 keV with unprecedented precision. If no neutrino mass signal is found, the KATRIN sensitivity after 3 years of measurements is mν<0.2 eV (90%CL.); a ν-mass signal of mν=0.35(0.30) eV can be measured with 5 (3) σ evidence. The experiment is scheduled to start first tritium runs in late 2008.