KATRIN - a next generation tritium beta decay experiment with sub-eV sensitivity for the electron neutrino mass

With the compelling evidence for massive neutrinos from recent v-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. The absolute value of v-masses will have crucial implications for cosmology, astrophysics and particle physics. We present the case for a next generation tritium β decay experiment to perform a high precision direct measurement of the absolute mass of the electron neutrino with sub-eV sensitivity. We discuss the experimental requirements and technical challenges of the proposed Karlsruhe Tritium Neutrino experiment (KATRIN) and outline its physics potential.