Determination of Neutrino Mass from Tritium Beta Decay

The most sensitive way to determine the neutrino mass scale without further assumptions is to measure the shape of a tritium beta spectrum near its endpoint. Tritium is the nucleus of choice because of its low endpoint energy, superallowed decay, simple nuclear properties and simple atomic structure. Tritium beta decay experiments have been performed for more than 60 years yielding in an upper limit of the electron neutrino mass of 2 eV/c². The Karlsruhe Tritium Neutrino experiment (KATRIN) will improve the sensitivity on the neutrino mass by another order of magnitude. This article gives a short survey of 6 decades of tritium beta decay experiments and discusses the future steps.