ABSTRACT
The present lecture will give a survey of the methods used for the past five decades to measure absolute neutrino masses. The main focus will be on tritium β decay experiments, since for more than fifty years tritium has been the best isotope to search for a non-zero neutrino mass. The understanding of systematic effects is of utmost importance for each neutrino mass experiment. Mistakes in this field can lead to negative neutrino mass squares, something that happened in the nineties of the last century. Because of the importance of that topic a whole section is devoted to that question. Since the author1 has been a member of the Mainz neutrino mass experiment for more than 15 years, the Mainz experiment has been chosen to demonstrate the influence of systematic effects. At the end of the lectures KATRIN, the next generation neutrino mass experiment with a sub-eV sensitivity, is introduced.
