WHAT DOES KATRIN DO?

Until very late in the last century, no one was sure that neutrinos even had mass. But then physicists Takaaki Kajita and Arthur B. Mcdonald worked independently on the matter to prove the existence of neutrino oscillation and thus that the particles have mass. For their great discovery they shared the 2015 Nobel Prize in Physics. At about the same time, researchers in Germany completed the commissioning measurements on a 220-ton spectrometer called KATRIN (“Karlsruhe Tritium Neutrino experiment”), and they began conducting tests the following year. After several more years of preparations, a successful experiment in 2019 revealed that neutrinos weigh at most 1.1 electronvolts (ev). This key detail comes from the decay of the radioactive isotope tritium, which yields electron-neutrino pairs. While neutrinos cannot be measured directly, electrons can, and they shed light on the properties of neutrinos.