Are neutrinos really their own antiparticles? Why are they so light and what mass do they have? Scientists working on the GERDA and the future LEGEND experiments want to find out more about the properties of neutrinos.
Neutrinos are some of the most common particles in the universe. They are produced, for example, in the nuclear fusion taking place in the interior of stars, as well as in the Sun and during nuclear fission in power plants. Since they interact only via the weak force, they are extremely difficult to detect.
According to the present state of our knowledge, every known particle has an antiparticle with the opposite electric charge: anti-quarks, or anti-leptons (positron, anti-muon and anti-tau). As the neutrino is electrically neutral, it could be the odd one out here and be its own antiparticle. If the experiment can confirm this assumption, the researchers will have new starting points for gaining a better understanding of the physics of the universe.
How can scientists discover whether the neutrino is identical to its antiparticle? The solution lies in a very rare radioactive decay chain, which could at least theoretically occur in germanium – a semimetal.
With GERDA and, in the future, LEGEND, physicists are pursuing the goal of detecting this so-called neutrinoless double beta decay. Both experiments utilize germanium 76 detectors. This special element is at least theoretically capable of producing radioactive double beta decay and thus to prove the assumed "dual nature" of the neutrino.