Nexo Experiment

To understand more about neutrinos—tiny, nearly massless particles with no charge—the nEXO experiment is searching for a rare nuclear decay called neutrinoless double beta decay. Double beta decay is a process whereby a nucleus decays into another one and emits two electrons and two antineutrinos. A special version of double beta decay—the “neutrinoless” version—emits only two electrons and no antineutrinos. Neutrinoless double beta decay is at the boundaries of human knowledge since it has not yet been observed and cannot occur according to the laws of physics as we know them. However, many theories that may explain strange patterns observed in cosmology and particle and nuclear physics predict that this version could occur, but at an unimaginably small rate. Previous experiments have set limits on how rare the decay is, establishing that the half-life of this decay is longer than a million-billion (10^15) times the age of the Universe. The nEXO experiment is designed to extend knowledge of this rare decay to a level of 10^28 years, or 10^19 times the age of the Universe. nEXO includes many components beyond what has been described so far, including ultra-high vacuum, cryogenics (we will operate a large liquid nitrogen plant underground), and sophisticated mechanics and electronics. Components for the experiment are fabricated in many places around the world, because, in many cases, they are unique and are procured from wherever they are available. A consortium of over 150 scientists and technologists from 31 institutions and eight countries are contributing to the design and construction of nEXO. Everybody in the consortium will analyze the data, which is expected to flow over a period of ten years. See our website for more details: https://nexo.llnl.gov/