Current models suggest matter and antimatter should have been created in equal quantities in the Big Bang, but we are living in a Universe that is comprised mostly of matter. The LEGEND experiment is studying particles called neutrinos to find out why this is the case.
When a particle combines with its own antiparticle, they destroy each other and explode in a burst of energy. The antiparticle is like a mirror image of a particle: it has the same mass, but the opposite electric charge. LEGEND will investigate a type of radioactive decay called ‘neutrinoless double beta decay’, to explore the hypothesis that neutrinos, which have a tiny mass and no charge, are actually their own antiparticle. If this is the case, it would open up a route to help us understand the existence of matter over antimatter.
In the centre of the image is the LEGEND cryostat, into which the detector array will be placed. The cryostat lies inside a 590m3 tank, which will be filled with water, to shield the experiment from external influences.