DOM, light detector from IceCube at the South Pole
The spherical instrument is a light detector called DOM (Digital Optical Module). More than 5 000 such spheres are frozen deep down in the ice at the South Pole. They form part of a new kind of astronomical observatory that makes it possible to study cosmic neutrinos. The observatory is called IceCube and was completed in 2011. The researchers hope that IceCube will contribute to solving the mystery of dark matter in the universe. Every second, many billions of neutrinos pass straight through your body without you noticing. A neutrino is a chargeless particle, almost without mass. As long as a neutrino does not collide with an atom, something that rarely happens, it can pass straight through solid matter. Most neutrinos come from the sun, from the decay of radioactive elements, or from our atmosphere. More rarely, neutrinos come to us from distant parts of the galaxy, or beyond.
They bear witness to some of the most violent events in the universe, such as supernova explosions or matter being ejected from black holes.
IceCube´s light detectors have been installed at a depth of between 1450 and 2450 meters in the clear, pure ice of Antarctia, and communicate with computers at the surface. When a neutrino collides with an atom in the ice, the resulting blue light is registered by the detectors. The direction of travel of the neutrino is also recorded and thus it can be detected where they come from. The IceCube project is a joint initiative between three American research groups and researchers from Uppsala and Stockholm.