The Icecube Neutrino Observatory is a neutrino detector located at the South Pole. It consists of 5,160 optical sensors embedded in ice, which detect the Cherenkov radiation emitted by moving charged particles. The observatory covers a cubic kilometer of ice and is sensitive to neutrinos with energies between 10 GeV and 1 PeV.
Icecube was built in response to the lack of high-energy neutrino detectors. Prior to its construction, only two neutrino events with energies above 100 TeV had been observed: the 1972 Fly’s Eye event and the 1987 Supernova 1987A event. These events suggested that there was a population of high-energy neutrinos, but it was not possible to study them due to the lack of suitable detectors.
Construction of Icecube began in 2005 and was completed in 2010. The detector has since made several important discoveries, including the first evidence for extragalactic neutrinos (neutrinos with energies greater than 60 TeV) and the first observation of a cosmic ray air shower induced by a neutrino (a so-called “double bang” event).
Icecube has also been used to search for dark matter and exotic physics beyond the Standard Model. In particular, it has placed constraints on sterile neutrinos – hypothetical particles that do not interact via any known force – and on axions – hypothetical particles that could make up dark matter.