AMANDA TelescopeAn international facility operational since 1997 and sited in Antarctica for the purpose of detecting neutrinos. An improved version, AMANDA-II, came into service in 2000. AMANDA – the Antarctic Muon and Neutrino Detector Array – consists of an arrangement of 677 optical modules, each one as big as a glass basketball, strung on 19 electrical cables and buried deep in the pure clear ice beneath the South Pole. The AMANDA Telescope points downward to detect neutrinos passing right through the Earth from the skies above the northern hemisphere. Interference from other particles and from light radiation is filtered out by the body of the Earth and by the situation of the modules, located more than two kilometers below the surface of the ice.
A small number of the countless neutrinos that continually bombard and tear through our planet interact with subatomic particles in the polar ice and rock to produce negatively charged muons. Each muon speeding through the ice emits Cerenkov radiation, visible as a short-lived streak of faint blue light that illuminates phototubes within the modules. The phototubes convert the radiation to an electrical signal and transmit it to computers above ground. After an interaction, the muon continues to travel in almost exactly the same direction as the neutrino that produces it. Thus analysis of the muons' signals allows scientists to extrapolate information about their originating neutrinos, such as their paths, velocity, and frequency. Thus AMANDA makes it possible to track neutrinos back to their cosmic origins, such as gamma-ray bursts.
The AMANDA Telescope serves as a small-scale forerunner to a much larger array of neutrino detectors currently named Ice Cube. This device, covering a region of ice one cubic kilometer in volume and consisting of a planned 4800 optical modules on 80 cables, will include and expand upon the existing AMANDA detectors. Astronomers hope that it will be in operation by 2008.