Neutrino Telescope Is Born On The Floor Of The Mediterranean

The Antares telescope is a neutrino detector which has two main goals: high-energy astronomy and the search for dark matter.

Neutrinos hardly interact with matter at all. The only way to detect them is by using huge detectors which are shielded from the cosmic radiation that constantly bombards any terrestrial site, resulting in major continuous background noise. Located under the sea off Toulon (Var), Antares is protected from this radiation by the natural shielding provided by 2,500 meters depth of seawater. Photodetectors, the eyes of Antares, use a large volume of seawater to detect the very faintly luminous trails produced by muons coming up from below. The muons are produced by the interaction with the Earth's crust of neutrinos which have passed through the Earth. They can be detected because of the total darkness reigning at such immense depths. So Antares looks right through the Earth and observes the skies of the southern hemisphere, including the galactic center, which is the seat of intensely energetic phenomena.

The photodetectors are grouped in threes along umbilical cables which are 450 meters high, which carry signals as well as energy. A total of 900 such “eyes”, distributed along 12 lines covering an area of around 200 m x 200 m on the sea floor, will be scrutinizing the Universe by the end of 2007. Each line is connected to a junction box, which is linked by a 40-kilometer long electro-optical cable to the onshore station at the Institut Michel Pacha in La Seyne-sur-Mer. The installation of the Antares telescope benefited from Ifremer's logistics and expertise.

In addition, Antares forms a permanent multidisciplinary submarine scientific facility, recording both oceanographic data, including observation of the deep sea marine environment and bioluminescent phenomena, as well as geophysical data: for instance, a seismograph has been recording earthquakes for the past year.