The first detection line of the Antares neutrino telescope, lying under 2,500 meters of water, was connected by Ifremer's remotely operated robot Victor 6000 to the onshore station at La Seyne-sur-Mer (Var) on Thursday 2 March at 12:11. Several hours later, Antares took its first look at the heavens and detected its first muons. The link marked the effective birth of the Antares detector, the first deep water high energy neutrino telescope in the northern hemisphere. The event rewards ten years of work by around twenty European laboratories, including CEA/Dapnia and the CNRS/IN2P3 laboratories, who initiated the project in 1996.
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.
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