The ANTARES neutrino telescope

The ANTARES collaboration has completed since May 2008 the construction of the largest neutrino telescope in the Northern hemisphere. Thanks to its modular geometry ANTARES took data also before completion, since the deployment of its first line. It is installed about 40 km off the coast of Toulon, France, at a maximum depth of 2475 m in the Mediterranean Sea(42 degrees 48'N,6 degrees 10'E). The detector is a 3-dimensional array of photomultiplier tubes (PMTs) distributed along twelve lines. The lines are anchored at the seabed at distances of similar to 70 m from each other and tensioned by buoys at the top. Each line has 25 storeys placed every 14.5 m, each of them containing three optical modules (OMs) and a local control module for the corresponding electronics. The 885 OMs containing the PMTs point at 45 degrees below the horizontal. The total instrumented volume is about 10(7) m(3). Neutrino telescopes, unlike usual optical telescopes, are "looking downward". The challenge of measuring muon neutrinos via v(mu) + N -> mu + X consists in reconstructing the muon trajectory using the arrival times and the amplitudes of the Cherenkov light detected by the OMs, and of estimating the muon energy. Up-going muons can only be produced by interactions of up-going neutrinos. Only atmospheric neutrinos that have traversed the Earth represent the irreducible background for the study of cosmic neutrinos. The main goal of the experiment is the detection of high-energy neutrinos from astrophysical sources; other topics include the indirect detection of v's from dark matter annihilation coming from the Sun direction; the study of the penetrating radiation in the Cosmic Rays. A neutrino telescope in the Northern hemisphere can look at the centre of our Galaxy, and it is complementary to the AMANDA/ICECUBE Antarctic telescope. In parallel, research in several fields of marine sciences will be carried out. The first results from the ANTARES detector concerning the measurement of the atmospheric muon flux, the searches for point-like neutrino sources and the limits for a diffuse flux of cosmic v(mu) are presented.