Status and first results from the ARCA and ORCA lines of the KM3NeT experiment

KM3NeT is a network of submarine Cherenkov neutrino telescopes under construction in two different sites in the Mediterranean Sea [1]. The detector at the Italian site, close to the Sicilian coast and named ARCA, will be devoted to the detection of high-energy astrophysical neutrinos coming from sources in the Universe, while the detector at the French site, in the Toulon bay and named ORCA, will exploit atmospheric neutrinos to determine the neutrino mass hierarchy. The telescopes are an array of flexible strings anchored to the sea floor and held close to vertical by submerged buoys. The strings are instrumented with digital optical modules hosted within pressure-resistant glass spheres, each housing 31 3" photomultipliers tubes and the readout electronics. The geometry of the detectors has been adapted to their physics goals. The first calibrations and results of ARCA and ORCA are presented.