The positioning system of the ANTARES Neutrino Telescope

Abstract

The ANTARES neutrino telescope, located 40km off the coast of Toulon in the\nMediterranean Sea at a mooring depth of about 2475m, consists of twelve\ndetection lines equipped typically with 25 storeys. Every storey carries three\noptical modules that detect Cherenkov light induced by charged secondary\nparticles (typically muons) coming from neutrino interactions. As these lines\nare flexible structures fixed to the sea bed and held taut by a buoy, sea\ncurrents cause the lines to move and the storeys to rotate. The knowledge of\nthe position of the optical modules with a precision better than 10cm is\nessential for a good reconstruction of particle tracks. In this paper the\nANTARES positioning system is described. It consists of an acoustic positioning\nsystem, for distance triangulation, and a compass-tiltmeter system, for the\nmeasurement of the orientation and inclination of the storeys. Necessary\ncorrections are discussed and the results of the detector alignment procedure\nare described.\n