A Surface Detector to Measure the Absolute Pointing of the ANTARES Neutrino Telescope

Proceedings to comeIn the framework of point-like source searches, the ANTARES neutrino telescope has to measure the positions of astronomical objects, therefore requiring a good angular resolution as well as a reliable absolute pointing. To check the latter, an independent calibration system is required. A floating surface array made of scintillators and measuring events in coincidence with ANTARES is a way to perform this calibration. Such a project is currently on-going in the ANTARES collaboration: 16 detectors of 1m2 each are being built. They will be loaded onto a boat by the end of Summer 2011 and will be operated to detect atmospheric showers in the vicinity of the ANTARES site. Depending on the energy of the cosmic primary and on the location above ANTARES, surviving muons will be reconstructed by ANTARES. The matching of events will be made a posteriori, using the absolute time (GPS) and a first estimate of the direction. The comparison of the events measured by the 2 detectors will then provide a constraint on the absolute pointing of the telescope. We will describe the technical design of the surface array detector and give the expected performances. The results of the first tests will be given