First results from the NEMO Phase-1 experiment

The NEMO prototype detector, called “NEMO Phase-1”, has been successfully operated at 2000 m depth from December 2006 to May 2007. The apparatus comprises a Junction Box and a Mini-Tower hosting 16 optical sensors. Preliminary results are presented. Positions of the optical sensors in the Mini-Tower were reconstructed through the acoustic positioning system with a high level accuracy. Environmental parameters were analyzed. From data corresponding to a live time of 11.3 h, atmospheric muon tracks have been reconstructed and their angular distributions were measured and compared with Monte Carlo simulations.