A measurement of the cosmic-ray muon flux with a module of the NESTOR neutrino telescope

A module of the NESTOR underwater neutrino telescope was deployed at a depth of 3800 m in order to test the overall detector performance and particularly that of the data acquisition systems. A prolonged period of running under stable operating conditions made it possible to measure the cosmic ray muon flux, I0·cosα(θ), as a function of the zenith angle θ. Measured values of index α and the vertical intensity I0α=4.7±0.5(stat)±0.2(syst)I0=9.0×10-9±0.7×10-9(stat)±0.4×10-9(syst)cm-2s-1sr-1are in good agreement with previous measurements and phenomenological predictions.