Zenith distribution and flux of atmospheric muons measured with the 5-line ANTARES detector

The ANTARES high-energy neutrino telescope is a three-dimensional array of about 900 photomultipliers distributed over 12 mooring lines installed in the Mediterranean Sea. Between February and November 2007 it acquired data in a 5-line configuration. The zenith angular distribution of the atmospheric muon flux and the associated depth–intensity relation are measured and compared with previous measurements and Monte Carlo expectations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is presented.