Systematic uncertainties in MonteCarlo simulations of the atmospheric   muon flux in the 5-line ANTARES detector
  The ANTARES detector was operated in a configuration with 5 lines for a period of 10 months from February until November 2007. The duty cycle was better than 80% during this period and almost 2*10**7 atmospheric muon triggers were collected. This large sample was used to test Monte Carlo simulation programs and to evaluate possible systematic effects due to uncertainties on environmental parameters and detector description. First results are presented and discussed. 
A. Margiotta (for the ANTARES Collaboration)