The LHCf experiment at CERN: motivations and current status.

LHCf is an experiment currently installed at CERN at the LHC complex. It consists of two small calorimeters each one placed 140 meters away from the ATLAS interaction point. Their purpose is to study forward production of neutral particles in proton-proton collisions at extremely low angles. The results will provide invaluable inputs to the many air-shower Monte Carlo codes currently used For modeling cosmic rays interactions in the Earth atmosphere. Depending on machine start up, data will be taken from 900 GeV in the centre of mass tip to 14 TeV (laboratory equivalent collision energy of 10(17) ev), thus covering an energy range up to and beyond the "knee" of the cosmic ray spectrum.