The TOTEM experiment at LHC

The TOTEM experiment is designed to provide a precise measurement of the total proton-proton cross section at the LHC. A luminosity independent method, that requires the simultaneous measurements of elastic scattering at low momentum transfer and of the total inelastic rate, will be used. The aim is an absolute error of about 1 mb. The interface between TOTEM and the LHC machine is quite intricate since a special high-beta optics is required to observe small angle scattering. Besides, detectors close to the beam axis need to be installed in "Roman Pots" located about 150 m from the collision point. The integration of TOTEM with the machine layout is reviewed and the dedicated LHC beam conditions are discussed. The experiment does not need intense beams or high luminosity. It is therefore suited for running at the beginning of LHC operation, within a limited amount of machine time.