The Laser Tracker: a Major Tool for the Metrology of the LHC

Inside these magnets, the particle beam will circulate in a vacuum chamber so small that the loss of beam/mechanical aperture is rather important. The interconnection of all the tubes of two adjacent magnets is also a challenge. The positioning of the alignment targets, used during the alignment in the tunnel, with respect to the axis of the magnet is also to be done with a high accuracy even for the dipoles magnets.