A Device to Measure Magnetic and Mechanical Axis of Superconducting Magnets for the Large Hadron Collider at CERN

The LHC will be composed of 1232 horizontally curved, 15 meter long, cryodipoles and 474 short straight sections, being assembled by different manufacturers. Magnetic axis alignment is an essential part of the magnets quality for two reasons: first, to be able to install correctly the magnets in the tunnel w.r.t. the reference beam orbit; secondly, to assess the relative alignment between the magnets composing the assembly, i.e. spool pieces for the dipoles and larger correctors for the SSS. A system called AC mole is being used extensively to measure magnetic and geometric axis, as well as roll angle, for every single magnet composing all the SSS. This paper describes its performance, its first years of operation, as well as the improvements that have made it very powerful, versatile and easy to use