Qualification of the geo-magnetic cold measurement system for the LHC SSS

by P. Schnizer (LHC Division)

Thursday 17 Jan 2002, 14:15 → 15:15 Europe/Zurich

30-7-LHC (CERN)

The LHC arc quadrupoles have to be measured in cold conditions with an outstanding precision. We aim to reach a reproducibility of 1.5 . 10-4 on the field integral, while for the harmonic content we aim at 2 ppm of the main field. A scanner allowing the simultaneous measurement of the field axis geometry and of the field strength and quality (a geo-magnetic measurement) is the most complex system in the whole pool foreseen for the cold tests of the arc quadrupoles. In this talk I will show that the system as it stands fulfils the requirements for the magnetic measurement and the magnetic axis and thus provides a unique versatile equipment. The assessment was performed based on experimental results, direct calibration and using a new simulation tool. The main defects that affect a magnetic measurement are mechanical torsion and vibration of moving parts, electrical noise and power supply ripple, as well as their arbitrary combination.