LHC Dipole Axis, Spool Piece Alignment and Field Angle in Warm and Cold Conditions

The installation and commissioning of LHC requires knowledge of the magnetic alignment of the spool piece correctors mounted on the dipole end plates are, as well as of the dipole main field direction. The installation is based on the use of geometric information derived from mechanical measurements performed in warm conditions, assuming that geometric and magnetic axes coincide, and that thermal contractions of the assembly are homothetic. A series of measurements has been performed at room and superfluid Helium temperature to validate these assumptions. In this paper, a statistical analysis of the correlations obtained is presented for both corrector alignment and main field direction, and the results are compared with beam optics-based specifications.