Inluence of Copper Wedge Dimensions on Field Harmonics in the Main LHC Dipoles

In order to obtain the required magnetic field quality in the LHC main dipole, the superconductive cables blocks are separated by copper wedges. These components must respect geometrical tolerances of ±30 micrometers. Non-nominal copper wedge dimensions change the position of cables blocks and therefore affect field quality. In this paper we present the measurements of the copper wedges used in the main LHC dipoles. We then evaluate the influence of copper wedge dimensions on field quality, comparing it to the warm magnetic measurements of the collared coils. Finally, in order to foresee the impact of the copper wedge production on the random and on the systematic parts of the field harmonics we implement a Monte-Carlo method. Comparison with targets imposed by beam dynamics is used to judge how critical the tolerances on copper wedges are.