Status of the LHCb magnet system

The LHCb experiment focuses on the precision measurement of CP violation and rare decays in the B-meson system. It plans to operate with an average luminosity of 2 × 10³² cm^-2 s^-1, which should be obtained from the beginning of the LHC operation. The LHCb detector exploits the forward region of the pp collisions at the LHC collider. It requires a single-arm spectrometer for the separation and momentum measurement of the charged particles with a large dipole magnet of a free aperture of ±300 mrad horizontally and ±250 mrad vertically. The magnet is designed for a total integrated field of 4 Tm. The pole gap is 2.2 to 3.5 m vertically (the direction of the field) and 2.6 to 4.2 m horizontally. The overall length of the magnet (in beam direction) is 5 m and its total weight about 1500 t. The power dissipation in the aluminum coils will be 4.2 MW. The magnet yoke is constructed from low carbon steel plates of 100 mm thickness. The maximum weight of one plate does not exceed 25 t. The coils are wound from large hollow aluminum conductor of 50 mm × 50 mm cross-section with a central cooling channel of 25 mm diameter for the pressurized demineralized water. Each of the two coils is composed of 15 monolayer pancakes of 15 turns per pancake. To reach good field quality the coils are bent by 45° toward the gap along the horizontal aperture of ±300 mrad and the pole pieces have large shims. The underlying magnet design, its present status and milestones will be reviewed.