Cooling Scheme for BNL-Built LHC Magnets

Brookhaven National Laboratory (BNL) will provide four types of magnets, identified as D1, D2, D3 and D4, for the Insertion Regions of the Large Hadron Collider (LHC) as part of an international collaboration. These magnets utilize the dipole coil design of the Relativistic Heavy Ion Collider (RHIC) at BNL, for performance, reliability and cost reasons. The magnet cold mass and cryostat have been designed to ensure that these magnets meet all performance requirements in the LHC sloped tunnel using its cryogenic distribution system. D1 is a RHIC arc dipole magnet. D2 and D4 are 2-in-1 magnets, two coils in one cold mass, in a cryostat. D3 is a 1-in-1 magnet, one coil in one cold mass, with two cold masses side by side in a cryostat. D1 and D4 will be cooled by helium II at 1.9 K using a bayonet heat exchanger similar to the main cooling system of LHC. D2 and D3 will be cooled by liquid helium at 4.5 K using a Two-Feed scheme. A detailed description of the cooling scheme for these magnets, their cryostats, special features and interfaces with the LHC distribution system is given.