The LHC insertion magnets

The Large Hadron Collider comprises eight insertions, four of which are dedicated to the LHC experiments while the others are used for the major collider systems. The various functions of the insertions are fulfilled by a variety of magnet systems, most of them based on the technology of NbTi superconductors cooled by superfluid helium at 1.9 K. A number of stand-alone magnets in the matching sections are operated at 4.5 K, while in the high radiation areas specialized resistive magnets are used. In this paper, we review the concepts underlying the design of the LHC insertions, and report on the design, procurement and testing of the various specialized magnet systems.