Design of the superconducting end cap toroids for the ATLAS experiment at LHC

The ATLAS experiment proposed for LHC will use a toroidal magnet system to achieve high efficiency muon momentum resolution. The end cap toroids are designed to provide bending powers in the range 4-8 Tm over the rapidity span 1.5-2.8 in the important forward/backward regions. Each end cap toroid will have an outer diameter of approximately 11 m and an axial length of 5.6 m. This paper presents the magnetic, mechanical and cryogenic design of the end cap toroid magnet systems. Particular emphasis is placed on the interactive design issues imposed by the close proximity of the ATLAS barrel toroid. Proposals for the magnet fabrication and assembly are given.