Engineering design optimisation of the superconducting end cap toroid magnets for the ATLAS Experiment at LHC

Precision muon momentum measurements at the highest LHC luminosity is a pri me objective for the ATLAS Experiment. To realise this objective the muon d etector is based on a large, superconducting, air-cored toroid magnet syste m consisting of a long barrel and two end cap toroids, The end-cap toroids are required to produce strong bending powers, 4-8Tm, over a radial span fr om 1.5 - 5m, This paper presents the final engineering design which include s a number of design optimisation features. The optimisation of the cold ma ss structure to reduce internal stresses, the developments in resin technol ogy to give greater safety margins in operation and novel techniques for co ld mass support systems are described, Final design proposals for quench pr otection and control will be presented with manufacture, assembly and insta llation plans.