LEP spectrometer design

The important design parameters, as discussed in the initial proposal, were for: large solid-angle (approx. 36 msr), large momentum bite (+- 15%), good resolution (approx. 0.1%), and a short path length (approx. 2.5 m). The type of spectrometer envisaged was QQDD, similar to the recent projects at Indiana and MIT. When the design study was given to Prof. Harald Enge (MIT), he proposed a simpler, single-dipole solution. The dipole would have non-parallel pole faces, producing weak transverse focusing along the path length. This field configuration produces both a large solid-angle acceptance and a reduced value for one of the usually bothersome third-order aberration terms