Guide lines for the design of very large aperture quadrupole magnets

Very large aperture quadrupole magnets have been recently considered as possible spectrometers on high energy colliders. The interesting characteristics are zero field on beam axis, low fields at small angles, transverse field at large angles. Dimension range is 1 m to 5 m for clear bore and 2 m to 8 m for length; typical maximum field is 2.5 T. Superconducting magnets with cosine 2θ structure, coils with one or two layers and iron yoke have been modelised. Use of two types of conductors have been investigated: Rutherford cable and aluminium stabilized composite. The paper describes the optimization procedure and gives diagrams of feasibility. Two alternative structures are mentioned: superferric and active shield magnets