Aspects of superconducting magnet design for neutron scattering sample environments

The majority of superconducting magnets for neutron scattering experiments take the form of split pairs with magnetic field vector in the vertical plane. Sample environment access is along the vertical magnetic axis whilst neutron access is in the horizontal plane. Split pair superconducting magnets present significantly more challenges in terms of design than the simpler solenoid type arrangement and the addition of requirements for neutron access further complicates the situation. Many of the requirements of split pair magnets for neutron scattering are conflicting and often compromises have to be made. Presented here are some of the more important design criteria and the ways in which these are met in practical magnet designs. Topics covered range from the choice of superconducting material through to the control of magnetic flux density profiles and mechanical aspects of the magnet former providing the neutron access between the coils. Most of the information presented is based on recent or current production magnets manufactured by Oxford Instruments for a range of neutron related applications.