Design method of active shield steering magnet for fine tuning of muon injection orbit into g-2/EDM precision measurements magnet

This study is about a design method for ASSMs (Active Shield Steering Magnets). ASSMs will be applied to a g-2/EDM precise measurements experiment which is under preparation in J-PARC. The experiment needs a very homogeneous 3.0 T magnetic field using a superconducting magnet with iron yoke. Muons are injected through spiral orbits in the fringe field and two ASSMs are planned for orbit fine tuning. ASSMs need to generate steering magnetic fields without additional error field. Then, they need active shields, and they are ASSMs. For such ASSMs, a design method has been developed and trial design have been done, using a technique of the MRI GC design method which can well determine 3D current pattern on surfaces.