Magnet Sector Design for a 15-GeV Superconducting Cyclotron

Pole shape designs are presented which maintain focused and isochronous orbits in the two stages of a superconducting ring cyclotron kaon factory (CANUCK). The first stage of 15 sectors takes a 100 ¿A proton beam extracted from TRIUMF to 3.5 GeV. The second stage of 42 sectors continues the acceleration to 15 GeV. The orbit properties have been determined using a median plane magnetic field computed from the current distribution in the coils and in current sheets simulating the saturated steel. The design process and the effects of various factors, including softness of the edges, cross-section of the coils and negative field gullies, will be described.