Model test of trim coils for sector magnet

Trim coils for the sector magnet of the RIKEN separated sector cyclotron are made of wide copper plates. We have measured the magnetic field distribution produced by the plate coil. The experimental results are provided for calculations optimizing the configuration of trim coils. The obtained distribution agreed very well with the distribution predicted by Trim code. In this calculation, we used the current distribution in the plate coils calculated by the finite element method. This theoretical distribution was almost the same as that calculated by assuming the uniform current distribution in the coil. From the present model test, further, we could find the effective method of current supply to the plate coil. (author)