Radial Magnetic Field Optimization of the 5 T Superconducting Cyclotron for Medical Application

Mapping and shimming of magnetic field of cyclotron SC200 in Hefei, China is nearing completion. The results of magnetic field measurements are presented in the paper [1]. The beam dynamics simulation was done with the newest experimental map. It showed that beam completely lost near radius 13 cm. In order to decrease beam losses in central region, beam dynamics with different Br distribution was studied. Vertical and horizontal Br shimming coils are used to decrease Br field. These lead to an increase in beam transmission efficiency to radius 15 cm.