Field Mapping System for the KIRAMS-30 Cyclotron Magnet

Field Mapping System for the KIRAMS-30 Cyclotron Magnet K. H. Park, Y. D. Yoon, Y. G. Jung, D. E. Kim and B. K. Kang Pohang Accelerator Laboratory and Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 J. Kang Cyclotron Application Laboratory, Korea Institute of Radiological and Medical Science, Seoul 139-706 J. S. Chai School of Information & Communication Engineering, Sungkyunkwan University, Suwon 440-764 (Received 12 August 2008, in nal form 5 December 2008) This paper presents a Hall-probe mapping system for measuring a cyclotron magnet. The system fabricated for the 30-MeV cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The Hall probes were mounted on a precision mechanical rotational stage and mapped the magnetic eld in a cylindrical coordinate system. The mapping system used the \ ying" mode eld mapping method to reduce the data-acquisition time. The time required for mapping the whole gap-area of the cyclotron magnet was 75 minutes. The relative random uctuation error during the entire mapping process was less than 0.01 %. The cyclotron magnet was corrected using the measured data for the magnetic eld. After the correction, the total phase excursion of the cyclotron was less than 12 , which is within the total phase excursion tolerance of 20 . PACS numbers: 41.20.-q