Experimental Validation of the Field and Beam Dynamics Simulations for a Superconducting Cyclotron

The Ion-12SC is a sub-compact, 12.5 MeV proton super-conducting isochronous cyclotron for commercial medical isotope production recently developed at Ionetix Corporation. The machine features a patented cold steel and cryogen-free conduction cooling magnet, a low power internal cold-cathode PIG ion source, and an internal liquid target. It is designed to produce N-13 ammonia for dose on-demand cardiology applications but can also be used to produce F-18, Ga-68 and other medical isotopes widely used in Positron Emission Tomography (PET). The cyclotron is being installed and commissioned at several medical centers. During the initial machine operating periods, some issues appeared. In particular, imperfections in manufacturing and assembly of the magnet introduced unwanted low order magnetic harmonics that resulted in beam losses. This report presents results of analysis of the measured magnetic field and beam dynamics in the cyclotron that were initiated to solve the problem. The calculations led to a process for implementing compensating magnetic shims to improve the beam transmission.