Evaluation of shimmed DECY-13 MeV Cyclotron Magnet Using H- Beam Tracking Simulation

Abstract

Abstract –Using OPERA3DTM, the magnet poles’ shimming that provide an isochronous magnetic field in DECY-13 cyclotron was designed and calculated. The shimmed magnet poles as designed were placed in the magnet and the distribution of the magnetic field in the magnet axis direction (Bz) was measured in radial ( x and y) directions using 2 probes covering x=0 to 480 mm for one probe and 481 to 960 mm for the other, and y=0 to 960 mm, all were done at z=0 in 9 hours of scanning at 5 mm steps. This paper describes the interpolation and extrapolation to obtain data for magnetic field components (Bx, By,Bz) at 1 mm resolution and at z≠0 as required for beam tracking simulations. The tracking results are used to evaluate the distribution of the shimmed magnetic fields of DECY-13. The program for the interpolation and extrapolation was written and run using a free software Scilab 5.4.1, and tested against OPERA3DTM design data. The beam can reach final energy of 13 MeV when both data was applying in the beam tracking simulation.. However when the measured data was used, the final energy of the beam reached only 3 MeV, meaning that at the place where that energy was reached the magnetic field is no longer is of isochronous and the shimming of the magnetic poles’ must be improved or redesigned to reach the final beam energy of 13 MeV.Key words: isochronous, DECY-13 cyclotron, Scilab 5.4.1, interpolation and extrapolation, beam tracking simulation