Three-dimensional simulation code for SPring-8 RF gun system

To analyze the beam characteristics of an RF gun system, we developed a true three-dimensional beam tracking code. All forces imposed on each macrocharged particle are included in this code. Asymmetrical figures of beams and RF fields can be calculated with this code. In this paper, we describe the details of the developed code, and show comparisons between our code and PARMELA. In addition, we compare the results of our code and the experimental results of the SPring-8 S-band single-cell RF gun system. Using this code, significant differences in measured emittance values in horizontal and vertical directions resulted from an oblique incidence of a laser, that is, the difference of arrival time of the laser wavefront on the cathode.