Simulation study of slow extraction for the Shanghai Advanced Proton Therapy facility

The Shanghai Advanced Proton Therapy facility employs third-integer slow extraction. In order to achieve accurate treatment, high-quality spill is needed. Therefore, parameters that may affect slow extraction should be investigated by simulation. A computer model of the synchrotron operation slow extraction was constructed with MATLAB^®. By simulating the motion of the circulating protons, we could quantify the influence of machine and initial beam parameters on properties of the extracted beam, such as ripple, uniformity, stability, on- and off-time of the spill and spill width in the synchrotron. Suitable design parameters including the horizontal tunes, power supply ripple, longitudinal RF cavity voltage, RF-KO and the chromaticities were determined. (authors)