Conceptual design of a compact synchrotron for proton-and-helium therapy facility

Abstract In recent years, in-depth research on radiotherapy has revealed that helium ions demonstrate superior tumor-targeting precision due to their advantageous physical properties and biological effects. Furthermore, helium ions generate extremely low neutron doses, providing substantial clinical benefits for pediatric patients. Additionally, the size of helium ion therapy facilities are significantly smaller than those of carbon ion therapy systems. To this end, this paper proposes a conceptual design of a compact synchrotron for proton-and-helium therapy facility. This design employs eight specially designed high-field dipole magnets forming the deflection section. Through a dedicated beam optics design, the envelope function is maintained within a low level, significantly mitigating engineering challenges associated with the dipole magnets. Minimization of the ring circumference has been achieved through optimized lattice layout. Additionally, this design incorporates bump-painting multi-turn injection and mismatch-painting injection methods in horizontal and vertical planes, significantly minimizing the number of bump magnets. Based on these designs, a compact lattice layout with a circumference of only 28 m has been achieved. Furthermore, a novel adjustable electrostatic septum has been implemented, ensuring reliable injection and extraction processes in this synchrotron while providing the hardware foundation for subsequent multi-energy extraction designs.