基于Geant4的回旋加速器束流动力学计算

针对回旋加速器的束流动力学设计，基于Geant4模拟研究，提供一种可行的数值模拟方法。通过电磁场仿真软件Opera建立相应的电磁场数据导入到Geant4中进行插值计算，利用Geant4自带的电磁场微分方程与微分方程求解器计算粒子的平衡轨道，振荡频率以及加速轨道。其结果表明:对于横向运动而言，Geant4的计算结果与传统数值方法计算结果趋于一致；对于轴向运动而言，由于磁场插值方法的差异性，二者有一定的区别，对于在加速过程中的非平衡粒子，其能量变化围绕平衡粒子振荡。对于束损，通过限制粒子的运动时间，轴向位移加快计算效率，加入电极碰撞的判定使模拟更趋近实际情况。

Beam dynamics calculation of cyclotron based on Geant4

Based on GEANT4 simulation, a feasible numerical simulation method is provided for the beam dynamics design of cyclotron. Through the electromagnetic field simulation software Opera, the corresponding electromagnetic field data are imported into GEANT4 for interpolation calculation. The equilibrium orbit, oscillation frequency and acceleration orbit of particles are calculated by using the electromagnetic field differential equation and differential equation solver of GEANT4. The results show that: for the transverse motion, GEANT4 calculation results and the traditional numerical method calculation results tend to be consistent; for the axial motion, due to the difference of the magnetic field interpolation method, there is a certain difference between the two. For the acceleration of the non-equilibrium particle, its energy changes around the equilibrium particle. For the beam loss, the simulation is closer to the actual experimental situation by limiting the particle motion time, accelerating the calculation efficiency by axial displacement and adding the determination of electrode collision.