Integrating Geant4 Into PyORBIT for Accurate Beam Dynamics and Particle–Matter Interactions Simulation

In synchrotron designs, accurately simulating beam dynamics, space charge effects, and particle-matter interactions is crucial. However, few simulation tools can simultaneously achieve high precision in beam transport, beam acceleration, space charge effects, multiturn injection, and particle-matter interactions. This article introduces G4PyORBIT, which integrates the particle-matter interaction capabilities of Geant4 with the beam dynamics framework of PyORBIT to address these challenges. The newly developed G4PyORBIT code not only handles simulations of beam dynamics, including space charge effects, but also models complex scattering processes involving dynamic and complex geometries, and composite materials. It provides high-precision simulations of beam loss and visualization capabilities. The accuracy and effectiveness of the program have been validated through benchmark tests and its successful application in the physical design of the rapid cycling synchrotron (RCS) at the China Spallation Neutron Source (CSNS).