Realistic CAD-Based Geometries for Arbitrary Magnets with Beam Delivery Simulation (BDSIM)

Monte Carlo simulations are required to evaluate beam losses and secondary radiation accurately in particle accelerators and beamlines. Detailed CAD geometries are critical to account for a realistic distribution of material masses but increase the model complexity and often lead to code duplication. Beam Delivery Simulation (BDSIM) and the Python package pyg4ometry enable handling such accelerator models within a single, simplified workflow to run complete simulations of primary and secondary particle tracking and interactions with matter using Geant4 routines. Additional capabilities have been developed to model arbitrary bent magnets by associating externally modeled geometries to the magnet poles, yoke, and beampipe. Individual field descriptions can be associated with the yoke and vacuum pipe separately to provide fine-grained control of the magnet model. The implementation of these new features is described in detail and applied to the modeling of the CERN Proton Synchrotron (PS) combined function magnets.