The Software Anatomy of a Flexible Accelerator Simulation Engine
  A modular, maintainable and extensible particle beam simulation architecture is presented. Design considerations for single particle, multi particle, and rms envelope simulations (in two and three dimensions) are outlined. Envelope simulation results have been validated against Trace3D. Hybridization with a physics-centric contol-system abstraction provides a convenient environment for rapid deployment of applications employing model-reference control strategies. 
Nicholas D. Pattengale, Christopher K. Allen