MO-DE-BRA-03: TOPAS_edu: A Window Into the Stochastic World Through the TOPAS Tool for Particle Simulation




The stochastic nature of the subatomic world presents a challenge for physics education. Even experienced physicists can be amazed at the varied behavior of electrons, x-rays, protons, neutrons, ions and the any short-lived particles that make up the overall behavior of our accelerators, brachytherapy sources and medical imaging systems. The all-particle Monte Carlo particle transport tool, TOPAS Tool for Particle Simulation, originally developed for proton therapy research, has been repurposed into a physics teaching tool, TOPAS_edu.


TOPAS_edu students set up simulated particle sources, collimators, scatterers, imagers and scoring setups by writing simple ASCII files (in the TOPAS Parameter Control System format). Students visualize geometry setups and particle trajectories in a variety of modes from OpenGL graphics to VRML 3D viewers to gif and PostScript image files. Results written to simple comma separated values files are imported by the student into their preferred data analysis tool. Students can vary random seeds or adjust parameters of physics processes to better understand the stochastic nature of subatomic physics.


TOPAS_edu has been successfully deployed as the centerpiece of a physics course for master's students at Queen's University Belfast. Tutorials developed there takes students through a step by step course on the basics of particle transport and interaction, scattering, Bremsstrahlung, etc. At each step in the course, students build simulated experimental setups and then analyze the simulated results. Lessons build one upon another so that a student might end up with a full simulation of a medical accelerator, a water-phantom or an imager.


TOPAS_edu was well received by students. A second application of TOPAS_edu is currently in development at Zurich University of Applied Sciences, Switzerland. It is our eventual goal to make TOPAS_edu available free of charge to any non-profit organization, along with associated tutorial materials developed by the TOPAS_edu community.

Work supported in part by the U.S. Department of Energy under contract number DE-AC02-76SF00515. B. Villagomez-Bernabe is supported by CONACyT (Mexican Council for Science and Technology) project 231844.