Powerful and Intuitive Radiation Simulation Software

RSim is a Monte Carlo simulation tool that is based on Geant4, a well-established radiation transport model. Inspired by a project that designed radiation protection for the upcoming NASA Europa mission, RSim was further developed to offer ease of use, CAD importability, and visualization capabilities. With RSim, simulations are set up and run through the user-interface, eliminating the need for C++ or Geant4 input commands. Additionally, RSim is integrated with CAD and offers shape healing, making it ideal for users working with complex geometries.

RSim features a unique geometric biasing source capability to expedite simulation times while obtaining accurate statistics. Multiple shape and mesh scorers, such as energy deposition, dose and flux calculation, can be calculated using RSim and visualized in 3D against the modeled geometries. With RSim’s intuitive interface, rich database of materials, and multiple options for radiation source customization, engineers can easily predict radiation effects, perform shielding calculations, and assess survivability in harsh surroundings like space.

“RSim is enabling NASA to assess mission plans by quantifying human exposure to space radiation using complex CAD models, such as the crewed Orion exploration vehicle, and it does so with a GUI that allows a non-expert in Geant4 to get to meaningful results very quickly.”

Kerry Lee
Physical Scientist, NASA

RSim Advantages


RSim features an intuitive interface that shortens simulation set up time and increases design cycle efficiency. With RSim, users can import many existing types of CAD files and take advantage of RSim’s shape healing function, or can use RSim to create their own unique geometries through Boolean and array operations.

Versatile and Detailed

RSim includes a rich database of over 700 materials and users can create new materials as needed. A variety of radiation sources can be specified, and RSim users can compute multiple volume and mesh quantities.

With RSim, users receive results more detailed and refined than those received from current probe based radiation assessment equipment.


Tech-X’s team of scientists and engineers are leading contributors to the field of computational physics, and our simulation software products are found at many of the top research institutions worldwide. Our development team understands the rigorous standards required of the research community and the complex needs of our commercial users.

RSim Features

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Applications for RSim

Radiation Shielding

Radiation Effects

Radiation Containment

Dose Calculations

Our software can be found at institutions all over the world

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