TOPAS to simulate X-ray photons?

Hi, I am new to GEANT4/TOPAS. I want to ask if it is possible to simulate X-ray photons using TOPAS? From the user guide, it only includes the following beam particles (see image)

…but how about low-energy X-ray photons? Do I need an extension to TOPAS?

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Dear @weiyow87 ,

Better if you post on TOPAS forum.


Low-energy X-rays, indeed any kind of photon that is meant to interact via the Geant4 EM processes, will be given the name “gamma” (i.e., G4Gamma). There’s no extension or modification to TOPAS needed. The “gamma” will have whatever energy is appropriate, whether that’s 3.5 MeV from some nuclear de-excitation, or 0.7 keV from an X-ray emission.

The “opticalphoton” you see is meant only for particles like visible or infrared photons, where you care about reflection, refraction, and number counting, but you don’t care about the individual energy of each one.

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