Atomic deexcitation UV

How might one go about extending this with UV photon data?


again, I would suggest to you to contact Vladimir Ivantchenko, Sebastien Incerti and Daren Sawkey about this. This may be a new requirement for Geant4 and I think many users may use this functionality. So , please, talk with them.

If you want to do it yourself,
-one way may be to define a new process…e.g. UVDe-excitation, with cross section and final state.
-Or whenever you have the process that originates the vacancy, you can generate a UV photon sampling the probability and emission energy, and score the position of the interaction and energy of the UV in a output file F1. Then you have a second simulation where you transport the optical photons which are the primary particles of the simulation, originating them with position and energy as defined in the output file F1. I am not sure about the angular distribution. Maybe it can be assumed isotropic? I think this is the easiest solution.

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Thank you for the reply. That sounds promising. I was wondering if I could also simply extend the xray data down to uv and model the particles as G4 gammas instead of optical photons or is that too hacky?

You could extend the x-rays down to UV and model the particles as “gamma” but then they will not be transported using the optical photons processes. If you want to generate them and that’s all, it should work.

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I’ve thought about implementing a “converter” process, which would take a G4Gamma track as input, and convert it (by killing and replacing) with a G4OpticalPhoton. Having configuration parameters, like a maximum energy for such a conversion, might make it useful.

I can see lots of complications with this – it would mess up people’s SDs or scorers that look for killed photons, among other things. But if you’re doing it as part of your own application, where you can control everything, it might be useful.

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This is definitely something I would like to do. I am stuck on the implementation however. Is there a recommended approach to either adding supplementary atomic/molecular data or extending a process?


There is no real physical difference between G4Gamma and G4OpticalPhoton. Depending on task it is possible to work with one or another. Currently, we have UV photoelectric process only in liquid water. If there are cross section data, it is possible to extend this process to different materials. In any case, if simulation is needed it will require your extra effort to develop extra physics models.