Dear all , i want to generate the response function of scintillation detector. My question is which example is close to this work. I have to consider the primary photons and secondary electrons with all related interactions with matter.
If you don’t mind me asking, are you trying to generate a detector response function (DRF) for a scintillation detector that you possess? If you have the detector, the GADRAS-DRF software would be a better option than Geant4 for generating new detector response functions. Although you would have to first characterize the detector with some check sources.
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yes , i want to generate DRF but i don’t have the detector yet and i have to use geant4.
Based on that, I would suggest you look at energy deposition examples. You could output a energy deposition tally from Geant4 and then post process to statistical broaden your tally. For example it is not uncommon for folk to spread energy deposition tallies according to a power law based on Gaussian peak fitting of measured detector response spectra Validation and uncertainty quantification of detector response functions for a 1″×2″ NaI collimated detector intended for inverse radioisotope source mapping applications - ScienceDirect. Since you don’t have the detector yet perhaps fit based on what you expect your system’s energy resolution to be?
If you are not satisfied with the above, then you are in challenge that would be daunting even for someone well versed in Geant4. As properly simulating intrinsic resolution and optical photon transport is tricky, and even then you still need to post process the output to account variance in photoelectron multiplication of the photomultiplier, even more so if we don’t disregard electronic noise and covariance.
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Hi @Al_Harith,
Thanks for your question.
A good place to start is the beginner’s course material, available here [1]. At the end of the course, the example shows how to score deposited energy in a logical volume in a simple way (using the stepping action), and how to run the simulation in multi-threaded mode.
When getting the response functions for a detector, the biggest limitation is usually how accurate your geometry description is. In some special cases, the choice of physics models can also matter. Geant4 offers many physics models, and the electromagnetic (EM) ones are well tested and work over a wide energy range.
A common approach is to simulate the deposited energy, and then apply postprocessing to include optical effects and resolution effects. If you’re using optical physics, having good data for the optical properties might be crucial.
Best regards,
Alvaro
[1] First steps with Geant4 (19-23 May 2025): Timetable · Indico
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Thanks a lot for your suggestions.
Thanks a lot Alvaro, helpful information.