Simulating Characteristic 28 keV Iodine K X-ray Escape in a Gamma Spectrum

Dear Geant4 community,

Maybe you can help me. I want to model a NaI scintillation detector. I orientate myself on TestEm4. The result looks fine, but the characteristic 28 keV iodine K X-ray escape peak is missing (Origin of Gamma Spectrum Structure). I attach a plot showing the simulated gamma spectrum of Cs-137 in a NaI detector with the three simulation tools MCNP, OpenMC, and Geant4 (in the same setting). Is there any particular option in the physics list or something like this to account for this effect?

Thank you a lot!



TestEm4 is may be not the best example for this task. Use whatever else, for example TestEm5, and EM physics G4EmStandardPhysics_option4. See available macro files in TestEm5 directory.


Dear Vladimir,

Thanks a lot! I changed the physics to the G4EmStandardPhysics, and now I can see the second peak in the Geant4 results! You really helped me a lot.


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