How to get an accurate count of energy deposit events

Hello everyone,
I’m looking for a way to get a count per second on a gamma ray simulation. Here is what I have done:

  • the geometry, including the sensitive detector (a NaI crystal)
  • the source (a concrete formation with a custom energy spectrum)
  • setup a scorer, the same size as the sensitive detector, that records energy deposit
  • setup a root file output (I’m using btw) that records everything happening in the sensitive detector

The score file gives me a number of “entry” but so does the root file with the “deposited energy” and “total energy deposited” histograms.
The problem I’m facing is that these different scoring methods give me different mesures and I don’t know which one to pick.

Bonus side question : which physics list would you recommend for gamma rays < 3MeV. I’m using QGSP_BERT via the macro /physics_lists/select QGSP_BERT

See this post: Low ionizing event rate - #4 by guatelli
emDNAphysics, or G4EmStandardPhysics_option4 or emlivermore or empenelope

Thank you for pointing me to this post !
From what I understood, there is no way to get a count of the energy deposit events in my crystal because Geant4 condenses some of the tracks. The physics list for DNA solves that problem but I read it only works in water scenario. Are both of these statements correct ?

I would suggest to use QGSP_BIC_HP , as, since Geant4 10.5, it activates the option4 EM Physics List. Make sure the fluorescence is activated (which should be). I suggest to calculate the energy deposition per event. Then, provided the activity of the source (if you are using a gamma source) or the current of the beam, you should be able to retrieve the energy deposition per second. keep in mind that to have a more realistic description of the scintillator, the optical photons should modelled and then the optical photons should be counted when traversing the PMT window.

I hope this helps you


Thank you ! I will try this out and come back if I encounter any problem I can’t fix myself.