GetMeanFreePath for Geantino as surrogate opticalphotons

I am having difficulty in proceeding further and would really appreciate some pointers…


After photon gets scattered by Mie or Rayleigh, I am generating a Geantino directed towards the detector with the probability given by angular scattering phase function at that event else if absorption it kills it.

Problem statement

Next I would like to have it proceed towards the detector. But Geantino weight should be able to get attenuated by total scattering+absorption cross-section along its path by the time it reaches the detector i.e., I want to know the probability of geantino (fake photon) reaching the detector . I am aware that geantino only can do transport but no interaction (which is exactly what I want) but I assume this means it does take into account net attenuation along its path?


Can someone point out how can I do this? Any examples/tutorials of Geantino that I can find?

  1. Find out the logical volumes along the path
  2. Find out total attenuation according to scattering parameters
  3. Sum up all the cross-sections
  4. Calculate exp(-sum(attn))
    Is that the correct way?


I am getting errors (seg fault) at GetMeanFreePath for G4BoundaryProcess. This is because I am trying to get all the processes listed and then figuring out Meanfreepaths. I understand that meanfreepath for G4BoundaryProcess is 0 by default so I thought it should be Okay to retain it.
Where am I going wrong?
I would like to say at the outset that I am using GAMOS, however, that could be irrelevant.