Killing all particles except selected ones

[sergio]

For some calculations, I would want to track only selected particles (gammas and neutrons in my case). I have been trying to look into the different ways of doing this, and I am not quite sure what is the best way to go. These are the things I looked into:

• Using particle cuts.
  • Not suitable, because cuts can only be applied to gammas, electrons, positrons and protons.
• Creating a custom process similar to G4NeutronKiller.
  • This would work perfectly, but it would have to be attached to all potential particles which should not be tracked.
• Killing tracks in G4UserTrackingAction::PreUserTrackingAction().
  • This in principle works, but there are two issues:
    • It requires a const_cast, which suggests that this is not the right way to do it:
      const_cast<G4Track*>(track)->SetTrackStatus(fStopAndKill);
    • The remaining energy is not deposited (pretty much a non-issue, but there’s one thing I wanted to check).

Is this correct? Any other option I am missing? Does anyone have other suggestions?

[maire]

In examples/basic/B3, neutrino are killed in StackingAction.

[sergio]

Thank you @maire ! This is exactly what I need, it works like a charm.