I am modifying the example Par02 (parametrization), and I would like to check the simple decay process pi0 → photon,photon, and check the photons that hit the detector (smeared) from a pi0 as primary. However, it seems that Geant4 (release 11.0.4) is not making the primary pi0 decay. In the Physics List (Par02PhysicsList), I see that decays are implemented, but I am not sure if it is applicable to the primary pi0. Can someone give me a clue?
Decay (if enabled in PhysList) should be applied during tracking. Your primary generator send pi0 track for tracking and it does not matter how track was created. All tracks primary and secondary are tracked in the same way.