Physics list for calculating the positron range of F18

I’m trying to calculate the positron range of F18 in water. There are three examples provided with the installation files, which I think are directly related to this problem. They use different physics lists, and I wonder which one is most suitable for F18.

  1. The example ‘\basic\B3’ uses G4DecayPhysics, G4EmStandardPhysics, and G4RadioactiveDecayPhysics.

  2. The example ‘\extended\radioactivedecay\rdecay01’ uses G4Radioactivation.

  3. The example ‘\extended\radioactivedecay\rdecay02’ uses G4EmStandardPhysics, G4DecayPhysics, BiasedRDPhysics, G4HadronElasticPhysics, G4HadronPhysicsFTFP_BERT, G4IonElasticPhysics, G4IonPhysics, G4EmExtraPhysics.

2 uses only G4Radioactivation, so I assume it’s least accurate. 1 directly addresses the F18 simulation and it uses only three physics lists, so I assume it may be the optimal choice in terms of both computation time and accuracy. However, setting aside the computation time, would 3 provide the highest accuracy as it uses more physics lists than the others?

Since F18 is a simple beta-plus decay, assuming that you are emplacing the ion at rest (i.e., it’s not a beam on target), you really only need EM physics for this. Option 1 would be fine.

Even better would be to use one of the official Geant4 reference physics lists, like FTFP_BERT or something. You get all the hadronic stuff, but you also get all the right EM and decay physics. If something goes wrong, the G4 experts will be more likely to be able to help you debug it from one of the references PLs, than from a roll-your-own.

Perfect! Thank you so much!