G3 to G4
Cerenkov effect

Step limitation

• Geant3
  Forced - Generation for charged particle above Cerenkov threshold and in a tracking material with defined refractive index.
  

• Geant4
  Adapted from Geant3
  Optional: user specifies maximum (average) number of Cerenkov photons in one step.
  

Final state

• Geant3
  Uniform along track according to Cerenkov formula.
  Optional: suspend tracking the primary particle.
  

• Geant4
  Adapted from Geant3 including the suspension mechanism.