The difference between Geant4 and SRIM about recoil production


I am trying to reproduce SRIM by GEANT4 code, because GEANT4 can output more information.
I start with TestEM7,mainly use the EmStandardNR with G4ScreenedNuclearRecoil class to simulate 10 keV proton interact with a optical film (Au(100nm)/Cr(5nm)/Si-substrate).

If I set the RecoilCutOff to be 25eV, same as SRIM default value, there will be no recoils in Geant4. But SRIM output shows that value is 3.2/Ion. If I set the value to be 1 eV, Geant4 will produce recoils, but the amount is still less than that of SRIM.

I have set the Range cut-off to be very low for all particles (0.1nm).

I don’t why!!! Should I add hadron processes to PhysicsList ? Or there are some other details I don’t know.

Thanks a lot.


Is there anyone can help me ?