Transport threshold of FTFP_BERT_LIV?

[Takagi_Shogo]

Geant4 Version:11.3.2
Operating System:windows11
Compiler/Version:Microsoft Visual Studio Commnity 2022
*CMake Version:*3.24.202208181-MSVC_2

The energy of the electrons that have traveled a certain distance in ScH2 with random enrgy is obtained.

When I used Shielding, the lowest energy was higher than 1keV.

When I used FTFP_BERT_LIV, the lowest energy was higher than 100eV.

It seems the electrons that have lower energy than 1keV in shielding and 100eV in FTFP_BERT_LIV is stopped at that point

Are there transport threshold in each physics lists?

Thanks.

[ctwhite]

With FTFP_BERT_LIV the electro-magnetic physics constructor is EM Livermore Physics (hence the “LIV”) which sets the lowest electron energy to 100 eV. Shielding on the other hand defaults to EM Standard Physics (also known as EM Opt 0).

[Takagi_Shogo]

I am glad to confirm that the lowest energy you mentioned is exactly the same as the result of my simulation.

In my simulation result using LIV, transport threshold seems like 100eV but, electron generation by ionization threshold seems like 1keV.
By changing from LIV to penelope, electrons lower than 100eV was generated by ionization.

Where can I get infomation such a lowest energy of physics momdels?

[ctwhite]

The best place is to look is the documentation, in particular the Physics List Guide:

Geant4 Documentation

You can also look through the source code, however that might not be as clear as the documentation.

geant4 / geant4 · GitLab

The path to the Livermore physics constructor is

source/physics_lists/constructors/electromagnetic/src/G4EmLivermorePhysics.cc

And you can see line 120 sets the lowest electron energy:

param->SetLowestElectronEnergy(100*CLHEP::eV);

Note that you should never modify these files in your own install.

[Takagi_Shogo]

I found the infomation i really need.
Thank you!