SetMinEnergy and LowestElectronEnergy

Is there an overview description of what the G4EmParameter SetMinEnergy and LowestElectronEnergy is doing. I couldn’t really get the general idea from looking at the code

1 Like


there are description in Physics Reference Manual and Application Developer Manuel.

In short: SetMinEnergy defines low energy edge of internal tables for dEdx, Range, and others. LowestElectronEnergy is the tracking cut - when energy of e- or e+ is below, they are stopped.



Hi Vladimir,

Just to confirm, particles below the SetMinEnergy range will just be stopped as well.

So, the particle will stop if either it is below the SetMinEnergy value or the range limited by say SetDefaultCutValue.

I have been using 100eV and 1um respectively, but have been trying to figure out how low I can set SetMinEnergy for G4EmStandardPhysics_option4 (will it support 50eV?)



SetMinEnergy is only for table size, it is not tracking cut. Below low-edge of a table simple approximations are used.


Hi @civanch,

When I read your reply, I tried LowestElectronEnergy to order a local energy deposition (at its point of birth) for the positron after a pair production.

Unfortunately, it does not work.

It changes the tracking; instead of several multiple scatterings, bremsstrahlungs then an annihilation, the positron is annihilated almost directly now.

  • G4Track Information: Particle = e+, Track ID = 2, Parent ID = 1

Step# X(mm) Y(mm) Z(mm) KinE(MeV) dE(MeV) StepLeng TrackLeng NextVolume ProcName
0 -2.5 -29 -34.6 0.413 0 0 0 Slab4 initStep
1 -2.5 -29 -34.6 0 0.413 8.11e-05 8.11e-05 Slab4 msc
2 -2.5 -29 -34.6 0 0 0 8.11e-05 Slab4 boxMesh_1
:----- List of 2ndaries - #SpawnInStep= 2(Rest= 2,Along= 0,Post= 0), #SpawnTotal= 2
: -2.5 -29 -34.6 0.511 gamma
: -2.5 -29 -34.6 0.511 gamma
:----------------------------------------------------------------- EndOf2ndaries Info --------------

Is there a simple solution to stop the positron and deposit locally its energy like SetApplyCuts(true) does for electrons.

My simulation is a coupled photon-electron-positron simulation.

Thank you Vladimir.

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.