Does anybody know what does the Birks constant mean in Geant4?
I’ve found 4 examples:
extended/electromagnetic/TestEm3/… optical material is C9H10;
advanced/amsEcal/… optical material is C8H8;
extended/optical/OpNovice/ … optical material is water;
extended/optical/LXe/… optical matirial is LXe;
Although the optical materials are different in these examples, the Birks constant is the same – 0.126 mm/MeV.
Is this value specified in air equivalent or optical material’s equivalent?
For example, I have found in the literature that the value of the Birks constant for ZnS(Ag) is 1,37 сm air equivalent MeV^(-1). Is this mean that my code will be : ZnS->GetIonisation()->SetBirksConstant(1,37*сm/MeV)?
Or Birks constant will be : 1,37[сm/MeV]*0,00129[g/cm^3 – air density]/3,64[g/cm^3 – ZnS density]=0,00049[cm/MeV]?