G4BraggModel vs G4ICRU73QOModel : why different models for mu+ and mu- below 200 keV?

Physics Processes, Models and Cross Sections
1

Hello Geant4 experts,

I see in most of the applications G4BraggModel is used for mu+ but G4ICRU73QO is used for mu- below 200 keV. As I further investigated the model codes I found that the G4ICRU73QOModel.cc has the Barkas corrections and Blochs corrections implemented in it for the dE/dx calculation. Whereas G4BraggModel.cc does not appear to have these corrections implemented. It seems to me G4ICRU73QO is a better model than G4BraggModel. If this is true I am wondering why two separate models are used for positively and negatively charged muons. Can anything go wrong if I choose to use G4ICRU73QOModel for both mu+ and mu- ?

I would appreciate any information you may have to offer in this regard.

Thanks,
Samir Banik

2

Hello,

you may compare G4ICRU73QO model applied for proton with the G4BrggModel and with the data. Note, that PSTAR data from NIST were sertifies and seriously compared with available data. We simply have no manpower to do similar work for G4ICRU73QO. Note also, that at low energy screeneing by atomic shell is different for positivly and negatively charged projectile. Negatively charged muons and hadrons are absorbed by atomic nuclei.

VI