Problem 2277

Created attachment 642 [details]
G4DNA simulation results

Dear Vladimir,

I have one question about your code modification merged to the branches with the comment of "emutils-V10-06-02”.
In the function of "G4VEmProcess::StartTracking()”, you deleted the following line:

currentParticle = track->GetParticleDefinition();

(Please access here in detail:
  https://gitlab.cern.ch/geant4/geant4-dev/-/commit/821a2ed5733c40b399e10698173e09e68275b8a2#a2ae7495e67e8aca30e48e3a56af1c7ed5e9d785_607_605)

Could you please tell us the reason why you did that? 
As you know, for discrete processes relevant to generic ions,
this part plays an important role that it overwrites a G4GenericIon 
with a processing ion (e.g., carbon, lithium, etc.) before stepping.

Unfortunately, your code modification has left a critical issue on G4DNA simulations. 
G4DNARuddIonisationExtendedModel in 10.7.beta does not work for ions. 
It cannot calculate cross-section values for given ions every step due to your code change above. 
As a result, secondary particles are never generated when irradiating water target with heavy ions.

Actually, a Japanese user of G4DNA faced with this issue in his simulations. 
Then, he informed me about it, and I've reproduced the same problem as his on 10.7.beta and 10.6.ref-8.
In detail, please see his report (a pdf file) enclosed.

Your code change may also affect the other discrete processes related to EM Physics for generic ions.

Could you please fix it as soon as possible?

Best regards,
Shogo / KEK-CRC