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Forum: DNA/Very Low Energy
Re: Question G4DNA Carbon Ions (Nicholas Henthorn)
Re: None Re: G4DNA Carbon Ions (Ziad Francis)
Re: None Re: G4DNA Carbon Ions (Nicholas Henthorn)
Date: 28 Jul, 2017
From: Ziad Francis <Ziad Francis>

Dear Nicholas,

after verifying the cross sections nothing comes out meaning all seems smooth. However, the issue is most probably caused by the switch between normal and relativistic formulas in the G4DNARuddIonisationExtendedModel Class, and specifically in functions RejectionFunction and ProposedSampledEnergy, the value at which we use relativistic formulas is around ~100 MeV/amu and for carbon ions it corresponds to ~ 1200 MeV.

So if you definitely need to eliminate this you'll have to decrease all the energy limits down to let's say zero (in the file G4DNARuddIonisationExtendedModel.cc) and therefore you'll have only relativistic formulas in action, however since we never tried this you will have to validate what you obtain before using it, to make sure the proper energy loss is still there.

Anyway we will be addressing this issue for our next release, but until then you may look for the magic numbers ((tau/MeV)<5.447761194e-2) and ((k/MeV)/(particle->GetPDGMass()/MeV) <= 0.1 ) and change this into ((tau/MeV)<0) and ((k/MeV)/(particle->GetPDGMass()/MeV) <= 0 ), recompile Geant4 and your application and check the rest out.

Hope this helps a bit Ziad

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1 None: Re: G4DNA Carbon Ions   (Nicholas Henthorn - 28 Jul, 2017)
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