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Question Can the Standard and Low Energy Physics list used together? 

Forum: Physics List
Date: 16 Jul, 2008
From: valentina <valentina>

Hi all!

I'm working with the G4 simulation of an X-ray telescope, based on the X ray telescope example. Since I work with photons from about 0.5 keV to 100 MeV (and higher), I have extended the Physics list used by Gamma particles to the Low Energy.

I have tested the physics by shooting a monochromatic beam of 20 keV photons on a layer of Silicon in order to calculate the absorption efficiency.

My problem is that the GEANT4 resulting efficiency (60%) is almost 2 times the absorption efficiency analytically calculated with the NIST X-ray mass attenuation coefficient (37%, the right efficiency).

If I comment the Low Energy Physics code lines, then the resulting efficiency is right. This happens even if I comment the Standard Physics.

I think that there is something wrong in my code, because GEANT4 seems to use at the same time the Standard and the Low Energy physics and the probability of a photoelectric absorption is doubled.

Here my code (used with flag enableLowEnergyPhysic = true):

if (particleName == "gamma") {
 G4cout << "@@@@@ gamma" << G4endl;
 //gamma
 pmanager->AddDiscreteProcess(new G4PhotoElectricEffect());
 pmanager->AddDiscreteProcess(new G4ComptonScattering());
 pmanager->AddDiscreteProcess(new G4GammaConversion());
 //low energy
 if(gm.enableLowEnergyPhysic == true) {
 pmanager->AddDiscreteProcess(new G4LowEnergyCompton());
 pmanager->AddDiscreteProcess(new G4LowEnergyPolarizedCompton());
 pmanager->AddDiscreteProcess(new G4LowEnergyRayleigh());
 pmanager->AddDiscreteProcess(new G4LowEnergyGammaConversion());
 G4LowEnergyPhotoElectric* lepeprocess = new G4LowEnergyPhotoElectric();
 lepeprocess->ActivateAuger(true);
 pmanager->AddDiscreteProcess(lepeprocess);

}

Thank all for any comment!

Valentina

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1 Idea: Re: Can the Standard and Low Energy Physics list used together?   (Vladimir Ivanchenko - 21 Jul, 2008)
(_ Agree: Re: Can the Standard and Low Energy Physics list used together?   (valentina - 21 Jul, 2008)
(_ Idea: Re: Can the Standard and Low Energy Physics list used together?   (Vladimir Ivanchenko - 21 Jul, 2008)
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