I am simulating the production of X rays by shooting a Tungsten target with electrons with energies in the range 20 - 150 keV. When I activated the fluorescence flag in G4LowEnergyIonisation, my simulation simply continues working but no more particles are produced or changed. And no execution errors too. I activated the flag as follows: LeIoprocess = new G4LowEnergyIonisation(); LeIoprocess->ActivateFluorescence(true); When I activated the fluorescence flag in G4PenelopeIonisation, my simulation continues working but there is no changes in the final x-ray spectra. This is my penelope code: LeIoprocess = new G4PenelopeIonisation(); LeIoprocess->SetCutForLowEnSecPhotons(CutForSecondaries); LeIoprocess->SetCutForLowEnSecElectrons(CutForSecondaries); LeIoprocess->ActivateFluorescence(true); I think there is some problem with the function DeexciteAtom in G4LowEnergyIonisation. This function is used by G4eLowEnergyLoss when the fluorescence flag (called theFluo) is activated: if (theFluo) deexcitationProducts = DeexciteAtom(couple,E,edep); Curiously, I think the function DeexciteAtom should exist in G4PenelopeIonisation too. But there is not such function. Thanks in advance, Daniel
In the present version of Penelope processes (Compton, PhotoElectric, Ionisation) the fluorescence is triggered by default and cannot be switched on/off. The flag theFluo is not used and hence the ActivateFluorescence() method is uneffective for them. This is because the processes are tailored for low-energy-specific applications, where the effect of fluorescence is usually important. Luciano
I agree with the importance of the fluorescence. But if the flag theFluo should not be used, could you please specify where in the code the secondary particles of the fluorescence process are created for the "AlongStep" action in the Penelope Ionisation? And what about the Low Energy Ionisation? I found only for the "PostStep" action, but both Low energy Ionisation and Penelope Ionisation are ContinuousDiscrete processes. Right? Thanks for the support, Daniel
Yes, in G4PenelopeIonisation the fluorescence is generated, through the TransitionManager, in the PostStepDoIt method (lines 346-426). There is NO explicit delta-ray generation in the Continuous (AlongStep) part, since the energy loss is due to soft interactions. The energy losses above 250 eV (or above the cutForPhotons and cutForElectrons values) are treated by the Discrete part of the process. Best regards
Regarding LowEnergy processes, ActivateFluorescence activates fluorescence emission only for continuum processes, managed by G4eLowEnergyLoss. The contribution of this to fluorescence emission is an an effect of higher order, so it can be negligible respect to fluorescence emission from discrete ionization processes, like ionization and phototelectric, for which at the moment it cannot be de-activated.
I understand the penelope situation but the low energy case seems obscure for me. I tested my code using the Low Energy Physics in the present version of Geant4 (7.0) and for my surprise the simulation generated some results with ActivateFluorescence ON. A large increase of computing time was noticed too, when comparing with ActivateFluorescence OFF! The results shows 20% more fluorescence production for the energy of 9.7keV and 70% more for 8.4keV with ActivateFluorescence ON and using a tungsten target. I think these diferences aren't negligible when you are working in this energy range. If necessary I can send my results to you. By the way, my simulations with both Penelope and Low Energy models are showing fluorescence peaks lower in the k lines of tungsten (59.3keV and 67.2keV). I am comparing with a catalogue of spectra. Should I report this as a bug too? Thanks for the support, Daniel
I have already finished more simulations of X-ray production using Penelope and Low Energy models. Now I have used a molybdenum target too. I will present these results in a conference in Brazil. If someone is interested I can send the paper by email? Anyway, is there someone who could help me to improve my results?
