Geant4 Version: Geant4-11.3
Operating System: Win10
Compiler/Version:
CMake Version:
When I use electron gun to bombard the target of TEFLON,I can see the characteristic X-ray of Fluorine(~677eV)，but I can not see the characteristic X-ray of Carbon(~282eV).
On the contrary，when I switch the source to gamma ,I can get it.
PhysicsList:PenelopePhysics.
G4double defaultGammaCut = 0.001 * keV; // 1 eV
G4double defaultElectronCut = 0.01 * keV; // 10 eV
Who can help me to explain it?
Dear @Chang_Huifeng,
Welcome to the Geant4 forum!
Thanks for your question. I’m not an expert in atomic physics, but at low atomic number (Z), it looks like Auger emission is dominant over fluorescence. You can see this in Fig. 2.9 of [1], or in the original paper [2].
In Table 4 of [2], they quote an Auger yield is 99.7% for carbon and 98.7% for fluorine. Maybe it’s worth trying with more statistics(unless there’s some cutoff in Geant4 that stops fluorescence from being produced in case of carbon)
Since the cross-section depends on the energy of the electron gun, it’s important to choose the right energy. For electron-induced fluorescence, the energy should be above the shell binding energy, maybe 2 or 3 times higher? For photon-induced fluorescence, the cross-section increases sharply just above the shell binding energy. What energies are you using in each case?
I’ll leave it to other experts if they want to add more to this discussion.
Best,
Alvaro
[1] Soft x-ray spectromicroscopy of environmental and biological samples
[2] https://srd.nist.gov/jpcrdreprint/1.555594.pdf
Thank you for the reply !
The paper you sent is helpful.
The energy that I used for the target is 10KeV, it strange that electron gun can not,but gamma gun can.I’ll try smaller Energy of electron gun.
