|Message: Re: Optical photons stopping at boundary of scintillator||Not Logged In (login)|
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thanks for your answer. My next questions i will post in the Optical Physics Forum, thats for sure :)
Regarding to my simulation:
I have now added n=1 to my Air (do'h!) and use G4LogicalBorderSurface: It works! My photos can leave the scintillator.
So my next step is to simulate the wrapping around our scintillator for total internal refection.
I tried this using your advice "new G4LogicalSkinSurface("TiO2Surface",scintillator_log,TiO2Surface);"
The problem: When I do place a sensitive detector on a side of my scintillator, my HitCount is zero, because no photons can leave my scintillator. Thats a little bit too much internal reflection...
My next ansatz would be to place boxes of reflecting material on the 5 sides of my scintillator which should be reflecting. But I'm sure there is in geant4 a more dapper way than this...
Thanks for any advise!
On Thu, 18 Nov 2010 21:07:42 GMT, Gumplinger Peter wrote:
> Dear Mario, > > Your luck, I also monitor this Forum, but you are more guarantied to get > a response to this kind of question on the 'Optical Physics Forum'. > > I see that you define two types of surfaces: > > OpScintSurface->SetType(dielectric_dielectric); > G4LogicalBorderSurface* ScintSurface > new G4LogicalBorderSurface("OpScintSurface", > scintillator_phys,experimentalHall_phys,OpScintSurface); > > new G4LogicalSkinSurface("TiO2Surface",scintillator_log,OpScintSurface); > > Now, I think, this is partly because you wanted to toggle between a > dielectric_dielectric surface and a dielectric_metal one. So, the > second, should read: > > new G4LogicalSkinSurface("TiO2Surface",scintillator_log,TiO2Surface); > > BUT, one of the two definitions needs to be commented out. You cannot > have two definitions for essentially the same real surface. You have to > decide between one or the other. With both assigned, the logic in > G4OpBoundaryProcess gives precedent to the G4LogicalBorderSurface. Now, > a dielectric_dielectric, has to have a material on the outside that has > an index of refraction - your "Air". You have failed to assign n=1 to > the "Air". This is the reason that your photons just stop. Snell's Law > cannot be evaluated. > > If you'd used the G4LogicalSkinSurface, instead, with the above change, > everything should also work, though you'd get only absorption/reflection > (no refraction) even if the "Air" has no refractive index because, in > that case, none is required for the tracking. > > Hope this helps, Peter >
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