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Keywords: optical photon boolean subtraction
Forum: Processes Involving Optical Photons
Re: None Re: Optical problem with geometry subtraction (Whitney Armstrong)
Date: 23 Mar, 2007
From: Gumplinger Peter <Gumplinger Peter>

Hi Whitney,

Sorry, I am just coming to this discussion. I was away on vacation when this problem in the geometry forum was brought to my attention.

I can't explain all the different symptoms.

(1) addressing the photon stops with the intersection box:

As the optical photon G4 physics developer I can only say that G4OpBoundaryProcess stops a photon when the G4Navigator says it is hitting a volume boundary. You can best test what is going on by adding G4couts in:

geant4/source/processes/optical/src/G4OpBoundaryProcess.cc

G4OpBoundaryProcess::PostStepDoIt method.

For one, the DoIt returns and does nothing when:

pPostStepPoint->GetStepStatus() != fGeomBoundary

So clearly, the G4Navigator claims we are on a boundary when the photons hit the box. G4OpBoundary stops them because a needed optical property is not specified.

(2) addressing the problem of not seeing the mirror

This is either because the G4Navigator doesn't see the boundary; i.e. the simulation step doesn't end at the mirror, or because the G4OpBoundaryProcess finds that the boundary is dielectric_dielectric with the same index of refraction on both sides.

How did you specify the mirror surface? I understand you used a logical skin surface - and I agree with that. How did you define the G4OpticalSurface?

I would like to help more but I can't spend the time debugging this problem myself right now. We'll understand more if we analyse the logic followed in G4OpBoundaryProcess::PostStepDoIt for each of these symptoms.

Best regards, Peter

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1 More: Re: Optical problem with geometry subtraction   (Peter Gumplinger - 23 Mar, 2007)
1 More: Re: Optical problem with geometry subtraction   (Peter Gumplinger - 26 Mar, 2007)
3 None: Re: Optical problem with geometry subtraction   (alexandre Creusot - 21 Aug, 2008)
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