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Keywords: optical photon boolean subtraction
Forum: Geometry
Re: None Optical problem with geometry subtraction (Whitney Armstrong)
Re: None Re: Optical problem with geometry subtraction (Vladimir Grichine)
Re: None Re: Optical problem with geometry subtraction (Whitney Armstrong)
Re: Feedback Re: Optical problem with geometry subtraction (Gumplinger Peter)
Date: 23 Mar, 2007
From: Gumplinger Peter <Gumplinger Peter>

OK, I used your tar-file to debug a bit more

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

This, I now understand - at least why the photons stop. They stop because, yes, the G4Navigator finds the boundary of your mirror_log. G4OpBoundaryProcess wants an index of refraction for the medium being left behind. You have:

new G4LogicalVolume(farMirrorGlassElliptical, Glass,"sphere subtracted",0,0,0);

but your Glass doesn't have a MaterialPropertiesTable with an index of refraction.

If I fix this, then I get the first photon bounce around forever. My guess is that it now sees the LogicalSkinSurface all the time somewhere. To continue, you have to set the Reflectivity to some small value so the bounces end and we can visualize the ray.

We don't get the 'no index' problem on the first bounce because G4 thinks to be in the World when it bounces of the mirror which has an index (vacuum). Also, the initial trajectory misses the box - from the outside - but finds the mirror. So all is as expected but then, after reflection, it hits the box from the inside, because it is in toroid phys.

That's as far as I can take it for the moment......

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1 More: Re: Optical problem with geometry subtraction   (Peter Gumplinger - 26 Mar, 2007)
(_ Feedback: Re: Optical problem with geometry subtraction   (Gumplinger Peter - 04 Aug, 2009)
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