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Forum: Processes Involving Optical Photons
Re: Question general problem for optical photons at surfaces shared by different volumes (Erik Dietz-Laursonn)
Re: Idea Re: general problem for optical photons at surfaces shared by different volumes (Athreya Shankar)
Date: 22 Aug, 2012
From: Gumplinger Peter <Gumplinger Peter>

Dear Erik and Athreya,

The present version (9.5 and 9.6-beta) of G4 (as well as, I suspect, later correction patches to 9.4) are buggy in this respect; e.g. the G4Navigator does not return the correct surface normal in cases where daughter and mother volume share a common surface and the daughter has been placed inside the mother with a rotation.

Athreya pointed out the relevant bug report of this fundamental and severe problem. The user can perhaps circumvent the problem by defining his/her geometry slightly differently but that should really not be a requirement coming from the G4 software. Oliver Merle's proposed correction/modification to G4Navigator works perfectly for me, albeit it has not been sanctioned or adopted by the G4 expert developer. In the meantime, though, I have adopted it in my installed source/geometry/navigation/src/G4Navigator.cc code.

We are close to finding a verified and tested general solution to this problem. So, stay tuned and expect a correction patch soon.

Best regards, Peter

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1 Agree: Re: general problem for optical photons at surfaces shared by different volumes   (Erik Dietz-Laursonn - 23 Aug, 2012)
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