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Forum: Processes Involving Optical Photons
Re: Question Question about the photocathode simulation and how to Detect the photon? (Xiaodong Zhang)
Re: More Re: Question about the photocathode simulation and how to Detect the photon? (Xiaodong Zhang)
Date: 02 Apr, 2012
From: Gumplinger Peter <Gumplinger Peter>

Dear Xiaodong,

The code you posted looks correct to me. Of course, I don't know the numerical values you provided for the things like, realRefractiveIndex_Bialkali, imaginaryRefractiveIndex_Bialkali, quantumEfficiency_Bialkali, but I presume these are also reasonable and correct. If you followed the LXe example correctly you should get 'Detection'. The reason you didn't see it in the code of G4OpBoundaryProcess.cc is because that logic is actually inlined and resides in the file G4OpBoundaryProcess.hh [G4OpBoundaryProcess::DoAbsorption()]

HOWEVER, seeing that you find the program returns:

> When I call the G4OpBoundaryProcess::GetStatus, I got return value of

> 12, means "TotalInternalReflection", instead of "Detection".

makes me very suspicious whether you haven't also run into an (apparent) bug that I also just recently discovered. Which version of G4 are you using?

I have just reported a bug:

http://bugzilla-geant4.kek.jp/show_bug.cgi?id=1300

G4OpBoundaryProcess cannot work correctly if the geometry/navigator makes a mistake in providing it with the correct surface normal. Now, I don't know how this error, on its own, can cause your program to claim 'TotalInternalReflection' for a surface that is dielectric_metal (which should be impossible - total internal reflection is only possible between two dielectric media).

If you have access to the G4 source, I suggest you print out the local/global coordinates and the local/global normal (as suggested in my bug report) and see if those actually make sense to you for the orientation of the PMT cathode in question.

Peter

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1 None: Re: Question about the photocathode simulation and how to Detect the photon?   (Xiaodong Zhang - 02 Apr, 2012)
1 None: Re: Question about the photocathode simulation and how to Detect the photon?   (Xiaodong Zhang - 03 Apr, 2012)
1 Feedback: Re: Question about the photocathode simulation and how to Detect the photon?   (Gumplinger Peter - 03 Apr, 2012)
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2 Feedback: Re: Question about the photocathode simulation and how to Detect the photon?   (Gumplinger Peter - 03 Apr, 2012)
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