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Forum: Processes Involving Optical Photons
Re: None Problem with WLS fiber (Nathan Murtha)
Date: 20 Aug, 2014
From: Michael H. Kelsey <Michael H. Kelsey>

On Wed, 20 Aug 2014 15:03:47 GMT, Nathan Murtha wrote:
> I'm a very new user to Geant4, and I'm trying to make a WLS fiber
> embedded in a scintillating plastic bar. I *think* that I have my
> detector built properly, and I *think* that I've properly set up my
> physics list - but I'm having problems, meaning that I've made a mistake
> that I can't see.
> 
> Optical photons are hitting my WLS fiber, but the fiber is not
> re-emitting any photons. I'm not familiar enough with Geant4 to know
> where to start looking for this problem, so I'm hoping that someone here
> might have an idea! I've attached my physics list (heavily cannibalized
> from an example) and my detector construction files to this post.

Your physics list looks okay, as does your geometry. I'm not sure why you set a reflectivity for the fiber, rather than just treating it as transparent and letting the two RINDEX values determine reflection vs. refraction; but that shouldn't be a problem.

How do you know there is no re-emission? If you have tracking verbosity enabled, then you should see steps where G4OpWLS is the stopping process and a new secondary photon is created. Alternatively, you could run in the debugger and set a breakpoint at G4OpWLS::PostStepDoIt(). You could also turn on verbosity for G4OpWLS, and it should report each time it's invoked.

if you've made the fiber a sensitive detector, what does your SD code look like?

  -- Michael Kelsey

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1 Question: Re: Problem with WLS fiber   (Nathan Murtha - 20 Aug, 2014)
1 Warning: Re: Problem with WLS fiber   (Michael H. Kelsey - 20 Aug, 2014)
(_ Question: Re: Problem with WLS fiber   (Nathan Murtha - 21 Aug, 2014)
(_ Feedback: Re: Problem with WLS fiber   (Michael H. Kelsey - 21 Aug, 2014)
(_ Question: Re: Problem with WLS fiber   (Nathan Murtha - 22 Aug, 2014)
2 Question: Re: Problem with WLS fiber   (Nathan Murtha - 20 Aug, 2014)
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