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Question Adapting geometry to work w/ optical photon  

Forum: Processes Involving Optical Photons
Date: 06 Nov, 2013
From: Nicolas Maurissen <Nicolas Maurissen>

Dear Geant4 users,

I would like to adapt my current detector (plastic scintillator) geometry to be able to assess the losses from optical photons within the scintillator.

To do so, I intend to shoot bursts of optical photon from different points inside the scintillator, count how many of them reach the PMT, and create an 'optical performance map' of my detector.
   
From what I understand with the examples and the forum, I need to apply different ‘optical properties’ to materials and create surfaces to deal with the ‘optical physics’ (reflexion, refraction, absortion, etc…).

I tried what I could with the help of the LXe and underground_physics examples (I am still under Geant4.9.4 p02), but when the photon is not absorbed, I have line on my terminal telling me

$ Photon at Boundary!
$ thePrePV : Styrene // (name changed for ease)
$ thePostPV : Aluminum front plate // (name changed for ease)
$ Old Momentum Direction : (values)
$ Old Polarization : (values)
$ ***NoRINDEX***

I guess that mean that I didn’t correctly add the ‘optical properties’ to the correct volumes in my geometry.

Concerning my current geometry, as you can see on the attached file, the styrene scintillator is made of one box, covered with aluminum plates (one per face, those being the detector reflectors), themselves covered with a polyethylene layer. I used multiple volumes for the two coatings to be able to make the hole for the PMT. The quartz (glass) part of the PMT is in direct contact with the styrene scintillator.

Before starting over, I need a more basic understanding of what I should do. This is why I’d like to ask experts :

To which material do I need to add ‘optical properties’ ?

Do I have to define surfaces (or skin ?) between volumes ?

Is this the way to make my aluminum plates act as reflectors ?

If I need to define surfaces for my reflectors, is it ok to have two kind of surfaces sharing a same volume (aluminum / scintillator and quartz / scintillator on top of my detector) ? If not, how may I correct it ?

 
Thanks a lot in advance, any help will be really appreciated.

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      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/11/06/07.41-20159-Detector.png

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1 Feedback: Re: Adapting geometry to work w/ optical photon   (Gumplinger Peter - 06 Nov, 2013)
(_ Ok: Re: Adapting geometry to work w/ optical photon   (Nicolas Maurissen - 08 Nov, 2013)
(_ Feedback: Re: Adapting geometry to work w/ optical photon   (Gumplinger Peter - 08 Nov, 2013)
(_ Ok: Re: Adapting geometry to work w/ optical photon   (Nicolas Maurissen - 14 Nov, 2013)
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