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Question Optical Reflectivity 

Keywords: Optical photons reflectivity in pixellated detector
Forum: Processes Involving Optical Photons
Date: 30 Jun, 2006
From: <wmenges@sandia.gov>

Dear All,

I was trying to simulate the response of pixellated NaI to incident 662 keV gamma. With light yield of 38 photons/keV ee, I found that the photon count at the PMT strongly depends on the reflectivity of the surrounding material. As the detector is pixellated 2mmx2mm cross sectional area and length of 2 cm, there are quite significant multiple reflection events from the surrounding wall before the photons reach to the PMT located on one side. The light count I get from 97% reflectivity is like 50% of what is expected (0.97x38 photons/keV x 662keV) at 662 keV energy. When it is 99% reflectivity I get like 77%. If it is 100% then within the statistical limit of what is expected. Does the multiple bouncing result in the loss of counts? I mean increases the chance of photons getting into the surrounding wall and eventually absorbed. I appreciate any comment. Thank you.

Wond

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1 Feedback: Re: Optical Reflectivity   (Peter Gumplinger - 30 Jun, 2006)
1 None: Re: Optical Reflectivity   (wmenges@sandia.gov - 30 Jun, 2006)
3 None: Re: Optical Reflectivity   (Vladimir IVANTCHENKO - 03 Jul, 2006)
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