[Gate-users] Doubt with surface finish illumination in DETECT2000

[Martin Janecek]

I believe that is correct. The first sentence assumes the surface is in 
optical contact with another component. DETECT2000 and GATE 
differentiate between the actual surface and the material attached to 
it, although they assume the reflection occurs at the same location - 
the surface plane. What the code does is that it first evaluates if the 
surface produced a reflection. If yes, then we have a specular 
reflection (for a polished surface). If no, we refract the photon past 
the surface and let it interact with the material that it is in contact 
with. (I believe both programs assume Lambertian reflection as default.) 
The diffuse reflection that is produced is thereafter refracted back 
into the original material using Snell's law. That is at least my 
understanding of it.

Martin


green light wrote:
> Dear gaters:
>
>         In DETECT2000 user's manual, it is said that "The value of the 
> reflection coefficient is the probability that, if a photon escapes 
> from the surface, it is returned to the original medium by Lambertian 
> reflection." when talking about POLISH surface finish.
>
>         "Lambertian reflection" shows that there are diffuse 
> reflections when phontons get to the POLISH surface . But  is also 
> said ," If reflection is selected, the angle of reflection is set 
> equal to the angle of incidence. This shows specular refletions 
> happen. It seems the two sentences conflict.
>
>
>          I'll appreciate for your help.
>
>     
>
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