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Question Parameter Scan of Sigma_Alpha 

Forum: Processes Involving Optical Photons
Date: 01 Feb, 2011
From: Susanne Jungmann <Susanne Jungmann>

Hi Peter,

I have made a scan for different values of sigma_alpha (ranging from 0.01 to 0.4) and compared the results by looking on the number of detected photons by the MPPC.

I simulated a Cherenkov tile (30x30x4 mm), a positron beam and the four available surface finishings in the UNIFIED model: ground, polished, groundbackpainted and polishedbackpainted.

The reflection parameters were all set to zero except the diffuse lobe constant I set to 1, to emphasize the surface design as an assembly of micro facets. Since sigma_alpha is never set to zero (which would account for a completely flat surface; I assume this is not achieved in reality) I describe in the legend polishedbackpainted as "ground surface with a specular reflector".

Can you explain to me, why I see such large fluctuations (especially for the data points at sigma_alph = 0.05) in case I simulate a wrapping (reflectivity 0.98) and why for sigma_alpha values smaller than 0.1 the ouput of a "ground" surface is larger than if I simulate a "polished" surface (which should produce the highest output as it is perfectly polished and ignores sigma_alpha completely). I would have expected, that the first points of the green and black line overlay, no?!

Comparing the two wrapping configurations: Why is for larger values (>0.15) of sigma_alpha the output almost equal?

Sorry for so many questions, but you'd really help me in understanding the simulation.

It might be important to keep in mind that the simulated Cherenkov photons are directional.

Thanks a lot,

Susanne

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1 Question: Parameter Scan of Specularspike   (Susanne Jungmann - 12 Feb, 2011)
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