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Forum: Geometry
Re: Question wrapped cerenkov (andreas battaglia)
Date: 17 Oct, 2005
From: Gumplinger Peter <Gumplinger Peter>

Andreas,

Sorry for the delay in response but your posting was just brought to my attention.

It seems to me that you want to define your G4OpticalSurface along the lines of 'Source listing 5.2.9' in the Application Developers Manual:

SetFinish(groundbackpainted) or SetFinish(polishedbackpainted)

depending on whether your wrapping is a diffuse or polished reflector.

'backpainted' means that there is a dielectric layer between your detector and the wrapping (not the case with 'frontpainted').

myST1->AddProperty("RINDEX", Ephoton, RefractiveIndex, num);

This sets the refractive index of the dielectric layer between your detector and the wrapping. Note, with the wrapping (paint) in place, the refractive index of the physiWorld outside is of no significance.

myST1 -> AddProperty("REFLECTIVITY",pp,reflectivity,NUM);

This sets the reflectivity of your back-wrapping; i.e. your wapping may not be a perfect reflector. - The EFFICIENCY is not really required because photons absorbed by the wrapping don't get counted as "detected".

Note,

OpSurface -> SetSigmaAlpha(sigma_alpha);

SMPT -> AddProperty("SPECULARLOBECONSTANT",pp,specularlobe,NUM);

SMPT -> AddProperty("SPECULARSPIKECONSTANT",pp,specularspike,NUM);

SMPT -> AddProperty("BACKSCATTERCONSTANT",pp,backscatter,NUM);

concern the interface between your detector and the thin dielectric layer between it and the wrapping, while:

SMPT -> AddProperty("REFLECTIVITY",pp,reflectivity,NUM);

and 'polishedbackpainted' or 'groundbackpainted' concern the wrapping.

Hope this helps, Peter

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1 Disagree: Re: wrapped cerenkov   (Peter Gumplinger - 31 Jul, 2006)
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