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Forum: Processes Involving Optical Photons
Re: None Boundary process and copies of the mother volume (Paola Marini)
Re: Feedback Re: Boundary process and copies of the mother volume (Gumplinger Peter)
Date: 14 Oct, 2010
From: Paola Marini <Paola Marini>

Hello Peter,
     thank you for your reply.
I managed to make it work with the following lines:

     G4OpticalSurface* ScintWrap= new G4OpticalSurface("ScintWrap");
     new G4LogicalBorderSurface("ScintWrap", physiScinti, 
physiWrapTeflon, ScintWrap);
     ScintWrap->SetType(dielectric_metal);
     ScintWrap->SetFinish(polished);
     ScintWrap->SetModel(glisur);

     const G4int NUM=2;
     G4double pp[NUM]={2.0*eV,10.*eV};
     G4double reflectivity[NUM]={1., 1.};
     G4double efficiency[NUM]={0.0, 0.0};
     G4MaterialPropertiesTable *ScintWrapProperty = new 
G4MaterialPropertiesTable();
     ScintWrapProperty->AddProperty("REFLECTIVITY",pp,reflectivity,NUM);
     ScintWrapProperty->AddProperty("EFFICIENCY",pp,efficiency,NUM);
     ScintWrap->SetMaterialPropertiesTable(ScintWrapProperty);


while it doesn't work with:


     // Define Reflective properties of Scint - Shell Boundry--------

     //scintillator - teflon
     // G4OpticalSurface* OpSurface_Scint = new 
4OpticalSurface("OpSurface_Scint");
//     G4LogicalBorderSurface* Surface = new 
G4LogicalBorderSurface("Surface",physiScint,physiWrapTeflon,OpSurface_Scint);

//     OpSurface_Scint->SetType(dielectric_metal);
//     G4double rindex_Scint[NUM_Scint] = {1.35,1.4,1.4};
//     G4double reflectivity_Scint[NUM_Scint] = {1.0, 1.0, 1.0};
//     G4double efficiency_Scint[NUM_Scint] = {0.0, 0.0, 0.0};
//     OpSurface_Scint->SetModel(unified);
//     OpSurface_Scint->SetSigmaAlpha(1.0);

//     G4MaterialPropertiesTable *OpSurfaceProperty_Scint = new 
G4MaterialPropertiesTable();

//     
OpSurfaceProperty_Scint->AddProperty("REFLECTIVITY",pp_Scint,reflectivity_Scint,NUM_Scint);
//     
OpSurfaceProperty_Scint->AddProperty("EFFICIENCY",pp_Scint,efficiency_Scint,NUM_Scint);
//     OpSurface_Scint->SetMaterialPropertiesTable(OpSurfaceProperty_Scint);


Was the choice of the model the problem? And why with the unified model 
it was working just with one copy of my detector but not with all the 
copies?

I have also an other question Peter. With the teflon on the outter side 
of my detector, when i position the copies, I end up with a surface 
between two scintillators. How do I set the Surface properties? The 
physics volume names are the same: always Scinti, but a Scinti belonging 
to an other copy of the mother volume.

Thank you for your help
Paola


On 10/13/2010 08:24 PM, Gumplinger Peter wrote:
> *** Discussion title: Processes Involving Optical Photons
>
> Hello Paola,
>
> What you do seems perfectly correct. I understand you have a trapezoid
> mother volume into which you place two smaller trapezoids, one that'll
> be closer to the axis being the scintillator, and a thinner one that'll
> be the outside backing representing the teflon. Between the two of them
> they completely fill the volume of the mother. You then define a
> dielectric_metal boundary between two positioned volumes - a
> G4LogicalBorderSurface. In the definition of it you use the pointers to
> the positioned scintillator and teflon volumes (into their mother). It
> should now not matter how often you place the mother into the world.
> Every time a optical photons encounters a boundary between scintillator
> and teflon the surface should be recognized as dielectric_metal.
>
> You have another option, you could define your whole mother as teflon
> and only place the scintillator in it. You then define the
> G4LogicalBorderSurface between the mother and the scintillator. That
> should work just the same. A photon leaving the scintillator but not
> seeing the teflon of the mother (because it simulataneously also leaves
> the mother) should not encounter the border surface and refract out in
> most cases.
>
> Hope this helps, Peter
>
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