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Question Re: how to reflect most of the optical photon? 

Forum: Processes Involving Optical Photons
Re: Question how to reflect most of the optical photon?
Re: Feedback Re: how to reflect most of the optical photon? (Gumplinger Peter)
Date: 19 Oct, 2016
From: <lili>

Dear Peter,

Thanks so much for your prompt reply. In fact, I did change the model and type of the surface, but there is still only few of optical photons that reflect off the surface (Indeed, I have tried all of the combinations of the models and types). See attached, most of the photons refract from the surface instead of reflecting back.

    G4OpticalSurface* OpSurface = new G4OpticalSurface("crystal");

    G4LogicalSkinSurface* Surface = new G4LogicalSkinSurface("crystal",logicCrystal,OpSurface);

    OpSurface -> SetType(dielectric_metal);

    OpSurface -> SetFinish(ground);

    OpSurface -> SetModel(glisur);

    G4double airCry_pp[2]                = {1.84*eV, 4.08*eV};

    G4double airCry_reflectivity[2]      = {1.00, 1.00};

    G4double airCry_efficiency[2]        = {0.0, 0.0};

    G4MaterialPropertiesTable *OpSurfaceProperty = new G4MaterialPropertiesTable();

    OpSurfaceProperty -> AddProperty("REFLECTIVITY",airCry_pp,airCry_reflectivity,2);

    OpSurfaceProperty -> AddProperty("EFFICIENCY",airCry_pp,airCry_efficiency,2);

    OpSurface -> SetMaterialPropertiesTable(OpSurfaceProperty);

or

  // surface between scintillator and Air

    G4double WrappedLSO_sigma_alpha = 1 ;

    G4OpticalSurface* wrappedLSO = new G4OpticalSurface("wrappedLSO");

    G4LogicalBorderSurface* wrappedLSO_border =
            new G4LogicalBorderSurface("wrappedLSO",
                                       physWorld,fPhysCryst,wrappedLSO);

    wrappedLSO->SetType(dielectric_metal);

    wrappedLSO->SetFinish(ground);

    wrappedLSO->SetModel(glisur);

    wrappedLSO->SetSigmaAlpha(WrappedLSO_sigma_alpha);

    const G4int airCry_NUM = 2;

    G4double airCry_pp[airCry_NUM]                = {1.84*eV, 4.08*eV};

    G4double airCry_specularlobe[airCry_NUM]      = {1., 1.};

    G4double airCry_specularspike[airCry_NUM]     = {0., 0.};

    G4double airCry_backscatter[airCry_NUM]       = {0., 0.};

    G4double airCry_rindex[airCry_NUM]            = {1., 1.};

    G4double airCry_reflectivity[airCry_NUM]      = {1.00, 1.00};

    G4double airCry_efficiency[airCry_NUM]        = {0.0, 0.0};

    G4MaterialPropertiesTable* airCry_Property = new G4MaterialPropertiesTable();

    airCry_Property->AddProperty("RINDEX",airCry_pp,airCry_rindex,airCry_NUM);

    airCry_Property->AddProperty("SPECULARLOBECONSTANT",airCry_pp,airCry_specularlobe,airCry_NUM);

    airCry_Property->AddProperty("SPECULARSPIKECONSTANT",airCry_pp,airCry_specularspike,airCry_NUM);
    airCry_Property->AddProperty("BACKSCATTERCONSTANT",airCry_pp,airCry_backscatter,airCry_NUM);

    airCry_Property->AddProperty("REFLECTIVITY",airCry_pp,airCry_reflectivity,airCry_NUM);

    airCry_Property->AddProperty("EFFICIENCY",airCry_pp,airCry_efficiency,airCry_NUM);

    wrappedLSO->SetMaterialPropertiesTable(airCry_Property);

 I have no idea why this happens? Could you help me out? Thanks for any reply.

 Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2016/10/19/17.48-87792-demo.jpg

Best Lili

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