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Forum: Processes Involving Optical Photons
Re: Question Optical Photons not getting reflected from Auminium. (Ashwath Rao)
Date: 25 Apr, 2012
From: Ashwath Rao <Ashwath Rao>

Respected Sir,
   Very sorry for not attaching the new codes.

I had realised the mistake and hence had changed it accordingly.. Sorry for the trouble.

The following codes are from the present work. I am getting photons released and also reflected from the aluminium layer (always a spike reflection). The present issue is that there is not much variation in the optical photon count and also in the sum of energies of optical photons for each gamma event is not varying.

CRYSTAL : NaI(Tl) ||| GAMMA : 662 keV ||| HOUSING/CASING : ALUMINIUM

I am using PhysicsList of N06 with no major changes to it. Just commented the undesired ones.

The detector construction has these codes:

                    // FOR NAI-TL CRYSTAL

  const G4int numentries = 2;
G4double naitlEnergies[numentries] = {2.363*eV, 3.817*eV};
G4double naitlFastcomp[numentries] = {1.0, 0.0001};
G4double naitlSlowcomp[numentries] = {0.9, 0.1};
G4double naitlRindices[numentries] = {1.82, 1.82};
G4double naitlAbsorptionLength[numentries] = {  6.0*cm,6.0*cm };

  G4MaterialPropertiesTable* naitlprop = new G4MaterialPropertiesTable();

  naitlprop->AddProperty("SLOWCOMPONENT", naitlEnergies, naitlSlowcomp, numentries);
  naitlprop->AddProperty("RINDEX",        naitlEnergies, naitlRindices, numentries);
  naitlprop->AddProperty("ABSLENGTH",     naitlEnergies, naitlAbsorptionLength,numentries);

  naitlprop->AddConstProperty("SCINTILLATIONYIELD",38.0/keV); // saint-gobain
  naitlprop->AddConstProperty("RESOLUTIONSCALE",7.0);
  naitlprop->AddConstProperty("SLOWTIMECONSTANT",250.0*ns); // saint-gobain
  NaI_Tl->SetMaterialPropertiesTable(naitlprop);

                             // FOR AIR

 G4double AirRindices[numentries] = { 1.0, 1.0};
  G4double reflectivity[numentries] = {1., 1.};
  G4double efficiency[numentries] = {0, 0.};

  G4MaterialPropertiesTable* AirT = new G4MaterialPropertiesTable(); 

  AirT->AddProperty("RINDEX", naitlEnergies, AirRindices, numentries);
  AirT->AddProperty("REFLECTIVITY", naitlEnergies, reflectivity, numentries);
  AirT->AddProperty("EFFICIENCY", naitlEnergies, efficiency, numentries);

  Air->SetMaterialPropertiesTable(AirT);

               // FOR ALUMINIUM SURFACE AND SURFACE PROPERTY

 G4OpticalSurface* AlOpSurface = new G4OpticalSurface("HousingSurface");
AlOpSurface->SetType(dielectric_metal);
AlOpSurface->SetFinish(polished);
AlOpSurface->SetModel(glisur);
AlOpSurface->SetPolish(1.0);

  G4LogicalBorderSurface* HousingSurface = new G4LogicalBorderSurface("HousingSurface", pTube, pHouse,  AlOpSurface); 

  const G4int numentries = 2;
  G4double pp[numentries] = {1.5*eV, 3.5*keV};

  G4double AlmRindices[numentries] = { 1.49, 1.49};
  G4double reflectivity[numentries] = {1., 1.};
  G4double efficiency[numentries] = {0, 0.};

  G4MaterialPropertiesTable* myST1 = new G4MaterialPropertiesTable(); 

  myST1->AddProperty("RINDEX", pp, AlmRindices, numentries);
  myST1->AddProperty("REFLECTIVITY",pp,reflectivity,numentries); 
  myST1->AddProperty("EFFICIENCY",pp,efficiency,numentries);

AlOpSurface->SetMaterialPropertiesTable(myST1);
                 //////////////////////////////////////////////////

doubts : 1) why always spike reflection for aluminium?

2) why total internal reflection from world ?

3) still unable to obtain the the desired histogram (signature spectrum for NaI(Tl))

4) how to obtain backscattering ?

5) should the energy (dE) of optical photon change when ever it reflects? if so how to obtain it?

thank you Sir.

Regards,

Ashwath.

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1 Feedback: Re: Optical Photons not getting reflected from Auminium.   (Athreya Shankar - 27 Apr, 2012)
(_ Feedback: Re: Optical Photons not getting reflected from Auminium.   (Ashwath Rao - 29 Apr, 2012)
(_ Feedback: Re: Optical Photons not getting reflected from Auminium.   (Athreya Shankar - 04 May, 2012)
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