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Question photons not reflecting from Aluminium. 

Forum: Physics List
Date: 21 Apr, 2012
From: Ashwath Rao <Ashwath Rao>

Respecteed Experts,

I observe that the optical photons are not crossing the crystal boundary. I had thought that this could be because of the OpBoundaryProcess(), but then commenting it made the photons to scatter throughout my world volume area.

 pmanager->AddDiscreteProcess (new G4OpBoundaryProcess());
 pmanager->AddDiscreteProcess(new G4OpAbsorption());

Now there are two issues, I wish to get cleared with : 1) How to control the optical photons spread (a) for within the crystal and (b) scatter outside the crystal ?

2) There is an Aluminium layer over the NaI(Tl) crystal. (a) When the optical photons cross the crystal's boundary, how to make them, get reflected back into the crystal from the inner surface of the Al housing ? // in Detector Construction

  G4double pp[numentries] = {0.5*eV, 600.5*keV};
  G4double AlmRindices[numentries] = { 1.49, 1.49};
  G4double AlAbsorptionLength[numentries] = { 7.0*m,7.0*m };
  G4double specularlobe[numentries] = {0.0, 0.0};
  G4double specularspike[numentries] = {0.3, 0.3};
  G4double backscatter[numentries] = {.2, .2};
  G4double reflectivity[numentries] = {1., 1.};
  G4double efficiency[numentries] = {0, 0.};

  Alnm->AddProperty("RINDEX", pp, AlmRindices, numentries);
  Alnm->AddProperty("ABSLENGTH", pp,AlAbsorptionLength,numentries);
  Alnm->AddProperty("SPECULARLOBECONSTANT",pp,specularlobe,numentries);  
  Alnm->AddProperty("SPECULARSPIKECONSTANT",pp,specularspike,numentries);
  Alnm->AddProperty("BACKSCATTER",pp,backscatter,numentries);
  Alnm->AddProperty("REFLECTIVITY",pp,reflectivity,numentries); 
  Alnm->AddProperty("EFFICIENCY",pp,efficiency,numentries);

   G4OpticalSurface* NaI_Tl = 
   new G4OpticalSurface("CrystalSurface",glisur,polished,dielectric_metal);

   G4LogicalBorderSurface* CrystalSurface =
   new G4LogicalBorderSurface("CrystalSurface", pTube, pHouse, NaI_Tl);
   //pTube is for crystal and pHouse is for crystal housing.

  G4OpticalSurface* Al = 
  new G4OpticalSurface("HousingSurface",glisur,polished,dielectric_metal);

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

Thanking everyone in advance, Regards, Ashwath.

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