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Feedback Re: Proposal for Photomultiplyers Detection of Optical Photons. 

Keywords: Photomultiplyer optical photon detection
Forum: Particles
Re: None Proposal for Photomultiplyers Detection of Optical Photons. (Igor Machulin)
Date: 17 Apr, 2003
From: Gumplinger Peter <Gumplinger Peter>

Hi Igor,

Thanks for your proposal and reference. In some respect, what you want to do already exists. You can define a dielectric_metal G4OpticalSurface with an efficiency which is wavelength dependent. The method 'DoAbsorption' in the G4OpBoundaryProcess class sets 'theStatus' to "Detection" with this probablility. You can access 'theStatus' in your G4UserSteppingAction with the public method:

G4OpBoundaryProcessStatus G4OpBoundaryProcess::GetStatus()

Hence, you can not only count how many photons hit the PMT but how many were 'detected'.

In your G4UserDetectorConstruction you do something like this:

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

  G4LogicalBorderSurface* PMTSurface =                                     
          new G4LogicalBorderSurface("PMTSurface", 
                  tank_phys,PMT_phys,OpSurface);

  OpSurface->SetType(dielectric_metal);
  OpSurface->SetFinish(polished);
  OpSurface->SetModel(glisur);

  const G4int num = 2;
  G4double Ephoton[num] = {2.038*eV, 4.144*eV};

  G4double Reflectivity[num] = {0.1, 0.2};
  G4double Efficiency[num]   = {0.8, 1.0};

  G4MaterialPropertiesTable *myST = new G4MaterialPropertiesTable();

  myST->AddProperty("REFLECTIVITY", Ephoton, Reflectivity, num);
  myST->AddProperty("EFFICIENCY",   Ephoton, Efficiency,   num);

  OpSurface->SetMaterialPropertiesTable(myST);

If the photons have no means by which they can change their energy, you could also sample the PMT quantum efficiency by making a minor modification in G4Cerenkov/G4Scintillation and save tracking time that way.

Peter

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1 Ok: Re: Merci bien.   (Igor Machulin - 18 Apr, 2003)
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