42/5000 What is the difference between plastic scintillation fiber PSF and wavelengthshift fiber WLS in geant4? Optical properties of materials

Geometry, Fields and Transportation
1

Is the absorption length the attenuation length in the fiber product manual? Does the absorption length of the coating need to be the same as the optical core? Plastic scintillation fiber should not have wavelength shift function, am I correct?

  //--------------------------------------------------

  //  Polystyrene 

  //--------------------------------------------------

  std::vector<G4double> refractiveIndexPS = {1.59, 1.59};

  std::vector<G4double> absPS = {4. * m, 4. * m};

  std::vector<G4double> scintilFast = {

      0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.01, 0.01, 0.02, 0.02,

      0.03, 0.03, 0.04, 0.05, 0.06, 0.07, 0.09, 0.10, 0.13, 0.15,

      0.18, 0.22, 0.26, 0.31, 0.36, 0.43, 0.49, 0.56, 0.64, 0.71,

      0.78, 0.85, 0.91, 0.97, 1.00, 0.99, 0.94, 0.76, 0.46, 0.21,

      0.08, 0.03, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00};

  // Add entries into properties table

  auto mptPolystyrene = new G4MaterialPropertiesTable();

  mptPolystyrene->AddProperty("RINDEX", energySmall, refractiveIndexPS);    

  mptPolystyrene->AddProperty("ABSLENGTH", energySmall, absPS);             

  mptPolystyrene->AddProperty("SCINTILLATIONCOMPONENT1", energy, scintilFast);

  mptPolystyrene->AddConstProperty("SCINTILLATIONYIELD", 8000 / MeV);     

  mptPolystyrene->AddConstProperty("RESOLUTIONSCALE", 1.0);               

  mptPolystyrene->AddConstProperty("SCINTILLATIONTIMECONSTANT1", 2.8 * ns); 

  mptPolystyrene->AddConstProperty("SCINTILLATIONYIELD1", 1.);    

  fPolystyrene->SetMaterialPropertiesTable(mptPolystyrene);

  // Set the Birks Constant for the Polystyrene scintillator

  fPolystyrene->GetIonisation()->SetBirksConstant(0.126 * mm / MeV);

_Geant4 Version:_11.2.1
_Operating System:_ubuntu20.04
_Compiler/Version:_gcc9.4.0
_CMake Version:_camke3.16.3

2

The absorption length tells Geant4 how far an optical photon will travel before being absorbed. In a scintillator, this means the photon is absorbed and is lost (typically absorption length is long for scintillators - they are mostly transparent). For WLS, the absorption length also will determine how far an exciting photon will travel before being absorbed and reemitting a lower energy photon. So the absorption length is wavelength dependant.