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Feedback Re: What the parameters mean in material properties tables? 

Keywords: optics photon
Forum: Processes Involving Optical Photons
Date: 08 Sep, 2005
From: Gumplinger Peter <Gumplinger Peter>

  G4double LXe_Energy[LXe_NUMENTRIES]    = { 7.0*eV , 7.07*eV, 7.14*eV };

// they should be optics photon's energy, right?

right!

// another question, how about the emission spectrum is continuous?

  G4double LXe_SCINT[LXe_NUMENTRIES] = { 0.1, 1.0, 0.1 };

In this case, the emission spectrum IS continuous. The emission spectrum has a peak at 7.07eV and drops to 10% on either side within +-0.07eV. A linear interpolation is done between points of this triangular spectrum.

// what's these? Are they the relative light output or others?

Yes, relative light output.

  G4double LXe_RIND[LXe_NUMENTRIES]  = { 1.59 , 1.57, 1.54 };

//refractive index,right?

correct

  G4double LXe_ABSL[LXe_NUMENTRIES]  = { 35.*cm, 35.*cm, 35.*cm}; 

//absorbed length, just equal to attenuation length?

correct

  LXe_mt = new G4MaterialPropertiesTable();
  LXe_mt->AddProperty("FASTCOMPONENT", LXe_Energy, LXe_SCINT, LXe_NUMENTRIES);
  LXe_mt->AddProperty("SLOWCOMPONENT", LXe_Energy, LXe_SCINT, LXe_NUMENTRIES);

//time component array.

  LXe_mt->AddProperty("RINDEX",LXe_Energy, LXe_RIND,  LXe_NUMENTRIES);

//refractive index array

 LXe_mt->AddProperty("ABSLENGTH",LXe_Energy, LXe_ABSL,  LXe_NUMENTRIES);

//absorbed lenght array.

all correct

LXe_mt->AddConstProperty("SCINTILLATIONYIELD",12000./MeV);

//scintillation yield,just mean that produce 12000. photons per 1 MeV.

correct

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

//is it resolution scale? Can somebody tell me its definition.

This (and everything above) is explained (I'd hope - but let me know - if not) sufficiently in the documentation:

http://wwwasd.web.cern.ch/wwwasd/geant4/G4UsersDocuments/UsersGuides/ForApplicationDeveloper/html/TrackingAndPhysics/physicsProcess.html#5.2.5

and an intrinsic resolution, RESOLUTIONSCALE, which generally broadens the statistical distribution of generated photons. A wider intrinsic resolution is due to impurities which are typical for doped crystals like NaI(Tl) and CsI(Tl). On the other hand, the intrinsic resolution can also be narrower when the Fano factor plays a role. The actual number of emitted photons during a step fluctuates around the mean number of photons with a width given by ResolutionScale*sqrt(MeanNumberOfPhotons).

  LXe_mt->AddConstProperty("FASTTIMECONSTANT",20.*ns);          
  LXe_mt->AddConstProperty("SLOWTIMECONSTANT",45.*ns);

//arise time and decay time,right?

No! You can specify two decay constants, one for the fast scintillation component and one for a slow component (rise-time is instant).

  LXe_mt->AddConstProperty("YIELDRATIO",1.0);   

//energy transfer efficiency?

The relative strength of the fast component as a fraction of total scintillation yield is given by the YIELDRATIO

  LXe->SetMaterialPropertiesTable(LXe_mt);

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