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Sad Problems with emission energy of optical photons generating from scintillation 

Keywords: energy optical photons scintillation
Forum: Particles
Date: 09 Sep, 2005
From: Maria Lucia <lucia.magliozzi@iss.infn.it>

Hello!

I'm simulating a gamma camera using 
optically-isolated NaI scintillator crystals.

I set the scintillating material properties as below:

  const G4int nEntries = 5;
  G4double PhotonEnergy[nEntries] =  { 2.58*eV, 2.76*eV, 2.99*eV, 3.26*eV, 3.54*eV};

  // NaITl	 
  G4double ScintilFast[nEntries]  =  {0.0100,  0.2400,   0.500,   0.2400,  0.0100};
  G4double ScintilSlow[nEntries]  =  {0.0 ,    0.0 ,     0.0,     0.0,     0.0};
	      
  G4double NaI_RIND[nEntries]     =  { 1.85,    1.85,    1.85,    1.85,    1.85};
  G4double NaI_ABSL[nEntries]     =  {35.*cm,   35.*cm,  35.*cm,  35.*cm,  35.*cm};

  G4MaterialPropertiesTable* NaI_MPT = new G4MaterialPropertiesTable();
  NaI_MPT->AddProperty("RINDEX",       PhotonEnergy, NaI_RIND,    nEntries);
  NaI_MPT->AddProperty("ABSLENGTH",    PhotonEnergy, NaI_ABSL,    nEntries);
  NaI_MPT->AddProperty("FASTCOMPONENT",PhotonEnergy, ScintilFast, nEntries);
  NaI_MPT->AddProperty("SLOWCOMPONENT",PhotonEnergy, ScintilSlow, nEntries);
 
  NaI_MPT->AddConstProperty("SCINTILLATIONYIELD", 38000./MeV);
  NaI_MPT->AddConstProperty("RESOLUTIONSCALE", 1.0);
  NaI_MPT->AddConstProperty("FASTTIMECONSTANT", 250.*ns);
  NaI_MPT->AddConstProperty("SLOWTIMECONSTANT", 620.*ns);
  NaI_MPT->AddConstProperty("YIELDRATIO", 1.);
  
  NaITl->SetMaterialPropertiesTable(NaI_MPT);

In this way the emission energy histogram of opticals 
looks like:

       _________
      |         |
      |         |
      |         |
      |         |
   ___|         |___
  |                 |
__|_________________|______
 2.6 2.8 3.0 3.2 3.4 3.6   eV

instead of something like this:

          ____
         |    |
      ___|    |___
     |            |
  ___|            |___
_|____________________|______
 2.6 2.8  3.0  3.3 3.6   eV


What's wrong?

If I try to increase the number of energy entries,
during run obtain the warning messages:

Warning: G4MaterialPropertyVector::GetProperty  ==> 
attempt to Retrieve Property above range

Warning: G4MaterialPropertyVector::GetProperty  ==> 
attempt to Retrieve Property below range

Can someone tell me what's happening?

Thank you

Maria Lucia Magliozzi

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1 Idea: Re: Problems with emission energy of optical photons generating from scintillation   (Peter Gumplinger - 09 Sep, 2005)
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