G4PEEffectFluoModel.cc

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// $Id$
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4PEEffectFluoModel
//
// Author:        Vladimir Ivanchenko on base of G4PEEffectModel
//
// Creation date: 13.06.2010
//
// Modifications:
//
// Class Description:
// Implementation of the photo-electric effect with deexcitation
//
// -------------------------------------------------------------------
//
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#include "G4PEEffectFluoModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Electron.hh"
#include "G4Gamma.hh"
#include "Randomize.hh"
#include "G4DataVector.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4VAtomDeexcitation.hh"
#include "G4LossTableManager.hh"
#include "G4SauterGavrilaAngularDistribution.hh"

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using namespace std;

G4PEEffectFluoModel::G4PEEffectFluoModel(const G4String& nam)
  : G4VEmModel(nam)
{
  theGamma    = G4Gamma::Gamma();
  theElectron = G4Electron::Electron();
  fminimalEnergy = 1.0*eV;
  SetDeexcitationFlag(true);
  fParticleChange = 0;
  fAtomDeexcitation = 0;

  // default generator
  SetAngularDistribution(new G4SauterGavrilaAngularDistribution());
}

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G4PEEffectFluoModel::~G4PEEffectFluoModel()
{}

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void G4PEEffectFluoModel::Initialise(const G4ParticleDefinition*,
                                     const G4DataVector&)
{
  fAtomDeexcitation = G4LossTableManager::Instance()->AtomDeexcitation();
  if(!fParticleChange) { fParticleChange = GetParticleChangeForGamma(); }
}

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G4double 
G4PEEffectFluoModel::ComputeCrossSectionPerAtom(const G4ParticleDefinition*,
                                                G4double energy,
                                                G4double Z, G4double,
                                                G4double, G4double)
{
  G4double* SandiaCof = G4SandiaTable::GetSandiaCofPerAtom((G4int)Z, energy);

  G4double energy2 = energy*energy;
  G4double energy3 = energy*energy2;
  G4double energy4 = energy2*energy2;

  return SandiaCof[0]/energy  + SandiaCof[1]/energy2 +
    SandiaCof[2]/energy3 + SandiaCof[3]/energy4;
}

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G4double 
G4PEEffectFluoModel::CrossSectionPerVolume(const G4Material* material,
                                           const G4ParticleDefinition*,
                                           G4double energy,
                                           G4double, G4double)
{
  G4double* SandiaCof = 
    material->GetSandiaTable()->GetSandiaCofForMaterial(energy);
                                
  G4double energy2 = energy*energy;
  G4double energy3 = energy*energy2;
  G4double energy4 = energy2*energy2;
          
  return SandiaCof[0]/energy  + SandiaCof[1]/energy2 +
    SandiaCof[2]/energy3 + SandiaCof[3]/energy4; 
}

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void 
G4PEEffectFluoModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect,
                                       const G4MaterialCutsCouple* couple,
                                       const G4DynamicParticle* aDynamicPhoton,
                                       G4double,
                                       G4double)
{
  const G4Material* aMaterial = couple->GetMaterial();

  G4double energy = aDynamicPhoton->GetKineticEnergy();

  // select randomly one element constituing the material.
  const G4Element* anElement = SelectRandomAtom(aMaterial,theGamma,energy);
  
  //
  // Photo electron
  //

  // Select atomic shell
  G4int nShells = anElement->GetNbOfAtomicShells();
  G4int i = 0;  
  for(; i<nShells; ++i) {
    /*
    G4cout << "i= " << i << " E(eV)= " << energy/eV 
           << " Eb(eV)= " << anElement->GetAtomicShell(i)/eV
           << "  " << anElement->GetName() 
           << G4endl;
    */
    if(energy >= anElement->GetAtomicShell(i)) { break; }
  }

  G4double edep = energy;

  // Normally one shell is available 
  if (i < nShells) { 
  
    G4double bindingEnergy  = anElement->GetAtomicShell(i);
    G4double elecKineEnergy = energy - bindingEnergy;

    // create photo electron
    //
    if (elecKineEnergy > fminimalEnergy) {
      edep = bindingEnergy;
      G4ThreeVector elecDirection =
        GetAngularDistribution()->SampleDirection(aDynamicPhoton, 
                                                  elecKineEnergy,
                                                  i, 
                                                  couple->GetMaterial());
   
      G4DynamicParticle* aParticle = 
        new G4DynamicParticle(theElectron, elecDirection, elecKineEnergy);
      fvect->push_back(aParticle);
    } 

    // sample deexcitation
    //
    if(fAtomDeexcitation) {
      G4int index = couple->GetIndex();
      if(fAtomDeexcitation->CheckDeexcitationActiveRegion(index)) {
        G4int Z = G4lrint(anElement->GetZ());
        G4AtomicShellEnumerator as = G4AtomicShellEnumerator(i);
        const G4AtomicShell* shell = fAtomDeexcitation->GetAtomicShell(Z, as);
        size_t nbefore = fvect->size();
        fAtomDeexcitation->GenerateParticles(fvect, shell, Z, index);
        size_t nafter = fvect->size();
        if(nafter > nbefore) {
          for (size_t j=nbefore; j<nafter; ++j) {
            edep -= ((*fvect)[j])->GetKineticEnergy();
          } 
        }
      }
    }
  }

  // kill primary photon
  fParticleChange->SetProposedKineticEnergy(0.);
  fParticleChange->ProposeTrackStatus(fStopAndKill);
  if(edep > 0.0) {
    fParticleChange->ProposeLocalEnergyDeposit(edep);
  }
}

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