G4MicroElecElasticModel.cc

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// G4MicroElecElasticModel.cc, 2011/08/29 A.Valentin, M. Raine
//
// Based on the following publications
//          - Geant4 physics processes for microdosimetry simulation:
//          very low energy electromagnetic models for electrons in Si,
//          NIM B, vol. 288, pp. 66 - 73, 2012.
//
//
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#include "G4MicroElecElasticModel.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"

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using namespace std;

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G4MicroElecElasticModel::G4MicroElecElasticModel(const G4ParticleDefinition*,
                                             const G4String& nam)
:G4VEmModel(nam),isInitialised(false)
{
  nistSi = G4NistManager::Instance()->FindOrBuildMaterial("G4_Si");

  killBelowEnergy = 16.7 * eV; // Minimum e- energy for energy loss by excitation
  lowEnergyLimit = 0 * eV; 
  lowEnergyLimitOfModel = 5 * eV; // The model lower energy is 5 eV
  highEnergyLimit = 100. * MeV;
  SetLowEnergyLimit(lowEnergyLimit);
  SetHighEnergyLimit(highEnergyLimit);

  verboseLevel= 0;
  // Verbosity scale:
  // 0 = nothing 
  // 1 = warning for energy non-conservation 
  // 2 = details of energy budget
  // 3 = calculation of cross sections, file openings, sampling of atoms
  // 4 = entering in methods
  
  if( verboseLevel>0 ) 
  { 
    G4cout << "MicroElec Elastic model is constructed " << G4endl
           << "Energy range: "
           << lowEnergyLimit / eV << " eV - "
           << highEnergyLimit / keV << " keV"
           << G4endl;
  }
  fParticleChangeForGamma = 0;
}

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G4MicroElecElasticModel::~G4MicroElecElasticModel()
{  
  // For total cross section
  
  std::map< G4String,G4MicroElecCrossSectionDataSet*,std::less<G4String> >::iterator pos;
  for (pos = tableData.begin(); pos != tableData.end(); ++pos)
  {
    G4MicroElecCrossSectionDataSet* table = pos->second;
    delete table;
  }

   // For final state
   
   eVecm.clear();

}

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void G4MicroElecElasticModel::Initialise(const G4ParticleDefinition* /*particle*/,
                                       const G4DataVector& /*cuts*/)
{

  if (verboseLevel > 3)
    G4cout << "Calling G4MicroElecElasticModel::Initialise()" << G4endl;

  // Energy limits
  
  if (LowEnergyLimit() < lowEnergyLimit)
  {
    G4cout << "G4MicroElecElasticModel: low energy limit increased from " << 
        LowEnergyLimit()/eV << " eV to " << lowEnergyLimit/eV << " eV" << G4endl;
    SetLowEnergyLimit(lowEnergyLimit);
    }

  if (HighEnergyLimit() > highEnergyLimit)
  {
    G4cout << "G4MicroElecElasticModel: high energy limit decreased from " << 
        HighEnergyLimit()/MeV << " MeV to " << highEnergyLimit/MeV << " MeV" << G4endl;
    SetHighEnergyLimit(highEnergyLimit);
  }

  // Reading of data files 
  
  G4double scaleFactor = 1e-18 * cm * cm;

  G4String fileElectron("microelec/sigma_elastic_e_Si");

  G4ParticleDefinition* electronDef = G4Electron::ElectronDefinition();
  G4String electron;

    // For total cross section
    
    electron = electronDef->GetParticleName();

    tableFile[electron] = fileElectron;

    G4MicroElecCrossSectionDataSet* tableE = new G4MicroElecCrossSectionDataSet(new G4LogLogInterpolation, eV,scaleFactor );
    tableE->LoadData(fileElectron);
    tableData[electron] = tableE;
    
    // For final state
    
    char *path = getenv("G4LEDATA");
 
    if (!path)
    {
      G4Exception("G4MicroElecElasticModel::Initialise","em0006",FatalException,"G4LEDATA environment variable not set.");
      return;
    }

    std::ostringstream eFullFileName;
    eFullFileName << path << "/microelec/sigmadiff_elastic_e_Si.dat";
    std::ifstream eDiffCrossSection(eFullFileName.str().c_str());
     
    if (!eDiffCrossSection) 
        G4Exception("G4MicroElecElasticModel::Initialise","em0003",FatalException,"Missing data file: /microelec/sigmadiff_elastic_e_Si.dat");
      
    eTdummyVec.push_back(0.);

    while(!eDiffCrossSection.eof())
    {
        double tDummy;
        double eDummy;
        eDiffCrossSection>>tDummy>>eDummy;

        // SI : mandatory eVecm initialization
        if (tDummy != eTdummyVec.back()) 
        { 
          eTdummyVec.push_back(tDummy); 
          eVecm[tDummy].push_back(0.);
        }
          
        eDiffCrossSection>>eDiffCrossSectionData[tDummy][eDummy];

        // SI : only if not end of file reached !
        if (!eDiffCrossSection.eof()) eDiffCrossSectionData[tDummy][eDummy]*=scaleFactor;
          
        if (eDummy != eVecm[tDummy].back()) eVecm[tDummy].push_back(eDummy);
          
    }

    // End final state
  
  if (verboseLevel > 2) 
    G4cout << "Loaded cross section files for MicroElec Elastic model" << G4endl;

  if( verboseLevel>0 ) 
  { 
    G4cout << "MicroElec Elastic model is initialized " << G4endl
           << "Energy range: "
           << LowEnergyLimit() / eV << " eV - "
           << HighEnergyLimit() / keV << " keV"
           << G4endl;
  }

  if (isInitialised) { return; }
  fParticleChangeForGamma = GetParticleChangeForGamma();
  isInitialised = true;

  // InitialiseElementSelectors(particle,cuts);
}

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G4double G4MicroElecElasticModel::CrossSectionPerVolume(const G4Material* material,
                                           const G4ParticleDefinition* p,
                                           G4double ekin,
                                           G4double,
                                           G4double)
{
  if (verboseLevel > 3)
    G4cout << "Calling CrossSectionPerVolume() of G4MicroElecElasticModel" << G4endl;

 // Calculate total cross section for model

 G4double sigma=0;
 
 G4double density = material->GetTotNbOfAtomsPerVolume();

 if (material == nistSi || material->GetBaseMaterial() == nistSi)
 {
  const G4String& particleName = p->GetParticleName();

  if (ekin < highEnergyLimit)
  {
      //SI : XS must not be zero otherwise sampling of secondaries method ignored
      if (ekin < lowEnergyLimitOfModel) ekin = lowEnergyLimitOfModel;
      //      
      
        std::map< G4String,G4MicroElecCrossSectionDataSet*,std::less<G4String> >::iterator pos;
        pos = tableData.find(particleName);
        
        if (pos != tableData.end())
        {
          G4MicroElecCrossSectionDataSet* table = pos->second;
          if (table != 0)
          {
            sigma = table->FindValue(ekin);
          }
        }
        else
        {
            G4Exception("G4MicroElecElasticModel::ComputeCrossSectionPerVolume","em0002",FatalException,"Model not applicable to particle type.");
        }
  }

  if (verboseLevel > 3)
  {
    G4cout << "---> Kinetic energy(eV)=" << ekin/eV << G4endl;
    G4cout << " - Cross section per Si atom (cm^2)=" << sigma/cm/cm << G4endl;
    G4cout << " - Cross section per Si atom (cm^-1)=" << sigma*density/(1./cm) << G4endl;
  } 

 } 
         
 return sigma*density;             
}

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void G4MicroElecElasticModel::SampleSecondaries(std::vector<G4DynamicParticle*>* /*fvect*/,
                                              const G4MaterialCutsCouple* /*couple*/,
                                              const G4DynamicParticle* aDynamicElectron,
                                              G4double,
                                              G4double)
{

  if (verboseLevel > 3)
    G4cout << "Calling SampleSecondaries() of G4MicroElecElasticModel" << G4endl;

  G4double electronEnergy0 = aDynamicElectron->GetKineticEnergy();
  
  if (electronEnergy0 < killBelowEnergy)
  {
    fParticleChangeForGamma->ProposeTrackStatus(fStopAndKill);
    fParticleChangeForGamma->ProposeLocalEnergyDeposit(electronEnergy0);
    return ;
  }

  if (electronEnergy0>= killBelowEnergy && electronEnergy0 < highEnergyLimit)
  {  
    G4double cosTheta = RandomizeCosTheta(electronEnergy0);
  
    G4double phi = 2. * pi * G4UniformRand();

    G4ThreeVector zVers = aDynamicElectron->GetMomentumDirection();
    G4ThreeVector xVers = zVers.orthogonal();
    G4ThreeVector yVers = zVers.cross(xVers);

    G4double xDir = std::sqrt(1. - cosTheta*cosTheta);
    G4double yDir = xDir;
    xDir *= std::cos(phi);
    yDir *= std::sin(phi);

    G4ThreeVector zPrimeVers((xDir*xVers + yDir*yVers + cosTheta*zVers));

    fParticleChangeForGamma->ProposeMomentumDirection(zPrimeVers.unit()) ;

    fParticleChangeForGamma->SetProposedKineticEnergy(electronEnergy0);
  }

}

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G4double G4MicroElecElasticModel::Theta
  (G4ParticleDefinition * particleDefinition, G4double k, G4double integrDiff)                                                    
{

  G4double theta = 0.;
  G4double valueT1 = 0;
  G4double valueT2 = 0;
  G4double valueE21 = 0;
  G4double valueE22 = 0;
  G4double valueE12 = 0;
  G4double valueE11 = 0;
  G4double xs11 = 0;   
  G4double xs12 = 0; 
  G4double xs21 = 0; 
  G4double xs22 = 0; 


  if (particleDefinition == G4Electron::ElectronDefinition()) 
  {
    std::vector<double>::iterator t2 = std::upper_bound(eTdummyVec.begin(),eTdummyVec.end(), k);
    std::vector<double>::iterator t1 = t2-1;
 
    std::vector<double>::iterator e12 = std::upper_bound(eVecm[(*t1)].begin(),eVecm[(*t1)].end(), integrDiff);
    std::vector<double>::iterator e11 = e12-1;
          
    std::vector<double>::iterator e22 = std::upper_bound(eVecm[(*t2)].begin(),eVecm[(*t2)].end(), integrDiff);
    std::vector<double>::iterator e21 = e22-1;
                
    valueT1  =*t1;
    valueT2  =*t2;
    valueE21 =*e21;
    valueE22 =*e22;
    valueE12 =*e12;
    valueE11 =*e11;

    xs11 = eDiffCrossSectionData[valueT1][valueE11];
    xs12 = eDiffCrossSectionData[valueT1][valueE12];
    xs21 = eDiffCrossSectionData[valueT2][valueE21];
    xs22 = eDiffCrossSectionData[valueT2][valueE22];

}
  
  if (xs11==0 || xs12==0 ||xs21==0 ||xs22==0) return (0.);
     
  theta = QuadInterpolator(  valueE11, valueE12, 
                             valueE21, valueE22, 
                             xs11, xs12, 
                             xs21, xs22, 
                             valueT1, valueT2, 
                             k, integrDiff );

  return theta;
}

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G4double G4MicroElecElasticModel::LinLogInterpolate(G4double e1, 
                                                        G4double e2, 
                                                        G4double e, 
                                                        G4double xs1, 
                                                        G4double xs2)
{
  G4double d1 = std::log(xs1);
  G4double d2 = std::log(xs2);
  G4double value = std::exp(d1 + (d2 - d1)*(e - e1)/ (e2 - e1));
  return value;
}

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G4double G4MicroElecElasticModel::LogLogInterpolate(G4double e1, 
                                                        G4double e2, 
                                                        G4double e, 
                                                        G4double xs1, 
                                                        G4double xs2)
{
  G4double a = (std::log10(xs2)-std::log10(xs1)) / (std::log10(e2)-std::log10(e1));
  G4double b = std::log10(xs2) - a*std::log10(e2);
  G4double sigma = a*std::log10(e) + b;
  G4double value = (std::pow(10.,sigma));
  return value;
}

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G4double G4MicroElecElasticModel::QuadInterpolator(G4double e11, G4double e12, 
                                                       G4double e21, G4double e22, 
                                                       G4double xs11, G4double xs12, 
                                                       G4double xs21, G4double xs22, 
                                                       G4double t1, G4double t2, 
                                                       G4double t, G4double e)
{
// Lin-Log
  G4double interpolatedvalue1 = LinLogInterpolate(e11, e12, e, xs11, xs12);
  G4double interpolatedvalue2 = LinLogInterpolate(e21, e22, e, xs21, xs22);
  G4double value = LinLogInterpolate(t1, t2, t, interpolatedvalue1, interpolatedvalue2);
  return value;
}

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G4double G4MicroElecElasticModel::RandomizeCosTheta(G4double k) 
{
  G4double integrdiff=0;
 G4double uniformRand=G4UniformRand();
 integrdiff = uniformRand;
 
 G4double theta=0.;
 G4double cosTheta=0.;
 theta = Theta(G4Electron::ElectronDefinition(),k/eV,integrdiff);

 cosTheta= std::cos(theta*pi/180);

 return cosTheta; 
}