G4LivermoreGammaConversionModel Class Reference

#include <G4LivermoreGammaConversionModel.hh>

Inheritance diagram for G4LivermoreGammaConversionModel:

Public Member Functions
	G4LivermoreGammaConversionModel (const G4ParticleDefinition *p=0, const G4String &nam="LivermoreConversion")
virtual	~G4LivermoreGammaConversionModel ()
virtual void	Initialise (const G4ParticleDefinition *, const G4DataVector &)
virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A=0, G4double cut=0, G4double emax=DBL_MAX)
virtual void	SampleSecondaries (std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin, G4double maxEnergy)
Public Member Functions inherited from G4VEmModel
	G4VEmModel (const G4String &nam)
virtual	~G4VEmModel ()
virtual void	Initialise (const G4ParticleDefinition *, const G4DataVector &)=0
virtual void	SampleSecondaries (std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin=0.0, G4double tmax=DBL_MAX)=0
virtual G4double	ComputeDEDXPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=DBL_MAX)
virtual G4double	CrossSectionPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A=0., G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
virtual G4double	ChargeSquareRatio (const G4Track &)
virtual G4double	GetChargeSquareRatio (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual G4double	GetParticleCharge (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual void	StartTracking (G4Track *)
virtual void	CorrectionsAlongStep (const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double &eloss, G4double &niel, G4double length)
virtual G4double	Value (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy)
virtual G4double	MinPrimaryEnergy (const G4Material *, const G4ParticleDefinition *)
virtual void	SetupForMaterial (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual void	DefineForRegion (const G4Region *)
void	InitialiseElementSelectors (const G4ParticleDefinition *, const G4DataVector &)
G4double	ComputeDEDX (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=DBL_MAX)
G4double	CrossSection (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
G4double	ComputeMeanFreePath (const G4ParticleDefinition *, G4double kineticEnergy, const G4Material *, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, const G4Element *, G4double kinEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
G4int	SelectIsotopeNumber (const G4Element *)
const G4Element *	SelectRandomAtom (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
const G4Element *	SelectRandomAtom (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
void	SetParticleChange (G4VParticleChange *, G4VEmFluctuationModel *f=0)
void	SetCrossSectionTable (G4PhysicsTable *)
G4PhysicsTable *	GetCrossSectionTable ()
G4VEmFluctuationModel *	GetModelOfFluctuations ()
G4VEmAngularDistribution *	GetAngularDistribution ()
void	SetAngularDistribution (G4VEmAngularDistribution *)
G4double	HighEnergyLimit () const
G4double	LowEnergyLimit () const
G4double	HighEnergyActivationLimit () const
G4double	LowEnergyActivationLimit () const
G4double	PolarAngleLimit () const
G4double	SecondaryThreshold () const
G4bool	LPMFlag () const
G4bool	DeexcitationFlag () const
G4bool	ForceBuildTableFlag () const
void	SetHighEnergyLimit (G4double)
void	SetLowEnergyLimit (G4double)
void	SetActivationHighEnergyLimit (G4double)
void	SetActivationLowEnergyLimit (G4double)
G4bool	IsActive (G4double kinEnergy)
void	SetPolarAngleLimit (G4double)
void	SetSecondaryThreshold (G4double)
void	SetLPMFlag (G4bool val)
void	SetDeexcitationFlag (G4bool val)
void	ForceBuildTable (G4bool val)
G4double	MaxSecondaryKinEnergy (const G4DynamicParticle *dynParticle)
const G4String &	GetName () const
void	SetCurrentCouple (const G4MaterialCutsCouple *)
const G4Element *	GetCurrentElement () const

Additional Inherited Members
Protected Member Functions inherited from G4VEmModel
G4ParticleChangeForLoss *	GetParticleChangeForLoss ()
G4ParticleChangeForGamma *	GetParticleChangeForGamma ()
virtual G4double	MaxSecondaryEnergy (const G4ParticleDefinition *, G4double kineticEnergy)
const G4MaterialCutsCouple *	CurrentCouple () const
void	SetCurrentElement (const G4Element *)
Protected Attributes inherited from G4VEmModel
G4VParticleChange *	pParticleChange
G4PhysicsTable *	xSectionTable
const std::vector< G4double > *	theDensityFactor
const std::vector< G4int > *	theDensityIdx

Detailed Description

Definition at line 40 of file G4LivermoreGammaConversionModel.hh.

Constructor & Destructor Documentation

G4LivermoreGammaConversionModel()

G4LivermoreGammaConversionModel::G4LivermoreGammaConversionModel	(	const G4ParticleDefinition *	p = 0,
		const G4String &	nam = "LivermoreConversion"
	)

Definition at line 40 of file G4LivermoreGammaConversionModel.cc.

:G4VEmModel(nam),smallEnergy(2.*MeV),isInitialised(false),maxZ(99)
{
  fParticleChange = 0;
 
  lowEnergyLimit = 2.0*electron_mass_c2;
  data.resize(maxZ+1,0); 
     
  verboseLevel= 0;
  // Verbosity scale for debugging purposes:
  // 0 = nothing 
  // 1 = calculation of cross sections, file openings...
  // 2 = entering in methods
 
  if(verboseLevel > 0) 
  {
    G4cout << "G4LivermoreGammaConversionModel is constructed " << G4endl;
  }
}

~G4LivermoreGammaConversionModel()

G4LivermoreGammaConversionModel::~G4LivermoreGammaConversionModel ( )

virtual

Definition at line 63 of file G4LivermoreGammaConversionModel.cc.

{  
  for(G4int i=0; i<=maxZ; ++i) { delete data[i]; }
}

Member Function Documentation

ComputeCrossSectionPerAtom()

G4double G4LivermoreGammaConversionModel::ComputeCrossSectionPerAtom ( const G4ParticleDefinition *  , G4double  kinEnergy, G4double  Z, G4double  A = 0, G4double  cut = 0, G4double  emax = DBL_MAX  )

virtual

Reimplemented from G4VEmModel.

Definition at line 182 of file G4LivermoreGammaConversionModel.cc.

{
  if (verboseLevel > 1) 
  {
    G4cout << "Calling ComputeCrossSectionPerAtom() of G4LivermoreGammaConversionModel" 
       << G4endl;
  }
 
  if (GammaEnergy < lowEnergyLimit) { return 0.0; } 
 
  G4double xs = 0.0;
  
  G4int intZ=G4int(Z);
 
  if(intZ < 1 || intZ > maxZ) { return xs; }
 
  G4LPhysicsFreeVector* pv = data[intZ];
 
  // element was not initialised
  if(!pv) 
  {
    char* path = getenv("G4LEDATA");
    ReadData(intZ, path);
    pv = data[intZ];
    if(!pv) { return xs; }
  }
  // x-section is taken from the table
  xs = pv->Value(GammaEnergy); 
 
  if(verboseLevel > 0)
  {
    G4int n = pv->GetVectorLength() - 1;
    G4cout  <<  "****** DEBUG: tcs value for Z=" << Z << " at energy (MeV)=" << GammaEnergy/MeV << G4endl;
    G4cout  <<  "  cs (Geant4 internal unit)=" << xs << G4endl;
    G4cout  <<  "    -> first cs value in EADL data file (iu) =" << (*pv)[0] << G4endl;
    G4cout  <<  "    -> last  cs value in EADL data file (iu) =" << (*pv)[n] << G4endl;
    G4cout  <<  "*********************************************************" << G4endl;
  }
 
  return xs;
 
}

Initialise()

void G4LivermoreGammaConversionModel::Initialise ( const G4ParticleDefinition *  particle, const G4DataVector &  cuts  )

virtual

Implements G4VEmModel.

Definition at line 71 of file G4LivermoreGammaConversionModel.cc.

{
  if (verboseLevel > 1) 
  {
    G4cout << "Calling Initialise() of G4LivermoreGammaConversionModel." << G4endl
       << "Energy range: "
       << LowEnergyLimit() / MeV << " MeV - "
       << HighEnergyLimit() / GeV << " GeV"
       << G4endl;
  }
 
  // Initialise element selector
  
  InitialiseElementSelectors(particle, cuts);
 
  // Access to elements
  
  char* path = getenv("G4LEDATA");
 
  G4ProductionCutsTable* theCoupleTable =
    G4ProductionCutsTable::GetProductionCutsTable();
  G4int numOfCouples = theCoupleTable->GetTableSize();
  
  for(G4int i=0; i<numOfCouples; ++i) 
  {
    const G4Material* material = 
      theCoupleTable->GetMaterialCutsCouple(i)->GetMaterial();
    const G4ElementVector* theElementVector = material->GetElementVector();
    G4int nelm = material->GetNumberOfElements();
    
    for (G4int j=0; j<nelm; ++j) 
    {
        
      G4int Z = (G4int)(*theElementVector)[j]->GetZ();
      if(Z < 1)          { Z = 1; }
      else if(Z > maxZ)  { Z = maxZ; }
      if(!data[Z]) { ReadData(Z, path); }
    }
  }
  //
  
  if(isInitialised) { return; }
  fParticleChange = GetParticleChangeForGamma();
  isInitialised = true;
}

SampleSecondaries()

void G4LivermoreGammaConversionModel::SampleSecondaries ( std::vector< G4DynamicParticle * > *  fvect, const G4MaterialCutsCouple *  couple, const G4DynamicParticle *  aDynamicGamma, G4double  tmin, G4double  maxEnergy  )

virtual

Implements G4VEmModel.

Definition at line 230 of file G4LivermoreGammaConversionModel.cc.

{
 
// The energies of the e+ e- secondaries are sampled using the Bethe - Heitler
// cross sections with Coulomb correction. A modified version of the random
// number techniques of Butcher & Messel is used (Nuc Phys 20(1960),15).
 
// Note 1 : Effects due to the breakdown of the Born approximation at low
// energy are ignored.
// Note 2 : The differential cross section implicitly takes account of
// pair creation in both nuclear and atomic electron fields. However triplet
// prodution is not generated.
 
  if (verboseLevel > 1)
    G4cout << "Calling SampleSecondaries() of G4LivermoreGammaConversionModel" << G4endl;
 
  G4double photonEnergy = aDynamicGamma->GetKineticEnergy();
  G4ParticleMomentum photonDirection = aDynamicGamma->GetMomentumDirection();
 
  G4double epsilon ;
  G4double epsilon0Local = electron_mass_c2 / photonEnergy ;
 
  // Do it fast if photon energy < 2. MeV
  if (photonEnergy < smallEnergy )
  {
    epsilon = epsilon0Local + (0.5 - epsilon0Local) * G4UniformRand();
  }
  else
  {
    // Select randomly one element in the current material
 
    const G4ParticleDefinition* particle =  aDynamicGamma->GetDefinition();
    const G4Element* element = SelectRandomAtom(couple,particle,photonEnergy);
 
    if (element == 0)
      {
    G4cout << "G4LivermoreGammaConversionModel::SampleSecondaries - element = 0" 
           << G4endl;
    return;
      }
    G4IonisParamElm* ionisation = element->GetIonisation();
    if (ionisation == 0)
      {
    G4cout << "G4LivermoreGammaConversionModel::SampleSecondaries - ionisation = 0" 
           << G4endl;
    return;
      }
 
    // Extract Coulomb factor for this Element
    G4double fZ = 8. * (ionisation->GetlogZ3());
    if (photonEnergy > 50. * MeV) fZ += 8. * (element->GetfCoulomb());
 
    // Limits of the screening variable
    G4double screenFactor = 136. * epsilon0Local / (element->GetIonisation()->GetZ3()) ;
    G4double screenMax = std::exp ((42.24 - fZ)/8.368) - 0.952 ;
    G4double screenMin = std::min(4.*screenFactor,screenMax) ;
 
    // Limits of the energy sampling
    G4double epsilon1 = 0.5 - 0.5 * std::sqrt(1. - screenMin / screenMax) ;
    G4double epsilonMin = std::max(epsilon0Local,epsilon1);
    G4double epsilonRange = 0.5 - epsilonMin ;
 
    // Sample the energy rate of the created electron (or positron)
    G4double screen;
    G4double gReject ;
 
    G4double f10 = ScreenFunction1(screenMin) - fZ;
    G4double f20 = ScreenFunction2(screenMin) - fZ;
    G4double normF1 = std::max(f10 * epsilonRange * epsilonRange,0.);
    G4double normF2 = std::max(1.5 * f20,0.);
 
    do 
      {
    if (normF1 / (normF1 + normF2) > G4UniformRand() )
      {
        epsilon = 0.5 - epsilonRange * std::pow(G4UniformRand(), 0.333333) ;
        screen = screenFactor / (epsilon * (1. - epsilon));
        gReject = (ScreenFunction1(screen) - fZ) / f10 ;
      }
    else
      {
        epsilon = epsilonMin + epsilonRange * G4UniformRand();
        screen = screenFactor / (epsilon * (1 - epsilon));
        gReject = (ScreenFunction2(screen) - fZ) / f20 ;
      }
      } while ( gReject < G4UniformRand() );
    
  }   //  End of epsilon sampling
 
  // Fix charges randomly
 
  G4double electronTotEnergy;
  G4double positronTotEnergy;
 
  if (G4UniformRand() > 0.5)
    {
      electronTotEnergy = (1. - epsilon) * photonEnergy;
      positronTotEnergy = epsilon * photonEnergy;
    }
  else
    {
      positronTotEnergy = (1. - epsilon) * photonEnergy;
      electronTotEnergy = epsilon * photonEnergy;
    }
 
  // Scattered electron (positron) angles. ( Z - axis along the parent photon)
  // Universal distribution suggested by L. Urban (Geant3 manual (1993) Phys211),
  // derived from Tsai distribution (Rev. Mod. Phys. 49, 421 (1977)
 
  G4double u;
  const G4double a1 = 0.625;
  G4double a2 = 3. * a1;
  //  G4double d = 27. ;
 
  //  if (9. / (9. + d) > G4UniformRand())
  if (0.25 > G4UniformRand())
    {
      u = - std::log(G4UniformRand() * G4UniformRand()) / a1 ;
    }
  else
    {
      u = - std::log(G4UniformRand() * G4UniformRand()) / a2 ;
    }
 
  G4double thetaEle = u*electron_mass_c2/electronTotEnergy;
  G4double thetaPos = u*electron_mass_c2/positronTotEnergy;
  G4double phi  = twopi * G4UniformRand();
 
  G4double dxEle= std::sin(thetaEle)*std::cos(phi),dyEle= std::sin(thetaEle)*std::sin(phi),dzEle=std::cos(thetaEle);
  G4double dxPos=-std::sin(thetaPos)*std::cos(phi),dyPos=-std::sin(thetaPos)*std::sin(phi),dzPos=std::cos(thetaPos);
  
  
  // Kinematics of the created pair:
  // the electron and positron are assumed to have a symetric angular 
  // distribution with respect to the Z axis along the parent photon
  
  G4double electronKineEnergy = std::max(0.,electronTotEnergy - electron_mass_c2) ;
  
  G4ThreeVector electronDirection (dxEle, dyEle, dzEle);
  electronDirection.rotateUz(photonDirection);
      
  G4DynamicParticle* particle1 = new G4DynamicParticle (G4Electron::Electron(),
                            electronDirection,
                            electronKineEnergy);
 
  // The e+ is always created 
  G4double positronKineEnergy = std::max(0.,positronTotEnergy - electron_mass_c2) ;
 
  G4ThreeVector positronDirection (dxPos, dyPos, dzPos);
  positronDirection.rotateUz(photonDirection);   
  
  // Create G4DynamicParticle object for the particle2 
  G4DynamicParticle* particle2 = new G4DynamicParticle(G4Positron::Positron(),
                               positronDirection, 
                               positronKineEnergy);
  // Fill output vector
  fvect->push_back(particle1);
  fvect->push_back(particle2);
 
  // kill incident photon
  fParticleChange->SetProposedKineticEnergy(0.);
  fParticleChange->ProposeTrackStatus(fStopAndKill);   
 
}

---

The documentation for this class was generated from the following files:

• G4LivermoreGammaConversionModel.hh
• G4LivermoreGammaConversionModel.cc