#include <G4LowEPComptonModel.hh>

Inheritance diagram for G4LowEPComptonModel:

Public Member Functions
	G4LowEPComptonModel (const G4ParticleDefinition *p=nullptr, const G4String &nam="LowEPComptonModel")

virtual	~G4LowEPComptonModel ()

void	Initialise (const G4ParticleDefinition *, const G4DataVector &) override

void	InitialiseLocal (const G4ParticleDefinition , G4VEmModel masterModel) override

void	InitialiseForElement (const G4ParticleDefinition *, G4int Z) override

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

void	SampleSecondaries (std::vector< G4DynamicParticle * > , const G4MaterialCutsCouple , const G4DynamicParticle *, G4double tmin, G4double maxEnergy) override

G4LowEPComptonModel &	operator= (const G4LowEPComptonModel &right)=delete

	G4LowEPComptonModel (const G4LowEPComptonModel &)=delete

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 void	InitialiseLocal (const G4ParticleDefinition , G4VEmModel masterModel)

virtual void	InitialiseForMaterial (const G4ParticleDefinition , const G4Material )

virtual void	InitialiseForElement (const G4ParticleDefinition *, G4int Z)

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	GetPartialCrossSection (const G4Material , G4int level, const G4ParticleDefinition , G4double kineticEnergy)

virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A=0., G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)

virtual G4double	ComputeCrossSectionPerShell (const G4ParticleDefinition *, G4int Z, G4int shellIdx, G4double kinEnergy, 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 , const G4double &length, G4double &eloss)

virtual G4double	Value (const G4MaterialCutsCouple , const G4ParticleDefinition , G4double kineticEnergy)

virtual G4double	MinPrimaryEnergy (const G4Material , const G4ParticleDefinition , G4double cut=0.0)

virtual G4double	MinEnergyCut (const G4ParticleDefinition , const G4MaterialCutsCouple )

virtual void	SetupForMaterial (const G4ParticleDefinition , const G4Material , G4double kineticEnergy)

virtual void	DefineForRegion (const G4Region *)

virtual void	FillNumberOfSecondaries (G4int &numberOfTriplets, G4int &numberOfRecoil)

virtual void	ModelDescription (std::ostream &outFile) const

void	InitialiseElementSelectors (const G4ParticleDefinition *, const G4DataVector &)

std::vector< G4EmElementSelector * > *	GetElementSelectors ()

void	SetElementSelectors (std::vector< G4EmElementSelector * > *)

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)

const G4Element *	SelectRandomAtom (const G4MaterialCutsCouple , const G4ParticleDefinition , G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)

const G4Element *	SelectTargetAtom (const G4MaterialCutsCouple , const G4ParticleDefinition , G4double kineticEnergy, G4double logKineticEnergy, 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)

const G4Element *	GetCurrentElement (const G4Material *mat=nullptr) const

G4int	SelectRandomAtomNumber (const G4Material *) const

const G4Isotope *	GetCurrentIsotope (const G4Element *elm=nullptr) const

G4int	SelectIsotopeNumber (const G4Element *) const

void	SetParticleChange (G4VParticleChange , G4VEmFluctuationModel f=nullptr)

void	SetCrossSectionTable (G4PhysicsTable *, G4bool isLocal)

G4ElementData *	GetElementData ()

G4PhysicsTable *	GetCrossSectionTable ()

G4VEmFluctuationModel *	GetModelOfFluctuations ()

G4VEmAngularDistribution *	GetAngularDistribution ()

G4VEmModel *	GetTripletModel ()

void	SetTripletModel (G4VEmModel *)

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

G4bool	UseAngularGeneratorFlag () const

void	SetAngularGeneratorFlag (G4bool)

void	SetHighEnergyLimit (G4double)

void	SetLowEnergyLimit (G4double)

void	SetActivationHighEnergyLimit (G4double)

void	SetActivationLowEnergyLimit (G4double)

G4bool	IsActive (G4double kinEnergy) const

void	SetPolarAngleLimit (G4double)

void	SetSecondaryThreshold (G4double)

void	SetLPMFlag (G4bool val)

void	SetDeexcitationFlag (G4bool val)

void	SetForceBuildTable (G4bool val)

void	SetFluctuationFlag (G4bool val)

void	SetMasterThread (G4bool val)

G4bool	IsMaster () const

void	SetUseBaseMaterials (G4bool val)

G4bool	UseBaseMaterials () const

G4double	MaxSecondaryKinEnergy (const G4DynamicParticle *dynParticle)

const G4String &	GetName () const

void	SetCurrentCouple (const G4MaterialCutsCouple *)

G4bool	IsLocked () const

void	SetLocked (G4bool)

G4VEmModel &	operator= (const G4VEmModel &right)=delete

	G4VEmModel (const G4VEmModel &)=delete

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
G4ElementData *	fElementData = nullptr

G4VParticleChange *	pParticleChange = nullptr

G4PhysicsTable *	xSectionTable = nullptr

const G4Material *	pBaseMaterial = nullptr

const std::vector< G4double > *	theDensityFactor = nullptr

const std::vector< G4int > *	theDensityIdx = nullptr

G4double	inveplus

G4double	pFactor = 1.0

size_t	currentCoupleIndex = 0

size_t	basedCoupleIndex = 0

G4bool	lossFlucFlag = true

Detailed Description

Definition at line 81 of file G4LowEPComptonModel.hh.

Constructor & Destructor Documentation

◆ G4LowEPComptonModel() [1/2]

G4LowEPComptonModel::G4LowEPComptonModel	(	const G4ParticleDefinition *	p = `nullptr`,
		const G4String &	nam = `"LowEPComptonModel"`
	)

explicit

Definition at line 97 of file G4LowEPComptonModel.cc.

  : G4VEmModel(nam),isInitialised(false)
{
  verboseLevel=1 ;
  // 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>1 ) {
    G4cout << "Low energy photon Compton model is constructed " << G4endl;
  }
 
  //Mark this model as "applicable" for atomic deexcitation
  SetDeexcitationFlag(true);
 
  fParticleChange = nullptr;
  fAtomDeexcitation = nullptr;
}

◆ ~G4LowEPComptonModel()

G4LowEPComptonModel::~G4LowEPComptonModel ( )

virtual

Definition at line 122 of file G4LowEPComptonModel.cc.

{
  if(IsMaster()) {
    delete shellData;
    shellData = nullptr;
    delete profileData;
    profileData = nullptr;
  }
}

◆ G4LowEPComptonModel() [2/2]

G4LowEPComptonModel::G4LowEPComptonModel ( const G4LowEPComptonModel & )

delete

Member Function Documentation

◆ ComputeCrossSectionPerAtom()

G4double G4LowEPComptonModel::ComputeCrossSectionPerAtom	(	const G4ParticleDefinition *	,
		G4double	kinEnergy,
		G4double	Z,
		G4double	A = `0`,
		G4double	cut = `0`,
		G4double	emax = `DBL_MAX`
	)

overridevirtual

Reimplemented from G4VEmModel.

Definition at line 258 of file G4LowEPComptonModel.cc.

{
  if (verboseLevel > 3) {
    G4cout << "G4LowEPComptonModel::ComputeCrossSectionPerAtom()"
           << G4endl;
  }
  G4double cs = 0.0;
 
  if (GammaEnergy < LowEnergyLimit()) { return 0.0; }
 
  G4int intZ = G4lrint(Z);
  if(intZ < 1 || intZ > maxZ) { return cs; }
 
  G4PhysicsFreeVector* pv = data[intZ];
 
  // if element was not initialised
  // do initialisation safely for MT mode
  if(!pv)
    {
      InitialiseForElement(0, intZ);
      pv = data[intZ];
      if(!pv) { return cs; }
    }
 
  G4int n = G4int(pv->GetVectorLength() - 1);
  G4double e1 = pv->Energy(0);
  G4double e2 = pv->Energy(n);
 
  if(GammaEnergy <= e1)      { cs = GammaEnergy/(e1*e1)*pv->Value(e1); }
  else if(GammaEnergy <= e2) { cs = pv->Value(GammaEnergy)/GammaEnergy; }
  else if(GammaEnergy > e2)  { cs = pv->Value(e2)/GammaEnergy; }
 
  return cs;
}

◆ Initialise()

void G4LowEPComptonModel::Initialise	(	const G4ParticleDefinition *	particle,
		const G4DataVector &	cuts
	)

overridevirtual

Implements G4VEmModel.

Definition at line 134 of file G4LowEPComptonModel.cc.

{
  if (verboseLevel > 1) {
    G4cout << "Calling G4LowEPComptonModel::Initialise()" << G4endl;
  }
 
  // Initialise element selector
  if(IsMaster()) {
 
    // Access to elements
    const char* path = G4FindDataDir("G4LEDATA");
 
    G4ProductionCutsTable* theCoupleTable =
      G4ProductionCutsTable::GetProductionCutsTable();
    G4int numOfCouples = (G4int)theCoupleTable->GetTableSize();
 
    for(G4int i=0; i<numOfCouples; ++i) {
      const G4Material* material =
        theCoupleTable->GetMaterialCutsCouple(i)->GetMaterial();
      const G4ElementVector* theElementVector = material->GetElementVector();
      std::size_t nelm = material->GetNumberOfElements();
 
      for (std::size_t j=0; j<nelm; ++j) {
        G4int Z = G4lrint((*theElementVector)[j]->GetZ());
        if(Z < 1)        { Z = 1; }
        else if(Z > maxZ){ Z = maxZ; }
 
        if( (!data[Z]) ) { ReadData(Z, path); }
      }
    }
 
    // For Doppler broadening
    if(!shellData) {
      shellData = new G4ShellData();
      shellData->SetOccupancyData();
      G4String file = "/doppler/shell-doppler";
      shellData->LoadData(file);
    }
    if(!profileData) { profileData = new G4DopplerProfile(); }
 
    InitialiseElementSelectors(particle, cuts);
  }
 
  if (verboseLevel > 2) {
    G4cout << "Loaded cross section files" << G4endl;
  }
 
  if( verboseLevel>1 ) {
    G4cout << "G4LowEPComptonModel is initialized " << G4endl
           << "Energy range: "
           << LowEnergyLimit() / eV << " eV - "
           << HighEnergyLimit() / GeV << " GeV"
           << G4endl;
  }
 
  if(isInitialised) { return; }
  
  fParticleChange = GetParticleChangeForGamma();
  fAtomDeexcitation  = G4LossTableManager::Instance()->AtomDeexcitation();
  isInitialised = true;
}

◆ InitialiseForElement()

void G4LowEPComptonModel::InitialiseForElement	(	const G4ParticleDefinition *	,
		G4int	Z
	)

overridevirtual

Reimplemented from G4VEmModel.

Definition at line 670 of file G4LowEPComptonModel.cc.

{
  G4AutoLock l(&LowEPComptonModelMutex);
  if(!data[Z]) { ReadData(Z); }
  l.unlock();
}

Referenced by ComputeCrossSectionPerAtom().

◆ InitialiseLocal()

void G4LowEPComptonModel::InitialiseLocal	(	const G4ParticleDefinition *	,
		G4VEmModel *	masterModel
	)

overridevirtual

Reimplemented from G4VEmModel.

Definition at line 199 of file G4LowEPComptonModel.cc.

{
  SetElementSelectors(masterModel->GetElementSelectors());
}

◆ operator=()

G4LowEPComptonModel & G4LowEPComptonModel::operator= ( const G4LowEPComptonModel & right )

delete

◆ SampleSecondaries()

void G4LowEPComptonModel::SampleSecondaries	(	std::vector< G4DynamicParticle * > *	fvect,
		const G4MaterialCutsCouple *	couple,
		const G4DynamicParticle *	aDynamicGamma,
		G4double	tmin,
		G4double	maxEnergy
	)

overridevirtual

Implements G4VEmModel.

Definition at line 298 of file G4LowEPComptonModel.cc.

{
 
  // The scattered gamma energy is sampled according to Klein - Nishina formula.
  // then accepted or rejected depending on the Scattering Function multiplied
  // by factor from Klein - Nishina formula.
  // Expression of the angular distribution as Klein Nishina
  // angular and energy distribution and Scattering fuctions is taken from
  // D. E. Cullen "A simple model of photon transport" Nucl. Instr. Meth.
  // Phys. Res. B 101 (1995). Method of sampling with form factors is different
  // data are interpolated while in the article they are fitted.
  // Reference to the article is from J. Stepanek New Photon, Positron
  // and Electron Interaction Data for GEANT in Energy Range from 1 eV to 10
  // TeV (draft).
  // The random number techniques of Butcher & Messel are used
  // (Nucl Phys 20(1960),15).
 
  G4double photonEnergy0 = aDynamicGamma->GetKineticEnergy()/MeV;
 
  if (verboseLevel > 3) {
    G4cout << "G4LowEPComptonModel::SampleSecondaries() E(MeV)= "
           << photonEnergy0/MeV << " in " << couple->GetMaterial()->GetName()
           << G4endl;
  }
  // do nothing below the threshold
  // should never get here because the XS is zero below the limit
  if (photonEnergy0 < LowEnergyLimit())
    return ;
 
  G4double e0m = photonEnergy0 / electron_mass_c2 ;
  G4ParticleMomentum photonDirection0 = aDynamicGamma->GetMomentumDirection();
 
  // Select randomly one element in the current material
  const G4ParticleDefinition* particle =  aDynamicGamma->GetDefinition();
  const G4Element* elm = SelectRandomAtom(couple,particle,photonEnergy0);
  G4int Z = (G4int)elm->GetZ();
 
  G4double LowEPCepsilon0 = 1. / (1. + 2. * e0m);
  G4double LowEPCepsilon0Sq = LowEPCepsilon0 * LowEPCepsilon0;
  G4double alpha1 = -std::log(LowEPCepsilon0);
  G4double alpha2 = 0.5 * (1. - LowEPCepsilon0Sq);
 
  G4double wlPhoton = h_Planck*c_light/photonEnergy0;
 
  // Sample the energy of the scattered photon
  G4double LowEPCepsilon;
  G4double LowEPCepsilonSq;
  G4double oneCosT;
  G4double sinT2;
  G4double gReject;
 
  if (verboseLevel > 3) {
    G4cout << "Started loop to sample gamma energy" << G4endl;
  }
 
  do
    {
      if ( alpha1/(alpha1+alpha2) > G4UniformRand())
        {
          LowEPCepsilon = G4Exp(-alpha1 * G4UniformRand());
          LowEPCepsilonSq = LowEPCepsilon * LowEPCepsilon;
        }
      else
        {
          LowEPCepsilonSq = LowEPCepsilon0Sq + (1. - LowEPCepsilon0Sq) * G4UniformRand();
          LowEPCepsilon = std::sqrt(LowEPCepsilonSq);
        }
 
      oneCosT = (1. - LowEPCepsilon) / ( LowEPCepsilon * e0m);
      sinT2 = oneCosT * (2. - oneCosT);
      G4double x = std::sqrt(oneCosT/2.) / (wlPhoton/cm);
      G4double scatteringFunction = ComputeScatteringFunction(x, Z);
      gReject = (1. - LowEPCepsilon * sinT2 / (1. + LowEPCepsilonSq)) * scatteringFunction;
 
    } while(gReject < G4UniformRand()*Z);
 
  G4double cosTheta = 1. - oneCosT;
  G4double sinTheta = std::sqrt(sinT2);
  G4double phi = twopi * G4UniformRand();
  G4double dirx = sinTheta * std::cos(phi);
  G4double diry = sinTheta * std::sin(phi);
  G4double dirz = cosTheta ;
 
  // Scatter photon energy and Compton electron direction - Method based on:
  // J. M. C. Brown, M. R. Dimmock, J. E. Gillam and D. M. Paganin'
  // "A low energy bound atomic electron Compton scattering model for Geant4"
  // NIMB, Vol. 338, 77-88, 2014.
 
  // Set constants and initialize scattering parameters
  const G4double vel_c = c_light / (m/s);
  const G4double momentum_au_to_nat = halfpi* hbar_Planck / Bohr_radius / (kg*m/s);
  const G4double e_mass_kg =  electron_mass_c2 / c_squared / kg ;
 
  const G4int maxDopplerIterations = 1000;
  G4double bindingE = 0.;
  G4double pEIncident = photonEnergy0 ;
  G4double pERecoil =  -1.;
  G4double eERecoil = -1.;
  G4double e_alpha =0.;
  G4double e_beta = 0.;
 
  G4double CE_emission_flag = 0.;
  G4double ePAU = -1;
  G4int shellIdx = 0;
  G4double u_temp = 0;
  G4double cosPhiE =0;
  G4double sinThetaE =0;
  G4double cosThetaE =0;
  G4int iteration = 0;
 
  if (verboseLevel > 3) {
    G4cout << "Started loop to sample photon energy and electron direction" << G4endl;
  }
 
  do{
      // ******************************************
      // |     Determine scatter photon energy    |
      // ******************************************   
    do
      {
    iteration++;
    // ********************************************
    // |     Sample bound electron information    |
    // ********************************************
    
    // Select shell based on shell occupancy    
    shellIdx = shellData->SelectRandomShell(Z);
    bindingE = shellData->BindingEnergy(Z,shellIdx)/MeV;
    
    // Randomly sample bound electron momentum (memento: the data set is in Atomic Units)
    ePAU = profileData->RandomSelectMomentum(Z,shellIdx);
    
    // Convert to SI units     
    G4double ePSI = ePAU * momentum_au_to_nat;
 
    //Calculate bound electron velocity and normalise to natural units
    u_temp = sqrt( ((ePSI*ePSI)*(vel_c*vel_c)) / ((e_mass_kg*e_mass_kg)*(vel_c*vel_c)+(ePSI*ePSI)) )/vel_c;
    
    // Sample incident electron direction, amorphous material, to scattering photon scattering plane 
    e_alpha = pi*G4UniformRand();
    e_beta = twopi*G4UniformRand();
 
    // Total energy of system  
    
    G4double eEIncident = electron_mass_c2 / sqrt( 1 - (u_temp*u_temp));
    G4double systemE = eEIncident + pEIncident;
    G4double gamma_temp = 1.0 / sqrt( 1 - (u_temp*u_temp));
    G4double numerator = gamma_temp*electron_mass_c2*(1 - u_temp * std::cos(e_alpha));
    G4double subdenom1 =  u_temp*cosTheta*std::cos(e_alpha);
    G4double subdenom2 = u_temp*sinTheta*std::sin(e_alpha)*std::cos(e_beta);
    G4double denominator = (1.0 - cosTheta) +  (gamma_temp*electron_mass_c2*(1 - subdenom1 - subdenom2) / pEIncident);
    pERecoil = (numerator/denominator);
    eERecoil = systemE - pERecoil;
    CE_emission_flag = pEIncident - pERecoil;
      } while ( (iteration <= maxDopplerIterations) && (CE_emission_flag < bindingE));
    
    // End of recalculation of photon energy with Doppler broadening
    
    // *******************************************************
    // |     Determine ejected Compton electron direction    |
    // *******************************************************      
    
    // Calculate velocity of ejected Compton electron   
    
    G4double a_temp = eERecoil / electron_mass_c2;
    G4double u_p_temp = sqrt(1 - (1 / (a_temp*a_temp)));
    
    // Coefficients and terms from simulatenous equations     
    G4double sinAlpha = std::sin(e_alpha);
    G4double cosAlpha = std::cos(e_alpha);
    G4double sinBeta = std::sin(e_beta);
    G4double cosBeta = std::cos(e_beta);
    
    G4double gamma = 1.0 / sqrt(1 - (u_temp*u_temp));
    G4double gamma_p = 1.0 / sqrt(1 - (u_p_temp*u_p_temp));
    
    G4double var_A = pERecoil*u_p_temp*sinTheta;
    G4double var_B = u_p_temp* (pERecoil*cosTheta-pEIncident);
    G4double var_C = (pERecoil-pEIncident) - ( (pERecoil*pEIncident) / (gamma_p*electron_mass_c2))*(1 - cosTheta);
    
    G4double var_D1 = gamma*electron_mass_c2*pERecoil;
    G4double var_D2 = (1 - (u_temp*cosTheta*cosAlpha) - (u_temp*sinTheta*cosBeta*sinAlpha));
    G4double var_D3 = ((electron_mass_c2*electron_mass_c2)*(gamma*gamma_p - 1)) - (gamma_p*electron_mass_c2*pERecoil);
    G4double var_D = var_D1*var_D2 + var_D3;
    
    G4double var_E1 = ((gamma*gamma_p)*(electron_mass_c2*electron_mass_c2)*(u_temp*u_p_temp)*cosAlpha);
    G4double var_E2 = gamma_p*electron_mass_c2*pERecoil*u_p_temp*cosTheta;
    G4double var_E = var_E1 - var_E2;
    
    G4double var_F1 = ((gamma*gamma_p)*(electron_mass_c2*electron_mass_c2)*(u_temp*u_p_temp)*cosBeta*sinAlpha);
    G4double var_F2 = (gamma_p*electron_mass_c2*pERecoil*u_p_temp*sinTheta);
    G4double var_F = var_F1 - var_F2;
    
    G4double var_G = (gamma*gamma_p)*(electron_mass_c2*electron_mass_c2)*(u_temp*u_p_temp)*sinBeta*sinAlpha;
    
    // Two equations form a quadratic form of Wx^2 + Yx + Z = 0
    // Coefficents and solution to quadratic
    G4double var_W1 = (var_F*var_B - var_E*var_A)*(var_F*var_B - var_E*var_A);
    G4double var_W2 = (var_G*var_G)*(var_A*var_A) + (var_G*var_G)*(var_B*var_B);
    G4double var_W = var_W1 + var_W2;
    
    G4double var_Y = 2.0*(((var_A*var_D-var_F*var_C)*(var_F*var_B-var_E*var_A)) - ((var_G*var_G)*var_B*var_C));
    
    G4double var_Z1 = (var_A*var_D - var_F*var_C)*(var_A*var_D - var_F*var_C);
    G4double var_Z2 = (var_G*var_G)*(var_C*var_C) - (var_G*var_G)*(var_A*var_A);
    G4double var_Z = var_Z1 + var_Z2;
    G4double diff1 = var_Y*var_Y;
    G4double diff2 = 4*var_W*var_Z;
    G4double diff = diff1 - diff2;
 
    // Check if diff is less than zero, if so ensure it is due to FPE
    //Determine number of digits (in decimal base) that G4double can accurately represent
    G4double g4d_order = G4double(numeric_limits<G4double>::digits10);
    G4double g4d_limit = std::pow(10.,-g4d_order);
    //Confirm that diff less than zero is due FPE, i.e if abs of diff / diff1 and diff/ diff2 is less 
    //than 10^(-g4d_order), then set diff to zero
    
    if ((diff < 0.0) && (abs(diff / diff1) < g4d_limit) && (abs(diff / diff2) < g4d_limit) )
      {
    diff = 0.0;
      }
    
    
    // Plus and minus of quadratic
    G4double X_p = (-var_Y + sqrt (diff))/(2*var_W);
    G4double X_m = (-var_Y - sqrt (diff))/(2*var_W);
    
    // Floating point precision protection
    // Check if X_p and X_m are greater than or less than 1 or -1, if so clean up FPE 
    // Issue due to propagation of FPE and only impacts 8th sig fig onwards    
    if(X_p >1){X_p=1;} if(X_p<-1){X_p=-1;}
    if(X_m >1){X_m=1;} if(X_m<-1){X_m=-1;}
    // End of FP protection
 
    G4double ThetaE = 0.;   
    // Randomly sample one of the two possible solutions and determin theta angle of ejected Compton electron
    G4double sol_select = G4UniformRand();
    
    if (sol_select < 0.5)
      {
    ThetaE = std::acos(X_p);
      }
    if (sol_select > 0.5)
      {
    ThetaE = std::acos(X_m);
      }
    cosThetaE = std::cos(ThetaE);
    sinThetaE = std::sin(ThetaE);
    G4double Theta = std::acos(cosTheta);
    
    //Calculate electron Phi
    G4double iSinThetaE = std::sqrt(1+std::tan((pi/2.0)-ThetaE)*std::tan((pi/2.0)-ThetaE));
    G4double iSinTheta = std::sqrt(1+std::tan((pi/2.0)-Theta)*std::tan((pi/2.0)-Theta));
    G4double ivar_A = iSinTheta/ (pERecoil*u_p_temp);
    // Trigs
    cosPhiE = (var_C - var_B*cosThetaE)*(ivar_A*iSinThetaE);
    
    // End of calculation of ejection Compton electron direction    
    //Fix for floating point errors
    
  } while ( (iteration <= maxDopplerIterations) && (abs(cosPhiE) > 1));
  
  // Revert to original if maximum number of iterations threshold has been reached     
  if (iteration >= maxDopplerIterations)
    {
      pERecoil = photonEnergy0 ;
      bindingE = 0.;
      dirx=0.0;
      diry=0.0;
      dirz=1.0;
    }
 
  // Set "scattered" photon direction and energy
  G4ThreeVector photonDirection1(dirx,diry,dirz);
  photonDirection1.rotateUz(photonDirection0);
  fParticleChange->ProposeMomentumDirection(photonDirection1) ;
 
  if (pERecoil > 0.)
    {
     fParticleChange->SetProposedKineticEnergy(pERecoil) ;
 
     // Set ejected Compton electron direction and energy
     G4double PhiE = std::acos(cosPhiE);
     G4double eDirX = sinThetaE * std::cos(phi+PhiE);
     G4double eDirY = sinThetaE * std::sin(phi+PhiE);
     G4double eDirZ = cosThetaE;
 
     G4double eKineticEnergy = pEIncident - pERecoil - bindingE;
 
     G4ThreeVector eDirection(eDirX,eDirY,eDirZ);
     eDirection.rotateUz(photonDirection0);
     G4DynamicParticle* dp = new G4DynamicParticle (G4Electron::Electron(),
                                                   eDirection,eKineticEnergy) ;
     fvect->push_back(dp);
 
    }
  else
    {
      fParticleChange->SetProposedKineticEnergy(0.);
      fParticleChange->ProposeTrackStatus(fStopAndKill);
    }
 
  // sample deexcitation
  //
  if (verboseLevel > 3) {
    G4cout << "Started atomic de-excitation " << fAtomDeexcitation << G4endl;
  }
 
  if(fAtomDeexcitation && iteration < maxDopplerIterations) {
    G4int index = couple->GetIndex();
    if(fAtomDeexcitation->CheckDeexcitationActiveRegion(index)) {
      std::size_t nbefore = fvect->size();
      G4AtomicShellEnumerator as = G4AtomicShellEnumerator(shellIdx);
      const G4AtomicShell* shell = fAtomDeexcitation->GetAtomicShell(Z, as);
      fAtomDeexcitation->GenerateParticles(fvect, shell, Z, index);
      std::size_t nafter = fvect->size();
      if(nafter > nbefore) {
        for (std::size_t i=nbefore; i<nafter; ++i) {
          //Check if there is enough residual energy 
          if (bindingE >= ((*fvect)[i])->GetKineticEnergy())
           {
             //Ok, this is a valid secondary: keep it
             bindingE -= ((*fvect)[i])->GetKineticEnergy();
           }
          else
           {
             //Invalid secondary: not enough energy to create it!
             //Keep its energy in the local deposit
             delete (*fvect)[i];
             (*fvect)[i]=nullptr;
           }
        }
      }
    }
  }
 
  //This should never happen
  if(bindingE < 0.0)
     G4Exception("G4LowEPComptonModel::SampleSecondaries()",
                 "em2051",FatalException,"Negative local energy deposit");
 
  fParticleChange->ProposeLocalEnergyDeposit(bindingE);
}

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

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ G4LowEPComptonModel() [1/2]

◆ ~G4LowEPComptonModel()

◆ G4LowEPComptonModel() [2/2]

Member Function Documentation

◆ ComputeCrossSectionPerAtom()

◆ Initialise()

◆ InitialiseForElement()

◆ InitialiseLocal()

◆ operator=()

◆ SampleSecondaries()