#include <G4PairProductionRelModel.hh>

Inheritance diagram for G4PairProductionRelModel:

Public Member Functions
	G4PairProductionRelModel (const G4ParticleDefinition *p=0, const G4String &nam="BetheHeitlerLPM")

virtual	~G4PairProductionRelModel ()

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

virtual void	InitialiseLocal (const G4ParticleDefinition , G4VEmModel masterModel)

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)

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

void	SetCurrentElement (G4double)

void	SetLPMconstant (G4double val)

G4double	LPMconstant () const

void	SetLPMflag (G4bool)

G4bool	LPMflag () const

Public Member Functions inherited from G4VEmModel
	G4VEmModel (const G4String &nam)

virtual	~G4VEmModel ()

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	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 , G4double cut=0.0)

virtual G4double	MinEnergyCut (const G4ParticleDefinition , const G4MaterialCutsCouple )

virtual void	DefineForRegion (const G4Region *)

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)

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)

G4int	SelectRandomAtomNumber (const G4Material *)

void	SetParticleChange (G4VParticleChange , G4VEmFluctuationModel f=0)

void	SetCrossSectionTable (G4PhysicsTable *, G4bool isLocal)

G4ElementData *	GetElementData ()

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

G4bool	UseAngularGeneratorFlag () const

void	SetAngularGeneratorFlag (G4bool)

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	SetForceBuildTable (G4bool val)

void	SetMasterThread (G4bool val)

G4bool	IsMaster () const

G4double	MaxSecondaryKinEnergy (const G4DynamicParticle *dynParticle)

const G4String &	GetName () const

void	SetCurrentCouple (const G4MaterialCutsCouple *)

const G4Element *	GetCurrentElement () const

Protected Member Functions
G4double	Phi1 (G4double delta) const

G4double	Phi2 (G4double delta) const

G4double	ScreenFunction1 (G4double ScreenVariable)

G4double	ScreenFunction2 (G4double ScreenVariable)

G4double	DeltaMax () const

G4double	DeltaMin (G4double) const

void	CalcLPMFunctions (G4double k, G4double eplus)

G4double	ComputeXSectionPerAtom (G4double totalEnergy, G4double Z)

G4double	ComputeDXSectionPerAtom (G4double eplusEnergy, G4double totalEnergy, G4double Z)

G4double	ComputeRelDXSectionPerAtom (G4double eplusEnergy, G4double totalEnergy, G4double Z)

G4PairProductionRelModel &	operator= (const G4PairProductionRelModel &right)

	G4PairProductionRelModel (const G4PairProductionRelModel &)

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
G4NistManager *	nist

G4ParticleDefinition *	theGamma

G4ParticleDefinition *	theElectron

G4ParticleDefinition *	thePositron

G4ParticleChangeForGamma *	fParticleChange

G4double	fLPMconstant

G4bool	fLPMflag

G4double	z13

G4double	z23

G4double	lnZ

G4double	Fel

G4double	Finel

G4double	fCoulomb

G4double	currentZ

G4double	lpmEnergy

G4double	xiLPM

G4double	phiLPM

G4double	gLPM

G4bool	use_completescreening

Protected Attributes inherited from G4VEmModel
G4ElementData *	fElementData

G4VParticleChange *	pParticleChange

G4PhysicsTable *	xSectionTable

const std::vector< G4double > *	theDensityFactor

const std::vector< G4int > *	theDensityIdx

size_t	idxTable

Static Protected Attributes
static const G4double	xgi [8]

static const G4double	wgi [8]

static const G4double	Fel_light [5] = {0., 5.31 , 4.79 , 4.74 , 4.71}

static const G4double	Finel_light [5] = {0., 6.144 , 5.621 , 5.805 , 5.924}

static const G4double	facFel = G4Log(184.15)

static const G4double	facFinel = G4Log(1194.)

static const G4double	preS1 = 1./(184.15*184.15)

static const G4double	logTwo = G4Log(2.)

Detailed Description

Definition at line 61 of file G4PairProductionRelModel.hh.

Constructor & Destructor Documentation

G4PairProductionRelModel::G4PairProductionRelModel	(	const G4ParticleDefinition *	p = `0`,
		const G4String &	nam = `"BetheHeitlerLPM"`
	)

Definition at line 90 of file G4PairProductionRelModel.cc.

References currentZ, G4Electron::Electron(), fCoulomb, Fel, Finel, fParticleChange, G4Gamma::Gamma(), gLPM, G4NistManager::Instance(), lnZ, nist, phiLPM, G4Positron::Positron(), theElectron, theGamma, thePositron, xiLPM, z13, and z23.

   : G4VEmModel(nam),
     fLPMconstant(fine_structure_const*electron_mass_c2*electron_mass_c2/(4.*pi*hbarc)*0.5),
     fLPMflag(true),
     lpmEnergy(0.),
     use_completescreening(false)
 {
   fParticleChange = 0;
   theGamma    = G4Gamma::Gamma();
   thePositron = G4Positron::Positron();
   theElectron = G4Electron::Electron();
 
   nist = G4NistManager::Instance();  
 
   currentZ = z13 = z23 = lnZ = Fel = Finel = fCoulomb = phiLPM = gLPM = xiLPM = 0;
 
 }

G4PairProductionRelModel::~G4PairProductionRelModel ( )

virtual

Definition at line 111 of file G4PairProductionRelModel.cc.

112 {}

G4PairProductionRelModel::G4PairProductionRelModel ( const G4PairProductionRelModel & )

protected

Member Function Documentation

void G4PairProductionRelModel::CalcLPMFunctions	(	G4double	k,
		G4double	eplus
	)

protected

Definition at line 234 of file G4PairProductionRelModel.cc.

References facFel, G4Exp(), G4Log(), gLPM, lnZ, logTwo, lpmEnergy, phiLPM, python.hepunit::pi, preS1, G4InuclParticleNames::s0, sqr(), xiLPM, and z23.

Referenced by ComputeRelDXSectionPerAtom(), and SampleSecondaries().

 {
   // *** calculate lpm variable s & sprime ***
   // Klein eqs. (78) & (79)
   G4double sprime = sqrt(0.125*k*lpmEnergy/(eplusEnergy*(k-eplusEnergy)));
 
   G4double s1 = preS1*z23;
   G4double logS1 = 2./3.*lnZ-2.*facFel;
   G4double logTS1 = logTwo+logS1;
 
   xiLPM = 2.;
 
   if (sprime>1) 
     xiLPM = 1.;
   else if (sprime>sqrt(2.)*s1) {
     G4double h  = G4Log(sprime)/logTS1;
     xiLPM = 1+h-0.08*(1-h)*(1-sqr(1-h))/logTS1;
   }
 
   G4double s0 = sprime/sqrt(xiLPM); 
   //   G4cout<<"k="<<k<<" y="<<eplusEnergy/k<<G4endl;
   //   G4cout<<"s0="<<s0<<G4endl;
   
   // *** calculate supression functions phi and G ***
   // Klein eqs. (77)
   G4double s2=s0*s0;
   G4double s3=s0*s2;
   G4double s4=s2*s2;
 
   if (s0<0.1) {
     // high suppression limit
     phiLPM = 6.*s0 - 18.84955592153876*s2 + 39.47841760435743*s3 
       - 57.69873135166053*s4;
     gLPM = 37.69911184307752*s2 - 236.8705056261446*s3 + 807.7822389*s4;
   }
   else if (s0<1.9516) {
     // intermediate suppression
     // using eq.77 approxim. valid s0<2.      
     phiLPM = 1.-G4Exp(-6.*s0*(1.+(3.-pi)*s0)
         +s3/(0.623+0.795*s0+0.658*s2));
     if (s0<0.415827397755) {
       // using eq.77 approxim. valid 0.07<s<2
       G4double psiLPM = 1-G4Exp(-4*s0-8*s2/(1+3.936*s0+4.97*s2-0.05*s3+7.50*s4));
       gLPM = 3*psiLPM-2*phiLPM;
     }
     else {
       // using alternative parametrisiation
       G4double pre = -0.16072300849123999 + s0*3.7550300067531581 + s2*-1.7981383069010097 
     + s3*0.67282686077812381 + s4*-0.1207722909879257;
       gLPM = tanh(pre);
     }
   }
   else {
     // low suppression limit valid s>2.
     phiLPM = 1. - 0.0119048/s4;
     gLPM = 1. - 0.0230655/s4;
   }
 
   // *** make sure suppression is smaller than 1 ***
   // *** caused by Migdal approximation in xi    ***
   if (xiLPM*phiLPM>1. || s0>0.57)  xiLPM=1./phiLPM;
 }

G4double G4PairProductionRelModel::ComputeCrossSectionPerAtom	(	const G4ParticleDefinition *	,
		G4double	kinEnergy,
		G4double	Z,
		G4double	A = `0.`,
		G4double	cut = `0.`,
		G4double	emax = `DBL_MAX`
	)

virtual

Reimplemented from G4VEmModel.

Definition at line 301 of file G4PairProductionRelModel.cc.

References ComputeXSectionPerAtom(), python.hepunit::electron_mass_c2, fCoulomb, Fel, Finel, and SetCurrentElement().

 {
   G4double crossSection = 0.0 ;
   //  if ( Z < 0.9 ) return crossSection;
   if ( gammaEnergy <= 2.0*electron_mass_c2 ) return crossSection;
 
   SetCurrentElement(Z);
   // choose calculator according to parameters and switches
   // in the moment only one calculator:
   crossSection=ComputeXSectionPerAtom(gammaEnergy,Z);
 
   G4double xi = Finel/(Fel - fCoulomb); // inelastic contribution
   crossSection *= xsfactor*Z*(Z+xi);
 
   return crossSection;
 }

G4double G4PairProductionRelModel::ComputeDXSectionPerAtom	(	G4double	eplusEnergy,
		G4double	totalEnergy,
		G4double	Z
	)

protected

Definition at line 177 of file G4PairProductionRelModel.cc.

References DeltaMin(), fCoulomb, Fel, lnZ, Phi1(), Phi2(), and use_completescreening.

Referenced by ComputeXSectionPerAtom().

 {
   // most simple case - complete screening:
 
   //  dsig/dE+ = 4 * alpha * Z**2 * r0**2 / k
   //     * [ (y**2 + (1-y**2) + 2/3*y*(1-y) ) * ( log (183 * Z**-1/3)  + 1/9 * y*(1-y) ]
   // y = E+/k
   G4double yp=eplusEnergy/totalEnergy;
   G4double ym=1.-yp;
 
   G4double cross = 0.;
   if (use_completescreening) 
     cross = (yp*yp + ym*ym + 2./3.*ym*yp)*(Fel - fCoulomb) + 1./9.*yp*ym;
   else {
     G4double delta = 0.25*DeltaMin(totalEnergy)/(yp*ym);
     cross = (yp*yp + ym*ym)*(0.25*Phi1(delta) - lnZ/3. - fCoulomb)
       + 2./3.*ym*yp*(0.25*Phi2(delta) - lnZ/3. - fCoulomb);
   }
   return cross/totalEnergy;
 
 }

G4double G4PairProductionRelModel::ComputeRelDXSectionPerAtom	(	G4double	eplusEnergy,
		G4double	totalEnergy,
		G4double	Z
	)

protected

Definition at line 203 of file G4PairProductionRelModel.cc.

References CalcLPMFunctions(), DeltaMin(), fCoulomb, Fel, gLPM, lnZ, Phi1(), Phi2(), phiLPM, use_completescreening, and xiLPM.

Referenced by ComputeXSectionPerAtom().

 {
   // most simple case - complete screening:
 
   //  dsig/dE+ = 4 * alpha * Z**2 * r0**2 / k
   //     * [ (y**2 + (1-y**2) + 2/3*y*(1-y) ) * ( log (183 * Z**-1/3)  + 1/9 * y*(1-y) ]
   // y = E+/k
   G4double yp=eplusEnergy/totalEnergy;
   G4double ym=1.-yp;
 
   CalcLPMFunctions(totalEnergy,eplusEnergy); // gamma
 
   G4double cross = 0.;
   if (use_completescreening) 
     cross = xiLPM*(2./3.*phiLPM*(yp*yp + ym*ym) + gLPM)*(Fel - fCoulomb);
   else {
     G4double delta = 0.25*DeltaMin(totalEnergy)/(yp*ym);
     cross = (1./3.*gLPM + 2./3.*phiLPM)*(yp*yp + ym*ym)
                              *(0.25*Phi1(delta) - lnZ/3. - fCoulomb) 
            + 2./3.*gLPM*ym*yp*(0.25*Phi2(delta) - lnZ/3. - fCoulomb);
     cross *= xiLPM;
   }
   return cross/totalEnergy;
 
 }

G4double G4PairProductionRelModel::ComputeXSectionPerAtom	(	G4double	totalEnergy,
		G4double	Z
	)

protected

Definition at line 133 of file G4PairProductionRelModel.cc.

References ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), DeltaMax(), DeltaMin(), python.hepunit::electron_mass_c2, fLPMflag, python.hepunit::GeV, G4INCL::Math::max(), G4INCL::Math::min(), n, wgi, and xgi.

Referenced by ComputeCrossSectionPerAtom().

 {
   G4double cross = 0.0;
 
   // number of intervals and integration step 
   G4double vcut = electron_mass_c2/totalEnergy ;
 
   // limits by the screening variable
   G4double dmax = DeltaMax();
   G4double dmin = min(DeltaMin(totalEnergy),dmax);
   G4double vcut1 = 0.5 - 0.5*sqrt(1. - dmin/dmax) ;
   vcut = max(vcut, vcut1);
 
 
   G4double vmax = 0.5;
   G4int n = 1;  // needs optimisation
 
   G4double delta = (vmax - vcut)*totalEnergy/G4double(n);
 
   G4double e0 = vcut*totalEnergy;
   G4double xs; 
 
   // simple integration
   for(G4int l=0; l<n; l++,e0 += delta) {
     for(G4int i=0; i<8; i++) {
 
       G4double eg = (e0 + xgi[i]*delta);
       if (fLPMflag && totalEnergy>100.*GeV) 
     xs = ComputeRelDXSectionPerAtom(eg,totalEnergy,Z);
       else
     xs = ComputeDXSectionPerAtom(eg,totalEnergy,Z);
       cross += wgi[i]*xs;
 
     }
   }
 
   cross *= delta*2.;
 
   return cross;
 }

G4double G4PairProductionRelModel::DeltaMax ( ) const

inlineprotected

Definition at line 277 of file G4PairProductionRelModel.hh.

References fCoulomb, and lnZ.

Referenced by ComputeXSectionPerAtom().

 {
   // k > 50 MeV
   G4double FZ = 8.*(lnZ/3. + fCoulomb);
   return std::exp( (42.24-FZ)/8.368 ) + 0.952;
 }

G4double G4PairProductionRelModel::DeltaMin ( G4double k ) const

inlineprotected

Definition at line 284 of file G4PairProductionRelModel.hh.

References z13.

Referenced by ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), and ComputeXSectionPerAtom().

 {
   return 4.*136./z13*(CLHEP::electron_mass_c2/k);
 }

void G4PairProductionRelModel::Initialise	(	const G4ParticleDefinition *	p,
		const G4DataVector &	cuts
	)

virtual

Implements G4VEmModel.

Definition at line 116 of file G4PairProductionRelModel.cc.

References fParticleChange, G4VEmModel::GetParticleChangeForGamma(), G4VEmModel::InitialiseElementSelectors(), and G4VEmModel::IsMaster().

 {
   if(!fParticleChange) { fParticleChange = GetParticleChangeForGamma(); }
   if(IsMaster()) { InitialiseElementSelectors(p, cuts); }
 }

void G4PairProductionRelModel::InitialiseLocal	(	const G4ParticleDefinition *	,
		G4VEmModel *	masterModel
	)

virtual

Reimplemented from G4VEmModel.

Definition at line 125 of file G4PairProductionRelModel.cc.

References G4VEmModel::GetElementSelectors(), and G4VEmModel::SetElementSelectors().

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

G4double G4PairProductionRelModel::LPMconstant ( ) const

inline

Definition at line 169 of file G4PairProductionRelModel.hh.

References fLPMconstant.

 {
   return fLPMconstant;
 }

G4bool G4PairProductionRelModel::LPMflag ( ) const

inline

Definition at line 185 of file G4PairProductionRelModel.hh.

References fLPMflag.

 {
   return fLPMflag;
 }

G4PairProductionRelModel& G4PairProductionRelModel::operator= ( const G4PairProductionRelModel & right )

protected

G4double G4PairProductionRelModel::Phi1 ( G4double delta ) const

inlineprotected

Definition at line 216 of file G4PairProductionRelModel.hh.

Referenced by ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), and SampleSecondaries().

 {
    G4double screenVal;
 
    if (delta > 1.)
      screenVal = 21.12 - 4.184*std::log(delta+0.952);
    else
      screenVal = 20.868 - delta*(3.242 - 0.625*delta);
 
    return screenVal;
 }

G4double G4PairProductionRelModel::Phi2 ( G4double delta ) const

inlineprotected

Definition at line 230 of file G4PairProductionRelModel.hh.

Referenced by ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), and SampleSecondaries().

 {
    G4double screenVal;
 
    if (delta > 1.)
      screenVal = 21.12 - 4.184*std::log(delta+0.952);
    else
      screenVal = 20.209 - delta*(1.930 + 0.086*delta);
 
    return screenVal;
 }

void G4PairProductionRelModel::SampleSecondaries	(	std::vector< G4DynamicParticle * > *	fvect,
		const G4MaterialCutsCouple *	couple,
		const G4DynamicParticle *	aDynamicGamma,
		G4double	tmin,
		G4double	maxEnergy
	)

virtual

Implements G4VEmModel.

Definition at line 323 of file G4PairProductionRelModel.cc.

References CalcLPMFunctions(), python.hepunit::electron_mass_c2, F10, F20, fLPMflag, fParticleChange, fStopAndKill, G4Exp(), G4Log(), G4UniformRand, G4Element::GetfCoulomb(), G4Element::GetIonisation(), G4DynamicParticle::GetKineticEnergy(), G4IonisParamElm::GetlogZ3(), G4MaterialCutsCouple::GetMaterial(), G4DynamicParticle::GetMomentumDirection(), G4NistManager::GetZ13(), G4IonisParamElm::GetZ3(), python.hepunit::GeV, gLPM, G4INCL::Math::max(), python.hepunit::MeV, G4INCL::Math::min(), nist, Phi1(), Phi2(), phiLPM, G4VParticleChange::ProposeTrackStatus(), CLHEP::Hep3Vector::rotateUz(), ScreenFunction1(), ScreenFunction2(), G4VEmModel::SelectRandomAtom(), G4ParticleChangeForGamma::SetProposedKineticEnergy(), SetupForMaterial(), theElectron, theGamma, thePositron, python.hepunit::twopi, and xiLPM.

 {
   const G4Material* aMaterial = couple->GetMaterial();
 
   G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
   G4ParticleMomentum GammaDirection = aDynamicGamma->GetMomentumDirection();
 
   G4double epsil ;
   G4double epsil0 = electron_mass_c2/GammaEnergy ;
   if(epsil0 > 1.0) { return; }
 
   // do it fast if GammaEnergy < 2. MeV
   SetupForMaterial(theGamma, aMaterial, GammaEnergy);
 
   // select randomly one element constituing the material
   const G4Element* anElement = 
     SelectRandomAtom(aMaterial, theGamma, GammaEnergy);
 
   if (GammaEnergy < Egsmall) {
 
     epsil = epsil0 + (0.5-epsil0)*G4UniformRand();
 
   } else {
     // now comes the case with GammaEnergy >= 2. MeV
 
     // Extract Coulomb factor for this Element
     G4double FZ = 8.*(anElement->GetIonisation()->GetlogZ3());
     if (GammaEnergy > 50.*MeV) { FZ += 8.*(anElement->GetfCoulomb()); }
 
     // limits of the screening variable
     G4double screenfac = 136.*epsil0/(anElement->GetIonisation()->GetZ3());
     G4double screenmax = G4Exp ((42.24 - FZ)/8.368) - 0.952 ;
     G4double screenmin = min(4.*screenfac,screenmax);
 
     // limits of the energy sampling
     G4double epsil1 = 0.5 - 0.5*sqrt(1. - screenmin/screenmax) ;
     G4double epsilmin = max(epsil0,epsil1) , epsilrange = 0.5 - epsilmin;
 
     //
     // sample the energy rate of the created electron (or positron)
     //
     //G4double epsil, screenvar, greject ;
     G4double  screenvar, greject ;
 
     G4double F10 = ScreenFunction1(screenmin) - FZ;
     G4double F20 = ScreenFunction2(screenmin) - FZ;
     G4double NormF1 = max(F10*epsilrange*epsilrange,0.); 
     G4double NormF2 = max(1.5*F20,0.);
 
     do {
       if ( NormF1/(NormF1+NormF2) > G4UniformRand() ) {
     epsil = 0.5 - epsilrange*nist->GetZ13(G4UniformRand());
     screenvar = screenfac/(epsil*(1-epsil));
     if (fLPMflag && GammaEnergy>100.*GeV) {
       CalcLPMFunctions(GammaEnergy,GammaEnergy*epsil);
       greject = xiLPM*((gLPM+2.*phiLPM)*Phi1(screenvar) - 
                gLPM*Phi2(screenvar) - phiLPM*FZ)/F10;
     }
     else {
       greject = (ScreenFunction1(screenvar) - FZ)/F10;
     }
               
       } else { 
     epsil = epsilmin + epsilrange*G4UniformRand();
     screenvar = screenfac/(epsil*(1-epsil));
     if (fLPMflag && GammaEnergy>100.*GeV) {
       CalcLPMFunctions(GammaEnergy,GammaEnergy*epsil);
       greject = xiLPM*((0.5*gLPM+phiLPM)*Phi1(screenvar) + 
                0.5*gLPM*Phi2(screenvar) - 0.5*(gLPM+phiLPM)*FZ)/F20;
     }
     else {
       greject = (ScreenFunction2(screenvar) - FZ)/F20;
     }
       }
 
     } while( greject < G4UniformRand() );
 
   }   //  end of epsil sampling
    
   //
   // fixe charges randomly
   //
 
   G4double ElectTotEnergy, PositTotEnergy;
   if (G4UniformRand() > 0.5) {
 
     ElectTotEnergy = (1.-epsil)*GammaEnergy;
     PositTotEnergy = epsil*GammaEnergy;
      
   } else {
     
     PositTotEnergy = (1.-epsil)*GammaEnergy;
     ElectTotEnergy = epsil*GammaEnergy;
   }
 
   //
   // 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;
   static const G4double a1 = 0.625; 
   static const G4double a2 = 3.*a1;
   static const G4double  d = 27. ;
 
   if (9./(9.+d) >G4UniformRand()) u= - G4Log(G4UniformRand()*G4UniformRand())/a1;
   else                            u= - G4Log(G4UniformRand()*G4UniformRand())/a2;
 
   G4double TetEl = u*electron_mass_c2/ElectTotEnergy;
   G4double TetPo = u*electron_mass_c2/PositTotEnergy;
   G4double Phi  = twopi * G4UniformRand();
   G4double dxEl= sin(TetEl)*cos(Phi),dyEl= sin(TetEl)*sin(Phi),dzEl=cos(TetEl);
   G4double dxPo=-sin(TetPo)*cos(Phi),dyPo=-sin(TetPo)*sin(Phi),dzPo=cos(TetPo);
    
   //
   // kinematic 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 ElectKineEnergy = max(0.,ElectTotEnergy - electron_mass_c2);
 
   G4ThreeVector ElectDirection (dxEl, dyEl, dzEl);
   ElectDirection.rotateUz(GammaDirection);   
 
   // create G4DynamicParticle object for the particle1  
   G4DynamicParticle* aParticle1= new G4DynamicParticle(
              theElectron,ElectDirection,ElectKineEnergy);
   
   // the e+ is always created (even with Ekine=0) for further annihilation.
 
   G4double PositKineEnergy = max(0.,PositTotEnergy - electron_mass_c2);
 
   G4ThreeVector PositDirection (dxPo, dyPo, dzPo);
   PositDirection.rotateUz(GammaDirection);   
 
   // create G4DynamicParticle object for the particle2 
   G4DynamicParticle* aParticle2= new G4DynamicParticle(
                       thePositron,PositDirection,PositKineEnergy);
 
   // Fill output vector
   fvect->push_back(aParticle1);
   fvect->push_back(aParticle2);
 
   // kill incident photon
   fParticleChange->SetProposedKineticEnergy(0.);
   fParticleChange->ProposeTrackStatus(fStopAndKill);   
 }

G4double G4PairProductionRelModel::ScreenFunction1 ( G4double ScreenVariable )

inlineprotected

Definition at line 242 of file G4PairProductionRelModel.hh.

Referenced by SampleSecondaries().

 {
    G4double screenVal;
 
    if (ScreenVariable > 1.)
      screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
    else
      screenVal = 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable);
 
    return screenVal;
 }

G4double G4PairProductionRelModel::ScreenFunction2 ( G4double ScreenVariable )

inlineprotected

Definition at line 259 of file G4PairProductionRelModel.hh.

Referenced by SampleSecondaries().

 {
    G4double screenVal;
 
    if (ScreenVariable > 1.)
      screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
    else
      screenVal = 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable);
 
    return screenVal;
 }

void G4PairProductionRelModel::SetCurrentElement ( G4double Z )

inline

Definition at line 192 of file G4PairProductionRelModel.hh.

References currentZ, facFel, facFinel, fCoulomb, Fel, Fel_light, Finel, Finel_light, G4VEmModel::GetCurrentElement(), G4Element::GetfCoulomb(), G4NistManager::GetLOGZ(), G4NistManager::GetZ13(), iz, lnZ, nist, z13, and z23.

Referenced by ComputeCrossSectionPerAtom().

 {
   if(Z != currentZ) {
     currentZ = Z;
 
     G4int iz = G4int(Z);
     z13 = nist->GetZ13(iz);
     z23 = z13*z13;
     lnZ = nist->GetLOGZ(iz);
 
     if (iz <= 4) {
       Fel = Fel_light[iz];  
       Finel = Finel_light[iz] ; 
     }
     else {
       Fel = facFel - lnZ/3. ;
       Finel = facFinel - 2.*lnZ/3. ;
     }
     fCoulomb=GetCurrentElement()->GetfCoulomb();
   }
 }

void G4PairProductionRelModel::SetLPMconstant ( G4double val )

inline

Definition at line 161 of file G4PairProductionRelModel.hh.

References fLPMconstant.

 {
   fLPMconstant = val;
 }

void G4PairProductionRelModel::SetLPMflag ( G4bool val )

inline

Definition at line 177 of file G4PairProductionRelModel.hh.

References fLPMflag.

 {
   fLPMflag = val;
 }

void G4PairProductionRelModel::SetupForMaterial	(	const G4ParticleDefinition *	,
		const G4Material *	mat,
		G4double
	)

virtual

Reimplemented from G4VEmModel.

Definition at line 493 of file G4PairProductionRelModel.cc.

References fLPMconstant, G4Material::GetRadlen(), and lpmEnergy.

Referenced by SampleSecondaries().

 {
   lpmEnergy = mat->GetRadlen()*fLPMconstant;
   //  G4cout<<" lpmEnergy="<<lpmEnergy<<G4endl;
 }

Field Documentation

G4double G4PairProductionRelModel::currentZ

protected

Definition at line 138 of file G4PairProductionRelModel.hh.

Referenced by G4PairProductionRelModel(), and SetCurrentElement().

const G4double G4PairProductionRelModel::facFel = G4Log(184.15)

staticprotected

Definition at line 150 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), and SetCurrentElement().

const G4double G4PairProductionRelModel::facFinel = G4Log(1194.)

staticprotected

Definition at line 151 of file G4PairProductionRelModel.hh.

Referenced by SetCurrentElement().

G4double G4PairProductionRelModel::fCoulomb

protected

Definition at line 137 of file G4PairProductionRelModel.hh.

Referenced by ComputeCrossSectionPerAtom(), ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), DeltaMax(), G4PairProductionRelModel(), and SetCurrentElement().

G4double G4PairProductionRelModel::Fel

protected

Definition at line 137 of file G4PairProductionRelModel.hh.

Referenced by ComputeCrossSectionPerAtom(), ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), G4PairProductionRelModel(), and SetCurrentElement().

const G4double G4PairProductionRelModel::Fel_light = {0., 5.31 , 4.79 , 4.74 , 4.71}

staticprotected

Definition at line 148 of file G4PairProductionRelModel.hh.

Referenced by SetCurrentElement().

G4double G4PairProductionRelModel::Finel

protected

Definition at line 137 of file G4PairProductionRelModel.hh.

Referenced by ComputeCrossSectionPerAtom(), G4PairProductionRelModel(), and SetCurrentElement().

const G4double G4PairProductionRelModel::Finel_light = {0., 6.144 , 5.621 , 5.805 , 5.924}

staticprotected

Definition at line 149 of file G4PairProductionRelModel.hh.

Referenced by SetCurrentElement().

G4double G4PairProductionRelModel::fLPMconstant

protected

Definition at line 132 of file G4PairProductionRelModel.hh.

Referenced by LPMconstant(), SetLPMconstant(), and SetupForMaterial().

G4bool G4PairProductionRelModel::fLPMflag

protected

Definition at line 133 of file G4PairProductionRelModel.hh.

Referenced by ComputeXSectionPerAtom(), LPMflag(), SampleSecondaries(), and SetLPMflag().

G4ParticleChangeForGamma* G4PairProductionRelModel::fParticleChange

protected

Definition at line 130 of file G4PairProductionRelModel.hh.

Referenced by G4PairProductionRelModel(), Initialise(), and SampleSecondaries().

G4double G4PairProductionRelModel::gLPM

protected

Definition at line 142 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), ComputeRelDXSectionPerAtom(), G4PairProductionRelModel(), and SampleSecondaries().

G4double G4PairProductionRelModel::lnZ

protected

Definition at line 136 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), ComputeDXSectionPerAtom(), ComputeRelDXSectionPerAtom(), DeltaMax(), G4PairProductionRelModel(), and SetCurrentElement().

const G4double G4PairProductionRelModel::logTwo = G4Log(2.)

staticprotected

Definition at line 153 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions().

G4double G4PairProductionRelModel::lpmEnergy

protected

Definition at line 141 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), and SetupForMaterial().

G4NistManager* G4PairProductionRelModel::nist

protected

Definition at line 125 of file G4PairProductionRelModel.hh.

Referenced by G4PairProductionRelModel(), SampleSecondaries(), and SetCurrentElement().

G4double G4PairProductionRelModel::phiLPM

protected

Definition at line 142 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), ComputeRelDXSectionPerAtom(), G4PairProductionRelModel(), and SampleSecondaries().

const G4double G4PairProductionRelModel::preS1 = 1./(184.15*184.15)

staticprotected

Definition at line 153 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions().

G4ParticleDefinition* G4PairProductionRelModel::theElectron

protected

Definition at line 128 of file G4PairProductionRelModel.hh.

Referenced by G4PairProductionRelModel(), and SampleSecondaries().

G4ParticleDefinition* G4PairProductionRelModel::theGamma

protected

Definition at line 127 of file G4PairProductionRelModel.hh.

Referenced by G4PairProductionRelModel(), and SampleSecondaries().

G4ParticleDefinition* G4PairProductionRelModel::thePositron

protected

Definition at line 129 of file G4PairProductionRelModel.hh.

Referenced by G4PairProductionRelModel(), and SampleSecondaries().

G4bool G4PairProductionRelModel::use_completescreening

protected

Definition at line 145 of file G4PairProductionRelModel.hh.

Referenced by ComputeDXSectionPerAtom(), and ComputeRelDXSectionPerAtom().

const G4double G4PairProductionRelModel::wgi

staticprotected

Initial value:

={ 0.0506, 0.1112, 0.1569, 0.1813,

0.1813, 0.1569, 0.1112, 0.0506 }

Definition at line 147 of file G4PairProductionRelModel.hh.

Referenced by ComputeXSectionPerAtom().

const G4double G4PairProductionRelModel::xgi

staticprotected

Initial value:

={ 0.0199, 0.1017, 0.2372, 0.4083,

0.5917, 0.7628, 0.8983, 0.9801 }

Definition at line 147 of file G4PairProductionRelModel.hh.

Referenced by ComputeXSectionPerAtom().

G4double G4PairProductionRelModel::xiLPM

protected

Definition at line 142 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), ComputeRelDXSectionPerAtom(), G4PairProductionRelModel(), and SampleSecondaries().

G4double G4PairProductionRelModel::z13

protected

Definition at line 136 of file G4PairProductionRelModel.hh.

Referenced by DeltaMin(), G4PairProductionRelModel(), and SetCurrentElement().

G4double G4PairProductionRelModel::z23

protected

Definition at line 136 of file G4PairProductionRelModel.hh.

Referenced by CalcLPMFunctions(), G4PairProductionRelModel(), and SetCurrentElement().

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

Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Field Documentation