#include <G4LowEnergyGammaConversion.hh>

Inheritance diagram for G4LowEnergyGammaConversion:

Public Member Functions
	G4LowEnergyGammaConversion (const G4String &processName="LowEnConversion")

	~G4LowEnergyGammaConversion ()

G4bool	IsApplicable (const G4ParticleDefinition &photon)

void	BuildPhysicsTable (const G4ParticleDefinition &photon)

G4VParticleChange *	PostStepDoIt (const G4Track &aTrack, const G4Step &aStep)

G4double	DumpMeanFreePath (const G4Track &aTrack, G4double previousStepSize, G4ForceCondition *condition)

Public Member Functions inherited from G4VDiscreteProcess
	G4VDiscreteProcess (const G4String &, G4ProcessType aType=fNotDefined)

	G4VDiscreteProcess (G4VDiscreteProcess &)

virtual	~G4VDiscreteProcess ()

virtual G4double	PostStepGetPhysicalInteractionLength (const G4Track &track, G4double previousStepSize, G4ForceCondition *condition)

virtual G4double	AlongStepGetPhysicalInteractionLength (const G4Track &, G4double, G4double, G4double &, G4GPILSelection *)

virtual G4double	AtRestGetPhysicalInteractionLength (const G4Track &, G4ForceCondition *)

virtual G4VParticleChange *	AtRestDoIt (const G4Track &, const G4Step &)

virtual G4VParticleChange *	AlongStepDoIt (const G4Track &, const G4Step &)

Public Member Functions inherited from G4VProcess
	G4VProcess (const G4String &aName="NoName", G4ProcessType aType=fNotDefined)

	G4VProcess (const G4VProcess &right)

virtual	~G4VProcess ()

G4int	operator== (const G4VProcess &right) const

G4int	operator!= (const G4VProcess &right) const

G4double	GetCurrentInteractionLength () const

void	SetPILfactor (G4double value)

G4double	GetPILfactor () const

G4double	AlongStepGPIL (const G4Track &track, G4double previousStepSize, G4double currentMinimumStep, G4double &proposedSafety, G4GPILSelection *selection)

G4double	AtRestGPIL (const G4Track &track, G4ForceCondition *condition)

G4double	PostStepGPIL (const G4Track &track, G4double previousStepSize, G4ForceCondition *condition)

virtual void	PreparePhysicsTable (const G4ParticleDefinition &)

virtual G4bool	StorePhysicsTable (const G4ParticleDefinition *, const G4String &, G4bool)

virtual G4bool	RetrievePhysicsTable (const G4ParticleDefinition *, const G4String &, G4bool)

const G4String &	GetPhysicsTableFileName (const G4ParticleDefinition *, const G4String &directory, const G4String &tableName, G4bool ascii=false)

const G4String &	GetProcessName () const

G4ProcessType	GetProcessType () const

void	SetProcessType (G4ProcessType)

G4int	GetProcessSubType () const

void	SetProcessSubType (G4int)

virtual void	StartTracking (G4Track *)

virtual void	EndTracking ()

virtual void	SetProcessManager (const G4ProcessManager *)

virtual const G4ProcessManager *	GetProcessManager ()

virtual void	ResetNumberOfInteractionLengthLeft ()

G4double	GetNumberOfInteractionLengthLeft () const

G4double	GetTotalNumberOfInteractionLengthTraversed () const

G4bool	isAtRestDoItIsEnabled () const

G4bool	isAlongStepDoItIsEnabled () const

G4bool	isPostStepDoItIsEnabled () const

virtual void	DumpInfo () const

void	SetVerboseLevel (G4int value)

G4int	GetVerboseLevel () const

virtual void	SetMasterProcess (G4VProcess *masterP)

const G4VProcess *	GetMasterProcess () const

virtual void	BuildWorkerPhysicsTable (const G4ParticleDefinition &part)

virtual void	PrepareWorkerPhysicsTable (const G4ParticleDefinition &)

Protected Member Functions
G4double	GetMeanFreePath (const G4Track &aTrack, G4double previousStepSize, G4ForceCondition *condition)

Protected Member Functions inherited from G4VProcess
void	SubtractNumberOfInteractionLengthLeft (G4double previousStepSize)

void	ClearNumberOfInteractionLengthLeft ()

Additional Inherited Members
Static Public Member Functions inherited from G4VProcess
static const G4String &	GetProcessTypeName (G4ProcessType)

Protected Attributes inherited from G4VProcess
const G4ProcessManager *	aProcessManager

G4VParticleChange *	pParticleChange

G4ParticleChange	aParticleChange

G4double	theNumberOfInteractionLengthLeft

G4double	currentInteractionLength

G4double	theInitialNumberOfInteractionLength

G4String	theProcessName

G4String	thePhysicsTableFileName

G4ProcessType	theProcessType

G4int	theProcessSubType

G4double	thePILfactor

G4bool	enableAtRestDoIt

G4bool	enableAlongStepDoIt

G4bool	enablePostStepDoIt

G4int	verboseLevel

Detailed Description

Definition at line 62 of file G4LowEnergyGammaConversion.hh.

Constructor & Destructor Documentation

G4LowEnergyGammaConversion::G4LowEnergyGammaConversion ( const G4String & processName = "LowEnConversion" )

Definition at line 78 of file G4LowEnergyGammaConversion.cc.

References FatalException, G4cout, G4endl, G4Exception(), G4VProcess::GetProcessName(), python.hepunit::GeV, G4RDVCrossSectionHandler::Initialise(), python.hepunit::MeV, and G4VProcess::verboseLevel.

   : G4VDiscreteProcess(processName),
     lowEnergyLimit(1.022000*MeV),
     highEnergyLimit(100*GeV),
     intrinsicLowEnergyLimit(1.022000*MeV),
     intrinsicHighEnergyLimit(100*GeV),
     smallEnergy(2.*MeV)
 
 {
   if (lowEnergyLimit < intrinsicLowEnergyLimit || 
       highEnergyLimit > intrinsicHighEnergyLimit)
     {
       G4Exception("G4LowEnergyGammaConversion::G4LowEnergyGammaConversion()",
                   "OutOfRange", FatalException,
                   "Energy limit outside intrinsic process validity range!");
     }
 
   // The following pointer is owned by G4DataHandler
   
   crossSectionHandler = new G4RDCrossSectionHandler();
   crossSectionHandler->Initialise(0,1.0220*MeV,100.*GeV,400);
   meanFreePathTable = 0;
   rangeTest = new G4RDRangeTest;
 
    if (verboseLevel > 0) 
      {
        G4cout << GetProcessName() << " is created " << G4endl
           << "Energy range: " 
           << lowEnergyLimit / MeV << " MeV - "
           << highEnergyLimit / GeV << " GeV" 
           << G4endl;
      }
 }

G4LowEnergyGammaConversion::~G4LowEnergyGammaConversion ( )

Definition at line 112 of file G4LowEnergyGammaConversion.cc.

 {
   delete meanFreePathTable;
   delete crossSectionHandler;
   delete rangeTest;
 }

Member Function Documentation

void G4LowEnergyGammaConversion::BuildPhysicsTable ( const G4ParticleDefinition & photon )

virtual

Reimplemented from G4VProcess.

Definition at line 119 of file G4LowEnergyGammaConversion.cc.

References G4RDVCrossSectionHandler::BuildMeanFreePathForMaterials(), G4RDVCrossSectionHandler::Clear(), and G4RDVCrossSectionHandler::LoadData().

 {
 
   crossSectionHandler->Clear();
   G4String crossSectionFile = "pair/pp-cs-";
   crossSectionHandler->LoadData(crossSectionFile);
 
   delete meanFreePathTable;
   meanFreePathTable = crossSectionHandler->BuildMeanFreePathForMaterials();
 }

G4double G4LowEnergyGammaConversion::DumpMeanFreePath	(	const G4Track &	aTrack,
		G4double	previousStepSize,
		G4ForceCondition *	condition
	)

inline

Definition at line 78 of file G4LowEnergyGammaConversion.hh.

References GetMeanFreePath().

81 { return GetMeanFreePath(aTrack, previousStepSize, condition); }

condition

G4double condition(const G4ErrorSymMatrix &m)

G4LowEnergyGammaConversion::GetMeanFreePath

G4double GetMeanFreePath(const G4Track &aTrack, G4double previousStepSize, G4ForceCondition *condition)

Definition: G4LowEnergyGammaConversion.cc:319

G4double G4LowEnergyGammaConversion::GetMeanFreePath	(	const G4Track &	aTrack,
		G4double	previousStepSize,
		G4ForceCondition *	condition
	)

protectedvirtual

Implements G4VDiscreteProcess.

Definition at line 319 of file G4LowEnergyGammaConversion.cc.

References DBL_MAX, energy(), G4RDVEMDataSet::FindValue(), G4Track::GetDynamicParticle(), G4MaterialCutsCouple::GetIndex(), G4DynamicParticle::GetKineticEnergy(), G4Track::GetMaterialCutsCouple(), and photon.

Referenced by DumpMeanFreePath().

 {
   const G4DynamicParticle* photon = track.GetDynamicParticle();
   G4double energy = photon->GetKineticEnergy();
   const G4MaterialCutsCouple* couple = track.GetMaterialCutsCouple();
   size_t materialIndex = couple->GetIndex();
 
   G4double meanFreePath;
   if (energy > highEnergyLimit) meanFreePath = meanFreePathTable->FindValue(highEnergyLimit,materialIndex);
   else if (energy < lowEnergyLimit) meanFreePath = DBL_MAX;
   else meanFreePath = meanFreePathTable->FindValue(energy,materialIndex);
   return meanFreePath;
 }

G4bool G4LowEnergyGammaConversion::IsApplicable ( const G4ParticleDefinition & photon )

virtual

Reimplemented from G4VProcess.

Definition at line 314 of file G4LowEnergyGammaConversion.cc.

References G4Gamma::Gamma().

 {
   return ( &particle == G4Gamma::Gamma() ); 
 }

G4VParticleChange * G4LowEnergyGammaConversion::PostStepDoIt	(	const G4Track &	aTrack,
		const G4Step &	aStep
	)

virtual

Reimplemented from G4VDiscreteProcess.

Definition at line 130 of file G4LowEnergyGammaConversion.cc.

References G4ParticleChange::AddSecondary(), G4VProcess::aParticleChange, G4Electron::Electron(), python.hepunit::electron_mass_c2, python.hepunit::epsilon0, G4RDVRangeTest::Escape(), fStopAndKill, G4cout, G4endl, G4UniformRand, G4Track::GetDynamicParticle(), G4Element::GetfCoulomb(), G4Element::GetIonisation(), G4DynamicParticle::GetKineticEnergy(), G4IonisParamElm::GetlogZ3(), G4Track::GetMaterialCutsCouple(), G4DynamicParticle::GetMomentumDirection(), G4Step::GetPostStepPoint(), G4StepPoint::GetSafety(), G4IonisParamElm::GetZ3(), G4ParticleChange::Initialize(), G4INCL::Math::max(), python.hepunit::MeV, G4INCL::Math::min(), G4Positron::Positron(), G4VDiscreteProcess::PostStepDoIt(), G4ParticleChange::ProposeEnergy(), G4VParticleChange::ProposeLocalEnergyDeposit(), G4ParticleChange::ProposeMomentumDirection(), G4VParticleChange::ProposeTrackStatus(), CLHEP::Hep3Vector::rotateUz(), G4RDVCrossSectionHandler::SelectRandomElement(), G4VParticleChange::SetNumberOfSecondaries(), CLHEP::RandBit::shootBit(), and python.hepunit::twopi.

 {
 // 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.
 
   aParticleChange.Initialize(aTrack);
 
   const G4MaterialCutsCouple* couple = aTrack.GetMaterialCutsCouple();
 
   const G4DynamicParticle* incidentPhoton = aTrack.GetDynamicParticle();
   G4double photonEnergy = incidentPhoton->GetKineticEnergy();
   G4ParticleMomentum photonDirection = incidentPhoton->GetMomentumDirection();
 
   G4double epsilon ;
   G4double epsilon0 = electron_mass_c2 / photonEnergy ;
 
   // Do it fast if photon energy < 2. MeV
   if (photonEnergy < smallEnergy )
     {
       epsilon = epsilon0 + (0.5 - epsilon0) * G4UniformRand();
     }
   else
     {
       // Select randomly one element in the current material
       const G4Element* element = crossSectionHandler->SelectRandomElement(couple,photonEnergy);
 
       if (element == 0)
     {
       G4cout << "G4LowEnergyGammaConversion::PostStepDoIt - element = 0" << G4endl;
     }
       G4IonisParamElm* ionisation = element->GetIonisation();
        if (ionisation == 0)
     {
       G4cout << "G4LowEnergyGammaConversion::PostStepDoIt - ionisation = 0" << G4endl;
     }
 
       // 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. * epsilon0 / (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(epsilon0,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(), 0.3333) ;
         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 (CLHEP::RandBit::shootBit())
     {
       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 localEnergyDeposit = 0. ;
   
   aParticleChange.SetNumberOfSecondaries(2) ; 
   G4double electronKineEnergy = std::max(0.,electronTotEnergy - electron_mass_c2) ;
   
   // Generate the electron only if with large enough range w.r.t. cuts and safety
   
   G4double safety = aStep.GetPostStepPoint()->GetSafety();
   
   if (rangeTest->Escape(G4Electron::Electron(),couple,electronKineEnergy,safety))
     {
       G4ThreeVector electronDirection (dxEle, dyEle, dzEle);
       electronDirection.rotateUz(photonDirection);
       
       G4DynamicParticle* particle1 = new G4DynamicParticle (G4Electron::Electron(),
                                 electronDirection,
                                 electronKineEnergy);
       aParticleChange.AddSecondary(particle1) ;
     }
   else
     {
       localEnergyDeposit += electronKineEnergy ;
     }
 
   // The e+ is always created (even with kinetic energy = 0) for further annihilation
   G4double positronKineEnergy = std::max(0.,positronTotEnergy - electron_mass_c2) ;
 
   // Is the local energy deposit correct, if the positron is always created?
   if (! (rangeTest->Escape(G4Positron::Positron(),couple,positronKineEnergy,safety)))
     {
       localEnergyDeposit += positronKineEnergy ;
       positronKineEnergy = 0. ;
     }
 
   G4ThreeVector positronDirection (dxPos, dyPos, dzPos);
   positronDirection.rotateUz(photonDirection);   
   
   // Create G4DynamicParticle object for the particle2 
   G4DynamicParticle* particle2 = new G4DynamicParticle(G4Positron::Positron(),
                                positronDirection, positronKineEnergy);
   aParticleChange.AddSecondary(particle2) ; 
 
   aParticleChange.ProposeLocalEnergyDeposit(localEnergyDeposit) ;
   
   // Kill the incident photon 
   aParticleChange.ProposeMomentumDirection(0.,0.,0.) ;
   aParticleChange.ProposeEnergy(0.) ; 
   aParticleChange.ProposeTrackStatus(fStopAndKill) ;
 
   //  Reset NbOfInteractionLengthLeft and return aParticleChange
   return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
 }

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

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation