G4AnnihiToMuPair Class Reference

#include <G4AnnihiToMuPair.hh>

Inheritance diagram for G4AnnihiToMuPair:

Public Member Functions
	G4AnnihiToMuPair (const G4String &processName="AnnihiToMuPair", G4ProcessType type=fElectromagnetic)
	~G4AnnihiToMuPair () override
G4bool	IsApplicable (const G4ParticleDefinition &) override
void	BuildPhysicsTable (const G4ParticleDefinition &) override
void	PrintInfoDefinition ()
void	SetCrossSecFactor (G4double fac)
G4double	GetCrossSecFactor ()
G4double	CrossSectionPerVolume (G4double positronEnergy, const G4Material *)
G4double	ComputeCrossSectionPerElectron (const G4double energy)
G4double	ComputeCrossSectionPerAtom (const G4double energy, const G4double Z)
G4double	GetMeanFreePath (const G4Track &aTrack, G4double previousStepSize, G4ForceCondition *) override
G4VParticleChange *	PostStepDoIt (const G4Track &aTrack, const G4Step &aStep) override
G4AnnihiToMuPair &	operator= (const G4AnnihiToMuPair &right)=delete
	G4AnnihiToMuPair (const G4AnnihiToMuPair &)=delete
Public Member Functions inherited from G4VDiscreteProcess
	G4VDiscreteProcess (const G4String &aName, G4ProcessType aType=fNotDefined)
	G4VDiscreteProcess (G4VDiscreteProcess &)
virtual	~G4VDiscreteProcess ()
G4VDiscreteProcess &	operator= (const G4VDiscreteProcess &)=delete
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 &)
virtual G4double	GetCrossSection (const G4double, const G4MaterialCutsCouple *)
virtual G4double	MinPrimaryEnergy (const G4ParticleDefinition *, const G4Material *)
Public Member Functions inherited from G4VProcess
	G4VProcess (const G4String &aName="NoName", G4ProcessType aType=fNotDefined)
	G4VProcess (const G4VProcess &right)
virtual	~G4VProcess ()
G4VProcess &	operator= (const G4VProcess &)=delete
G4bool	operator== (const G4VProcess &right) const
G4bool	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 const G4VProcess *	GetCreatorProcess () const
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
virtual void	ProcessDescription (std::ostream &outfile) 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 &)

Additional Inherited Members
Static Public Member Functions inherited from G4VProcess
static const G4String &	GetProcessTypeName (G4ProcessType)
Protected Member Functions inherited from G4VDiscreteProcess
Protected Member Functions inherited from G4VProcess
void	SubtractNumberOfInteractionLengthLeft (G4double prevStepSize)
void	ClearNumberOfInteractionLengthLeft ()
Protected Attributes inherited from G4VProcess
const G4ProcessManager *	aProcessManager = nullptr
G4VParticleChange *	pParticleChange = nullptr
G4ParticleChange	aParticleChange
G4double	theNumberOfInteractionLengthLeft = -1.0
G4double	currentInteractionLength = -1.0
G4double	theInitialNumberOfInteractionLength = -1.0
G4String	theProcessName
G4String	thePhysicsTableFileName
G4ProcessType	theProcessType = fNotDefined
G4int	theProcessSubType = -1
G4double	thePILfactor = 1.0
G4int	verboseLevel = 0
G4bool	enableAtRestDoIt = true
G4bool	enableAlongStepDoIt = true
G4bool	enablePostStepDoIt = true

Detailed Description

Definition at line 57 of file G4AnnihiToMuPair.hh.

Constructor & Destructor Documentation

G4AnnihiToMuPair() [1/2]

G4AnnihiToMuPair::G4AnnihiToMuPair ( const G4String & processName = "AnnihiToMuPair", G4ProcessType type = fElectromagnetic )

explicit

Definition at line 59 of file G4AnnihiToMuPair.cc.

                       :G4VDiscreteProcess (processName, type)
{
  //e+ Energy threshold
  if(processName == "AnnihiToTauPair") {
    SetProcessSubType(fAnnihilationToTauTau);
    part1 = G4TauPlus::TauPlus();
    part2 = G4TauMinus::TauMinus();
    fInfo = "e+e->tau+tau-";
  } else {
    SetProcessSubType(fAnnihilationToMuMu);
    part1 = G4MuonPlus::MuonPlus();
    part2 = G4MuonMinus::MuonMinus();
  }
  fMass = part1->GetPDGMass();
  fLowEnergyLimit = 2. * fMass * fMass / CLHEP::electron_mass_c2 - CLHEP::electron_mass_c2;
 
  // model is ok up to 1000 TeV due to neglected Z-interference
  fHighEnergyLimit = 1000. * TeV;
 
  fCurrentSigma = 0.0;
  fCrossSecFactor = 1.;
  fManager = G4LossTableManager::Instance();
  fManager->Register(this);
}

~G4AnnihiToMuPair()

G4AnnihiToMuPair::~G4AnnihiToMuPair ( )

override

Definition at line 87 of file G4AnnihiToMuPair.cc.

{ 
  fManager->DeRegister(this);
}

G4AnnihiToMuPair() [2/2]

G4AnnihiToMuPair::G4AnnihiToMuPair ( const G4AnnihiToMuPair & )

delete

Member Function Documentation

BuildPhysicsTable()

void G4AnnihiToMuPair::BuildPhysicsTable ( const G4ParticleDefinition & )

overridevirtual

Reimplemented from G4VProcess.

Definition at line 101 of file G4AnnihiToMuPair.cc.

{
  PrintInfoDefinition();
}

ComputeCrossSectionPerAtom()

G4double G4AnnihiToMuPair::ComputeCrossSectionPerAtom	(	const G4double	energy,
		const G4double	Z )

Definition at line 150 of file G4AnnihiToMuPair.cc.

{
  return ComputeCrossSectionPerElectron(energy)*Z;
}

ComputeCrossSectionPerElectron()

G4double G4AnnihiToMuPair::ComputeCrossSectionPerElectron

(

const G4double

energy

)

Definition at line 118 of file G4AnnihiToMuPair.cc.

{
  G4double rmuon = CLHEP::elm_coupling/fMass; //classical particle radius
  G4double sig0 = CLHEP::pi*rmuon*rmuon/3.;   //constant in crossSection
  const G4double pial = CLHEP::pi*CLHEP::fine_structure_const; // pi * alphaQED
 
  if (e <= fLowEnergyLimit) return 0.0;
   
  const G4double xi = fLowEnergyLimit/e;
  const G4double piaxi = pial * std::sqrt(xi);
  G4double sigma = sig0 * xi * (1. + xi*0.5);
  //G4cout << "### xi= " << xi << " piaxi=" << piaxi << G4endl;
 
  // argument of the exponent below 0.1 or above 10
  // Sigma per electron * number of electrons per atom
  if(xi <= 1.0 - 100*piaxi*piaxi) {
    sigma *= std::sqrt(1.0 - xi);
  }
  else if (xi >= 1.0 - 0.01 * piaxi * piaxi) {
    sigma *= piaxi;
  }
  else {
    sigma *= piaxi / (1. - G4Exp(-piaxi / std::sqrt(1 - xi)));
  }
  // G4cout << "### sigma= " << sigma << G4endl;
  return sigma;
}

Referenced by ComputeCrossSectionPerAtom(), and CrossSectionPerVolume().

CrossSectionPerVolume()

G4double G4AnnihiToMuPair::CrossSectionPerVolume	(	G4double	positronEnergy,
		const G4Material *	aMaterial )

Definition at line 158 of file G4AnnihiToMuPair.cc.

{
  return ComputeCrossSectionPerElectron(energy)*aMaterial->GetTotNbOfElectPerVolume();
}

Referenced by GetMeanFreePath(), and PostStepDoIt().

GetCrossSecFactor()

G4double G4AnnihiToMuPair::GetCrossSecFactor ( )

inline

Definition at line 81 of file G4AnnihiToMuPair.hh.

{return fCrossSecFactor;};

GetMeanFreePath()

G4double G4AnnihiToMuPair::GetMeanFreePath ( const G4Track & aTrack, G4double previousStepSize, G4ForceCondition *  )

overridevirtual

Implements G4VDiscreteProcess.

Definition at line 166 of file G4AnnihiToMuPair.cc.

{
  const G4DynamicParticle* aDynamicPositron = aTrack.GetDynamicParticle();
  G4double energy = aDynamicPositron->GetTotalEnergy();
  const G4Material* aMaterial = aTrack.GetMaterial();
 
  // cross section before step
  fCurrentSigma = CrossSectionPerVolume(energy, aMaterial);
 
  // increase the CrossSection by CrossSecFactor (default 1)
  return (fCurrentSigma > 0.0) ? 1.0/(fCurrentSigma*fCrossSecFactor) : DBL_MAX;
}

IsApplicable()

G4bool G4AnnihiToMuPair::IsApplicable ( const G4ParticleDefinition & particle )

overridevirtual

Reimplemented from G4VProcess.

Definition at line 94 of file G4AnnihiToMuPair.cc.

{
  return ( &particle == G4Positron::Positron() );
}

operator=()

G4AnnihiToMuPair & G4AnnihiToMuPair::operator= ( const G4AnnihiToMuPair & right )

delete

PostStepDoIt()

G4VParticleChange * G4AnnihiToMuPair::PostStepDoIt ( const G4Track & aTrack, const G4Step & aStep )

overridevirtual

Reimplemented from G4VDiscreteProcess.

Definition at line 183 of file G4AnnihiToMuPair.cc.

{
  aParticleChange.Initialize(aTrack);
 
  // current Positron energy and direction, return if energy too low
  const G4DynamicParticle *aDynamicPositron = aTrack.GetDynamicParticle();
  const G4double Mele = CLHEP::electron_mass_c2;
  G4double Epos = aDynamicPositron->GetTotalEnergy();
  G4double xs = CrossSectionPerVolume(Epos, aTrack.GetMaterial());
 
  // test of cross section
  if(xs > 0.0 && fCurrentSigma*G4UniformRand() > xs) {
    return G4VDiscreteProcess::PostStepDoIt(aTrack,aStep);
  }
 
  const G4ThreeVector PosiDirection = aDynamicPositron->GetMomentumDirection();
  G4double xi = fLowEnergyLimit/Epos; // xi is always less than 1,
                                      // goes to 0 at high Epos
 
  // generate cost; probability function 1+cost**2 at high Epos
  //
  G4double cost;
  do { cost = 2.*G4UniformRand()-1.; }
  // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
  while (2.*G4UniformRand() > 1.+xi+cost*cost*(1.-xi) ); 
  G4double sint = std::sqrt(1.-cost*cost);
 
  // generate phi
  //
  G4double phi = 2.*CLHEP::pi*G4UniformRand();
 
  G4double Ecm   = std::sqrt(0.5*Mele*(Epos+Mele));
  G4double Pcm   = std::sqrt(Ecm*Ecm - fMass*fMass);
  G4double beta  = std::sqrt((Epos-Mele)/(Epos+Mele));
  G4double gamma = Ecm/Mele;
  G4double Pt    = Pcm*sint;
  
  // energy and momentum of the muons in the Lab
  //
  G4double EmuPlus   = gamma*(Ecm + cost*beta*Pcm);
  G4double EmuMinus  = gamma*(Ecm - cost*beta*Pcm);
  G4double PmuPlusZ  = gamma*(beta*Ecm + cost*Pcm);
  G4double PmuMinusZ = gamma*(beta*Ecm - cost*Pcm);
  G4double PmuPlusX  = Pt*std::cos(phi);
  G4double PmuPlusY  = Pt*std::sin(phi);
  G4double PmuMinusX =-PmuPlusX;
  G4double PmuMinusY =-PmuPlusY;
  // absolute momenta
  G4double PmuPlus  = std::sqrt(Pt*Pt+PmuPlusZ *PmuPlusZ );
  G4double PmuMinus = std::sqrt(Pt*Pt+PmuMinusZ*PmuMinusZ);
 
  // mu+ mu- directions for Positron in z-direction
  //
  G4ThreeVector MuPlusDirection(PmuPlusX / PmuPlus, PmuPlusY / PmuPlus, PmuPlusZ / PmuPlus);
  G4ThreeVector MuMinusDirection(PmuMinusX / PmuMinus, PmuMinusY / PmuMinus, PmuMinusZ / PmuMinus);
 
  // rotate to actual Positron direction
  //
  MuPlusDirection.rotateUz(PosiDirection);
  MuMinusDirection.rotateUz(PosiDirection);
 
  aParticleChange.SetNumberOfSecondaries(2);
 
  // create G4DynamicParticle object for the particle1
  auto aParticle1 = new G4DynamicParticle(part1, MuPlusDirection, EmuPlus - fMass);
  aParticleChange.AddSecondary(aParticle1);
  // create G4DynamicParticle object for the particle2
  auto aParticle2 = new G4DynamicParticle(part2, MuMinusDirection, EmuMinus - fMass);
  aParticleChange.AddSecondary(aParticle2);
 
  // Kill the incident positron 
  //
  aParticleChange.ProposeEnergy(0.); 
  aParticleChange.ProposeTrackStatus(fStopAndKill);
 
  return &aParticleChange;
}

PrintInfoDefinition()

void G4AnnihiToMuPair::PrintInfoDefinition

(

)

Definition at line 267 of file G4AnnihiToMuPair.cc.

{
  G4String comments = fInfo + " annihilation, atomic e- at rest, SubType=";
  G4cout << G4endl << GetProcessName() << ":  " << comments << GetProcessSubType() << G4endl;
  G4cout << "        threshold at " << fLowEnergyLimit / CLHEP::GeV << " GeV"
         << " good description up to " << fHighEnergyLimit / CLHEP::TeV << " TeV for all Z."
         << G4endl;
}

Referenced by BuildPhysicsTable().

SetCrossSecFactor()

void G4AnnihiToMuPair::SetCrossSecFactor

(

G4double

fac

)

Definition at line 108 of file G4AnnihiToMuPair.cc.

{ 
  fCrossSecFactor = fac;
  //G4cout << "The cross section for AnnihiToMuPair is artificially "
  //       << "increased by the CrossSecFactor=" << fCrossSecFactor << G4endl;
}

Referenced by G4EmExtraPhysics::ConstructProcess().

---

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

• G4AnnihiToMuPair.hh
• G4AnnihiToMuPair.cc