G4ChargeExchange Class Reference

#include <G4ChargeExchange.hh>

Inheritance diagram for G4ChargeExchange:

Public Member Functions
	G4ChargeExchange (G4ChargeExchangeXS *)
	~G4ChargeExchange () override
	G4ChargeExchange (const G4ChargeExchange &right)=delete
const G4ChargeExchange &	operator= (const G4ChargeExchange &right)=delete
G4bool	operator== (const G4ChargeExchange &right) const =delete
G4bool	operator!= (const G4ChargeExchange &right) const =delete
G4HadFinalState *	ApplyYourself (const G4HadProjectile &aTrack, G4Nucleus &targetNucleus) override
G4double	SampleT (const G4ParticleDefinition *theSec, const G4int A, const G4double tmax) const
Public Member Functions inherited from G4HadronicInteraction
	G4HadronicInteraction (const G4String &modelName="HadronicModel")
virtual	~G4HadronicInteraction ()
virtual G4double	SampleInvariantT (const G4ParticleDefinition *p, G4double plab, G4int Z, G4int A)
virtual G4bool	IsApplicable (const G4HadProjectile &aTrack, G4Nucleus &targetNucleus)
G4double	GetMinEnergy () const
G4double	GetMinEnergy (const G4Material *aMaterial, const G4Element *anElement) const
void	SetMinEnergy (G4double anEnergy)
void	SetMinEnergy (G4double anEnergy, const G4Element *anElement)
void	SetMinEnergy (G4double anEnergy, const G4Material *aMaterial)
G4double	GetMaxEnergy () const
G4double	GetMaxEnergy (const G4Material *aMaterial, const G4Element *anElement) const
void	SetMaxEnergy (const G4double anEnergy)
void	SetMaxEnergy (G4double anEnergy, const G4Element *anElement)
void	SetMaxEnergy (G4double anEnergy, const G4Material *aMaterial)
G4int	GetVerboseLevel () const
void	SetVerboseLevel (G4int value)
const G4String &	GetModelName () const
void	DeActivateFor (const G4Material *aMaterial)
void	ActivateFor (const G4Material *aMaterial)
void	DeActivateFor (const G4Element *anElement)
void	ActivateFor (const G4Element *anElement)
G4bool	IsBlocked (const G4Material *aMaterial) const
G4bool	IsBlocked (const G4Element *anElement) const
void	SetRecoilEnergyThreshold (G4double val)
G4double	GetRecoilEnergyThreshold () const
virtual const std::pair< G4double, G4double >	GetFatalEnergyCheckLevels () const
virtual std::pair< G4double, G4double >	GetEnergyMomentumCheckLevels () const
void	SetEnergyMomentumCheckLevels (G4double relativeLevel, G4double absoluteLevel)
virtual void	ModelDescription (std::ostream &outFile) const
virtual void	BuildPhysicsTable (const G4ParticleDefinition &)
virtual void	InitialiseModel ()
	G4HadronicInteraction (const G4HadronicInteraction &right)=delete
const G4HadronicInteraction &	operator= (const G4HadronicInteraction &right)=delete
G4bool	operator== (const G4HadronicInteraction &right) const =delete
G4bool	operator!= (const G4HadronicInteraction &right) const =delete

Additional Inherited Members
Protected Member Functions inherited from G4HadronicInteraction
void	SetModelName (const G4String &nam)
G4bool	IsBlocked () const
void	Block ()
Protected Attributes inherited from G4HadronicInteraction
G4HadFinalState	theParticleChange
G4int	verboseLevel
G4double	theMinEnergy
G4double	theMaxEnergy
G4bool	isBlocked

Detailed Description

Definition at line 51 of file G4ChargeExchange.hh.

Constructor & Destructor Documentation

G4ChargeExchange() [1/2]

G4ChargeExchange::G4ChargeExchange ( G4ChargeExchangeXS * ptr )

explicit

Definition at line 65 of file G4ChargeExchange.cc.

  : G4HadronicInteraction("ChargeExchange"),
    fXSection(ptr), fXSWeightFactor(1.0)
{
  lowEnergyLimit = 1.*CLHEP::MeV;
  secID = G4PhysicsModelCatalog::GetModelID( "model_ChargeExchange" );
  nist = G4NistManager::Instance();
  fHandler = new G4ExcitationHandler();
  if (nullptr != fXSection) {
    fXSWeightFactor = 1.0/fXSection->GetCrossSectionFactor();
  }
}

Referenced by G4ChargeExchange(), operator!=(), operator=(), and operator==().

~G4ChargeExchange()

G4ChargeExchange::~G4ChargeExchange ( )

override

Definition at line 78 of file G4ChargeExchange.cc.

{
  delete fHandler;
}

G4ChargeExchange() [2/2]

G4ChargeExchange::G4ChargeExchange ( const G4ChargeExchange & right )

delete

Member Function Documentation

ApplyYourself()

G4HadFinalState * G4ChargeExchange::ApplyYourself ( const G4HadProjectile & aTrack, G4Nucleus & targetNucleus )

overridevirtual

Reimplemented from G4HadronicInteraction.

Definition at line 83 of file G4ChargeExchange.cc.

{
  theParticleChange.Clear();
  auto part = aTrack.GetDefinition();
  G4double ekin = aTrack.GetKineticEnergy();
 
  G4int A = targetNucleus.GetA_asInt();
  G4int Z = targetNucleus.GetZ_asInt();
  
  if (ekin <= lowEnergyLimit) {
    return &theParticleChange;
  }
  theParticleChange.SetWeightChange(fXSWeightFactor);
 
  G4int projPDG = part->GetPDGEncoding();
  // for hydrogen targets and positive projectile change exchange
  // is not possible on proton, only on deuteron
  if (1 == Z && (211 == projPDG || 321 == projPDG)) { A = 2; } 
  
  if (verboseLevel > 1) {
    G4cout << "G4ChargeExchange for " << part->GetParticleName()
       << " PDGcode= " << projPDG << " on nucleus Z= " << Z
       << " A= " << A << " N= " << A - Z
       << G4endl;
  }
 
  G4double mass1 = G4NucleiProperties::GetNuclearMass(A, Z);
  G4LorentzVector lv0 = aTrack.Get4Momentum();
 
  // select final state
  const G4ParticleDefinition* theSecondary =
    fXSection->SampleSecondaryType(part, aTrack.GetMaterial(),
                   Z, A, aTrack.GetTotalEnergy());
  G4int pdg = theSecondary->GetPDGEncoding();
 
  if (verboseLevel > 1)
    G4cout << "    Secondary " << theSecondary->GetParticleName() << "  pdg=" << pdg << G4endl;
 
  // omega(782) and f2(1270)
  G4bool isShortLived = (pdg == 223 || pdg == 225);
 
  // atomic number of the recoil nucleus
  if (projPDG == -211) { --Z; }
  else if (projPDG == 211) { ++Z; }
  else if (projPDG == -321) { --Z; }
  else if (projPDG == 321) { ++Z; }
  else if (projPDG == 130) {
    if (theSecondary->GetPDGCharge() > 0.0) { --Z; }
    else { ++Z; }
  } else {
    // not ready for other projectile
    return &theParticleChange;
  }
 
  // recoil nucleus
  const G4ParticleDefinition* theRecoil = nullptr;
  if (Z == 0 && A == 1) { theRecoil = G4Neutron::Neutron(); }
  else if (Z == 1 && A == 1) { theRecoil = G4Proton::Proton(); }
  else if (Z == 1 && A == 2) { theRecoil = G4Deuteron::Deuteron(); }
  else if (Z == 1 && A == 3) { theRecoil = G4Triton::Triton(); }
  else if (Z == 2 && A == 3) { theRecoil = G4He3::He3(); }
  else if (Z == 2 && A == 4) { theRecoil = G4Alpha::Alpha(); }
 
  // check if there is enough energy for the final state
  // and sample mass of produced state
  // sample kinematics
  G4LorentzVector lv1(0.0, 0.0, 0.0, mass1);
  G4LorentzVector lv = lv0 + lv1;
  G4double m0 = lv.mag();
  const G4double mass0 = theSecondary->GetPDGMass();
  G4double mass2 = mass0;
  G4double mass3;
  G4bool ok = false;
 
  if (verboseLevel > 1) {
    G4cout << " Secondary meson " << theSecondary->GetParticleName()
       << " mass(MeV)=" << mass2 << " pdg=" << pdg
       << " Final Z=" << Z << " isShortLived=" << isShortLived
       << "  " << lv
       << G4endl;
  }
  // fixed recoil mass
  if (nullptr != theRecoil) {
    mass3 = theRecoil->GetPDGMass();
    ok = (m0 > mass2 + mass3);
 
    // excited nuclear state
  } else {
    G4double mass30 = G4NucleiProperties::GetNuclearMass(A, Z);
    const G4double eFermi = 10*CLHEP::MeV;
    for (G4int i=0; i<10; ++i) {
      mass3 = mass30 + eFermi*G4UniformRand();
      if (m0 > mass2 + mass3) {
    ok = true;
    break;
      }
    }
  }
  if (isShortLived) {
    const G4double elim = 300*CLHEP::MeV;
    ok = false;
    for (G4int i=0; i<10; ++i) {
      if (SampleMass(mass2, theSecondary->GetPDGWidth(), elim)) {
        if (m0 > mass2 + mass3) {
      ok = true;
      break;
    }
      }
    }
  }
 
  // not possible kinematically
  if (!ok) { return &theParticleChange; }
 
  G4double e2 = (m0*m0 + mass2*mass2 - mass3*mass3)/(2*m0);
  G4double momentumCMS = std::sqrt(e2*e2 - mass2*mass2);
  G4double tmax = 4*momentumCMS*momentumCMS; 
 
  // for projectile pion t depends on final state
  G4double t;
  if (fXSection->isPion()) {
    t = fXSection->SampleTforPion(aTrack.GetTotalEnergy(), tmax);
  }
  else {
    t = SampleT(theSecondary, A, tmax);
  } 
   
  G4double phi = G4UniformRand()*CLHEP::twopi;
  G4double cost = 1. - 2.0*t/tmax;
 
  // if cos(theta) negative, there is a numerical problem
  // instead of making scattering backward, make in this case
  // no scattering
  if (std::abs(cost) > 1.0) { cost = 1.0; }
 
  G4double sint = std::sqrt((1.0 - cost)*(1.0 + cost));
 
  if (verboseLevel > 1) {
    G4cout << " t= " << t << " tmax(GeV^2)= " << tmax/(GeV*GeV) 
       << " cos(t)=" << cost << " sin(t)=" << sint << G4endl;
  }
  G4LorentzVector lv2(momentumCMS*sint*std::cos(phi),
              momentumCMS*sint*std::sin(phi),
              momentumCMS*cost, e2);
 
  // kinematics in the final state, may be a warning should be added if 
  G4ThreeVector bst = lv.boostVector();
  lv2.boost(bst);
  lv -= lv2;
  if (lv.e() < mass3) {
    lv.setE(mass3);
  }
 
  // prepare secondary particles
  theParticleChange.SetStatusChange(stopAndKill);
  theParticleChange.SetEnergyChange(0.0);
  theParticleChange.SetWeightChange(fXSWeightFactor);
 
  if (!isShortLived) {
    auto aSec = new G4DynamicParticle(theSecondary, lv2);
    theParticleChange.AddSecondary(aSec, secID);
  } else {
    auto channel = theSecondary->GetDecayTable()->SelectADecayChannel(mass2);
    auto products = channel->DecayIt(mass2);
    G4ThreeVector bst1 = lv2.boostVector();
    G4int N = products->entries();
    for (G4int i=0; i<N; ++i) {
      auto p = (*products)[i];
      auto lvp = p->Get4Momentum();
      lvp.boost(bst1);
      auto pnew = new G4DynamicParticle(*p);
      pnew->Set4Momentum(lvp);
      theParticleChange.AddSecondary(pnew, secID);
    }
    delete products;
  }
 
  // recoil is a stable isotope
  if (nullptr != theRecoil) {
    auto aRec = new G4DynamicParticle(theRecoil, lv);
    theParticleChange.AddSecondary(aRec, secID);
  } else {
    // recoil is a fragment, which may be unstable
    G4Fragment frag(A, Z, lv);
    auto products = fHandler->BreakItUp(frag);
    for (auto & prod : *products) {
      auto dp = new G4DynamicParticle(prod->GetDefinition(), prod->GetMomentum());
      theParticleChange.AddSecondary(dp, secID);
      delete prod;
    }
    delete products;
  }
  return &theParticleChange;
}

operator!=()

G4bool G4ChargeExchange::operator!= ( const G4ChargeExchange & right ) const

delete

operator=()

const G4ChargeExchange & G4ChargeExchange::operator= ( const G4ChargeExchange & right )

delete

operator==()

G4bool G4ChargeExchange::operator== ( const G4ChargeExchange & right ) const

delete

SampleT()

G4double G4ChargeExchange::SampleT	(	const G4ParticleDefinition *	theSec,
		const G4int	A,
		const G4double	tmax ) const

Definition at line 279 of file G4ChargeExchange.cc.

{
  const G4double GeV2 = CLHEP::GeV*CLHEP::GeV;
  const G4double numLimit = 18.;
 
  G4double tmax = ltmax/GeV2;
  if (verboseLevel > 1) {
    G4cout << "G4ChargeExchange::SampleT tmax(GeV^2)=" << tmax << G4endl;
  }
 
  G4double aa, bb, cc, dd;
  G4Pow* g4pow = G4Pow::GetInstance();
  G4double a13 = g4pow->Z13(A);
  if (A <= 62) {
    aa = (A*A);
    bb = 14.5*a13*a13;
    cc = 1.4*a13;
    dd = 10.;
  } else {
    aa = g4pow->powZ(A, 1.33);
    bb = 60.*a13;
    cc = 0.4*g4pow->powZ(A, 0.40);
    dd = 10.;
  }
  G4double q1 = 1.0 - G4Exp(-std::min(bb*tmax, numLimit));
  G4double q2 = 1.0 - G4Exp(-std::min(dd*tmax, numLimit));
  G4double s1 = q1*aa;
  G4double s2 = q2*cc;
  if ((s1 + s2)*G4UniformRand() < s2) {
    q1 = q2;
    bb = dd;
  }
  return -GeV2*G4Log(1.0 - G4UniformRand()*q1)/bb;
}

Referenced by ApplyYourself().

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

• G4ChargeExchange.hh
• G4ChargeExchange.cc