G4WentzelVIRelModel Class Reference

#include <G4WentzelVIRelModel.hh>

Inheritance diagram for G4WentzelVIRelModel:

Public Member Functions
	G4WentzelVIRelModel (const G4String &nam="WentzelVIUni")
virtual	~G4WentzelVIRelModel ()
virtual void	Initialise (const G4ParticleDefinition *, const G4DataVector &)
void	StartTracking (G4Track *)
virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double KineticEnergy, G4double AtomicNumber, G4double AtomicWeight=0., G4double cut=DBL_MAX, G4double emax=DBL_MAX)
virtual G4ThreeVector &	SampleScattering (const G4ThreeVector &, G4double safety)
virtual G4double	ComputeTruePathLengthLimit (const G4Track &track, G4double &currentMinimalStep)
virtual G4double	ComputeGeomPathLength (G4double truePathLength)
virtual G4double	ComputeTrueStepLength (G4double geomStepLength)
Public Member Functions inherited from G4VMscModel
	G4VMscModel (const G4String &nam)
virtual	~G4VMscModel ()
virtual void	SampleSecondaries (std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin, G4double tmax)
void	SetStepLimitType (G4MscStepLimitType)
void	SetLateralDisplasmentFlag (G4bool val)
void	SetRangeFactor (G4double)
void	SetGeomFactor (G4double)
void	SetSkin (G4double)
void	SetSampleZ (G4bool)
G4VEnergyLossProcess *	GetIonisation () const
void	SetIonisation (G4VEnergyLossProcess *, const G4ParticleDefinition *part)
G4double	ComputeSafety (const G4ThreeVector &position, G4double limit)
G4double	ComputeGeomLimit (const G4Track &, G4double &presafety, G4double limit)
G4double	GetDEDX (const G4ParticleDefinition *part, G4double kineticEnergy, const G4MaterialCutsCouple *couple)
G4double	GetRange (const G4ParticleDefinition *part, G4double kineticEnergy, const G4MaterialCutsCouple *couple)
G4double	GetEnergy (const G4ParticleDefinition *part, G4double range, const G4MaterialCutsCouple *couple)
G4double	GetTransportMeanFreePath (const G4ParticleDefinition *part, G4double kinEnergy)
Public Member Functions inherited from G4VEmModel
	G4VEmModel (const G4String &nam)
virtual	~G4VEmModel ()
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	ChargeSquareRatio (const G4Track &)
virtual G4double	GetChargeSquareRatio (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual G4double	GetParticleCharge (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
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	SetupForMaterial (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
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

Additional Inherited Members
Protected Member Functions inherited from G4VMscModel
G4ParticleChangeForMSC *	GetParticleChangeForMSC (const G4ParticleDefinition *p=0)
G4double	ConvertTrueToGeom (G4double &tLength, G4double &gLength)
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 G4VMscModel
G4double	facrange
G4double	facgeom
G4double	facsafety
G4double	skin
G4double	dtrl
G4double	lambdalimit
G4double	geomMin
G4double	geomMax
G4ThreeVector	fDisplacement
G4MscStepLimitType	steppingAlgorithm
G4bool	samplez
G4bool	latDisplasment
Protected Attributes inherited from G4VEmModel
G4ElementData *	fElementData
G4VParticleChange *	pParticleChange
G4PhysicsTable *	xSectionTable
const std::vector< G4double > *	theDensityFactor
const std::vector< G4int > *	theDensityIdx
size_t	idxTable

Detailed Description

Definition at line 69 of file G4WentzelVIRelModel.hh.

Constructor & Destructor Documentation

G4WentzelVIRelModel::G4WentzelVIRelModel

(

const G4String &

nam = "WentzelVIUni"

)

Definition at line 73 of file G4WentzelVIRelModel.cc.

References python.hepunit::eV, G4Pow::GetInstance(), G4NistManager::Instance(), G4LossTableManager::Instance(), and python.hepunit::mm.

                                                            :
  G4VMscModel(nam),
  numlimit(0.1),
  currentCouple(0),
  cosThetaMin(1.0),
  inside(false),
  singleScatteringMode(false)
{
  invsqrt12 = 1./sqrt(12.);
  tlimitminfix = 1.e-6*mm;
  lowEnergyLimit = 1.0*eV;
  particle = 0;
  nelments = 5;
  xsecn.resize(nelments);
  prob.resize(nelments);
  theManager = G4LossTableManager::Instance();
  fNistManager = G4NistManager::Instance();
  fG4pow = G4Pow::GetInstance();
  wokvi = new G4WentzelVIRelXSection();

  preKinEnergy = tPathLength = zPathLength = lambdaeff = currentRange = xtsec = 0;
  currentMaterialIndex = 0;
  cosThetaMax = cosTetMaxNuc = 1.0;

  fParticleChange = 0;
  currentCuts = 0;
  currentMaterial = 0;
}

G4WentzelVIRelModel::~G4WentzelVIRelModel ( )

virtual

Definition at line 104 of file G4WentzelVIRelModel.cc.

{
  delete wokvi;
}

Member Function Documentation

G4double G4WentzelVIRelModel::ComputeCrossSectionPerAtom ( const G4ParticleDefinition *  p, G4double  KineticEnergy, G4double  AtomicNumber, G4double  AtomicWeight = 0., G4double  cut = DBL_MAX, G4double  emax = DBL_MAX  )

virtual

Reimplemented from G4VEmModel.

Definition at line 133 of file G4WentzelVIRelModel.cc.

References G4WentzelVIRelXSection::ComputeTransportCrossSectionPerAtom(), G4VEmModel::CurrentCouple(), FatalException, G4Exception(), G4lrint(), G4WentzelVIRelXSection::SetupKinematic(), and G4WentzelVIRelXSection::SetupTarget().

{
  G4double cross = 0.0;
  if(p != particle) { SetupParticle(p); }
  if(kinEnergy < lowEnergyLimit) { return cross; }
  if(!CurrentCouple()) {
    G4Exception("G4WentzelVIRelModel::ComputeCrossSectionPerAtom", "em0011",
        FatalException, " G4MaterialCutsCouple is not defined");
    return 0.0;
  }
  DefineMaterial(CurrentCouple());
  cosTetMaxNuc = wokvi->SetupKinematic(kinEnergy, currentMaterial);
  if(cosTetMaxNuc < 1.0) {
    cosTetMaxNuc = wokvi->SetupTarget(G4lrint(Z), cutEnergy);
    cross = wokvi->ComputeTransportCrossSectionPerAtom(cosTetMaxNuc);
    /*
    if(p->GetParticleName() == "e-")      
    G4cout << "G4WentzelVIRelModel::CS: Z= " << G4int(Z) << " e(MeV)= " << kinEnergy 
       << " 1-cosN= " << 1 - cosTetMaxNuc << " cross(bn)= " << cross/barn
       << " " << particle->GetParticleName() << G4endl;
    */
  }
  return cross;
}

G4double G4WentzelVIRelModel::ComputeGeomPathLength ( G4double  truePathLength )

virtual

Reimplemented from G4VMscModel.

Definition at line 268 of file G4WentzelVIRelModel.cc.

References DBL_MAX, G4Exp(), G4VMscModel::GetEnergy(), G4VMscModel::GetTransportMeanFreePath(), and G4WentzelVIRelXSection::SetupKinematic().

{
  tPathLength  = truelength;
  zPathLength  = tPathLength;

  if(lambdaeff > 0.0 && lambdaeff != DBL_MAX) {
    G4double tau = tPathLength/lambdaeff;
    //G4cout << "ComputeGeomPathLength: tLength= " << tPathLength
    //   << " Leff= " << lambdaeff << " tau= " << tau << G4endl; 
    // small step
    if(tau < numlimit) {
      zPathLength *= (1.0 - 0.5*tau + tau*tau/6.0);

      // medium step
    } else {
      G4double e1 = 0.0;
      if(currentRange > tPathLength) {
    e1 = GetEnergy(particle,currentRange-tPathLength,currentCouple);
      }
      e1 = 0.5*(e1 + preKinEnergy);
      cosTetMaxNuc = wokvi->SetupKinematic(e1, currentMaterial);
      lambdaeff = GetTransportMeanFreePath(particle,e1);
      zPathLength = lambdaeff*(1.0 - G4Exp(-tPathLength/lambdaeff));
    }
  } else { lambdaeff = DBL_MAX; }
  //G4cout<<"Comp.geom: zLength= "<<zPathLength<<" tLength= "<<tPathLength<<G4endl;
  return zPathLength;
}

G4double G4WentzelVIRelModel::ComputeTruePathLengthLimit ( const G4Track &  track, G4double &  currentMinimalStep  )

virtual

Reimplemented from G4VMscModel.

Definition at line 172 of file G4WentzelVIRelModel.cc.

References G4VMscModel::ComputeGeomLimit(), G4VMscModel::ComputeSafety(), G4VMscModel::ConvertTrueToGeom(), G4VMscModel::facgeom, G4VMscModel::facrange, G4VMscModel::facsafety, fGeomBoundary, fUseDistanceToBoundary, G4Track::GetDynamicParticle(), G4DynamicParticle::GetKineticEnergy(), G4Track::GetMaterialCutsCouple(), G4StepPoint::GetPosition(), G4Step::GetPreStepPoint(), G4ProductionCuts::GetProductionCut(), G4MaterialCutsCouple::GetProductionCuts(), G4Material::GetRadlen(), G4VMscModel::GetRange(), G4StepPoint::GetSafety(), G4Track::GetStep(), G4StepPoint::GetStepStatus(), G4VMscModel::GetTransportMeanFreePath(), G4INCL::Math::max(), G4INCL::Math::min(), G4WentzelVIRelXSection::SetupKinematic(), G4InuclParticleNames::sp, and G4VMscModel::steppingAlgorithm.

{
  G4double tlimit = currentMinimalStep;
  const G4DynamicParticle* dp = track.GetDynamicParticle();
  G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
  G4StepStatus stepStatus = sp->GetStepStatus();
  singleScatteringMode = false;
  //G4cout << "G4WentzelVIRelModel::ComputeTruePathLengthLimit stepStatus= " 
  //     << stepStatus << G4endl;


  // initialisation for each step, lambda may be computed from scratch
  preKinEnergy  = dp->GetKineticEnergy();
  DefineMaterial(track.GetMaterialCutsCouple());
  lambdaeff = GetTransportMeanFreePath(particle,preKinEnergy);
  currentRange = GetRange(particle,preKinEnergy,currentCouple);
  cosTetMaxNuc = wokvi->SetupKinematic(preKinEnergy, currentMaterial);

  // extra check for abnormal situation
  // this check needed to run MSC with eIoni and eBrem inactivated
  if(tlimit > currentRange) { tlimit = currentRange; }

  // stop here if small range particle
  if(inside || tlimit < tlimitminfix) { 
    return ConvertTrueToGeom(tlimit, currentMinimalStep); 
  }

  // pre step
  G4double presafety = sp->GetSafety();
  // far from geometry boundary
  if(currentRange < presafety) {
    inside = true;  
    return ConvertTrueToGeom(tlimit, currentMinimalStep);
  }

  // compute presafety again if presafety <= 0 and no boundary
  // i.e. when it is needed for optimization purposes
  if(stepStatus != fGeomBoundary && presafety < tlimitminfix) {
    presafety = ComputeSafety(sp->GetPosition(), tlimit); 
    if(currentRange < presafety) {
      inside = true;  
      return ConvertTrueToGeom(tlimit, currentMinimalStep);
    }
  }
  /*  
  G4cout << "e(MeV)= " << preKinEnergy/MeV
     << "  " << particle->GetParticleName() 
     << " CurLimit(mm)= " << tlimit/mm <<" safety(mm)= " << presafety/mm
     << " R(mm)= " <<currentRange/mm
     << " L0(mm^-1)= " << lambdaeff*mm 
     <<G4endl;
  */

  // natural limit for high energy
  G4double rlimit = std::max(facrange*currentRange, 
                 0.7*(1.0 - cosTetMaxNuc)*lambdaeff);

  // low-energy e-
  if(cosThetaMax > cosTetMaxNuc) {
    rlimit = std::min(rlimit, facsafety*presafety);
  }
   
  // cut correction
  G4double rcut = currentCouple->GetProductionCuts()->GetProductionCut(1);
  //G4cout << "rcut= " << rcut << " rlimit= " << rlimit << " presafety= " << presafety 
  // << " 1-cosThetaMax= " <<1-cosThetaMax << " 1-cosTetMaxNuc= " << 1-cosTetMaxNuc
  // << G4endl;
  if(rcut > rlimit) { rlimit = std::min(rlimit, rcut*sqrt(rlimit/rcut)); }

  if(rlimit < tlimit) { tlimit = rlimit; }

  tlimit = std::max(tlimit, tlimitminfix);

  // step limit in infinite media
  tlimit = std::min(tlimit, 50*currentMaterial->GetRadlen()/facgeom);

  //compute geomlimit and force few steps within a volume
  if (steppingAlgorithm == fUseDistanceToBoundary && stepStatus == fGeomBoundary)
    {
      G4double geomlimit = ComputeGeomLimit(track, presafety, currentRange);
      tlimit = std::min(tlimit, geomlimit/facgeom);
    } 

  /*  
  G4cout << particle->GetParticleName() << " e= " << preKinEnergy
     << " L0= " << lambdaeff << " R= " << currentRange
     << "tlimit= " << tlimit  
     << " currentMinimalStep= " << currentMinimalStep << G4endl;
  */
  return ConvertTrueToGeom(tlimit, currentMinimalStep);
}

G4double G4WentzelVIRelModel::ComputeTrueStepLength ( G4double  geomStepLength )

virtual

Reimplemented from G4VMscModel.

Definition at line 299 of file G4WentzelVIRelModel.cc.

References DBL_MAX, G4Log(), G4VMscModel::GetEnergy(), G4VMscModel::GetTransportMeanFreePath(), and G4WentzelVIRelXSection::SetupKinematic().

{
  // initialisation of single scattering x-section
  xtsec = 0.0;
  cosThetaMin = cosTetMaxNuc;

  //G4cout << "Step= " << geomStepLength << "  Lambda= " <<  lambdaeff 
  //     << " 1-cosThetaMaxNuc= " << 1 - cosTetMaxNuc << G4endl;
  // pathalogical case
  if(lambdaeff == DBL_MAX) { 
    singleScatteringMode = true;
    zPathLength  = geomStepLength;
    tPathLength  = geomStepLength;
    cosThetaMin = 1.0;

    // normal case
  } else {

    // small step use only single scattering
    static const G4double singleScatLimit = 1.0e-7;
    if(geomStepLength < lambdaeff*singleScatLimit*(1.0 - cosTetMaxNuc)) {
      singleScatteringMode = true;
      cosThetaMin = 1.0;
      zPathLength  = geomStepLength;
      tPathLength  = geomStepLength;

      // step defined by transportation 
    } else if(geomStepLength != zPathLength) { 

      // step defined by transportation 
      zPathLength  = geomStepLength;
      G4double tau = geomStepLength/lambdaeff;
      tPathLength  = zPathLength*(1.0 + 0.5*tau + tau*tau/3.0); 

      // energy correction for a big step
      if(tau > numlimit) {
    G4double e1 = 0.0;
    if(currentRange > tPathLength) {
      e1 = GetEnergy(particle,currentRange-tPathLength,currentCouple);
    }
    e1 = 0.5*(e1 + preKinEnergy);
    cosTetMaxNuc = wokvi->SetupKinematic(e1, currentMaterial);
    lambdaeff = GetTransportMeanFreePath(particle,e1);
    tau = zPathLength/lambdaeff;
      
    if(tau < 0.999999) { tPathLength = -lambdaeff*G4Log(1.0 - tau); } 
    else               { tPathLength = currentRange; }
      }
    }
  }

  // check of step length
  // define threshold angle between single and multiple scattering 
  if(!singleScatteringMode) { cosThetaMin = 1.0 - 1.5*tPathLength/lambdaeff; }

  // recompute transport cross section - do not change energy
  // anymore - cannot be applied for big steps
  if(cosThetaMin > cosTetMaxNuc) {

    // new computation
    G4double cross = ComputeXSectionPerVolume();
    //G4cout << "%%%% cross= " << cross << "  xtsec= " << xtsec << G4endl;
    if(cross <= 0.0) {
      singleScatteringMode = true;
      tPathLength = zPathLength; 
      lambdaeff = DBL_MAX;
    } else if(xtsec > 0.0) {

      lambdaeff = 1./cross; 
      G4double tau = zPathLength*cross;
      if(tau < numlimit) { tPathLength = zPathLength*(1.0 + 0.5*tau + tau*tau/3.0); } 
      else if(tau < 0.999999) { tPathLength = -lambdaeff*G4Log(1.0 - tau); } 
      else                    { tPathLength = currentRange; }

      if(tPathLength > currentRange) { tPathLength = currentRange; }
    } 
  }

  /*      
  G4cout <<"Comp.true: zLength= "<<zPathLength<<" tLength= "<<tPathLength
     <<" Leff(mm)= "<<lambdaeff/mm<<" sig0(1/mm)= " << xtsec <<G4endl;
  G4cout << particle->GetParticleName() << " 1-cosThetaMin= " << 1-cosThetaMin
     << " 1-cosTetMaxNuc= " << 1-cosTetMaxNuc 
     << " e(MeV)= " << preKinEnergy/MeV << "  "  << singleScatteringMode << G4endl;
  */
  return tPathLength;
}

void G4WentzelVIRelModel::Initialise ( const G4ParticleDefinition *  p, const G4DataVector &  cuts  )

virtual

Implements G4VEmModel.

Definition at line 111 of file G4WentzelVIRelModel.cc.

References G4VMscModel::GetParticleChangeForMSC(), G4WentzelVIRelXSection::Initialise(), and G4VEmModel::PolarAngleLimit().

{
  // reset parameters
  SetupParticle(p);
  currentRange = 0.0;

  cosThetaMax = cos(PolarAngleLimit());
  wokvi->Initialise(p, cosThetaMax);
  /*  
  G4cout << "G4WentzelVIRelModel: " << particle->GetParticleName()
         << "  1-cos(ThetaLimit)= " << 1 - cosThetaMax 
     << G4endl;
  */
  currentCuts = &cuts;

  // set values of some data members
  fParticleChange = GetParticleChangeForMSC(p);
}

G4ThreeVector & G4WentzelVIRelModel::SampleScattering ( const G4ThreeVector &  oldDirection, G4double  safety  )

virtual

Reimplemented from G4VMscModel.

Definition at line 390 of file G4WentzelVIRelModel.cc.

References DBL_MAX, G4VMscModel::fDisplacement, G4Exp(), G4Log(), G4lrint(), G4UniformRand, G4Material::GetElementVector(), G4Material::GetNumberOfElements(), G4VMscModel::latDisplasment, G4ParticleChangeForMSC::ProposeMomentumDirection(), CLHEP::Hep3Vector::rotateUz(), G4WentzelVIRelXSection::SampleSingleScattering(), CLHEP::Hep3Vector::set(), G4WentzelVIRelXSection::SetupTarget(), G4INCL::DeJongSpin::shoot(), python.hepunit::twopi, z, and G4InuclParticleNames::z0.

{
  fDisplacement.set(0.0,0.0,0.0);
  //G4cout << "!##! G4WentzelVIRelModel::SampleScattering for " 
  //     << particle->GetParticleName() << G4endl;

  // ignore scattering for zero step length and energy below the limit
  if(preKinEnergy < lowEnergyLimit || tPathLength <= 0.0) 
    { return fDisplacement; }
  
  G4double invlambda = 0.0;
  if(lambdaeff < DBL_MAX) { invlambda = 0.5/lambdaeff; }

  // use average kinetic energy over the step
  G4double cut = (*currentCuts)[currentMaterialIndex];
  /*
  G4cout <<"SampleScat: E0(MeV)= "<< preKinEnergy/MeV
     << " Leff= " << lambdaeff <<" sig0(1/mm)= " << xtsec 
     << " xmsc= " <<  tPathLength*invlambda << " safety= " << safety << G4endl;
  */

  // step limit due msc
  G4double x0 = tPathLength;
  //  const G4double thinlimit = 0.5; 
  static const G4double thinlimit = 0.1; 
  G4int nMscSteps = 1;
  // large scattering angle case - two step approach
  if(tPathLength*invlambda > thinlimit && safety > tlimitminfix) { 
    x0 *= 0.5; 
    nMscSteps = 2; 
  } 

  // step limit due to single scattering
  G4double x1 = 2*tPathLength;
  if(0.0 < xtsec) { x1 = -G4Log(G4UniformRand())/xtsec; }

  const G4ElementVector* theElementVector = 
    currentMaterial->GetElementVector();
  G4int nelm = currentMaterial->GetNumberOfElements();

  // geometry
  G4double sint, cost, phi;
  G4ThreeVector temp(0.0,0.0,1.0);

  // current position and direction relative to the end point
  // because of magnetic field geometry is computed relatively to the 
  // end point of the step 
  G4ThreeVector dir(0.0,0.0,1.0);
  fDisplacement.set(0.0,0.0,-zPathLength);
  G4double mscfac = zPathLength/tPathLength;

  // start a loop 
  G4double x2 = x0;
  G4double step, z;
  G4bool singleScat;
  /*
    G4cout << "Start of the loop x1(mm)= " << x1 << "  x2(mm)= " << x2 
     << " 1-cost1= " << 1 - cosThetaMin << "  " << singleScatteringMode 
     << " xtsec= " << xtsec << G4endl;
  */
  do {

    // single scattering case
    if(x1 < x2) { 
      step = x1;
      singleScat = true;
    } else {
      step = x2;
      singleScat = false;
    }

    // new position
    fDisplacement += step*mscfac*dir;

    if(singleScat) {

      // select element
      G4int i = 0;
      if(nelm > 1) {
    G4double qsec = G4UniformRand()*xtsec;
    for (; i<nelm; ++i) { if(xsecn[i] >= qsec) { break; } }
      }
      G4double cosTetM = 
    wokvi->SetupTarget(G4lrint((*theElementVector)[i]->GetZ()), cut);
      //G4cout << "!!! " << cosThetaMin << "  " << cosTetM << "  " << prob[i] << G4endl;
      temp = wokvi->SampleSingleScattering(cosThetaMin, cosTetM, prob[i]);

      // direction is changed
      temp.rotateUz(dir);
      dir = temp;

      // new proposed step length
      x1  = -G4Log(G4UniformRand())/xtsec; 
      x2 -= step; 
      if(x2 <= 0.0) { --nMscSteps; }

    // multiple scattering
    } else { 
      --nMscSteps;
      x1 -= step;
      x2  = x0;

      // for multiple scattering x0 should be used as a step size
      if(!singleScatteringMode) {
        G4double z0 = x0*invlambda;

    // correction to keep first moment
 
    // sample z in interval 0 - 1
        if(z0 > 5.0) { z = G4UniformRand(); }
    else {
      G4double zzz = 0.0;
      if(z0 > 0.01) { zzz = G4Exp(-1.0/z0); }
      z = -z0*G4Log(1.0 - (1.0 - zzz)*G4UniformRand());
      //  /(1.0 - (1.0/z0 + 1.0)*zzz); 
    }

    cost = 1.0 - 2.0*z/*factCM*/;
    if(cost > 1.0)       { cost = 1.0; }
    else if(cost < -1.0) { cost =-1.0; }
    sint = sqrt((1.0 - cost)*(1.0 + cost));
    phi  = twopi*G4UniformRand();
    G4double vx1 = sint*cos(phi);
    G4double vy1 = sint*sin(phi);

    // change direction
    temp.set(vx1,vy1,cost);
    temp.rotateUz(dir);
    dir = temp;

    // lateral displacement  
    if (latDisplasment && x0 > tlimitminfix) {
      G4double rms = invsqrt12*sqrt(2*z0);
          G4double r   = x0*mscfac;
      G4double dx  = r*(0.5*vx1 + rms*G4RandGauss::shoot(0.0,1.0));
      G4double dy  = r*(0.5*vy1 + rms*G4RandGauss::shoot(0.0,1.0));
      G4double dz;
      G4double d   = r*r - dx*dx - dy*dy;
      if(d >= 0.0)  { dz = sqrt(d) - r; }
      else          { dx = dy = dz = 0.0; }

      // change position
      temp.set(dx,dy,dz);
      temp.rotateUz(dir); 
      fDisplacement += temp;
    }
      }
    }
  } while (0 < nMscSteps);
    
  dir.rotateUz(oldDirection);

  //G4cout << "G4WentzelVIRelModel sampling of scattering is done" << G4endl;
  // end of sampling -------------------------------

  fParticleChange->ProposeMomentumDirection(dir);

  // lateral displacement  
  fDisplacement.rotateUz(oldDirection);

  /*            
     G4cout << " r(mm)= " << fDisplacement.mag() 
        << " safety= " << safety
        << " trueStep(mm)= " << tPathLength
        << " geomStep(mm)= " << zPathLength
        << " x= " << fDisplacement.x() 
        << " y= " << fDisplacement.y() 
        << " z= " << fDisplacement.z()
        << G4endl;
  */

  //G4cout<< "G4WentzelVIRelModel::SampleScattering end NewDir= " << dir<< G4endl;
  return fDisplacement;
}

void G4WentzelVIRelModel::StartTracking ( G4Track *  track )

virtual

Reimplemented from G4VEmModel.

Definition at line 164 of file G4WentzelVIRelModel.cc.

References G4DynamicParticle::GetDefinition(), and G4Track::GetDynamicParticle().

{
  SetupParticle(track->GetDynamicParticle()->GetDefinition());
  inside = false;
}

---

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

• G4WentzelVIRelModel.hh
• G4WentzelVIRelModel.cc