#include <G4GoudsmitSaundersonMscModel.hh>

Inheritance diagram for G4GoudsmitSaundersonMscModel:

Collaboration diagram for G4GoudsmitSaundersonMscModel:

Public Member Functions
	G4GoudsmitSaundersonMscModel (const G4String &nam="GoudsmitSaunderson")

virtual	~G4GoudsmitSaundersonMscModel ()

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

void	StartTracking (G4Track *)

G4double	GetTransportMeanFreePath (const G4ParticleDefinition *, G4double)

void	SingleScattering (G4double &cost, G4double &sint)

void	SampleMSC ()

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)

void	SetOptionPWAScreening (G4bool opt)

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) override

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=DBL_MAX)

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	GetPartialCrossSection (const G4Material , G4int level, const G4ParticleDefinition , G4double kineticEnergy)

virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A=0., G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)

virtual G4double	ComputeCrossSectionPerShell (const G4ParticleDefinition *, G4int Z, G4int shellIdx, G4double kinEnergy, 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 *)

virtual void	ModelDescription (std::ostream &outFile) const

void	InitialiseElementSelectors (const G4ParticleDefinition *, const G4DataVector &)

std::vector < G4EmElementSelector * > *	GetElementSelectors ()

void	SetElementSelectors (std::vector< G4EmElementSelector * > *)

virtual 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=nullptr)

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	SetFluctuationFlag (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

const G4Isotope *	GetCurrentIsotope () const

G4bool	IsLocked () const

void	SetLocked (G4bool)

Additional Inherited Members
Protected Member Functions inherited from G4VMscModel
G4ParticleChangeForMSC *	GetParticleChangeForMSC (const G4ParticleDefinition *p=nullptr)

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

G4bool	lossFlucFlag

Static Protected Attributes inherited from G4VEmModel
static const G4double	inveplus = 1.0/CLHEP::eplus

Detailed Description

Definition at line 111 of file G4GoudsmitSaundersonMscModel.hh.

Constructor & Destructor Documentation

G4GoudsmitSaundersonMscModel::G4GoudsmitSaundersonMscModel ( const G4String & nam = "GoudsmitSaunderson" )

Definition at line 125 of file G4GoudsmitSaundersonMscModel.cc.

   : G4VMscModel(nam),lowKEnergy(0.1*keV),highKEnergy(1.*GeV) {
   charge               = 0;
   currentMaterialIndex = -1;
 
   lambdalimit   = 1.*mm ;
   fr            = 0.02     ;
   rangeinit     = 0.;
   geombig       = 1.e50*mm;
   geomlimit     = geombig;
   tgeom         = geombig;
   tlimit        = 1.e+10*mm;
   presafety     = 0.*mm;
 
   particle         = 0;
   theManager       = G4LossTableManager::Instance();
   firstStep        = true;
   currentKinEnergy = 0.0;
   currentRange     = 0.0;
 
   tlimitminfix2 = 1.*nm;
   par1=par2=par3= 0.0;
   tausmall      = 1.e-16;
   mass          = electron_mass_c2;
   taulim        = 1.e-6;
 
   currentCouple = 0;
   fParticleChange = 0;
 
   // by default Moliere screeing parameter will be used but it can be set to the
   // PWA screening before calling the Initialise method
   fIsUsePWATotalXsecData = false;
 
   //*****************
   fLambda0 = 0.0; // elastic mean free path
   fLambda1 = 0.0; // first transport mean free path
   fScrA    = 0.0; // screening parameter
   fG1      = 0.0; // first transport coef.
   //******************
   fTheTrueStepLenght    = 0.;
   fTheTransportDistance = 0.;
   fTheZPathLenght       = 0.;
   fTheDisplacementVector.set(0.,0.,0.);
   fTheNewDirection.set(0.,0.,1.);
 
   fIsEverythingWasDone  = false;
   fIsMultipleSacettring = false;
   fIsSingleScattering   = false;
   fIsEndedUpOnBoundary  = false;
   fIsNoScatteringInMSC  = false;
   fIsNoDisplace         = false;
   fIsInsideSkin         = false;
   fIsWasOnBoundary      = false;
   fIsFirstRealStep      = false;
 
   fZeff = 1.;
   //+++++++++++++
 
   rndmEngineMod = G4Random::getTheEngine();
 
   //===================  base
   facsafety     = 0.6;
 }

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G4GoudsmitSaundersonMscModel::~G4GoudsmitSaundersonMscModel ( )

virtual

Definition at line 190 of file G4GoudsmitSaundersonMscModel.cc.

                                                            {
   if(IsMaster()){
     if(fgGSTable){
       delete fgGSTable;
       fgGSTable = 0;
     }
     if(fgPWAXsecTable){
       delete fgPWAXsecTable;
       fgPWAXsecTable = 0;
     }
   }
 }

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Member Function Documentation

G4double G4GoudsmitSaundersonMscModel::ComputeGeomPathLength ( G4double truePathLength )

virtual

Reimplemented from G4VMscModel.

Definition at line 702 of file G4GoudsmitSaundersonMscModel.cc.

 {
   //
   // convert true ->geom
   // It is called from the step limitation ComputeTruePathLengthLimit if
   // !fIsEverythingWasDone but protect:
   //
   par1 = -1. ;
   par2 = par3 = 0. ;
 
   // if fIsEverythingWasDone = TRUE  => fTheZPathLenght is already set
   // so return with the already known value
   // Otherwise:
   if(!fIsEverythingWasDone) {
      // this correction needed to run MSC with eIoni and eBrem inactivated
      // and makes no harm for a normal run
      fTheTrueStepLenght = std::min(fTheTrueStepLenght,currentRange);
 
      //  do the true -> geom transformation
      fTheZPathLenght = fTheTrueStepLenght;
 
      // z = t for very small true-path-length
      if(fTheTrueStepLenght < tlimitminfix2) return fTheZPathLenght;
 
      G4double tau = fTheTrueStepLenght/fLambda1;
 
      if (tau <= tausmall) {
        fTheZPathLenght = std::min(fTheTrueStepLenght, fLambda1);
      } else  if (fTheTrueStepLenght < currentRange*dtrl) {
        if(tau < taulim) fTheZPathLenght = fTheTrueStepLenght*(1.-0.5*tau) ;
        else             fTheZPathLenght = fLambda1*(1.-G4Exp(-tau));
      } else if(currentKinEnergy < mass || fTheTrueStepLenght == currentRange)  {
        par1 = 1./currentRange ;     // alpha =1/range_init for Ekin<mass
        par2 = 1./(par1*fLambda1) ;  // 1/(alphaxlambda01)
        par3 = 1.+par2 ;             // 1+1/
        if(fTheTrueStepLenght < currentRange) {
            fTheZPathLenght = 1./(par1*par3) * (1.-std::pow(1.-par1*fTheTrueStepLenght,par3));
        } else {
          fTheZPathLenght = 1./(par1*par3);
        }
 
     } else {
       G4double rfin = std::max(currentRange-fTheTrueStepLenght, 0.01*currentRange);
       G4double T1 = GetEnergy(particle,rfin,currentCouple);
       G4double lambda1 = GetTransportMeanFreePathOnly(particle,T1);
 
       par1 = (fLambda1-lambda1)/(fLambda1*fTheTrueStepLenght);  // alpha
       par2 = 1./(par1*fLambda1);
       par3 = 1.+par2 ;
       G4Pow *g4calc = G4Pow::GetInstance();
       fTheZPathLenght = 1./(par1*par3) * (1.-g4calc->powA(1.-par1*fTheTrueStepLenght,par3));
     }
   }
   fTheZPathLenght = std::min(fTheZPathLenght, fLambda1);
 
  return fTheZPathLenght;
 }

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G4double G4GoudsmitSaundersonMscModel::ComputeTruePathLengthLimit	(	const G4Track &	track,
		G4double &	currentMinimalStep
	)

virtual

Reimplemented from G4VMscModel.

Definition at line 374 of file G4GoudsmitSaundersonMscModel.cc.

                                                                                      {
 
   G4double skindepth = 0.;
 
   const G4DynamicParticle* dp = track.GetDynamicParticle();
 
   G4StepPoint* sp = track.GetStep()->GetPreStepPoint();
   G4StepStatus stepStatus = sp->GetStepStatus();
   currentCouple = track.GetMaterialCutsCouple();
   SetCurrentCouple(currentCouple);
   currentMaterialIndex = currentCouple->GetIndex();
   currentKinEnergy = dp->GetKineticEnergy();
   currentRange = GetRange(particle,currentKinEnergy,currentCouple);
 
 
 
   // *** Elastic and first transport mfp, fScrA and fG1 are also set in this !!!
   fLambda1 = GetTransportMeanFreePath(particle,currentKinEnergy);
 
   //
   // Set initial values:
   //  : lengths are initialised to currentMinimalStep  which is the true, minimum
   //    step length from all other physics
   fTheTrueStepLenght    = currentMinimalStep;
   fTheTransportDistance = currentMinimalStep;
   fTheZPathLenght       = currentMinimalStep;  // will need to be converted
   fTheDisplacementVector.set(0.,0.,0.);
   fTheNewDirection.set(0.,0.,1.);
 
   // Can everything be done in the step limit phase ?
   fIsEverythingWasDone  = false;
   // Multiple scattering needs to be sample ?
   fIsMultipleSacettring = false;
   // Single scattering needs to be sample ?
   fIsSingleScattering   = false;
   // Was zero deflection in multiple scattering sampling ?
   fIsNoScatteringInMSC  = false;
   // Do not care about displacement in MSC sampling
   // ( used only in the case of fgIsOptimizationOn = true)
   fIsNoDisplace = false;
 
   // get pre-step point safety
   presafety = sp->GetSafety();
 
   // Zeff  = TotNbOfElectPerVolume/TotNbOfAtomsPerVolume
   fZeff = currentCouple->GetMaterial()->GetIonisation()->GetZeffective();
 
   // distance will take into account max-fluct.
   G4double distance = currentRange;
   distance *= (1.20-fZeff*(1.62e-2-9.22e-5*fZeff));
 
 
 
   //
   // Possible optimization : if the distance is samller than the safety -> the
   // particle will never leave this volume -> dispalcement
   // as the effect of multiple elastic scattering can be skipped
   // Important : this optimization can cause problems if one does scoring
   // in a bigger volume since MSC won't be done deep inside the volume when
   // distance < safety so don't use optimized-mode in such case.
   if( fgIsOptimizationOn && (distance < presafety) ) {
      // Indicate that we need to do MSC after transportation and no dispalcement.
      fIsMultipleSacettring = true;
      fIsNoDisplace = true;
   } else if( steppingAlgorithm == fUseDistanceToBoundary ){
        //Compute geomlimit (and presafety) :
        // - geomlimit will be:
        //    == the straight line distance to the boundary if currentRange is
        //       longer than that
        //    == a big value [geombig = 1.e50*mm] if currentRange is shorter than
        //       the straight line distance to the boundary
        // - presafety will be updated as well
        // So the particle can travell 'gemlimit' distance (along a straight
        // line!) in its current direction:
        //  (1) before reaching a boundary (geomlimit < geombig) OR
        //  (2) before reaching its current range (geomlimit == geombig)
        geomlimit = ComputeGeomLimit(track, presafety, currentRange);
 
        // Record that the particle is on a boundary
        if( (stepStatus==fGeomBoundary) || (stepStatus==fUndefined && presafety==0.0))
           fIsWasOnBoundary = true;
 
        // Set skin depth = skin x elastic_mean_free_path
        skindepth = skin*fLambda0;
        // Init the flag that indicates that the particle are within a skindepth
        // distance from a boundary
        fIsInsideSkin = false;
        // Check if we can try Single Scattering because we are within skindepth
        // distance from/to a boundary OR the current minimum true-step-length is
        // shorter than skindepth. NOTICE: the latest has only efficieny reasons
        // because the MSC angular sampling is fine for any short steps but much
        // faster to try single scattering in case of short steps.
        if( (stepStatus == fGeomBoundary) || (presafety < skindepth) || (fTheTrueStepLenght < skindepth)){
          // check if we are within skindepth distance from a boundary
          if( (stepStatus == fGeomBoundary) || (presafety < skindepth))
            fIsInsideSkin = true;
          //Try single scattering:
          // - sample distance to next single scattering interaction (sslimit)
          // - compare to current minimum length
          //      == if sslimit is the shorter:
          //          - set the step length to sslimit
          //          - indicate that single scattering needs to be done
          //      == else : nothing to do
          //- in both cases, the step length was very short so geometrical and
          //  true path length are the same
          G4double sslimit = -1.*fLambda0*G4Log(rndmEngineMod->flat());
          // compare to current minimum step length
          if(sslimit < fTheTrueStepLenght) {
            fTheTrueStepLenght  = sslimit;
            fIsSingleScattering = true;
          }
 
           // short step -> true step length equal to geometrical path length
           fTheZPathLenght     = fTheTrueStepLenght;
           // Set taht everything is done in step-limit phase so no MSC call
           // We will check if we need to perform the single-scattering angular
           // sampling i.e. if single elastic scattering was the winer!
           fIsEverythingWasDone = true;
        } else {
        // After checking we know that we cannot try single scattering so we will
        // need to make an MSC step
          // Indicate that we need to make and MSC step. We do not check if we can
          // do it now i.e. if presafety>final_true_step_length so we let the
          // fIsEverythingWasDone = false which indicates that we will perform
          // MSC after transportation.
          fIsMultipleSacettring = true;
 
          // Init the first-real-step falg: it will indicate if we do the first
          // non-single scattering step in this volume with this particle
          fIsFirstRealStep = false;
          // If previously the partcile was on boundary it was within skin as
          // well. When it is not within skin anymore it has just left the skin
          // so we make the first real MSC step with the particle.
          if(fIsWasOnBoundary && !fIsInsideSkin){
              // reset the 'was on boundary' indicator flag
              fIsWasOnBoundary = false;
              fIsFirstRealStep = true;
          }
 
          // If this is the first-real msc step (the partcile has just left the
          // skin) or this is the first step with the particle (was born or
          // primary):
          //   - set the initial range that will be used later to limit its step
          //     (only in this volume, because after boundary crossing at the
          //     first-real MSC step we will reset)
          //  - don't let the partcile to cross the volume just in one step
          if(firstStep || fIsFirstRealStep){
            rangeinit = currentRange;
            // If geomlimit < geombig than the particle might reach the boundary
            // along its initial direction before losing its energy (in this step)
            // Otherwise we can be sure that the particle will lose it energy
            // before reaching the boundary along a starigth line so there is no
            // geometrical limit appalied. [However, tgeom is set only in the
            // first or the first-real MSC step. After the first or first real
            // MSC step the direction will change tgeom won't guaranty anything!
            // But we will try to end up within skindepth from the boundary using
            // the actual value of geomlimit(See later at step reduction close to
            // boundary).]
            if(geomlimit < geombig){
                // transfrom straight line distance to the boundary to real step
                // length based on the mean values (using the prestep point
                // first-transport mean free path i.e. no energy loss correction)
                if((1.-geomlimit/fLambda1) > 0.)
                  geomlimit = -fLambda1*G4Log(1.-geomlimit/fLambda1);
               // the 2-different case that could lead us here
               if(firstStep)
                 tgeom = 2.*geomlimit/facgeom;
                else
                 tgeom = geomlimit/facgeom;
            } else {
              tgeom = geombig;
            }
          }
 
          // True step length limit from range factor. Noteice, that the initial
          // range is used that was set at the first step or first-real MSC step
          // in this volume with this particle.
          tlimit = facrange*rangeinit;
          // Take the minimum of the true step length limits coming from
          // geometrical constraint or range-factor limitation
          tlimit = std::min(tlimit,tgeom);
 
          // Step reduction close to boundary: we try to end up within skindepth
          // from the boundary ( Notice: in case of mag. field it might not work
          // because geomlimit is the straigth line distance to the boundary in
          // the currect direction (if geomlimit<geombig) and mag. field can
          // change the initial direction. So te particle might hit some boundary
          // before in a different direction. However, here we restrict the true
          // path length to this (straight line) lenght so the corresponding
          // transport distance (straight line) will be even shorter than
          // geomlimit-0.999*skindepth after the change of true->geom.
          if(geomlimit < geombig)
            tlimit = std::min(tlimit, geomlimit-0.999*skindepth);
 
          // randomize 1st step or 1st 'normal' step in volume
          if(firstStep || fIsFirstRealStep) {
             fTheTrueStepLenght = std::min(fTheTrueStepLenght, Randomizetlimit());
          } else {
            fTheTrueStepLenght = std::min(fTheTrueStepLenght, tlimit);
          }
     }
   } else if (steppingAlgorithm == fUseSafety) { // THE ERROR_FREE stepping alg.
     presafety =  ComputeSafety(sp->GetPosition(),fTheTrueStepLenght);
     geomlimit = presafety;
 
     // Set skin depth = skin x elastic_mean_free_path
     skindepth = skin*fLambda0;
     // Check if we can try Single Scattering because we are within skindepth
     // distance from/to a boundary OR the current minimum true-step-length is
     // shorter than skindepth. NOTICE: the latest has only efficieny reasons
     // because the MSC angular sampling is fine for any short steps but much
     // faster to try single scattering in case of short steps.
     if( (stepStatus == fGeomBoundary) || (presafety < skindepth) || (fTheTrueStepLenght < skindepth)){
       //Try single scattering:
       // - sample distance to next single scattering interaction (sslimit)
       // - compare to current minimum length
       //      == if sslimit is the shorter:
       //          - set the step length to sslimit
       //          - indicate that single scattering needs to be done
       //      == else : nothing to do
       //- in both cases, the step length was very short so geometrical and
       //  true path length are the same
       G4double sslimit = -1.*fLambda0*G4Log(rndmEngineMod->flat());
       // compare to current minimum step length
       if(sslimit < fTheTrueStepLenght) {
         fTheTrueStepLenght  = sslimit;
         fIsSingleScattering = true;
       }
 
        // short step -> true step length equal to geometrical path length
        fTheZPathLenght     = fTheTrueStepLenght;
        // Set taht everything is done in step-limit phase so no MSC call
        // We will check if we need to perform the single-scattering angular
        // sampling i.e. if single elastic scattering was the winer!
        fIsEverythingWasDone = true;
     } else {
     // After checking we know that we cannot try single scattering so we will
     // need to make an MSC step
       // Indicate that we need to make and MSC step.
       fIsMultipleSacettring = true;
       fIsEverythingWasDone  = true;
 
       // limit from range factor
       fTheTrueStepLenght = std::min(fTheTrueStepLenght, facrange*currentRange);
 
       // never let the particle go further than the safety if we are out of the skin
       // if we are here we are out of the skin, presafety > 0.
       if(fTheTrueStepLenght > presafety)
         fTheTrueStepLenght = std::min(fTheTrueStepLenght, presafety);
 
       // make sure that we are still within the aplicability of condensed histry model
       // i.e. true step length is not longer than first transport mean free path.
       // We schould take into account energy loss along 0.5x lambda_transport1
       // step length as well. So let it 0.4 x lambda_transport1
       fTheTrueStepLenght = std::min(fTheTrueStepLenght, fLambda1*0.4);
     }
   } else {
 
     // This is the default stepping algorithm: the fastest but the least
     // accurate that corresponds to fUseSafety in Urban model. Note, that GS
     // model can handle any short steps so we do not need the minimum limits
 
     // NO single scattering in case of skin or short steps (by defult the MSC
     // model will be single or even no scattering in case of short steps
     // compared to the elastic mean free path.)
 
     // indicate that MSC needs to be done (always and always after transportation)
     fIsMultipleSacettring = true;
 
       if( stepStatus != fGeomBoundary ) {
         presafety = ComputeSafety(sp->GetPosition(),fTheTrueStepLenght);
       }
 
       // Far from boundary-> in optimized mode do not sample dispalcement.
       if( (distance < presafety) && (fgIsOptimizationOn)) {
         fIsNoDisplace = true;
       } else {
         // Urban like
         if(firstStep || (stepStatus == fGeomBoundary)) {
           rangeinit = currentRange;
           fr = facrange;
 // We don't use this: we won't converge to the single scattering results with
 //                    decreasing range-factor.          
 //              rangeinit = std::max(rangeinit, fLambda1);
 //              if(fLambda1 > lambdalimit) {
 //                fr *= (0.75+0.25*fLambda1/lambdalimit);
 //              }
 
         }
 
         //step limit
         tlimit = std::max(fr*rangeinit, facsafety*presafety);
 
         // first step randomization
         if(firstStep || stepStatus == fGeomBoundary) {
           fTheTrueStepLenght = std::min(fTheTrueStepLenght, Randomizetlimit());
         } else {
           fTheTrueStepLenght = std::min(fTheTrueStepLenght, tlimit);
         }
       }
   }
 
   // unset first-step
   firstStep =false;
 
   // performe single scattering, multiple scattering if this later can be done safely here
   if(fIsEverythingWasDone){
     if(fIsSingleScattering){
       // sample single scattering
       G4double cost,sint,cosPhi,sinPhi;
       SingleScattering(cost, sint);
       G4double phi = CLHEP::twopi*rndmEngineMod->flat();
       sinPhi = std::sin(phi);
       cosPhi = std::cos(phi);
       fTheNewDirection.set(sint*cosPhi,sint*sinPhi,cost);
     } else if(fIsMultipleSacettring){
       // sample multiple scattering
       SampleMSC(); // fTheZPathLenght, fTheDisplacementVector and fTheNewDirection will be set
     } // and if single scattering but it was longer => nothing to do
   } //else { do nothing here but after transportation
 
   return ConvertTrueToGeom(fTheTrueStepLenght,currentMinimalStep);
 }

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G4double G4GoudsmitSaundersonMscModel::ComputeTrueStepLength ( G4double geomStepLength )

virtual

Reimplemented from G4VMscModel.

Definition at line 761 of file G4GoudsmitSaundersonMscModel.cc.

 {
   // init
   fIsEndedUpOnBoundary = false;
 
   // step defined other than transportation
   if(geomStepLength == fTheZPathLenght) {
     return fTheTrueStepLenght;
   }
 
   // else ::
   // - set the flag that transportation was the winer so DoNothin in DOIT !!
   // - convert geom -> true by using the mean value
   fIsEndedUpOnBoundary = true; // OR LAST STEP
 
   fTheZPathLenght = geomStepLength;
 
   // was a short single scattering step
   if(fIsEverythingWasDone && !fIsMultipleSacettring) {
     fTheTrueStepLenght = geomStepLength;
     return fTheTrueStepLenght;
   }
 
   // t = z for very small step
   if(geomStepLength < tlimitminfix2) {
     fTheTrueStepLenght = geomStepLength;
   // recalculation
   } else {
     G4double tlength = geomStepLength;
     if(geomStepLength > fLambda1*tausmall ) {
       if(par1 <  0.) {
         tlength = -fLambda1*G4Log(1.-geomStepLength/fLambda1) ;
       } else {
        if(par1*par3*geomStepLength < 1.) {
            G4Pow *g4calc = G4Pow::GetInstance();
            tlength = (1.-g4calc->powA( 1.-par1*par3*geomStepLength,1./par3))/par1;
         } else {
           tlength = currentRange;
         }
       }
      if(tlength < geomStepLength)   { tlength = geomStepLength; }
      else if(tlength > fTheTrueStepLenght) { tlength = geomStepLength; }
     }
     fTheTrueStepLenght = tlength;
   }
   return fTheTrueStepLenght;
 }

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G4double G4GoudsmitSaundersonMscModel::GetTransportMeanFreePath	(	const G4ParticleDefinition *	,
		G4double	kineticEnergy
	)

Definition at line 246 of file G4GoudsmitSaundersonMscModel.cc.

                                                                                {
   // kinetic energy is assumed to be in Geant4 internal energy unit which is MeV
   G4double efEnergy = kineticEnergy;
   if(efEnergy<lowKEnergy) efEnergy=lowKEnergy;
   if(efEnergy>highKEnergy)efEnergy=highKEnergy;
 
   const G4Material*  mat = currentCouple->GetMaterial();
 
   fLambda0 = 0.0; // elastic mean free path
   fLambda1 = 0.0; // first transport mean free path
   fScrA    = 0.0; // screening parameter
   fG1      = 0.0; // first transport coef.
 
   if(fIsUsePWATotalXsecData) {
     // use PWA total xsec data to determine screening and lambda0 lambda1
     const G4ElementVector* theElementVector = mat->GetElementVector();
     const G4double* theAtomNumDensityVector = mat->GetVecNbOfAtomsPerVolume();
     G4int nelm = mat->GetNumberOfElements();
 
     int elowindx = fgPWAXsecTable->GetPWATotalXsecForZet( G4lrint((*theElementVector)[0]->GetZ()) )
                    ->GetPWATotalXsecEnergyBinIndex(efEnergy);
     for(G4int i=0;i<nelm;i++){
       int zet    = G4lrint((*theElementVector)[i]->GetZ());
       // total elastic scattering cross section in Geant4 internal length2 units
       int indx   = (G4int)(1.5 + charge*1.5); // specify that want to get the total elastic scattering xsection
       double elxsec = (fgPWAXsecTable->GetPWATotalXsecForZet(zet))->GetInterpXsec(efEnergy,elowindx,indx);
       // first transport cross section in Geant4 internal length2 units
       indx   = (G4int)(2.5 + charge*1.5); // specify that want to get the first tarnsport xsection
       double t1xsec = (fgPWAXsecTable->GetPWATotalXsecForZet(zet))->GetInterpXsec(efEnergy,elowindx,indx);
       fLambda0 += (theAtomNumDensityVector[i]*elxsec);
       fLambda1 += (theAtomNumDensityVector[i]*t1xsec);
     }
     if(fLambda0>0.0) { fLambda0 =1./fLambda0; }
     if(fLambda1>0.0) { fLambda1 =1./fLambda1; }
 
     // determine screening parameter such that it gives back PWA G1
     fG1=0.0;
     if(fLambda1>0.0) { fG1 = fLambda0/fLambda1; }
 
     fScrA = fgGSTable->GetScreeningParam(fG1);
   } else {
     // Get SCREENING FROM MOLIER
 
     // below 1 keV it can give bananas so prevet (1 keV)
     if(efEnergy<0.001) efEnergy = 0.001;
 
     // total mometum square in Geant4 internal energy2 units which is MeV2
     G4double pt2   = efEnergy*(efEnergy+2.0*electron_mass_c2);
     G4double beta2 = pt2/(pt2+electron_mass_c2*electron_mass_c2);
     G4int    matindx = mat->GetIndex();
     G4double bc = fgGSTable->GetMoliereBc(matindx);
     fScrA    = fgGSTable->GetMoliereXc2(matindx)/(4.0*pt2*bc);
     // total elastic mean free path in Geant4 internal lenght units
     fLambda0 = beta2/bc;//*(1.+fScrA);
     fG1      = 2.0*fScrA*((1.0+fScrA)*G4Log(1.0/fScrA+1.0)-1.0);
     fLambda1 = fLambda0/fG1;
   }
 
   return fLambda1;
 }

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void G4GoudsmitSaundersonMscModel::Initialise	(	const G4ParticleDefinition *	p,
		const G4DataVector &
	)

virtual

Implements G4VEmModel.

Definition at line 205 of file G4GoudsmitSaundersonMscModel.cc.

                                                                             {
   SetParticle(p);
   fParticleChange = GetParticleChangeForMSC(p);
   //
   // -create static GoudsmitSaundersonTable and PWATotalXsecTable is necessary
   //
   if(IsMaster()) {
 
    // Could delete as well if they are exist but then the same data are reloaded
    // in case of e+ for example.
 /*    if(fgGSTable) {
       delete fgGSTable;
       fgGSTable = 0;
     }
     if(fgPWAXsecTable) {
       delete fgPWAXsecTable;
       fgPWAXsecTable = 0;
     }
 */
     if(!fgGSTable)
       fgGSTable      = new G4GoudsmitSaundersonTable();
 
     // G4GSTable will be initialised (data are loaded) only if they are not there yet.
     fgGSTable->Initialise();
 
     if(fIsUsePWATotalXsecData) {
       if(!fgPWAXsecTable)
          fgPWAXsecTable = new G4PWATotalXsecTable();
 
       // Makes sure that all (and only those) atomic PWA data are in memory that
       // are in the current MaterilaTable.
       fgPWAXsecTable->Initialise();
     }
   }
 }

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void G4GoudsmitSaundersonMscModel::SampleMSC ( )

Definition at line 874 of file G4GoudsmitSaundersonMscModel.cc.

                                             {
   fIsNoScatteringInMSC = false;
   // kinetic energy is assumed to be in Geant4 internal energy unit which is MeV
   G4double kineticEnergy = currentKinEnergy;
 
   // Energy loss correction: 2 version
   G4double eloss  = 0.0;
 //  if (fTheTrueStepLenght > currentRange*dtrl) {
     eloss = kineticEnergy -
       GetEnergy(particle,currentRange-fTheTrueStepLenght,currentCouple);
 //  } else {
 //    eloss = fTheTrueStepLenght*GetDEDX(particle,kineticEnergy,currentCouple);
 //  }
 
 
   G4double tau  = 0.;//    = kineticEnergy/electron_mass_c2; // where kinEnergy is the mean kinetic energy
   G4double tau2 = 0.;//   = tau*tau;
   G4double eps0 = 0.;//   = eloss/kineticEnergy0; // energy loss fraction to the begin step energy
   G4double epsm = 0.;//   = eloss/kineticEnergy;  // energy loss fraction to the mean step energy
 
 
   // - init.
   G4double efEnergy = kineticEnergy;
   G4double efStep   = fTheTrueStepLenght;
 
   G4double kineticEnergy0 = kineticEnergy;
   if(fgIsUseAccurate) {    // - use accurate energy loss correction
      kineticEnergy -= 0.5*eloss;  // mean energy along the full step
 
      // other parameters for energy loss corrections
      tau    = kineticEnergy/electron_mass_c2; // where kinEnergy is the mean kinetic energy
      tau2   = tau*tau;
      eps0   = eloss/kineticEnergy0; // energy loss fraction to the begin step energy
      epsm   = eloss/kineticEnergy;  // energy loss fraction to the mean step energy
 
       efEnergy       = kineticEnergy * (1. - epsm*epsm*(6.+10.*tau+5.*tau2)/(24.*tau2+48.*tau+72.));
       G4double dum  = 0.166666*(4.+tau*(6.+tau*(7.+tau*(4.+tau))))*
                      (epsm/((tau+1.)*(tau+2.)))*(epsm/((tau+1.)*(tau+2.)));
       efStep =fTheTrueStepLenght*(1.-dum);
   } else {                              // - take only mean energy
       kineticEnergy -= 0.5*eloss;  // mean energy along the full step
       efEnergy       = kineticEnergy;
       G4double factor = 1./(1. + 0.9784671*kineticEnergy); //0.9784671 = 1/(2*rm)
       eps0= eloss/kineticEnergy0;
       epsm= eps0/(1.-0.5*eps0);
       G4double temp   = 0.3*(1. - factor*(1. - 0.333333*factor))*eps0*eps0;
       efStep = fTheTrueStepLenght*(1. + temp);
   }
 
   // Compute elastic mfp, first transport mfp, screening parameter, and G1
   fLambda1 = GetTransportMeanFreePath(particle,efEnergy);
 
   G4double lambdan=0.;
 
   if(fLambda0>0.0) { lambdan=efStep/fLambda0; }
   if(lambdan<=1.0e-12) {
       if(fIsEverythingWasDone)
         fTheZPathLenght = fTheTrueStepLenght;
     fIsNoScatteringInMSC = true;
     return;
   }
 
   // correction from neglected term 1+A (only for Moliere parameter)
   if(!fIsUsePWATotalXsecData)  
     lambdan = lambdan/(1.+fScrA);
 
   G4double Qn1 = lambdan *fG1;//2.* lambdan *scrA*((1.+scrA)*log(1.+1./scrA)-1.);
 
   // Sample scattering angles
   // new direction, relative to the orriginal one is in {uss,vss,wss}
   G4double cosTheta1 =1.0,sinTheta1 =0.0, cosTheta2 =1.0, sinTheta2 =0.0;
   G4double cosPhi1=1.0,sinPhi1=0.0, cosPhi2 =1.0, sinPhi2 =0.0;
   G4double uss=0.0,vss=0.0,wss=1.0,x_coord=0.0,y_coord=0.0,z_coord=1.0;
   G4double u2=0.0,v2=0.0;
 
   // if we are above the upper grid limit with lambdaxG1=true-length/first-trans-mfp
   // => izotropic distribution: lambG1_max =7.992 but set it to 7
   if(0.5*Qn1 > 7.0){
     G4double vrand[2];
     rndmEngineMod->flatArray(2,vrand); //get 2 random number
     cosTheta1 = 1.-2.*vrand[0];
     sinTheta1 = std::sqrt((1.-cosTheta1)*(1.+cosTheta1));
     cosTheta2 = 1.-2.*vrand[1];
     sinTheta2 = std::sqrt((1.-cosTheta2)*(1.+cosTheta2));
   } else {
      // sample 2 scattering cost1, sint1, cost2 and sint2 for half path
      fgGSTable->Sampling(0.5*lambdan, 0.5*Qn1, fScrA, cosTheta1, sinTheta1);
      fgGSTable->Sampling(0.5*lambdan, 0.5*Qn1, fScrA, cosTheta2, sinTheta2);
      if(cosTheta1 + cosTheta2 == 2.) { // no scattering happened
         if(fIsEverythingWasDone)
            fTheZPathLenght = fTheTrueStepLenght;
         fIsNoScatteringInMSC = true;
         return;
      }
   }
   // sample 2 azimuthal angles
   G4double vrand[2];
   rndmEngineMod->flatArray(2,vrand); //get 2 random number
   G4double phi1 = CLHEP::twopi*vrand[0];
   sinPhi1 = std::sin(phi1);
   cosPhi1 = std::cos(phi1);
   G4double phi2 = CLHEP::twopi*vrand[1];
   sinPhi2 = std::sin(phi2);
   cosPhi2 = std::cos(phi2);
 
   // compute final direction realtive to z-dir
   u2  = sinTheta2*cosPhi2;
   v2  = sinTheta2*sinPhi2;
   G4double u2p = cosTheta1*u2 + sinTheta1*cosTheta2;
   uss  = u2p*cosPhi1 - v2*sinPhi1;
   vss  = u2p*sinPhi1 + v2*cosPhi1;
   wss  = cosTheta1*cosTheta2 - sinTheta1*u2;
 
   fTheNewDirection.set(uss,vss,wss);
 
   // set the fTheZPathLenght if we don't sample displacement and
   // we should do everything at the step-limit-phase before we return
   if(fIsNoDisplace && fIsEverythingWasDone)
     fTheZPathLenght = fTheTrueStepLenght;
 
   // in optimized-mode if the current-safety > current-range we do not use dispalcement
   if(fIsNoDisplace)
     return;
 
   // Compute final position
   if(fgIsUseAccurate) {
      // correction parameter
      G4double par =1.;
      if(Qn1<0.7) par = 1.;
      else if (Qn1<7.0) par = -0.031376*Qn1+1.01356;
      else par = 0.79;
 
      // Moments with energy loss correction
      // --first the uncorrected (for energy loss) values of gamma, eta, a1=a2=0.5*(1-eta), delta
      // gamma = G_2/G_1 based on G2 computed from A by using the Wentzel DCS form of G2
      G4double loga   = G4Log(1.0+1.0/fScrA);
      G4double gamma  = 6.0*fScrA*(1.0 + fScrA)*(loga*(1.0 + 2.0*fScrA) - 2.0)/fG1;
      // sample eta from p(eta)=2*eta i.e. P(eta) = eta_square ;-> P(eta) = rand --> eta = sqrt(rand)
      G4double eta    = std::sqrt(rndmEngineMod->flat());
      G4double eta1   = 0.5*(1 - eta);  // used  more than once
      // 0.5 +sqrt(6)/6 = 0.9082483;
      // 1/(4*sqrt(6))  = 0.1020621;
      // (4-sqrt(6)/(24*sqrt(6))) = 0.026374715
      // delta = 0.9082483-(0.1020621-0.0263747*gamma)*Qn1 without energy loss cor.
      G4double delta  = 0.9082483-(0.1020621-0.0263747*gamma)*Qn1;
 
      // compute alpha1 and alpha2 for energy loss correction
      G4double temp1 = 2.0 + tau;
      G4double temp  = (2.0+tau*temp1)/((tau+1.0)*temp1);
      //Take logarithmic dependence
      temp = temp - (tau+1.0)/((tau+2.0)*(loga*(1.0+fScrA)-1.0));
      temp = temp * epsm;
      temp1 = 1.0 - temp;
      delta = delta + 0.40824829*(eps0*(tau+1.0)/((tau+2.0)*
              (loga*(1.0+fScrA)-1.0)*(loga*(1.0+2.0*fScrA)-2.0)) - 0.25*temp*temp);
      G4double b      = eta*delta;
      G4double c      = eta*(1.0-delta);
 
      //Calculate transport direction cosines:
      // ut,vt,wt is the final position divided by the true step length
      G4double w1v2 = cosTheta1*v2;
      G4double ut   = b*sinTheta1*cosPhi1 + c*(cosPhi1*u2 - sinPhi1*w1v2) + eta1*uss*temp1;
      G4double vt   = b*sinTheta1*sinPhi1 + c*(sinPhi1*u2 + cosPhi1*w1v2) + eta1*vss*temp1;
      G4double wt   = eta1*(1+temp) +       b*cosTheta1 +  c*cosTheta2    + eta1*wss*temp1;
 
      // long step correction
      ut *=par;
      vt *=par;
      wt *=par;
 
      // final position relative to the pre-step point in the scattering frame
      // ut = x_f/s so needs to multiply by s
      x_coord = ut*fTheTrueStepLenght;
      y_coord = vt*fTheTrueStepLenght;
      z_coord = wt*fTheTrueStepLenght;
 
      if(fIsEverythingWasDone){
        // We sample in the step limit so set fTheZPathLenght = transportDistance
        // and lateral displacement (x_coord,y_coord,z_coord-transportDistance)
        //Calculate transport distance
        G4double transportDistance  = std::sqrt(x_coord*x_coord+y_coord*y_coord+z_coord*z_coord);
        // protection
        if(transportDistance>fTheTrueStepLenght)
           transportDistance = fTheTrueStepLenght;
        fTheZPathLenght = transportDistance;
      }
      // else:: we sample in the DoIt so
      //       the fTheZPathLenght was already set and was taken as transport along zet
      fTheDisplacementVector.set(x_coord,y_coord,z_coord-fTheZPathLenght);
   } else {
      // compute zz = <z>/tPathLength
      // s -> true-path-length
      // z -> geom-path-length:: when PRESTA is used z =(def.) <z>
      // r -> lateral displacement = s/2 sin(theta)  => x_f = r cos(phi); y_f = r sin(phi)
      G4double zz = 0.0;
      if(fIsEverythingWasDone){
         // We sample in the step limit so set fTheZPathLenght = transportDistance
         // and lateral displacement (x_coord,y_coord,z_coord-transportDistance)
         if(Qn1<0.1) { // use 3-order Taylor approximation of (1-exp(-x))/x around x=0
           zz = 1.0 - Qn1*(0.5 - Qn1*(0.166666667 - 0.041666667*Qn1)); // 1/6 =0.166..7 ; 1/24=0.041..
         } else {
           zz = (1.-G4Exp(-Qn1))/Qn1;
         }
      } else {
         // we sample in the DoIt so
         // the fTheZPathLenght was already set and was taken as transport along zet
         zz = fTheZPathLenght/fTheTrueStepLenght;
      }
 
      G4double rr = (1.-zz*zz)/(1.-wss*wss); // s^2 >= <z>^2+r^2  :: where r^2 = s^2/4 sin^2(theta)
      if(rr >= 0.25) rr = 0.25;            // (1-<z>^2/s^2)/sin^2(theta) >= r^2/(s^2 sin^2(theta)) = 1/4 must hold
      G4double rperp = fTheTrueStepLenght*std::sqrt(rr);  // this is r/sint
      x_coord  = rperp*uss;
      y_coord  = rperp*vss;
      z_coord  = zz*fTheTrueStepLenght;
 
      if(fIsEverythingWasDone){
        G4double transportDistance = std::sqrt(x_coord*x_coord + y_coord*y_coord + z_coord*z_coord);
        fTheZPathLenght = transportDistance;
      }
 
      fTheDisplacementVector.set(x_coord,y_coord,z_coord- fTheZPathLenght);
    }
 }

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G4ThreeVector & G4GoudsmitSaundersonMscModel::SampleScattering	(	const G4ThreeVector &	oldDirection,
		G4double	safety
	)

virtual

Reimplemented from G4VMscModel.

Definition at line 811 of file G4GoudsmitSaundersonMscModel.cc.

                                                                                           {
   if(steppingAlgorithm == fUseDistanceToBoundary && fIsEverythingWasDone && fIsSingleScattering){ // ONLY single scattering is done in advance
       // single scattering was and scattering happend
       fTheNewDirection.rotateUz(oldDirection);
 //      fTheDisplacementVector.set(0.,0.,0.);
       fParticleChange->ProposeMomentumDirection(fTheNewDirection);
       return fTheDisplacementVector;
   } else if(steppingAlgorithm == fUseSafety) {
       if(fIsEndedUpOnBoundary) {// do nothing
 //        fTheDisplacementVector.set(0.,0.,0.);
         return fTheDisplacementVector;
       } else if(fIsEverythingWasDone) {// evrything is done if not optimizations case !!!
         // check single scattering and see if it happened
         if(fIsSingleScattering) {
           fTheNewDirection.rotateUz(oldDirection);
   //        fTheDisplacementVector.set(0.,0.,0.);
           fParticleChange->ProposeMomentumDirection(fTheNewDirection);
           return fTheDisplacementVector;
         }
 
         // check if multiple scattering happened and do things only if scattering was really happening
         if(fIsMultipleSacettring && !fIsNoScatteringInMSC){
              fTheNewDirection.rotateUz(oldDirection);
              fTheDisplacementVector.rotateUz(oldDirection);
              fParticleChange->ProposeMomentumDirection(fTheNewDirection);
         }
         // The only thing that could happen if we are here (fUseSafety and fIsEverythingWasDone)
         // is that  single scattering was tried but did not win so scattering did not happen.
         // So no displacement and no scattering
         return fTheDisplacementVector;
      }
      //
      // The only thing that could still happen with fUseSafety is that we are in the
      // optimization branch: so sample MSC angle here (no displacement)
   }
 
  //else
    // MSC needs to be done here
    SampleMSC();
    if(!fIsNoScatteringInMSC) {
       fTheNewDirection.rotateUz(oldDirection);
       fParticleChange->ProposeMomentumDirection(fTheNewDirection);
       if(!fIsNoDisplace)
         fTheDisplacementVector.rotateUz(oldDirection);
    }
    return fTheDisplacementVector;
 }

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void G4GoudsmitSaundersonMscModel::SetOptionPWAScreening ( G4bool opt )

inline

Definition at line 137 of file G4GoudsmitSaundersonMscModel.hh.

137 {fIsUsePWATotalXsecData=opt;}

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void G4GoudsmitSaundersonMscModel::SingleScattering	(	G4double &	cost,
		G4double &	sint
	)

Definition at line 860 of file G4GoudsmitSaundersonMscModel.cc.

                                                                                  {
     G4double rand1 = rndmEngineMod->flat();
     // sampling 1-cos(theta)
     G4double dum0  = 2.0*fScrA*rand1/(1.0 - rand1 + fScrA);
     // add protections
     if(dum0 < 0.0)       dum0 = 0.0;
     else if(dum0 > 2.0 ) dum0 = 2.0;
     // compute cos(theta) and sin(theta)
     cost = 1.0 - dum0;
     sint = std::sqrt(dum0*(2.0 - dum0));
 }

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void G4GoudsmitSaundersonMscModel::StartTracking ( G4Track * track )

virtual

Reimplemented from G4VEmModel.

Definition at line 365 of file G4GoudsmitSaundersonMscModel.cc.

 {
   SetParticle(track->GetDynamicParticle()->GetDefinition());
   firstStep = true;
   tlimit = tgeom = rangeinit = geombig;
 }

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

source/geant4.10.03.p02/source/processes/electromagnetic/standard/include/G4GoudsmitSaundersonMscModel.hh
source/geant4.10.03.p02/source/processes/electromagnetic/standard/src/G4GoudsmitSaundersonMscModel.cc

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