G4ScreenedNuclearRecoil Class Reference

A process which handles screened Coulomb collisions between nuclei. More...

#include <G4ScreenedNuclearRecoil.hh>

Inheritance diagram for G4ScreenedNuclearRecoil:

Collaboration diagram for G4ScreenedNuclearRecoil:

Public Member Functions
	G4ScreenedNuclearRecoil (const G4String &processName="ScreenedElastic", const G4String &ScreeningKey="zbl", G4bool GenerateRecoils=1, G4double RecoilCutoff=100.0 *eV, G4double PhysicsCutoff=10.0 *eV)
	Construct the process and set some physics parameters for it. More...
virtual	~G4ScreenedNuclearRecoil ()
	destructor More...
virtual G4double	GetMeanFreePath (const G4Track &, G4double, G4ForceCondition *)
	used internally by Geant4 machinery More...
virtual G4VParticleChange *	PostStepDoIt (const G4Track &aTrack, const G4Step &aStep)
	used internally by Geant4 machinery More...
virtual G4bool	IsApplicable (const G4ParticleDefinition &aParticleType)
	test if a prticle of type aParticleType can use this process More...
virtual void	BuildPhysicsTable (const G4ParticleDefinition &aParticleType)
	Build physics tables in advance. Not Implemented. More...
virtual void	DumpPhysicsTable (const G4ParticleDefinition &aParticleType)
	Export physics tables for persistency. Not Implemented. More...
virtual G4bool	CheckNuclearCollision (G4double A, G4double A1, G4double apsis)
	deterine if the moving particle is within the strong force range of the selected nucleus More...
virtual G4ScreenedCoulombCrossSection *	GetNewCrossSectionHandler (void)
G4double	GetNIEL () const
	Get non-ionizing energy loss for last step. More...
void	ResetTables ()
	clear precomputed screening tables More...
void	SetMaxEnergyForScattering (G4double energy)
	set the upper energy beyond which this process has no cross section More...
std::string	GetScreeningKey () const
	find out what screening function we are using More...
void	AllowEnergyDeposition (G4bool flag)
	enable or disable all energy deposition by this process More...
G4bool	GetAllowEnergyDeposition () const
	get flag indicating whether deposition is enabled More...
void	EnableRecoils (G4bool flag)
	enable or disable the generation of recoils. If recoils are disabled, the energy they would have received is just deposited. param flag if true, create recoil ions in cases in which the energy is above the recoilCutoff. If false, just deposit the energy. More...
G4bool	GetEnableRecoils () const
	find out if generation of recoils is enabled. More...
void	SetMFPScaling (G4double scale)
	set the mean free path scaling as specified More...
G4double	GetMFPScaling () const
	get the MFPScaling parameter More...
void	AvoidNuclearReactions (G4bool flag)
	enable or disable whether this process will skip collisions which are close enough they need hadronic phsyics. Default is true (skip close collisions). Disabling this results in excess nuclear stopping power. More...
G4bool	GetAvoidNuclearReactions () const
	get the flag indicating whether hadronic collisions are ignored. More...
void	SetRecoilCutoff (G4double energy)
	set the minimum energy (per nucleon) at which recoils can be generated, and the energy (per nucleon) below which all ions are stopped. More...
G4double	GetRecoilCutoff () const
	get the recoil cutoff More...
void	SetPhysicsCutoff (G4double energy)
	set the energy to which screening tables are computed. Typically, this is 10 eV or so, and not often changed. More...
G4double	GetPhysicsCutoff () const
	get the physics cutoff energy. More...
void	SetNIELPartitionFunction (const G4VNIELPartition *part)
	set the pointer to a class for paritioning energy into NIEL More...
void	SetCrossSectionHardening (G4double fraction, G4double HardeningFactor)
	set the cross section boost to provide faster computation of backscattering More...
G4double	GetHardeningFraction () const
	get the fraction of particles which will have boosted scattering More...
G4double	GetHardeningFactor () const
	get the boost factor in use. More...
G4double	GetCurrentInteractionLength () const
	the the interaciton length used in the last scattering. More...
void	SetExternalCrossSectionHandler (G4ScreenedCoulombCrossSection *cs)
	set a function to compute screening tables, if the user needs non-standard behavior. More...
G4int	GetVerboseLevel () const
	get the verbosity. More...
std::map< G4int, G4ScreenedCoulombCrossSection * > &	GetCrossSectionHandlers ()
void	ClearStages (void)
void	AddStage (G4ScreenedCollisionStage *stage)
G4CoulombKinematicsInfo &	GetKinematics ()
void	SetValidCollision (G4bool flag)
G4bool	GetValidCollision () const
class G4ParticleChange &	GetParticleChange ()
	get the pointer to our ParticleChange object. for internal use, primarily. More...
void	DepositEnergy (G4int z1, G4double a1, const G4Material *material, G4double energy)
	take the given energy, and use the material information to partition it into NIEL and ionizing energy. More...
Public Member Functions inherited from G4ScreenedCoulombCrossSectionInfo
	G4ScreenedCoulombCrossSectionInfo ()
	~G4ScreenedCoulombCrossSectionInfo ()
Public Member Functions inherited from G4VDiscreteProcess
	G4VDiscreteProcess (const G4String &, G4ProcessType aType=fNotDefined)
	G4VDiscreteProcess (G4VDiscreteProcess &)
virtual	~G4VDiscreteProcess ()
virtual G4double	PostStepGetPhysicalInteractionLength (const G4Track &track, G4double previousStepSize, G4ForceCondition *condition)
virtual G4double	AlongStepGetPhysicalInteractionLength (const G4Track &, G4double, G4double, G4double &, G4GPILSelection *)
virtual G4double	AtRestGetPhysicalInteractionLength (const G4Track &, G4ForceCondition *)
virtual G4VParticleChange *	AtRestDoIt (const G4Track &, const G4Step &)
virtual G4VParticleChange *	AlongStepDoIt (const G4Track &, const G4Step &)
Public Member Functions inherited from G4VProcess
	G4VProcess (const G4String &aName="NoName", G4ProcessType aType=fNotDefined)
	G4VProcess (const G4VProcess &right)
virtual	~G4VProcess ()
G4int	operator== (const G4VProcess &right) const
G4int	operator!= (const G4VProcess &right) const
G4double	GetCurrentInteractionLength () const
void	SetPILfactor (G4double value)
G4double	GetPILfactor () const
G4double	AlongStepGPIL (const G4Track &track, G4double previousStepSize, G4double currentMinimumStep, G4double &proposedSafety, G4GPILSelection *selection)
G4double	AtRestGPIL (const G4Track &track, G4ForceCondition *condition)
G4double	PostStepGPIL (const G4Track &track, G4double previousStepSize, G4ForceCondition *condition)
virtual void	PreparePhysicsTable (const G4ParticleDefinition &)
virtual G4bool	StorePhysicsTable (const G4ParticleDefinition *, const G4String &, G4bool)
virtual G4bool	RetrievePhysicsTable (const G4ParticleDefinition *, const G4String &, G4bool)
const G4String &	GetPhysicsTableFileName (const G4ParticleDefinition *, const G4String &directory, const G4String &tableName, G4bool ascii=false)
const G4String &	GetProcessName () const
G4ProcessType	GetProcessType () const
void	SetProcessType (G4ProcessType)
G4int	GetProcessSubType () const
void	SetProcessSubType (G4int)
virtual void	StartTracking (G4Track *)
virtual void	EndTracking ()
virtual void	SetProcessManager (const G4ProcessManager *)
virtual const G4ProcessManager *	GetProcessManager ()
virtual void	ResetNumberOfInteractionLengthLeft ()
G4double	GetNumberOfInteractionLengthLeft () const
G4double	GetTotalNumberOfInteractionLengthTraversed () const
G4bool	isAtRestDoItIsEnabled () const
G4bool	isAlongStepDoItIsEnabled () const
G4bool	isPostStepDoItIsEnabled () const
virtual void	DumpInfo () const
void	SetVerboseLevel (G4int value)
G4int	GetVerboseLevel () const
virtual void	SetMasterProcess (G4VProcess *masterP)
const G4VProcess *	GetMasterProcess () const
virtual void	BuildWorkerPhysicsTable (const G4ParticleDefinition &part)
virtual void	PrepareWorkerPhysicsTable (const G4ParticleDefinition &)

Protected Attributes
G4double	highEnergyLimit
	the energy per nucleon above which the MFP is constant More...
G4double	lowEnergyLimit
	the energy per nucleon below which the MFP is zero More...
G4double	processMaxEnergy
	the energy per nucleon beyond which the cross section is zero, to cross over to G4MSC More...
G4String	screeningKey
G4bool	generateRecoils
G4bool	avoidReactions
G4double	recoilCutoff
G4double	physicsCutoff
G4bool	registerDepositedEnergy
G4double	IonizingLoss
G4double	NIEL
G4double	MFPScale
G4double	hardeningFraction
G4double	hardeningFactor
G4ScreenedCoulombCrossSection *	externalCrossSectionConstructor
std::vector < G4ScreenedCollisionStage * >	collisionStages
std::map< G4int, G4ScreenedCoulombCrossSection * >	crossSectionHandlers
G4bool	validCollision
G4CoulombKinematicsInfo	kinematics
const G4VNIELPartition *	NIELPartitionFunction
Protected Attributes inherited from G4VProcess
const G4ProcessManager *	aProcessManager
G4VParticleChange *	pParticleChange
G4ParticleChange	aParticleChange
G4double	theNumberOfInteractionLengthLeft
G4double	currentInteractionLength
G4double	theInitialNumberOfInteractionLength
G4String	theProcessName
G4String	thePhysicsTableFileName
G4ProcessType	theProcessType
G4int	theProcessSubType
G4double	thePILfactor
G4bool	enableAtRestDoIt
G4bool	enableAlongStepDoIt
G4bool	enablePostStepDoIt
G4int	verboseLevel

Friends
class	G4ScreenedCollisionStage

Additional Inherited Members
Static Public Member Functions inherited from G4ScreenedCoulombCrossSectionInfo
static const char *	CVSHeaderVers ()
static const char *	CVSFileVers ()
Static Public Member Functions inherited from G4VProcess
static const G4String &	GetProcessTypeName (G4ProcessType)
Protected Member Functions inherited from G4VProcess
void	SubtractNumberOfInteractionLengthLeft (G4double previousStepSize)
void	ClearNumberOfInteractionLengthLeft ()

Detailed Description

A process which handles screened Coulomb collisions between nuclei.

Definition at line 208 of file G4ScreenedNuclearRecoil.hh.

Constructor & Destructor Documentation

G4ScreenedNuclearRecoil::G4ScreenedNuclearRecoil	(	const G4String &	processName = "ScreenedElastic",
		const G4String &	ScreeningKey = "zbl",
		G4bool	GenerateRecoils = 1,
		G4double	RecoilCutoff = 100.0*eV,
		G4double	PhysicsCutoff = 10.0*eV
	)

Construct the process and set some physics parameters for it.

Parameters

processName	the name to assign the process
ScreeningKey	the name of a screening function to use. The default functions are "zbl" (recommended for soft scattering), "lj" (recommended for backscattering) and "mol" (Moliere potential)
GenerateRecoils	if frue, ions struck by primary are converted into new moving particles. If false, energy is deposited, but no new moving ions are created.
RecoilCutoff	energy below which no new moving particles will be created, even if a GenerateRecoils is true. Also, a moving primary particle will be stopped if its energy falls below this limit.
PhysicsCutoff	the energy transfer to which screening tables are calucalted. There is no really compelling reason to change it from the 10.0 eV default. However, see the paper on running this in thin targets for further discussion, and its interaction with SetMFPScaling()

Definition at line 320 of file G4ScreenedNuclearRecoil.cc.

                                                                       : 
  G4VDiscreteProcess(processName, fElectromagnetic),
        screeningKey(ScreeningKey),
        generateRecoils(GenerateRecoils), avoidReactions(1), 
        recoilCutoff(RecoilCutoff), physicsCutoff(PhysicsCutoff),
        hardeningFraction(0.0), hardeningFactor(1.0),
        externalCrossSectionConstructor(0),
        NIELPartitionFunction(new G4LindhardRobinsonPartition)
{
  // for now, point to class instance of this. Doing it by creating a new 
  // one fails
  // to correctly update NIEL
  // not even this is needed... done in G4VProcess().
  // pParticleChange=&aParticleChange; 
  processMaxEnergy=50000.0*MeV;
  highEnergyLimit=100.0*MeV;
  lowEnergyLimit=physicsCutoff;
  registerDepositedEnergy=1; // by default, don't hide NIEL
  MFPScale=1.0;
  // SetVerboseLevel(2);
  AddStage(new G4ScreenedCoulombClassicalKinematics);
  AddStage(new G4SingleScatter); 
  SetProcessSubType(fCoulombScattering);
}

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G4ScreenedNuclearRecoil::~G4ScreenedNuclearRecoil ( )

virtual

destructor

Definition at line 391 of file G4ScreenedNuclearRecoil.cc.

{
        ResetTables();
}

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Member Function Documentation

void G4ScreenedNuclearRecoil::AddStage ( G4ScreenedCollisionStage *  stage )

inline

Definition at line 399 of file G4ScreenedNuclearRecoil.hh.

                                                    { 
                                     collisionStages.push_back(stage); }

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void G4ScreenedNuclearRecoil::AllowEnergyDeposition ( G4bool  flag )

inline

enable or disable all energy deposition by this process

Parameters

flag	if true, enable deposition of energy (the default). If false, disable deposition.

Definition at line 296 of file G4ScreenedNuclearRecoil.hh.

{registerDepositedEnergy=flag;}

void G4ScreenedNuclearRecoil::AvoidNuclearReactions ( G4bool  flag )

inline

enable or disable whether this process will skip collisions which are close enough they need hadronic phsyics. Default is true (skip close collisions). Disabling this results in excess nuclear stopping power.

Parameters

flag	true results in hard collisions being skipped. false allows hard collisions.

Definition at line 331 of file G4ScreenedNuclearRecoil.hh.

{ avoidReactions=flag; }

void G4ScreenedNuclearRecoil::BuildPhysicsTable ( const G4ParticleDefinition &  aParticleType )

virtual

Build physics tables in advance. Not Implemented.

Parameters

aParticleType

the type of particle to build tables for

Reimplemented from G4VProcess.

Definition at line 805 of file G4ScreenedNuclearRecoil.cc.

{
  G4String nam = aParticleType.GetParticleName();
  if(nam == "GenericIon" || nam == "proton" 
     || nam == "deuteron" || nam == "triton" 
     || nam == "alpha" || nam == "He3") {
    G4cout << G4endl << GetProcessName() << ":   for  " << nam
           << "    SubType= " << GetProcessSubType() 
           << "    maxEnergy(MeV)= " << processMaxEnergy/MeV << G4endl;
  }
}

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G4bool G4ScreenedNuclearRecoil::CheckNuclearCollision ( G4double  A, G4double  A1, G4double  apsis  )

virtual

deterine if the moving particle is within the strong force range of the selected nucleus

Parameters

A	the nucleon number of the beam
A1	the nucleon number of the target
apsis	the distance of closest approach

Definition at line 398 of file G4ScreenedNuclearRecoil.cc.

                                                                 {
  return avoidReactions && (apsis < (1.1*(std::pow(A,1.0/3.0)+
                                          std::pow(a1,1.0/3.0)) + 1.4)*fermi);
  // nuclei are within 1.4 fm (reduced pion Compton wavelength) of each 
  // other at apsis, 
  // this is hadronic, skip it
}

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void G4ScreenedNuclearRecoil::ClearStages

(

void

)

Definition at line 359 of file G4ScreenedNuclearRecoil.cc.

{
  // I don't think I like deleting the processes here... they are better 
  // abandoned
  // if the creator doesn't get rid of them
  // std::vector<G4ScreenedCollisionStage *>::iterator stage=
  //collisionStages.begin();
  //for(; stage != collisionStages.end(); stage++) delete (*stage);

        collisionStages.clear();
}

void G4ScreenedNuclearRecoil::DepositEnergy	(	G4int	z1,
		G4double	a1,
		const G4Material *	material,
		G4double	energy
	)

take the given energy, and use the material information to partition it into NIEL and ionizing energy.

Definition at line 378 of file G4ScreenedNuclearRecoil.cc.

{
        if(!NIELPartitionFunction) {
                IonizingLoss+=energy;
        } else {
          G4double part=NIELPartitionFunction->PartitionNIEL(z1, a1, 
            material, energy);
          IonizingLoss+=energy*(1-part);
          NIEL += energy*part;
        }
}

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void G4ScreenedNuclearRecoil::DumpPhysicsTable ( const G4ParticleDefinition &  aParticleType )

virtual

Export physics tables for persistency. Not Implemented.

Parameters

aParticleType

the type of particle to build tables for

Definition at line 819 of file G4ScreenedNuclearRecoil.cc.

{
}

void G4ScreenedNuclearRecoil::EnableRecoils ( G4bool  flag )

inline

enable or disable the generation of recoils. If recoils are disabled, the energy they would have received is just deposited. param flag if true, create recoil ions in cases in which the energy is above the recoilCutoff. If false, just deposit the energy.

Definition at line 308 of file G4ScreenedNuclearRecoil.hh.

{ generateRecoils=flag; }

G4bool G4ScreenedNuclearRecoil::GetAllowEnergyDeposition ( ) const

inline

get flag indicating whether deposition is enabled

Definition at line 299 of file G4ScreenedNuclearRecoil.hh.

{return registerDepositedEnergy;}

G4bool G4ScreenedNuclearRecoil::GetAvoidNuclearReactions ( ) const

inline

get the flag indicating whether hadronic collisions are ignored.

Definition at line 334 of file G4ScreenedNuclearRecoil.hh.

{ return avoidReactions; }

std::map<G4int, G4ScreenedCoulombCrossSection*>& G4ScreenedNuclearRecoil::GetCrossSectionHandlers ( )

inline

Definition at line 394 of file G4ScreenedNuclearRecoil.hh.

                { return crossSectionHandlers; }

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G4double G4ScreenedNuclearRecoil::GetCurrentInteractionLength ( ) const

inline

the the interaciton length used in the last scattering.

Definition at line 380 of file G4ScreenedNuclearRecoil.hh.

                                                  {
                                    return currentInteractionLength; }

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G4bool G4ScreenedNuclearRecoil::GetEnableRecoils ( ) const

inline

find out if generation of recoils is enabled.

Definition at line 311 of file G4ScreenedNuclearRecoil.hh.

{ return generateRecoils; }

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G4double G4ScreenedNuclearRecoil::GetHardeningFactor ( ) const

inline

get the boost factor in use.

Definition at line 377 of file G4ScreenedNuclearRecoil.hh.

{ return hardeningFactor; }

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G4double G4ScreenedNuclearRecoil::GetHardeningFraction ( ) const

inline

get the fraction of particles which will have boosted scattering

Definition at line 374 of file G4ScreenedNuclearRecoil.hh.

{ return hardeningFraction; }

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G4CoulombKinematicsInfo& G4ScreenedNuclearRecoil::GetKinematics ( )

inline

Definition at line 402 of file G4ScreenedNuclearRecoil.hh.

{ return kinematics; }

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G4double G4ScreenedNuclearRecoil::GetMeanFreePath ( const G4Track &  track, G4double  , G4ForceCondition *  cond  )

virtual

used internally by Geant4 machinery

Implements G4VDiscreteProcess.

Definition at line 417 of file G4ScreenedNuclearRecoil.cc.

{
        const G4DynamicParticle* incoming = track.GetDynamicParticle();
        G4double energy = incoming->GetKineticEnergy();
        G4double a1=incoming->GetDefinition()->GetPDGMass()/amu_c2;
        
        G4double meanFreePath;
        *cond=NotForced;
        
        if (energy < lowEnergyLimit || energy < recoilCutoff*a1) {
                *cond=Forced;
                return 1.0*nm; 
/* catch and stop slow particles to collect their NIEL! */
        } else if (energy > processMaxEnergy*a1) {
                return DBL_MAX; // infinite mean free path
        } else if (energy > highEnergyLimit*a1) energy=highEnergyLimit*a1; 
/* constant MFP at high energy */

        G4double fz1=incoming->GetDefinition()->GetPDGCharge();
        G4int z1=(G4int)(fz1/eplus + 0.5);

        std::map<G4int, G4ScreenedCoulombCrossSection*>::iterator xh=
                crossSectionHandlers.find(z1);
        G4ScreenedCoulombCrossSection *xs;
        
        if (xh==crossSectionHandlers.end()) {
                xs =crossSectionHandlers[z1]=GetNewCrossSectionHandler();
                xs->LoadData(screeningKey, z1, a1, physicsCutoff);
                xs->BuildMFPTables();
        } else xs=(*xh).second;
        
        const G4MaterialCutsCouple* materialCouple = 
          track.GetMaterialCutsCouple();
        size_t materialIndex = materialCouple->GetMaterial()->GetIndex();

        const G4_c2_function &mfp=*(*xs)[materialIndex];
        
        // make absolutely certain we don't get an out-of-range energy
        meanFreePath = mfp(std::min(std::max(energy, mfp.xmin()), mfp.xmax()));
        
        // G4cout << "MFP: " << meanFreePath << " index " << materialIndex 
        //<< " energy " << energy << " MFPScale " << MFPScale << G4endl;
        
        return meanFreePath*MFPScale;
}

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G4double G4ScreenedNuclearRecoil::GetMFPScaling ( ) const

inline

get the MFPScaling parameter

Definition at line 322 of file G4ScreenedNuclearRecoil.hh.

{ return MFPScale; }

G4ScreenedCoulombCrossSection * G4ScreenedNuclearRecoil::GetNewCrossSectionHandler ( void  )

virtual

Definition at line 408 of file G4ScreenedNuclearRecoil.cc.

                                                        {
  G4ScreenedCoulombCrossSection *xc;
  if(!externalCrossSectionConstructor) 
    xc=new G4NativeScreenedCoulombCrossSection;
        else xc=externalCrossSectionConstructor->create();
        xc->SetVerbosity(verboseLevel);
        return xc;
}

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G4double G4ScreenedNuclearRecoil::GetNIEL ( ) const

inline

Get non-ionizing energy loss for last step.

Definition at line 270 of file G4ScreenedNuclearRecoil.hh.

{ return NIEL; } 

class G4ParticleChange& G4ScreenedNuclearRecoil::GetParticleChange ( )

inline

get the pointer to our ParticleChange object. for internal use, primarily.

Definition at line 410 of file G4ScreenedNuclearRecoil.hh.

              { return static_cast<G4ParticleChange &>(*pParticleChange); }

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G4double G4ScreenedNuclearRecoil::GetPhysicsCutoff ( ) const

inline

get the physics cutoff energy.

Definition at line 354 of file G4ScreenedNuclearRecoil.hh.

{ return physicsCutoff; }

G4double G4ScreenedNuclearRecoil::GetRecoilCutoff ( ) const

inline

get the recoil cutoff

Definition at line 344 of file G4ScreenedNuclearRecoil.hh.

{ return recoilCutoff; }

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std::string G4ScreenedNuclearRecoil::GetScreeningKey ( ) const

inline

find out what screening function we are using

Definition at line 290 of file G4ScreenedNuclearRecoil.hh.

{ return screeningKey; }

G4bool G4ScreenedNuclearRecoil::GetValidCollision ( ) const

inline

Definition at line 406 of file G4ScreenedNuclearRecoil.hh.

{ return validCollision; }

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G4int G4ScreenedNuclearRecoil::GetVerboseLevel ( ) const

inline

get the verbosity.

Definition at line 392 of file G4ScreenedNuclearRecoil.hh.

{ return verboseLevel; }

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G4bool G4ScreenedNuclearRecoil::IsApplicable ( const G4ParticleDefinition &  aParticleType )

virtual

test if a prticle of type aParticleType can use this process

Parameters

aParticleType

the particle to test

Reimplemented from G4VProcess.

Definition at line 796 of file G4ScreenedNuclearRecoil.cc.

{
        return  aParticleType == *(G4Proton::Proton()) ||
        aParticleType.GetParticleType() == "nucleus" ||
        aParticleType.GetParticleType() == "static_nucleus";
}

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G4VParticleChange * G4ScreenedNuclearRecoil::PostStepDoIt ( const G4Track &  aTrack, const G4Step &  aStep  )

virtual

used internally by Geant4 machinery

Reimplemented from G4VDiscreteProcess.

Definition at line 465 of file G4ScreenedNuclearRecoil.cc.

{
        validCollision=1;
        pParticleChange->Initialize(aTrack);
        NIEL=0.0; // default is no NIEL deposited
        IonizingLoss=0.0;
        
        // do universal setup
        
        const G4DynamicParticle* incidentParticle = aTrack.GetDynamicParticle();
        G4ParticleDefinition *baseParticle=aTrack.GetDefinition();
        
        G4double fz1=baseParticle->GetPDGCharge()/eplus;
        G4int z1=(G4int)(fz1+0.5);
        G4double a1=baseParticle->GetPDGMass()/amu_c2;
        G4double incidentEnergy = incidentParticle->GetKineticEnergy();
                
        // Select randomly one element and (possibly) isotope in the 
        // current material.
        const G4MaterialCutsCouple* couple = aTrack.GetMaterialCutsCouple();
        
        const G4Material* mat = couple->GetMaterial();

        G4double P=0.0; // the impact parameter of this collision

        if(incidentEnergy < GetRecoilCutoff()*a1) { 
          // check energy sanity on entry
          DepositEnergy(z1, baseParticle->GetPDGMass()/amu_c2, mat, 
                        incidentEnergy);
          GetParticleChange().ProposeEnergy(0.0);
          // stop the particle and bail out
          validCollision=0;
        } else {
                
                G4double numberDensity=mat->GetTotNbOfAtomsPerVolume();
                G4double lattice=0.5/std::pow(numberDensity,1.0/3.0); 
                // typical lattice half-spacing
                G4double length=GetCurrentInteractionLength();
                G4double sigopi=1.0/(pi*numberDensity*length);  
                // this is sigma0/pi
                
                // compute the impact parameter very early, so if is rejected 
                // as too far away, little effort is wasted
                // this is the TRIM method for determining an impact parameter 
                // based on the flight path
                // this gives a cumulative distribution of 
                // N(P)= 1-exp(-pi P^2 n l)
                // which says the probability of NOT hitting a disk of area 
                // sigma= pi P^2 =exp(-sigma N l) 
                // which may be reasonable
                if(sigopi < lattice*lattice) { 
                        // normal long-flight approximation
                        P = std::sqrt(-std::log(G4UniformRand()) *sigopi);
                } else {
                        // short-flight limit
                        P = std::sqrt(G4UniformRand())*lattice;
                }
                        
                G4double fraction=GetHardeningFraction();
                if(fraction && G4UniformRand() < fraction) { 
                  // pick out some events, and increase the central cross 
                  // section by reducing the impact parameter
                  P /= std::sqrt(GetHardeningFactor());
                }
                
                
                // check if we are far enough away that the energy transfer 
                // must be below cutoff, 
                // and leave everything alone if so, saving a lot of time.
                if(P*P > sigopi) {
                  if(GetVerboseLevel() > 1) 
    printf("ScreenedNuclear impact reject: length=%.3f P=%.4f limit=%.4f\n",
           length/angstrom, P/angstrom,std::sqrt(sigopi)/angstrom);
                  // no collision, don't follow up with anything
                  validCollision=0;
                }
        }
        
        // find out what we hit, and record it in our kinematics block.
        kinematics.targetMaterial=mat;
        kinematics.a1=a1;
        
        if(validCollision) {
                G4ScreenedCoulombCrossSection *xsect=
                  GetCrossSectionHandlers()[z1];
                G4ParticleDefinition *recoilIon=
                        xsect->SelectRandomUnweightedTarget(couple);
                kinematics.crossSection=xsect;
                kinematics.recoilIon=recoilIon;
                kinematics.impactParameter=P;
                kinematics.a2=recoilIon->GetPDGMass()/amu_c2;
        } else {
                kinematics.recoilIon=0;
                kinematics.impactParameter=0;
                kinematics.a2=0;
        }
        
        std::vector<G4ScreenedCollisionStage *>::iterator stage=
          collisionStages.begin();
        
        for(; stage != collisionStages.end(); stage++) 
                (*stage)->DoCollisionStep(this,aTrack, aStep);
        
        if(registerDepositedEnergy) {
                pParticleChange->ProposeLocalEnergyDeposit(IonizingLoss+NIEL);
                pParticleChange->ProposeNonIonizingEnergyDeposit(NIEL);
                //MHM G4cout << "depositing energy, total = " 
                //<< IonizingLoss+NIEL << " NIEL = " << NIEL << G4endl;
        }

        return G4VDiscreteProcess::PostStepDoIt( aTrack, aStep );
}

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void G4ScreenedNuclearRecoil::ResetTables

(

)

clear precomputed screening tables

Definition at line 348 of file G4ScreenedNuclearRecoil.cc.

{
        
  std::map<G4int, G4ScreenedCoulombCrossSection*>::iterator xt=
    crossSectionHandlers.begin();
        for(;xt != crossSectionHandlers.end(); xt++) {
                delete (*xt).second;
        }
        crossSectionHandlers.clear();
}

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void G4ScreenedNuclearRecoil::SetCrossSectionHardening ( G4double  fraction, G4double  HardeningFactor  )

inline

set the cross section boost to provide faster computation of backscattering

Parameters

fraction	the fraction of particles to have their cross section boosted.
HardeningFactor	the factor by which to boost the scattering cross section.

Definition at line 368 of file G4ScreenedNuclearRecoil.hh.

                                                                               {
                hardeningFraction=fraction;
                hardeningFactor=HardeningFactor;
     }

void G4ScreenedNuclearRecoil::SetExternalCrossSectionHandler ( G4ScreenedCoulombCrossSection *  cs )

inline

set a function to compute screening tables, if the user needs non-standard behavior.

Parameters

cs	a class which constructs the screening tables.

Definition at line 387 of file G4ScreenedNuclearRecoil.hh.

                                                                            { 
                            externalCrossSectionConstructor=cs; 
     }

void G4ScreenedNuclearRecoil::SetMaxEnergyForScattering ( G4double  energy )

inline

set the upper energy beyond which this process has no cross section

This funciton is used to coordinate this process with G4MSC. Typically, G4MSC should not be allowed to operate in a range which overlaps that of this process. The criterion which is most reasonable is that the transition should be somewhere in the modestly relativistic regime (500 MeV/u for example). param energy energy per nucleon for the cutoff

Definition at line 287 of file G4ScreenedNuclearRecoil.hh.

{processMaxEnergy=energy;}

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void G4ScreenedNuclearRecoil::SetMFPScaling ( G4double  scale )

inline

set the mean free path scaling as specified

Parameters

scale

the factor by which the default MFP will be scaled. Set to less than 1 for very thin films, typically, to sample multiple scattering, or to greater than 1 for quick simulations with a very long flight path

Definition at line 319 of file G4ScreenedNuclearRecoil.hh.

{ MFPScale=scale; }

void G4ScreenedNuclearRecoil::SetNIELPartitionFunction

(

const G4VNIELPartition *

part

)

set the pointer to a class for paritioning energy into NIEL

part the pointer to the class.

Definition at line 371 of file G4ScreenedNuclearRecoil.cc.

{
        if(NIELPartitionFunction) delete NIELPartitionFunction;
        NIELPartitionFunction=part;
}

void G4ScreenedNuclearRecoil::SetPhysicsCutoff ( G4double  energy )

inline

set the energy to which screening tables are computed. Typically, this is 10 eV or so, and not often changed.

Parameters

energy

the cutoff energy

Definition at line 350 of file G4ScreenedNuclearRecoil.hh.

                                            { physicsCutoff=energy; 
                                              ResetTables(); }

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void G4ScreenedNuclearRecoil::SetRecoilCutoff ( G4double  energy )

inline

set the minimum energy (per nucleon) at which recoils can be generated, and the energy (per nucleon) below which all ions are stopped.

Parameters

energy

energy per nucleon

Definition at line 341 of file G4ScreenedNuclearRecoil.hh.

{ recoilCutoff=energy; }

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void G4ScreenedNuclearRecoil::SetValidCollision ( G4bool  flag )

inline

Definition at line 404 of file G4ScreenedNuclearRecoil.hh.

{ validCollision=flag; }

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Friends And Related Function Documentation

friend class G4ScreenedCollisionStage

friend

Definition at line 213 of file G4ScreenedNuclearRecoil.hh.

Member Data Documentation

G4bool G4ScreenedNuclearRecoil::avoidReactions

protected

Definition at line 430 of file G4ScreenedNuclearRecoil.hh.

std::vector<G4ScreenedCollisionStage *> G4ScreenedNuclearRecoil::collisionStages

protected

Definition at line 438 of file G4ScreenedNuclearRecoil.hh.

std::map<G4int, G4ScreenedCoulombCrossSection*> G4ScreenedNuclearRecoil::crossSectionHandlers

protected

Definition at line 440 of file G4ScreenedNuclearRecoil.hh.

G4ScreenedCoulombCrossSection* G4ScreenedNuclearRecoil::externalCrossSectionConstructor

protected

Definition at line 437 of file G4ScreenedNuclearRecoil.hh.

G4bool G4ScreenedNuclearRecoil::generateRecoils

protected

Definition at line 430 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::hardeningFactor

protected

Definition at line 435 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::hardeningFraction

protected

Definition at line 435 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::highEnergyLimit

protected

the energy per nucleon above which the MFP is constant

Definition at line 421 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::IonizingLoss

protected

Definition at line 433 of file G4ScreenedNuclearRecoil.hh.

G4CoulombKinematicsInfo G4ScreenedNuclearRecoil::kinematics

protected

Definition at line 443 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::lowEnergyLimit

protected

the energy per nucleon below which the MFP is zero

Definition at line 424 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::MFPScale

protected

Definition at line 434 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::NIEL

protected

Definition at line 433 of file G4ScreenedNuclearRecoil.hh.

const G4VNIELPartition* G4ScreenedNuclearRecoil::NIELPartitionFunction

protected

Definition at line 444 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::physicsCutoff

protected

Definition at line 431 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::processMaxEnergy

protected

the energy per nucleon beyond which the cross section is zero, to cross over to G4MSC

Definition at line 428 of file G4ScreenedNuclearRecoil.hh.

G4double G4ScreenedNuclearRecoil::recoilCutoff

protected

Definition at line 431 of file G4ScreenedNuclearRecoil.hh.

G4bool G4ScreenedNuclearRecoil::registerDepositedEnergy

protected

Definition at line 432 of file G4ScreenedNuclearRecoil.hh.

G4String G4ScreenedNuclearRecoil::screeningKey

protected

Definition at line 429 of file G4ScreenedNuclearRecoil.hh.

G4bool G4ScreenedNuclearRecoil::validCollision

protected

Definition at line 442 of file G4ScreenedNuclearRecoil.hh.

---

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

• source/geant4.10.03.p03/examples/extended/electromagnetic/TestEm7/include/G4ScreenedNuclearRecoil.hh
• source/geant4.10.03.p03/examples/extended/electromagnetic/TestEm7/src/G4ScreenedNuclearRecoil.cc