G4ElectroNuclearCrossSection Class Reference

#include <G4ElectroNuclearCrossSection.hh>

Inheritance diagram for G4ElectroNuclearCrossSection:

Collaboration diagram for G4ElectroNuclearCrossSection:

Public Member Functions
	G4ElectroNuclearCrossSection ()
virtual	~G4ElectroNuclearCrossSection ()
virtual void	CrossSectionDescription (std::ostream &) const
virtual G4bool	IsElementApplicable (const G4DynamicParticle *, G4int Z, const G4Material *)
virtual G4double	GetElementCrossSection (const G4DynamicParticle *, G4int Z, const G4Material *mat)
G4double	GetEquivalentPhotonEnergy ()
G4double	GetVirtualFactor (G4double nu, G4double Q2)
G4double	GetEquivalentPhotonQ2 (G4double nu)
Public Member Functions inherited from G4VCrossSectionDataSet
	G4VCrossSectionDataSet (const G4String &nam="")
virtual	~G4VCrossSectionDataSet ()
virtual G4bool	IsIsoApplicable (const G4DynamicParticle *, G4int Z, G4int A, const G4Element *elm=0, const G4Material *mat=0)
G4double	GetCrossSection (const G4DynamicParticle *, const G4Element *, const G4Material *mat=0)
G4double	ComputeCrossSection (const G4DynamicParticle *, const G4Element *, const G4Material *mat=0)
virtual G4double	GetIsoCrossSection (const G4DynamicParticle *, G4int Z, G4int A, const G4Isotope *iso=0, const G4Element *elm=0, const G4Material *mat=0)
virtual G4Isotope *	SelectIsotope (const G4Element *, G4double kinEnergy)
virtual void	BuildPhysicsTable (const G4ParticleDefinition &)
virtual void	DumpPhysicsTable (const G4ParticleDefinition &)
virtual G4int	GetVerboseLevel () const
virtual void	SetVerboseLevel (G4int value)
G4double	GetMinKinEnergy () const
void	SetMinKinEnergy (G4double value)
G4double	GetMaxKinEnergy () const
void	SetMaxKinEnergy (G4double value)
const G4String &	GetName () const

Static Public Member Functions
static const char *	Default_Name ()

Additional Inherited Members
Protected Member Functions inherited from G4VCrossSectionDataSet
void	SetName (const G4String &)
Protected Attributes inherited from G4VCrossSectionDataSet
G4int	verboseLevel

Detailed Description

Definition at line 58 of file G4ElectroNuclearCrossSection.hh.

Constructor & Destructor Documentation

G4ElectroNuclearCrossSection::G4ElectroNuclearCrossSection

(

)

Definition at line 2180 of file G4ElectroNuclearCrossSection.cc.

                                                          :G4VCrossSectionDataSet(Default_Name()),
currentN(0), currentZ(0), lastZ(0),
lastE(0), lastSig(0), lastG(0), lastL(0), mNeut(G4NucleiProperties::GetNuclearMass(1,0)), mProt(G4NucleiProperties::GetNuclearMass(1,1))
{
    //Initialize caches
    lastUsedCacheEl = new cacheEl_t;
    nistmngr = G4NistManager::Instance();
    
    for (G4int i=0;i<120;i++)
    {
        cache.push_back(0);
    }
    
}

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G4ElectroNuclearCrossSection::~G4ElectroNuclearCrossSection ( )

virtual

Definition at line 2195 of file G4ElectroNuclearCrossSection.cc.

{
     std::vector<cacheEl_t*>::iterator it = cache.begin();
     while ( it != cache.end() )  /* Loop checking, 08.01.2016, W. Pokorski */
     {
         if ( *it ) {
             delete[] (*it)->J1; (*it)->J1 = 0;
             delete[] (*it)->J2; (*it)->J2 = 0;
             delete[] (*it)->J3; (*it)->J3 = 0;
         }
     ++it;
     }
     cache.clear();
     delete lastUsedCacheEl;
}

Member Function Documentation

void G4ElectroNuclearCrossSection::CrossSectionDescription ( std::ostream &  outFile ) const

virtual

Reimplemented from G4VCrossSectionDataSet.

Definition at line 2243 of file G4ElectroNuclearCrossSection.cc.

{
    outFile << "G4ElectroNuclearCrossSection provides the total inelastic\n"
    << "cross section for e- and e+ interactions with nuclei.  The\n"
    << "cross sections are retrieved from a table which is\n"
    << "generated using the equivalent photon approximation.  In\n"
    << "this approximation real gammas are produced from the virtual\n"
    << "ones generated at the electromagnetic vertex.  This cross\n"
    << "section set is valid for incident electrons and positrons at\n"
    << "all energies.\n";
}

static const char* G4ElectroNuclearCrossSection::Default_Name ( )

inlinestatic

Definition at line 65 of file G4ElectroNuclearCrossSection.hh.

{return "ElectroNuclearXS";}

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G4double G4ElectroNuclearCrossSection::GetElementCrossSection ( const G4DynamicParticle *  aPart, G4int  Z, const G4Material *  mat  )

virtual

Reimplemented from G4VCrossSectionDataSet.

Definition at line 2261 of file G4ElectroNuclearCrossSection.cc.

{
    const G4double Energy = aPart->GetKineticEnergy()/MeV; // Energy of the electron

    if (Energy<=EMi) return 0.;              // Energy is below the minimum energy in the table
    
    if(ZZ!=lastZ)      // This nucleus was not the last used element
    {
        lastE    = 0.;                       // New history in the electron Energy
        lastG    = 0.;                       // New history in the photon Energy
        lastZ = ZZ;
        
        //key to search in cache
        if(!cache[ZZ]){
            lastUsedCacheEl->J1 = new G4double[nE];  // Allocate memory for the new J1 function
            lastUsedCacheEl->J2 = new G4double[nE];  // Allocate memory for the new J2 function
            lastUsedCacheEl->J3 = new G4double[nE];  // Allocate memory for the new J3 function
            G4double Aa = nistmngr->GetAtomicMassAmu(ZZ); // average A
            G4int N = (G4int)Aa - ZZ;
            lastUsedCacheEl->F  = GetFunctions(Aa,lastUsedCacheEl->J1,lastUsedCacheEl->J2,lastUsedCacheEl->J3); // new ZeroPos and filling of J-functions
            lastUsedCacheEl->H  = alop*Aa*(1.-.072*G4Log(Aa));// corresponds to lastSP from G4PhotonuclearCrossSection
            lastUsedCacheEl->TH = ThresholdEnergy(ZZ, N); // The last Threshold Energy
            cacheEl_t* new_el = new cacheEl_t(*lastUsedCacheEl);
            cache[ZZ] = new_el;
        }
        else
        { //found in cache
            const cacheEl_t& el = *(cache[ZZ]);
            lastUsedCacheEl->F  = el.F;
            lastUsedCacheEl->TH = el.TH;
            lastUsedCacheEl->H  = el.H;
            lastUsedCacheEl->J1 = el.J1;
            lastUsedCacheEl->J2 = el.J2;
            lastUsedCacheEl->J3 = el.J3;
        }
    }
    else
    { //current isotope is the same as previous one
        if ( lastE == Energy ) return lastSig*millibarn; // Don't calc. same CS twice
    }
    //End of optimization: now lastUsedCacheEl structure contains the correct data for this isotope

    // ============================== NOW Calculate the Cross Section ==========================
    lastE=Energy;                          // lastE - the electron energy
    
    if ( Energy <= lastUsedCacheEl->TH ) // check that the eE is higher than the ThreshE
    {
        lastSig=0.;
        return 0.;
    }
    
    G4double lE=G4Log(Energy);               // G4Log(eE) (it is necessary at this point for the fit)

    lastG=lE-lmel;                         // Gamma of the electron (used to recover G4Log(eE))
    G4double dlg1=lastG+lastG-1.;
    G4double lgoe=lastG/lastE;
    if(lE<lEMa) // Linear fit is made explicitly to fix the last bin for the randomization
    {
        G4double shift=(lE-lEMi)/dlnE;
        G4int    blast=static_cast<int>(shift);
        if(blast<0)   blast=0;
        if(blast>=mLL) blast=mLL-1;
        shift-=blast;
        lastL=blast+1;
        G4double YNi=dlg1*lastUsedCacheEl->J1[blast]-lgoe*(lastUsedCacheEl->J2[blast]+lastUsedCacheEl->J2[blast]-lastUsedCacheEl->J3[blast]/lastE);
        G4double YNj=dlg1*lastUsedCacheEl->J1[lastL]-lgoe*(lastUsedCacheEl->J2[lastL]+lastUsedCacheEl->J2[lastL]-lastUsedCacheEl->J3[lastL]/lastE);
        lastSig= YNi+shift*(YNj-YNi);
        if(lastSig>YNj)lastSig=YNj;
    }
    else
    {
        lastL=mLL;
        
        G4double term1=lastUsedCacheEl->J1[mLL]+lastUsedCacheEl->H*HighEnergyJ1(lE);
        
        G4double term2=lastUsedCacheEl->J2[mLL]+lastUsedCacheEl->H*HighEnergyJ2(lE, Energy);
        
        G4double En2 = Energy*Energy;
        G4double term3=lastUsedCacheEl->J3[mLL]+lastUsedCacheEl->H*HighEnergyJ3(lE, En2);

        lastSig=dlg1*term1-lgoe*(term2+term2-term3/lastE);
    }
    
    if(lastSig<0.) lastSig = 0.;

    return lastSig*millibarn;
}

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G4double G4ElectroNuclearCrossSection::GetEquivalentPhotonEnergy

(

)

Definition at line 2428 of file G4ElectroNuclearCrossSection.cc.

{
    if(lastSig <= 0.0) { return 0.0; }  // VI
    G4double phLE = 0.;                        // Prototype of the G4Log(nu=E_gamma)
    G4double Y[nE] = {0.0};                    // Prepare the array for randomization
    
    G4double lastLE=lastG+lmel;   // recover G4Log(eE) from the gamma (lastG)
    G4double dlg1=lastG+lastG-1.;
    G4double lgoe=lastG/lastE;
    for (G4int i=lastUsedCacheEl->F;i<=lastL;i++) {
        Y[i] = dlg1*lastUsedCacheEl->J1[i]-lgoe*(lastUsedCacheEl->J2[i]+lastUsedCacheEl->J2[i]-lastUsedCacheEl->J3[i]/lastE);
        if(Y[i] < 0.0) { Y[i] = 0.0; }
    }
    // Tempory IF of H.P.: delete it if the *HP* err message does not
    // show up M.K.
    if(lastSig>0.99*Y[lastL] && lastL<mLL && Y[lastL]<1.E-30)
    {
        G4cerr << "*HP*G4ElNucCS::GetEqPhotE:S=" << lastSig <<">" << Y[lastL]
        << ",l=" << lastL << ">" << mLL << G4endl;
        if(lastSig <= 0.0) { return 0.0; }  // VI
    }
    G4double ris = lastSig*G4UniformRand(); // Sig can be > Y[lastL = mLL], then it
    // is in the funct. region
    
    if (ris < Y[lastL]) {               // Search the table
        G4int j = lastUsedCacheEl->F;
        G4double Yj = Y[j];               // It must be 0 (sometimes just very small)
        while (ris > Yj && j < lastL) {   // Associative search  /* Loop checking, 08.01.2016, W. Pokorski */
            j++;
            Yj = Y[j];                      // Yj is first value above ris
        }
        G4int j1 = j-1;
        G4double Yi = Y[j1];              // Previous value is below ris
        phLE = lEMi + (j1 + (ris-Yi)/(Yj-Yi) )*dlnE;
    } else {                            // Search with the function
        if (lastL < mLL) G4cerr << "**G4EleNucCS::GetEfPhE:L=" << lastL << ",S="
            << lastSig << ",Y=" << Y[lastL] << G4endl;
        G4double f = (ris-Y[lastL])/lastUsedCacheEl->H;    // The scaled residual value of the cross-section integral
        phLE=SolveTheEquation(f);           // Solve the equation to find theLog(phE) (compare with lastLE)
    }
    
    if (phLE>lastLE) {
        G4cerr << "***G4ElectroNuclearCS::GetEquPhotE:N=" << currentN << ",Z="
        << currentZ << ", lpE" << phLE << ">leE" << lastLE << ",Sig="
        << lastSig << ",rndSig=" << ris << ",Beg=" << lastUsedCacheEl->F << ",End="
        << lastL << ",Y=" << Y[lastL] << G4endl;
        if(lastLE<7.2) phLE=G4Log(G4Exp(lastLE)-.511);
        else phLE=7.;
    }
    return G4Exp(phLE);
}

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G4double G4ElectroNuclearCrossSection::GetEquivalentPhotonQ2

(

G4double

nu

)

Definition at line 2507 of file G4ElectroNuclearCrossSection.cc.

{
    if(lastG <= 0.0 || lastE <= 0.0) { return 0.; } // VI
    if(lastSig <= 0.0) { return 0.0; }  // VI
    G4double y=nu/lastE;                    // Part of energy carried by the equivalent pfoton
    if(y>=1.-1./(lastG+lastG)) return 0.;   // The region where the method does not work
    G4double y2=y*y;                        // Squared photonic part of energy
    G4double ye=1.-y;                       // Part of energy carried by the secondary electron
    G4double Qi2=mel2*y2/ye;                // Minimum Q2
    G4double Qa2=4*lastE*lastE*ye;          // Maximum Q2
    G4double iar=Qi2/Qa2;                   // Q2min/Q2max ratio
    G4double Dy=ye+.5*y2;                   // D(y) function
    G4double Py=ye/Dy;                      // P(y) function
    G4double ePy=1.-G4Exp(Py);                // 1-std::exp(P(y)) part
    G4double Uy=Py*(1.-iar);                // U(y) function
    G4double Fy=(ye+ye)*(1.+ye)*iar/y2;     // F(y) function
    G4double fr=iar/(1.-ePy*iar);           // Q-fraction
    if(Fy<=-fr)
    {
        return 0.;
    }
    G4double LyQa2=G4Log(Fy+fr);              // L(y,Q2max) function
    G4bool cond=true;
    G4int maxTry=3;
    G4int cntTry=0;
    G4double Q2=Qi2;
    while(cond&&cntTry<maxTry)             // The loop to avoid x>1.  /* Loop checking, 08.01.2016, W. Pokorski */
    {
        G4double R=G4UniformRand();           // Random number (0,1)
        Q2=Qi2*(ePy+1./(G4Exp(R*LyQa2-(1.-R)*Uy)-Fy));
        cntTry++;
        cond = Q2>1878.*nu;
    }
    if(Q2<Qi2)
    {
        return Qi2;
    }
    if(Q2>Qa2)
    {
        return Qa2;
    }
    return Q2;
}

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G4double G4ElectroNuclearCrossSection::GetVirtualFactor	(	G4double	nu,
		G4double	Q2
	)

Definition at line 2551 of file G4ElectroNuclearCrossSection.cc.

{
    if(nu <= 0.0 || Q2 <= 0.0) { return 0.0; }
    //G4double x=Q2/dM/nu;                  // Direct x definition
    G4double K=nu-Q2/dM;                    // K=nu*(1-x)
    if(K <= 0.) // VI
    {
        return 0.;
    }
    G4double lK=G4Log(K);                     // ln(K)
    G4double x=1.-K/nu;                     // This definitin saves one div.
    G4double GD=1.+Q2/Q02;                  // Reversed nucleonic form-factor
    G4double b=G4Exp(bp*(lK-blK0));           // b-factor
    G4double c=G4Exp(cp*(lK-clK0));           // c-factor
    G4double r=.5*G4Log(Q2+nu*nu)-lK;         // r=.5*G4Log((Q^2+nu^2)/K^2)
    G4double ef=G4Exp(r*(b-c*r*r));           // exponential factor
    return (1.-x)*ef/GD/GD;
}

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G4bool G4ElectroNuclearCrossSection::IsElementApplicable ( const G4DynamicParticle *  , G4int  Z, const G4Material *    )

virtual

Reimplemented from G4VCrossSectionDataSet.

Definition at line 2255 of file G4ElectroNuclearCrossSection.cc.

{
    return true;
}

---

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

• geant4.10.03.p01/source/processes/hadronic/cross_sections/include/G4ElectroNuclearCrossSection.hh
• geant4.10.03.p01/source/processes/hadronic/cross_sections/src/G4ElectroNuclearCrossSection.cc