G4WentzelVIRelXSection Class Reference

#include <G4WentzelVIRelXSection.hh>

Collaboration diagram for G4WentzelVIRelXSection:

Public Member Functions
	G4WentzelVIRelXSection (G4bool combined=true)
virtual	~G4WentzelVIRelXSection ()
void	Initialise (const G4ParticleDefinition *, G4double CosThetaLim)
void	SetupParticle (const G4ParticleDefinition *)
G4double	SetupTarget (G4int Z, G4double cut)
G4double	ComputeTransportCrossSectionPerAtom (G4double CosThetaMax)
G4ThreeVector &	SampleSingleScattering (G4double CosThetaMin, G4double CosThetaMax, G4double elecRatio)
G4double	ComputeNuclearCrossSection (G4double CosThetaMin, G4double CosThetaMax)
G4double	ComputeElectronCrossSection (G4double CosThetaMin, G4double CosThetaMax)
G4double	SetupKinematic (G4double kinEnergy, const G4Material *mat, G4double cut, G4double tmass)
G4double	GetMomentumSquare () const
G4double	GetCosThetaNuc () const
G4double	GetCosThetaElec () const

Private Member Functions
void	ComputeMaxElectronScattering (G4double cut)
G4WentzelVIRelXSection &	operator= (const G4WentzelVIRelXSection &right)
	G4WentzelVIRelXSection (const G4WentzelVIRelXSection &)

Private Attributes
const G4ParticleDefinition *	theProton
const G4ParticleDefinition *	theElectron
const G4ParticleDefinition *	thePositron
const G4Material *	currentMaterial
G4NistManager *	fNistManager
G4Pow *	fG4pow
G4ThreeVector	temp
G4double	numlimit
G4int	nwarnings
G4int	nwarnlimit
G4bool	isCombined
G4double	coeff
G4double	cosTetMaxElec
G4double	cosTetMaxNuc
G4double	cosThetaMax
G4double	alpha2
const G4ParticleDefinition *	particle
G4double	chargeSquare
G4double	charge3
G4double	spin
G4double	mass
G4double	tkin
G4double	mom2
G4double	momCM2
G4double	invbeta2
G4double	kinFactor
G4double	etag
G4double	ecut
G4double	lowEnergyLimit
G4int	targetZ
G4double	targetMass
G4double	screenZ
G4double	formfactA
G4double	factorA2
G4double	factB
G4double	factB1
G4double	factD
G4double	gam0pcmp
G4double	pcmp2

Static Private Attributes
static G4double	ScreenRSquare [100] = {0.0}
static G4double	FormFactor [100] = {0.0}

Detailed Description

Definition at line 71 of file G4WentzelVIRelXSection.hh.

Constructor & Destructor Documentation

G4WentzelVIRelXSection() [1/2]

G4WentzelVIRelXSection::G4WentzelVIRelXSection

(

G4bool

combined = true

)

Definition at line 67 of file G4WentzelVIRelXSection.cc.

                                                              :
  temp(0.,0.,0.),
  numlimit(0.1),
  nwarnings(0),
  nwarnlimit(50),
  isCombined(combined),
  alpha2(fine_structure_const*fine_structure_const)
{
  fNistManager = G4NistManager::Instance();
  fG4pow = G4Pow::GetInstance();
  theElectron = G4Electron::Electron();
  thePositron = G4Positron::Positron();
  theProton   = G4Proton::Proton();
  lowEnergyLimit = 1.0*eV;
  G4double p0 = electron_mass_c2*classic_electr_radius;
  coeff = twopi*p0*p0;
  particle = 0;

  // Thomas-Fermi screening radii
  // Formfactors from A.V. Butkevich et al., NIM A 488 (2002) 282

  if(0.0 == ScreenRSquare[0]) {
    G4double a0 = electron_mass_c2/0.88534; 
    G4double constn = 6.937e-6/(MeV*MeV);

    ScreenRSquare[0] = alpha2*a0*a0;
    for(G4int j=1; j<100; ++j) {
      G4double x = a0*fG4pow->Z13(j);
      //ScreenRSquare[j] = 0.5*(1 + exp(-j*j*0.001))*alpha2*x*x;
      ScreenRSquare[j] = 0.5*alpha2*x*x;
      x = fNistManager->GetA27(j);
      FormFactor[j] = constn*x*x;
    } 
  }
  currentMaterial = 0;
  factB = factD = formfactA = screenZ = 0.0;
  cosTetMaxElec = cosTetMaxNuc = invbeta2 = kinFactor = gam0pcmp = pcmp2 = 1.0;
  cosThetaMax = 1.0;

  factB1= 0.5*CLHEP::pi*fine_structure_const;

  tkin = mom2 = momCM2 = factorA2 = mass = spin = chargeSquare = charge3 = 0.0;
  ecut = etag = DBL_MAX;
  targetZ = 0;
  targetMass = proton_mass_c2;
}

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~G4WentzelVIRelXSection()

G4WentzelVIRelXSection::~G4WentzelVIRelXSection ( )

virtual

Definition at line 116 of file G4WentzelVIRelXSection.cc.

{}

G4WentzelVIRelXSection() [2/2]

G4WentzelVIRelXSection::G4WentzelVIRelXSection ( const G4WentzelVIRelXSection &  )

private

Member Function Documentation

ComputeElectronCrossSection()

G4double G4WentzelVIRelXSection::ComputeElectronCrossSection ( G4double  CosThetaMin, G4double  CosThetaMax  )

inline

Definition at line 258 of file G4WentzelVIRelXSection.hh.

{
  G4double xsec = 0.0;
  G4double cost1 = std::max(cosTMin,cosTetMaxElec);
  G4double cost2 = std::max(cosTMax,cosTetMaxElec);
  if(cost1 > cost2) {
    xsec = kinFactor*(cost1 - cost2)/
      ((1.0 - cost1 + screenZ)*(1.0 - cost2 + screenZ));
  }
  return xsec;
}

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ComputeMaxElectronScattering()

void G4WentzelVIRelXSection::ComputeMaxElectronScattering ( G4double  cut )

private

Definition at line 329 of file G4WentzelVIRelXSection.cc.

{
  if(mass > MeV) {
    G4double ratio = electron_mass_c2/mass;
    G4double tau = tkin/mass;
    G4double tmax = 2.0*electron_mass_c2*tau*(tau + 2.)/
      (1.0 + 2.0*ratio*(tau + 1.0) + ratio*ratio);
    //tmax = std::min(tmax, targetZ*targetZ*10*eV); 
    cosTetMaxElec = 1.0 - std::min(cutEnergy, tmax)*electron_mass_c2/mom2;
  } else {

    G4double tmax = tkin;
    if(particle == theElectron) { tmax *= 0.5; }
    //tmax = std::min(tmax, targetZ*targetZ*10*eV); 
    G4double t = std::min(cutEnergy, tmax);
    G4double mom21 = t*(t + 2.0*electron_mass_c2);
    G4double t1 = tkin - t;
    //G4cout <<"tkin=" <<tkin<<" tmax= "<<tmax<<" t= " 
    //<<t<< " t1= "<<t1<<" cut= "<<ecut<<G4endl;
    if(t1 > 0.0) {
      G4double mom22 = t1*(t1 + 2.0*mass);
      G4double ctm = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22);
      if(ctm <  1.0) { cosTetMaxElec = ctm; }
      if(particle == theElectron && cosTetMaxElec < 0.0) { cosTetMaxElec = 0.0; }
    }
  }
}

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ComputeNuclearCrossSection()

G4double G4WentzelVIRelXSection::ComputeNuclearCrossSection ( G4double  CosThetaMin, G4double  CosThetaMax  )

inline

Definition at line 244 of file G4WentzelVIRelXSection.hh.

{
  G4double xsec = 0.0;
  if(cosTMax < cosTMin) {
    xsec = targetZ*kinFactor*(cosTMin - cosTMax)/
      ((1.0 - cosTMin + screenZ)*(1.0 - cosTMax + screenZ));
  }
  return xsec;
}

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ComputeTransportCrossSectionPerAtom()

G4double G4WentzelVIRelXSection::ComputeTransportCrossSectionPerAtom

(

G4double

CosThetaMax

)

Definition at line 184 of file G4WentzelVIRelXSection.cc.

{
  G4double xsec = 0.0;
  if(cosTMax >= 1.0) { return xsec; }
 
  G4double xSection = 0.0;
  G4double x = 0; 
  G4double y = 0;
  G4double x1= 0;
  G4double x2= 0;
  G4double xlog = 0.0;

  G4double costm = std::max(cosTMax,cosTetMaxElec); 
  G4double fb = screenZ*factB;

  // scattering off electrons
  if(costm < 1.0) {
    x = (1.0 - costm)/screenZ;
    if(x < numlimit) { 
      x2 = 0.5*x*x;
      y  = x2*(1.0 - 1.3333333*x + 3*x2);
      if(0.0 < factB) { y -= fb*x2*x*(0.6666667 - x); }
    } else { 
      x1= x/(1 + x);
      xlog = G4Log(1.0 + x);  
      y = xlog - x1; 
      if(0.0 < factB) { y -= fb*(x + x1 - 2*xlog); }
    }

    if(y < 0.0) {
      ++nwarnings;
      if(nwarnings < nwarnlimit) {
    G4cout << "G4WentzelVIRelXSection::ComputeTransportCrossSectionPerAtom scattering on e- <0"
           << G4endl;
    G4cout << "y= " << y 
           << " e(MeV)= " << tkin << " p(MeV/c)= " << sqrt(mom2) 
           << " Z= " << targetZ << "  " 
           << particle->GetParticleName() << G4endl;
    G4cout << " 1-costm= " << 1.0-costm << " screenZ= " << screenZ 
           << " x= " << x << G4endl;
      }
      y = 0.0;
    }
    xSection = y;
  }
  /* 
  G4cout << "G4WentzelVI:XS per A " << " Z= " << targetZ 
     << " e(MeV)= " << tkin/MeV << " XSel= " << xSection
     << " cut(MeV)= " << ecut/MeV  
     << " zmaxE= " << (1.0 - cosTetMaxElec)/screenZ 
     << " zmaxN= " << (1.0 - cosThetaMax)/screenZ 
         << " 1-costm= " << 1.0 - cosThetaMax << G4endl;
  */
  // scattering off nucleus
  if(cosTMax < 1.0) {
    x = (1.0 - cosTMax)/screenZ;
    if(x < numlimit) { 
      x2 = 0.5*x*x;
      y  = x2*(1.0 - 1.3333333*x + 3*x2); 
      if(0.0 < factB) { y -= fb*x2*x*(0.6666667 - x); }
    } else { 
      x1= x/(1 + x);
      xlog = G4Log(1.0 + x);  
      y = xlog - x1; 
      if(0.0 < factB) { y -= fb*(x + x1 - 2*xlog); }
    }

    if(y < 0.0) {
      ++nwarnings;
      if(nwarnings < nwarnlimit) {
    G4cout << "G4WentzelVIRelXSection::ComputeTransportCrossSectionPerAtom scattering on e- <0"
           << G4endl;
    G4cout << "y= " << y 
           << " e(MeV)= " << tkin << " Z= " << targetZ << "  " 
           << particle->GetParticleName() << G4endl;
    G4cout << " formfactA= " << formfactA << " screenZ= " << screenZ 
           << " x= " << " x1= " << x1 <<G4endl;
      }
      y = 0.0;
    }
    xSection += y*targetZ; 
  }
  xSection *= kinFactor;
  /*
  G4cout << "Z= " << targetZ << " XStot= " << xSection/barn 
     << " screenZ= " << screenZ << " formF= " << formfactA 
     << " for " << particle->GetParticleName() 
     << " m= " << mass << " 1/v= " << sqrt(invbeta2) << " p= " << sqrt(mom2)
     << " x= " << x 
     << G4endl;
  */
  return xSection; 
}

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GetCosThetaElec()

G4double G4WentzelVIRelXSection::GetCosThetaElec ( ) const

inline

Definition at line 236 of file G4WentzelVIRelXSection.hh.

{
  return cosTetMaxElec;
}

GetCosThetaNuc()

G4double G4WentzelVIRelXSection::GetCosThetaNuc ( ) const

inline

Definition at line 229 of file G4WentzelVIRelXSection.hh.

{
  return cosTetMaxNuc;
}

GetMomentumSquare()

G4double G4WentzelVIRelXSection::GetMomentumSquare ( ) const

inline

Definition at line 222 of file G4WentzelVIRelXSection.hh.

{
  return mom2;
}

Initialise()

void G4WentzelVIRelXSection::Initialise	(	const G4ParticleDefinition *	p,
		G4double	CosThetaLim
	)

Definition at line 121 of file G4WentzelVIRelXSection.cc.

{
  SetupParticle(p);
  tkin = mom2 = momCM2 = 0.0;
  ecut = etag = DBL_MAX;
  targetZ = 0;

  // cosThetaMax is below 1.0 only when MSC is combined with SS
  if(isCombined) { cosThetaMax = cosThetaLim; }

  G4double a = G4EmParameters::Instance()->FactorForAngleLimit()
    *CLHEP::hbarc/CLHEP::fermi;
  factorA2 = 0.5*a*a;
  currentMaterial = 0;
}

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operator=()

G4WentzelVIRelXSection& G4WentzelVIRelXSection::operator= ( const G4WentzelVIRelXSection &  right )

private

SampleSingleScattering()

G4ThreeVector & G4WentzelVIRelXSection::SampleSingleScattering	(	G4double	CosThetaMin,
		G4double	CosThetaMax,
		G4double	elecRatio
	)

Definition at line 281 of file G4WentzelVIRelXSection.cc.

{
  temp.set(0.0,0.0,1.0);
 
  CLHEP::HepRandomEngine* rndmEngine = G4Random::getTheEngine();

  G4double formf = formfactA;
  G4double cost1 = cosTMin;
  G4double cost2 = cosTMax;
  if(elecRatio > 0.0) {
    if(rndmEngine->flat() <= elecRatio) {
      formf = 0.0;
      cost1 = std::max(cost1,cosTetMaxElec);
      cost2 = std::max(cost2,cosTetMaxElec);
    }
  }
  if(cost1 < cost2) { return temp; }

  G4double w1 = 1. - cost1 + screenZ;
  G4double w2 = 1. - cost2 + screenZ;
  G4double z1 = w1*w2/(w1 + rndmEngine->flat()*(w2 - w1)) - screenZ;

  G4double fm =  1.0 + formf*z1;
  G4double grej = (1. - z1*factB + factB1*targetZ*sqrt(z1*factB)*(2 - z1))
                 /( (1.0 + z1*factD)*fm*fm );
  // "false" scattering
  if(rndmEngine->flat() > grej ) { return temp; }
    // } 
  G4double cost = 1.0 - z1;

  if(cost > 1.0)       { cost = 1.0; }
  else if(cost < -1.0) { cost =-1.0; }
  G4double sint = sqrt((1.0 - cost)*(1.0 + cost));
  //G4cout << "sint= " << sint << G4endl;
  G4double phi  = twopi*rndmEngine->flat();
  G4double vx1 = sint*cos(phi);
  G4double vy1 = sint*sin(phi);

  // only direction is changed
  temp.set(vx1,vy1,cost);
  return temp;
}

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SetupKinematic()

G4double G4WentzelVIRelXSection::SetupKinematic ( G4double  kinEnergy, const G4Material *  mat, G4double  cut, G4double  tmass  )

inline

Definition at line 179 of file G4WentzelVIRelXSection.hh.

{
  if(kinEnergy != tkin || mat != currentMaterial ||
     ecut != cut || tmass != targetMass) { 

    currentMaterial = mat;
    ecut = cut;
    tkin  = kinEnergy;
    G4double momLab2  = tkin*(tkin + 2.0*mass);
    
    G4double etot = tkin + mass;
    G4double ptot = std::sqrt(momLab2);
    G4double m12  = mass*mass;

    targetMass = tmass;

    // relativistic reduced mass from publucation
    // A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179
        
    //incident particle & target nucleus
    G4double Ecm = std::sqrt(m12 + targetMass*targetMass + 2.0*etot*targetMass);
    G4double mu_rel = mass*targetMass/Ecm;
    G4double momCM  = ptot*targetMass/Ecm;
    // relative system
    mom2 = momCM*momCM;
    invbeta2 = 1.0 +  mu_rel*mu_rel/mom2;

    factB = spin/invbeta2;
    factD = std::sqrt(mom2)/tmass;
    if(isCombined) {
      G4double cost = 1.-factorA2*mat->GetIonisation()->GetInvA23()/mom2;
      if(cost > cosTetMaxNuc) { cosTetMaxNuc = cost; }
    }
  } 
  return cosTetMaxNuc;

}

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SetupParticle()

void G4WentzelVIRelXSection::SetupParticle

(

const G4ParticleDefinition *

p

)

Definition at line 140 of file G4WentzelVIRelXSection.cc.

{
  particle = p;
  mass = particle->GetPDGMass();
  spin = particle->GetPDGSpin();
  if(0.0 != spin) { spin = 0.5; }
  G4double q = std::fabs(particle->GetPDGCharge()/eplus);
  chargeSquare = q*q;
  charge3 = chargeSquare*q;
  tkin = 0.0;
  currentMaterial = 0;
  targetZ = 0;
}

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SetupTarget()

G4double G4WentzelVIRelXSection::SetupTarget	(	G4int	Z,
		G4double	cut
	)

Definition at line 157 of file G4WentzelVIRelXSection.cc.

{
  G4double cosTetMaxNuc2 = cosTetMaxNuc;
  if(Z != targetZ || tkin != etag) {
    etag    = tkin; 
    targetZ = Z;

    kinFactor = coeff*targetZ*chargeSquare*invbeta2/mom2;

    screenZ = ScreenRSquare[targetZ]/mom2;
    if(Z > 1) {
      screenZ *= std::min(Z*1.13,1.13 +3.76*Z*Z*invbeta2*alpha2*chargeSquare);
    }
    if(targetZ == 1 && cosTetMaxNuc2 < 0.0 && particle == theProton) {
      cosTetMaxNuc2 = 0.0;
    }
    formfactA = FormFactor[targetZ]*mom2;

    cosTetMaxElec = 1.0;
    ComputeMaxElectronScattering(cut); 
  }
  return cosTetMaxNuc2;
} 

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Member Data Documentation

alpha2

G4double G4WentzelVIRelXSection::alpha2

private

Definition at line 142 of file G4WentzelVIRelXSection.hh.

charge3

G4double G4WentzelVIRelXSection::charge3

private

Definition at line 148 of file G4WentzelVIRelXSection.hh.

chargeSquare

G4double G4WentzelVIRelXSection::chargeSquare

private

Definition at line 147 of file G4WentzelVIRelXSection.hh.

coeff

G4double G4WentzelVIRelXSection::coeff

private

Definition at line 138 of file G4WentzelVIRelXSection.hh.

cosTetMaxElec

G4double G4WentzelVIRelXSection::cosTetMaxElec

private

Definition at line 139 of file G4WentzelVIRelXSection.hh.

cosTetMaxNuc

G4double G4WentzelVIRelXSection::cosTetMaxNuc

private

Definition at line 140 of file G4WentzelVIRelXSection.hh.

cosThetaMax

G4double G4WentzelVIRelXSection::cosThetaMax

private

Definition at line 141 of file G4WentzelVIRelXSection.hh.

currentMaterial

const G4Material* G4WentzelVIRelXSection::currentMaterial

private

Definition at line 122 of file G4WentzelVIRelXSection.hh.

ecut

G4double G4WentzelVIRelXSection::ecut

private

Definition at line 157 of file G4WentzelVIRelXSection.hh.

etag

G4double G4WentzelVIRelXSection::etag

private

Definition at line 156 of file G4WentzelVIRelXSection.hh.

factB

G4double G4WentzelVIRelXSection::factB

private

Definition at line 166 of file G4WentzelVIRelXSection.hh.

factB1

G4double G4WentzelVIRelXSection::factB1

private

Definition at line 167 of file G4WentzelVIRelXSection.hh.

factD

G4double G4WentzelVIRelXSection::factD

private

Definition at line 168 of file G4WentzelVIRelXSection.hh.

factorA2

G4double G4WentzelVIRelXSection::factorA2

private

Definition at line 165 of file G4WentzelVIRelXSection.hh.

fG4pow

G4Pow* G4WentzelVIRelXSection::fG4pow

private

Definition at line 125 of file G4WentzelVIRelXSection.hh.

fNistManager

G4NistManager* G4WentzelVIRelXSection::fNistManager

private

Definition at line 124 of file G4WentzelVIRelXSection.hh.

formfactA

G4double G4WentzelVIRelXSection::formfactA

private

Definition at line 164 of file G4WentzelVIRelXSection.hh.

FormFactor

G4double G4WentzelVIRelXSection::FormFactor = {0.0}

staticprivate

Definition at line 173 of file G4WentzelVIRelXSection.hh.

gam0pcmp

G4double G4WentzelVIRelXSection::gam0pcmp

private

Definition at line 169 of file G4WentzelVIRelXSection.hh.

invbeta2

G4double G4WentzelVIRelXSection::invbeta2

private

Definition at line 154 of file G4WentzelVIRelXSection.hh.

isCombined

G4bool G4WentzelVIRelXSection::isCombined

private

Definition at line 135 of file G4WentzelVIRelXSection.hh.

kinFactor

G4double G4WentzelVIRelXSection::kinFactor

private

Definition at line 155 of file G4WentzelVIRelXSection.hh.

lowEnergyLimit

G4double G4WentzelVIRelXSection::lowEnergyLimit

private

Definition at line 158 of file G4WentzelVIRelXSection.hh.

mass

G4double G4WentzelVIRelXSection::mass

private

Definition at line 150 of file G4WentzelVIRelXSection.hh.

mom2

G4double G4WentzelVIRelXSection::mom2

private

Definition at line 152 of file G4WentzelVIRelXSection.hh.

momCM2

G4double G4WentzelVIRelXSection::momCM2

private

Definition at line 153 of file G4WentzelVIRelXSection.hh.

numlimit

G4double G4WentzelVIRelXSection::numlimit

private

Definition at line 129 of file G4WentzelVIRelXSection.hh.

nwarnings

G4int G4WentzelVIRelXSection::nwarnings

private

Definition at line 132 of file G4WentzelVIRelXSection.hh.

nwarnlimit

G4int G4WentzelVIRelXSection::nwarnlimit

private

Definition at line 133 of file G4WentzelVIRelXSection.hh.

particle

const G4ParticleDefinition* G4WentzelVIRelXSection::particle

private

Definition at line 145 of file G4WentzelVIRelXSection.hh.

pcmp2

G4double G4WentzelVIRelXSection::pcmp2

private

Definition at line 170 of file G4WentzelVIRelXSection.hh.

ScreenRSquare

G4double G4WentzelVIRelXSection::ScreenRSquare = {0.0}

staticprivate

Definition at line 172 of file G4WentzelVIRelXSection.hh.

screenZ

G4double G4WentzelVIRelXSection::screenZ

private

Definition at line 163 of file G4WentzelVIRelXSection.hh.

spin

G4double G4WentzelVIRelXSection::spin

private

Definition at line 149 of file G4WentzelVIRelXSection.hh.

targetMass

G4double G4WentzelVIRelXSection::targetMass

private

Definition at line 162 of file G4WentzelVIRelXSection.hh.

targetZ

G4int G4WentzelVIRelXSection::targetZ

private

Definition at line 161 of file G4WentzelVIRelXSection.hh.

temp

G4ThreeVector G4WentzelVIRelXSection::temp

private

Definition at line 127 of file G4WentzelVIRelXSection.hh.

theElectron

const G4ParticleDefinition* G4WentzelVIRelXSection::theElectron

private

Definition at line 120 of file G4WentzelVIRelXSection.hh.

thePositron

const G4ParticleDefinition* G4WentzelVIRelXSection::thePositron

private

Definition at line 121 of file G4WentzelVIRelXSection.hh.

theProton

const G4ParticleDefinition* G4WentzelVIRelXSection::theProton

private

Definition at line 119 of file G4WentzelVIRelXSection.hh.

tkin

G4double G4WentzelVIRelXSection::tkin

private

Definition at line 151 of file G4WentzelVIRelXSection.hh.

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

• G4WentzelVIRelXSection.hh
• G4WentzelVIRelXSection.cc