G4IonCoulombCrossSection Class Reference

#include <G4IonCoulombCrossSection.hh>

Public Member Functions
	G4IonCoulombCrossSection ()
virtual	~G4IonCoulombCrossSection ()
void	Initialise (const G4ParticleDefinition *, G4double cosThetaLim)
G4double	NuclearCrossSection ()
G4double	SampleCosineTheta ()
void	SetupKinematic (G4double kinEnergy, G4double tmass)
void	SetupTarget (G4double Z, G4double kinEnergy, G4int heavycorr)
void	SetupParticle (const G4ParticleDefinition *)
G4double	GetMomentum2 ()

Detailed Description

Definition at line 69 of file G4IonCoulombCrossSection.hh.

Constructor & Destructor Documentation

G4IonCoulombCrossSection::G4IonCoulombCrossSection ( )

explicit

Definition at line 70 of file G4IonCoulombCrossSection.cc.

                                                  :
   cosThetaMin(1.0),
   cosThetaMax(-1.0),
   alpha2(fine_structure_const*fine_structure_const)
{
  fNistManager = G4NistManager::Instance();
  fG4pow = G4Pow::GetInstance();
  theProton   = G4Proton::Proton();
  particle=0;

  G4double p0 = electron_mass_c2*classic_electr_radius;
  coeff  = twopi*p0*p0;

  cosTetMinNuc=0;
  cosTetMaxNuc=0;
  nucXSection =0;

  chargeSquare = spin = mass = 0.0;
  tkinLab = momLab2 = invbetaLab2 = tkin = mom2 = invbeta2 = 0.0;

  targetZ = targetMass = screenZ = ScreenRSquare = etag = 0.0;
}

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G4IonCoulombCrossSection::~G4IonCoulombCrossSection ( )

virtual

Definition at line 94 of file G4IonCoulombCrossSection.cc.

{}

Member Function Documentation

G4double G4IonCoulombCrossSection::GetMomentum2 ( )

inline

Definition at line 159 of file G4IonCoulombCrossSection.hh.

{
  return mom2;
}

void G4IonCoulombCrossSection::Initialise	(	const G4ParticleDefinition *	p,
		G4double	cosThetaLim
	)

Definition at line 99 of file G4IonCoulombCrossSection.cc.

{
  SetupParticle(p);
  nucXSection = tkin = targetZ = mom2 = 0.0;
  etag = DBL_MAX;
  particle = p;     
  cosThetaMin = CosThetaLim; 
}

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G4double G4IonCoulombCrossSection::NuclearCrossSection

(

)

Definition at line 190 of file G4IonCoulombCrossSection.cc.

{
  // This method needs initialisation before be called
  // scattering with target nucleus
  G4double fac = coeff*targetZ*(targetZ)*chargeSquare*invbeta2/mom2;

  nucXSection  = 0.0;

  G4double x  = 1.0 - cosTetMinNuc;
  G4double x1 = x + screenZ;

  // scattering with nucleus
  if(cosTetMaxNuc < cosTetMinNuc) {
    nucXSection = fac*(cosTetMinNuc - cosTetMaxNuc)/
      (x1*(1.0 - cosTetMaxNuc + screenZ));
  }

  return nucXSection;
}

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G4double G4IonCoulombCrossSection::SampleCosineTheta

(

)

Definition at line 212 of file G4IonCoulombCrossSection.cc.

{   
  G4double z1 = 0.0;
  if(cosTetMaxNuc < cosTetMinNuc) {

    G4double x1 = 1. - cosTetMinNuc + screenZ;
    G4double x2 = 1. - cosTetMaxNuc + screenZ;
    G4double dx = cosTetMinNuc - cosTetMaxNuc;
    z1 = x1*x2/(x1 + G4UniformRand()*dx) - screenZ;
  }
  return z1;
}

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void G4IonCoulombCrossSection::SetupKinematic	(	G4double	kinEnergy,
		G4double	tmass
	)

Definition at line 111 of file G4IonCoulombCrossSection.cc.

{
  if(ekin != tkinLab || tmass != targetMass) {

    // lab
    tkinLab = ekin;
    momLab2 = tkinLab*(tkinLab + 2.0*mass);
    invbetaLab2 = 1.0 +  mass*mass/momLab2;

    G4double etot = tkinLab + mass;
    G4double ptot = sqrt(momLab2);
    G4double m12  = mass*mass;
    // relativistic reduced mass from publucation
    // A.P. Martynenko, R.N. Faustov, Teoret. mat. Fiz. 64 (1985) 179
        
    //incident particle & target nucleus
    targetMass = tmass;
    G4double Ecm=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;
    tkin = momCM*sqrt(invbeta2) - mu_rel;//Ekin of mu_rel

    cosTetMinNuc = cosThetaMin;
    cosTetMaxNuc = cosThetaMax;
  }
}

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void G4IonCoulombCrossSection::SetupParticle ( const G4ParticleDefinition *  p )

inline

Definition at line 147 of file G4IonCoulombCrossSection.hh.

{
  particle = p;
  mass = particle->GetPDGMass();
  spin = particle->GetPDGSpin();
  if(0.0 != spin) { spin = 0.5; }
  G4double q = particle->GetPDGCharge()/CLHEP::eplus;
  chargeSquare = q*q;
  tkin = 0.0;
}

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void G4IonCoulombCrossSection::SetupTarget	(	G4double	Z,
		G4double	kinEnergy,
		G4int	heavycorr
	)

Definition at line 143 of file G4IonCoulombCrossSection.cc.

{
  if(Z != targetZ || e != etag) {
    etag    = e;
    targetZ = Z;
    G4int iz= G4lrint(Z);

    SetScreenRSquare(iz);
    screenZ = 0;
    screenZ = ScreenRSquare/mom2;
    //heavycorr = 0;
    //  G4cout<< "heavycorr "<<heavycorr<<G4endl;

    G4double corr=5.*twopi*Z*std::sqrt(chargeSquare*alpha2);
    corr=G4Exp(G4Log(corr)*0.04);
    screenZ *=0.5*(1.13 + corr*3.76*Z*Z*chargeSquare*invbeta2*alpha2);
    // G4cout<<" heavycorr Z e corr....2As "<< heavycorr << "\t"
    //  <<Z <<"\t"<<e/MeV <<"\t"<<screenZ<<G4endl;
      
    if(1 == iz && particle == theProton && cosTetMaxNuc < 0.0) {
      cosTetMaxNuc = 0.0;
    }
  }
}

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

• geant4.10.03.p01/source/processes/electromagnetic/standard/include/G4IonCoulombCrossSection.hh
• geant4.10.03.p01/source/processes/electromagnetic/standard/src/G4IonCoulombCrossSection.cc