G4BohrFluctuations Class Reference

#include <G4BohrFluctuations.hh>

Inheritance diagram for G4BohrFluctuations:

Public Member Functions
	G4BohrFluctuations (const G4String &nam="BohrFluc")
virtual	~G4BohrFluctuations ()
G4double	SampleFluctuations (const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double, G4double, G4double)
G4double	Dispersion (const G4Material *, const G4DynamicParticle *, G4double, G4double)
void	InitialiseMe (const G4ParticleDefinition *)
Public Member Functions inherited from G4VEmFluctuationModel
	G4VEmFluctuationModel (const G4String &nam)
virtual	~G4VEmFluctuationModel ()
virtual void	SetParticleAndCharge (const G4ParticleDefinition *, G4double q2)
G4String	GetName () const

Detailed Description

Definition at line 58 of file G4BohrFluctuations.hh.

Constructor & Destructor Documentation

G4BohrFluctuations::G4BohrFluctuations

(

const G4String &

nam = "BohrFluc"

)

Definition at line 64 of file G4BohrFluctuations.cc.

References python.hepunit::proton_mass_c2.

 :G4VEmFluctuationModel(nam),
  particle(0),
  minNumberInteractionsBohr(2.0),
  minFraction(0.2),
  xmin(0.2),
  minLoss(0.001*eV)
{
  particleMass   = proton_mass_c2;
  chargeSquare   = 1.0;
  kineticEnergy  = 0.0;
  beta2          = 0.0;
}

G4BohrFluctuations::~G4BohrFluctuations ( )

virtual

Definition at line 80 of file G4BohrFluctuations.cc.

{}

Member Function Documentation

G4double G4BohrFluctuations::Dispersion ( const G4Material *  material, const G4DynamicParticle *  dp, G4double  tmax, G4double  length  )

virtual

Implements G4VEmFluctuationModel.

Definition at line 148 of file G4BohrFluctuations.cc.

References G4DynamicParticle::GetDefinition(), G4Material::GetElectronDensity(), G4DynamicParticle::GetKineticEnergy(), InitialiseMe(), and python.hepunit::twopi_mc2_rcl2.

Referenced by SampleFluctuations().

{
  if(!particle) { InitialiseMe(dp->GetDefinition()); }

  G4double electronDensity = material->GetElectronDensity();
  kineticEnergy = dp->GetKineticEnergy();
  G4double etot = kineticEnergy + particleMass;
  beta2 = kineticEnergy*(kineticEnergy + 2.0*particleMass)/(etot*etot);
  G4double siga  = (1.0/beta2 - 0.5) * twopi_mc2_rcl2 * tmax * length
                 * electronDensity * chargeSquare;

  return siga;
}

void G4BohrFluctuations::InitialiseMe ( const G4ParticleDefinition *  part )

virtual

Reimplemented from G4VEmFluctuationModel.

Definition at line 85 of file G4BohrFluctuations.cc.

References python.hepunit::eplus, G4ParticleDefinition::GetPDGCharge(), and G4ParticleDefinition::GetPDGMass().

Referenced by Dispersion().

{
  particle       = part;
  particleMass   = part->GetPDGMass();
  G4double q     = part->GetPDGCharge()/eplus;
  chargeSquare   = q*q;
}

G4double G4BohrFluctuations::SampleFluctuations ( const G4MaterialCutsCouple *  couple, const G4DynamicParticle *  dp, G4double  tmax, G4double  length, G4double  meanLoss  )

virtual

Implements G4VEmFluctuationModel.

Definition at line 96 of file G4BohrFluctuations.cc.

References Dispersion(), G4Poisson(), G4UniformRand, G4InuclParticleNames::gam, G4MaterialCutsCouple::GetMaterial(), eplot::material, n, G4INCL::DeJongSpin::shoot(), and test::x.

{
  if(meanLoss <= minLoss) { return meanLoss; }
  const G4Material* material = couple->GetMaterial();
  G4double siga = Dispersion(material,dp,tmax,length);
  G4double loss = meanLoss;

  G4double navr = meanLoss*meanLoss/siga;
  //G4cout << "### meanLoss= " << meanLoss << "  navr= " << navr << G4endl;
  if (navr >= minNumberInteractionsBohr) {
 
    // Increase fluctuations for big fractional energy loss
    if ( meanLoss > minFraction*kineticEnergy ) {
      G4double gam = (kineticEnergy - meanLoss)/particleMass + 1.0;
      G4double b2  = 1.0 - 1.0/(gam*gam);
      if(b2 < xmin*beta2) b2 = xmin*beta2;
      G4double x   = b2/beta2;
      G4double x3  = 1.0/(x*x*x);
      siga *= 0.25*(1.0 + x)*(x3 + (1.0/b2 - 0.5)/(1.0/beta2 - 0.5) );
    }
    siga = sqrt(siga);
    G4double twomeanLoss = meanLoss + meanLoss;
    //G4cout << "siga= " << siga << " 2edp= " << twomeanLoss <<G4endl;

    if(twomeanLoss < siga) {
      G4double x;
      do {
        loss = twomeanLoss*G4UniformRand();
    x = (loss - meanLoss)/siga;
      } while (1.0 - 0.5*x*x < G4UniformRand());
    } else {
      do {
        loss = G4RandGauss::shoot(meanLoss,siga);
      } while (0.0 > loss || loss > twomeanLoss);
    }

  // Poisson fluctuations
  } else {
    G4double n    = (G4double)(G4Poisson(navr));
    loss = meanLoss*n/navr;
  }
  //G4cout << "loss= " << loss << G4endl;

  return loss;
}

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

• G4BohrFluctuations.hh
• G4BohrFluctuations.cc