G4Generator2BS Class Reference

#include <G4Generator2BS.hh>

Inheritance diagram for G4Generator2BS:

Public Member Functions
	G4Generator2BS (const G4String &name="")
virtual	~G4Generator2BS ()
virtual G4ThreeVector &	SampleDirection (const G4DynamicParticle *dp, G4double out_energy, G4int Z, const G4Material *mat=0)
void	PrintGeneratorInformation () const
Public Member Functions inherited from G4VEmAngularDistribution
	G4VEmAngularDistribution (const G4String &name)
virtual	~G4VEmAngularDistribution ()
virtual G4ThreeVector &	SampleDirectionForShell (const G4DynamicParticle *dp, G4double finalTotalEnergy, G4int Z, G4int shellID, const G4Material *)
const G4String &	GetName () const

Protected Member Functions
G4double	RejectionFunction (G4double value) const

Additional Inherited Members
Protected Attributes inherited from G4VEmAngularDistribution
G4ThreeVector	fLocalDirection

Detailed Description

Definition at line 64 of file G4Generator2BS.hh.

Constructor & Destructor Documentation

G4Generator2BS::G4Generator2BS

(

const G4String &

name = ""

)

Definition at line 64 of file G4Generator2BS.cc.

References G4Pow::GetInstance().

  : G4VEmAngularDistribution("AngularGen2BS"),fz(1),ratio(1),
    ratio1(1),ratio2(1),delta(0)
{
  g4pow = G4Pow::GetInstance();
  nwarn = 0;
}

G4Generator2BS::~G4Generator2BS ( )

virtual

Definition at line 72 of file G4Generator2BS.cc.

{}

Member Function Documentation

void G4Generator2BS::PrintGeneratorInformation

(

)

const

Definition at line 140 of file G4Generator2BS.cc.

References G4cout, and G4endl.

{
  G4cout << "\n" << G4endl;
  G4cout << "Bremsstrahlung Angular Generator is 2BS Generator "
     << "from 2BS Koch & Motz distribution (Rev Mod Phys 31(4), 920 (1959))" << G4endl;
  G4cout << "Sampling algorithm adapted from PIRS-0203" << G4endl;
  G4cout << "\n" << G4endl;
} 

G4double G4Generator2BS::RejectionFunction ( G4double  value ) const

inlineprotected

Definition at line 101 of file G4Generator2BS.hh.

References test::x.

Referenced by SampleDirection().

{
  G4double y2 = (1 + y)*(1 + y);
  G4double x  = 4*y*ratio/y2;
  return 4*x - ratio1 - (ratio2 - x)*std::log(delta + fz/y2); 
}

G4ThreeVector & G4Generator2BS::SampleDirection ( const G4DynamicParticle *  dp, G4double  out_energy, G4int  Z, const G4Material *  mat = 0  )

virtual

Implements G4VEmAngularDistribution.

Definition at line 75 of file G4Generator2BS.cc.

References python.hepunit::electron_mass_c2, energy(), G4VEmAngularDistribution::fLocalDirection, G4cout, G4endl, G4UniformRand, G4DynamicParticle::GetMomentumDirection(), G4DynamicParticle::GetTotalEnergy(), gfun(), G4INCL::Math::max(), python.hepunit::MeV, RejectionFunction(), CLHEP::Hep3Vector::rotateUz(), CLHEP::Hep3Vector::set(), python.hepunit::twopi, and G4Pow::Z13().

Referenced by G4Generator2BN::SampleDirection().

{

  // Adapted from "Improved bremsstrahlung photon angular sampling in the EGS4 code system"
  // by Alex F. Bielajew, Rahde Mohan anc Chen-Shou Chui, PIRS-0203
  // Ionizing Radiation Standards
  // Institute for National Measurement Standards 
  // National Research Council of Canada
  // Departement of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York

  G4double energy = dp->GetTotalEnergy();
  ratio = final_energy/energy;
  ratio1 = (1 + ratio)*(1 + ratio);
  ratio2 = 1 + ratio*ratio;

  G4double gamma = energy/electron_mass_c2;
  G4double beta  = std::sqrt((gamma - 1)*(gamma + 1))/gamma;

  //G4double Zeff = std::sqrt(static_cast<G4double>(Z) * (static_cast<G4double>(Z) + 1.0));
  //z = (0.00008116224*(std::pow(Zeff,0.3333333)));

  // VI speadup
  fz = 0.00008116224*g4pow->Z13(Z)*g4pow->Z13(Z+1);

  // majoranta
  G4double ymax = 2*beta*(1 + beta)*gamma*gamma;
  G4double gMax = RejectionFunction(0.0);
  gMax = std::max(gMax,RejectionFunction(ymax));

  G4double y, gfun;

  do{
    G4double q = G4UniformRand();
    y = q*ymax/(1 + ymax*(1 - q));
    gfun = RejectionFunction(y);

    // violation point
    if(gfun > gMax && nwarn >= 20) {
      ++nwarn;
      G4cout << "### WARNING in G4Generator2BS: Etot(MeV)= " << energy/MeV 
         << "  Egamma(MeV)" << (energy - final_energy)/MeV
         << " gMax= " << gMax << "  < " << gfun
         << "  results are not reliable!" 
         << G4endl;
      if(20 == nwarn) { 
    G4cout << "   WARNING in G4Generator2BS is closed" << G4endl; 
      }
    }

  } while(G4UniformRand()*gMax > gfun || y > ymax);

  
  G4double cost = 1 - 2*y/ymax;
  G4double sint = std::sqrt((1 - cost)*(1 + cost));
  G4double phi  = twopi*G4UniformRand(); 

  fLocalDirection.set(sint*std::cos(phi), sint*std::sin(phi),cost);
  fLocalDirection.rotateUz(dp->GetMomentumDirection());

  return fLocalDirection;
}

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

• G4Generator2BS.hh
• G4Generator2BS.cc