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
Protected Member Functions
G4double	RejectionFunction (G4double value) const

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Detailed Description

Definition at line 64 of file G4Generator2BS.hh.

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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.

{}

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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 [inline, protected]

Definition at line 101 of file G4Generator2BS.hh.

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 G4VEmAngularDistribution::fLocalDirection, G4cout, G4endl, G4UniformRand, G4DynamicParticle::GetMomentumDirection(), G4DynamicParticle::GetTotalEnergy(), RejectionFunction(), 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

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