PrimaryGeneratorAction2 Class Reference

#include <PrimaryGeneratorAction2.hh>

Public Member Functions
	PrimaryGeneratorAction2 (G4ParticleGun *)
	~PrimaryGeneratorAction2 ()
void	GeneratePrimaries (G4Event *)
G4double	RejectAccept ()
G4double	InverseCumul ()

Detailed Description

Definition at line 47 of file PrimaryGeneratorAction2.hh.

Constructor & Destructor Documentation

PrimaryGeneratorAction2::PrimaryGeneratorAction2

(

G4ParticleGun *

gun

)

Definition at line 48 of file PrimaryGeneratorAction2.cc.

: fParticleGun(gun)
{    
  // energy distribution
  //
  InitFunction();
}

PrimaryGeneratorAction2::~PrimaryGeneratorAction2

(

)

Definition at line 58 of file PrimaryGeneratorAction2.cc.

{ }

Member Function Documentation

void PrimaryGeneratorAction2::GeneratePrimaries

(

G4Event *

anEvent

)

Definition at line 63 of file PrimaryGeneratorAction2.cc.

{
  //cosAlpha uniform in [cos(0), cos(pi)]
  G4double cosAlpha = 1. - 2*G4UniformRand();
  G4double sinAlpha = std::sqrt(1. - cosAlpha*cosAlpha);
  G4double psi      = twopi*G4UniformRand();  //psi uniform in [0, 2*pi]  
  G4ThreeVector dir(sinAlpha*std::cos(psi),sinAlpha*std::sin(psi),cosAlpha);

  fParticleGun->SetParticleMomentumDirection(dir);
  
  //set energy from a tabulated distribution
  //
  //G4double energy = RejectAccept();
  G4double energy = InverseCumul();  
  fParticleGun->SetParticleEnergy(energy);    

  //create vertex
  //   
  fParticleGun->GeneratePrimaryVertex(anEvent);
}

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G4double PrimaryGeneratorAction2::InverseCumul

(

)

Definition at line 148 of file PrimaryGeneratorAction2.cc.

{
  // tabulated function
  // Y is assumed positive, linear per segment, continuous 
  // --> cumulative function is second order polynomial
  
  //choose y randomly
  G4double Yrndm = G4UniformRand()*fYC[fNPoints-1];
  //find bin
  G4int j = fNPoints-2;
  while ((fYC[j] > Yrndm) && (j > 0)) j--;
  //y_rndm --> x_rndm :  fYC(x) is second order polynomial
  G4double Xrndm = fX[j];
  G4double a = fSlp[j];
  if (a != 0.) {
    G4double b = fY[j]/a, c = 2*(Yrndm - fYC[j])/a;
    G4double delta = b*b + c;
    G4int sign = 1; if (a < 0.) sign = -1;
    Xrndm += sign*std::sqrt(delta) - b;    
  } else if (fY[j] > 0.) {
    Xrndm += (Yrndm - fYC[j])/fY[j];
  };
  return Xrndm;
}

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G4double PrimaryGeneratorAction2::RejectAccept

(

)

Definition at line 126 of file PrimaryGeneratorAction2.cc.

{
  // tabulated function 
  // Y is assumed positive, linear per segment, continuous
  //  
  G4double Xrndm = 0., Yrndm = 0., Yinter = -1.;
  
  while (Yrndm > Yinter) {
    //choose a point randomly
    Xrndm = fX[0] + G4UniformRand()*(fX[fNPoints-1] - fX[0]);
    Yrndm = G4UniformRand()*fYmax;
    //find bin
    G4int j = fNPoints-2;
    while ((fX[j] > Xrndm) && (j > 0)) j--;
    //compute Y(x_rndm) by linear interpolation
    Yinter = fY[j] + fSlp[j]*(Xrndm - fX[j]);
  };
  return Xrndm;
}

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

• source/geant4.10.03.p03/examples/extended/eventgenerator/particleGun/include/PrimaryGeneratorAction2.hh
• source/geant4.10.03.p03/examples/extended/eventgenerator/particleGun/src/PrimaryGeneratorAction2.cc