PrimaryGeneratorAction1.cc

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/// \file eventgenerator/particleGun/src/PrimaryGeneratorAction1.cc
/// \brief Implementation of the PrimaryGeneratorAction1 class
//
//
// 
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#include "PrimaryGeneratorAction1.hh"
#include "PrimaryGeneratorAction.hh"

#include "G4Event.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

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PrimaryGeneratorAction1::PrimaryGeneratorAction1(G4ParticleGun* gun)
: fParticleGun(gun)
{ }

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void PrimaryGeneratorAction1::GeneratePrimaries(G4Event* anEvent)
{
  const G4double r = 2*mm;
  const G4double zmax = 8*mm;   
  
  //vertex 1 uniform on cylinder
  //
  G4double alpha = twopi*G4UniformRand();  //alpha uniform in (0, 2*pi)
  G4double ux = std::cos(alpha);
  G4double uy = std::sin(alpha);
  G4double z = zmax*(2*G4UniformRand() - 1);  //z uniform in (-zmax, +zmax)
        
  fParticleGun->SetParticlePosition(G4ThreeVector(r*ux,r*uy,z));
  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(ux,uy,0));    
  fParticleGun->SetParticleEnergy(1*MeV);
  fParticleGun->GeneratePrimaryVertex(anEvent);
  
  //vertex 2 at opposite
  //
  alpha += pi;
  ux = std::cos(alpha);
  uy = std::sin(alpha);        
  fParticleGun->SetParticlePosition(G4ThreeVector(r*ux,r*uy,z));
  
  //particle 2 at vertex 2
  //
  const G4double dalpha = 10*deg;
  ux = std::cos(alpha + dalpha);
  uy = std::sin(alpha + dalpha);        
  
  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(ux,uy,0));    
  fParticleGun->SetParticleEnergy(1*keV);
  fParticleGun->GeneratePrimaryVertex(anEvent);
   
  //particle 3 at vertex 3 (same as vertex 2)
  //
  ux = std::cos(alpha - dalpha);
  uy = std::sin(alpha - dalpha);        
  
  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(ux,uy,0));    
  fParticleGun->SetParticleEnergy(1*GeV);
  fParticleGun->GeneratePrimaryVertex(anEvent);
  
  // randomize time zero of anEvent
  //
  G4double tmin = 0*s, tmax = 10*s;
  G4double t0 = tmin + (tmax - tmin)*G4UniformRand();
  G4PrimaryVertex* aVertex = anEvent->GetPrimaryVertex();
  while (aVertex) {
    aVertex->SetT0(t0);
    aVertex = aVertex->GetNext();
  }
}

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