PrimaryGenerator.cc

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// $Id: PrimaryGenerator.cc 89705 2015-04-27 17:15:27Z maire $
// 
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#include "PrimaryGenerator.hh"

#include "G4Event.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"
#include "G4PrimaryParticle.hh"
#include "G4PrimaryVertex.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

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PrimaryGenerator::PrimaryGenerator()
: G4VPrimaryGenerator()
{ }

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PrimaryGenerator::~PrimaryGenerator()
{ }

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void PrimaryGenerator::GeneratePrimaryVertex(G4Event* event)
{
  //vertex A uniform on a cylinder
  //
  const G4double r = 2*mm;
  const G4double zmax = 8*mm;
  //
  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)
  G4ThreeVector positionA(r*ux,r*uy,z);
  G4double timeA = 0*s;
  // 
  G4PrimaryVertex* vertexA = new G4PrimaryVertex(positionA, timeA);
  
  //particle 1 at vertex A
  //
  G4ParticleDefinition* particleDefinition
           = G4ParticleTable::GetParticleTable()->FindParticle("geantino");
  G4PrimaryParticle* particle1 = new G4PrimaryParticle(particleDefinition);
  particle1->SetMomentumDirection(G4ThreeVector(ux,uy,0));    
  particle1->SetKineticEnergy(1*MeV);
  //
  vertexA->SetPrimary(particle1);
  event->AddPrimaryVertex(vertexA);

  //vertex (B) symetric to vertex A
  //
  alpha += pi;
  ux = std::cos(alpha);
  uy = std::sin(alpha);
  G4ThreeVector positionB(r*ux,r*uy,z);
  G4double timeB = 1*s;
  // 
  G4PrimaryVertex* vertexB = new G4PrimaryVertex(positionB, timeB);
  
  //particles 2 and 3 at vertex B
  //
  const G4double dalpha = 10*deg;
  ux = std::cos(alpha + dalpha);
  uy = std::sin(alpha + dalpha);        
  G4PrimaryParticle* particle2 = new G4PrimaryParticle(particleDefinition);
  particle2->SetMomentumDirection(G4ThreeVector(ux,uy,0));    
  particle2->SetKineticEnergy(1*keV);
  //
  ux = std::cos(alpha - dalpha);
  uy = std::sin(alpha - dalpha);        
  G4PrimaryParticle* particle3 = new G4PrimaryParticle(particleDefinition);
  particle3->SetMomentumDirection(G4ThreeVector(ux,uy,0));    
  particle3->SetKineticEnergy(1*GeV);
  //
  vertexB->SetPrimary(particle2);
  vertexB->SetPrimary(particle3);  
  event->AddPrimaryVertex(vertexB);
}

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