GammaRayTelPrimaryGeneratorAction.cc

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// $Id: GammaRayTelPrimaryGeneratorAction.cc 82630 2014-07-01 09:43:00Z gcosmo $
// ------------------------------------------------------------
//      GEANT 4 class implementation file
//      CERN Geneva Switzerland
//
//
//      ------------ GammaRayTelPrimaryGeneratorAction  ------
//           by  G.Santin, F.Longo & R.Giannitrapani (13 nov 2000)
//
// ************************************************************

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#include "G4RunManager.hh"
#include "GammaRayTelPrimaryGeneratorAction.hh"

#include "GammaRayTelDetectorConstruction.hh"
#include "GammaRayTelPrimaryGeneratorMessenger.hh"

#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Event.hh"
#include "G4ParticleGun.hh"
#include "G4GeneralParticleSource.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"
#include "Randomize.hh"

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GammaRayTelPrimaryGeneratorAction::GammaRayTelPrimaryGeneratorAction()
  :rndmFlag("off"),nSourceType(0),nSpectrumType(0),sourceGun(false)
{
  GammaRayTelDetector = static_cast<const GammaRayTelDetectorConstruction*>
    (G4RunManager::GetRunManager()->GetUserDetectorConstruction());

  //create a messenger for this class
  
  gunMessenger = new GammaRayTelPrimaryGeneratorMessenger(this);

  G4int n_particle = 1;

  particleGun  = new G4ParticleGun(n_particle);     
  // default particle kinematic
  
  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4String particleName;
  G4ParticleDefinition* particle
    = particleTable->FindParticle(particleName="e-");
  particleGun->SetParticleDefinition(particle);
  particleGun->SetParticleMomentumDirection(G4ThreeVector(0.,0.,-1.));
  particleGun->SetParticleEnergy(30.*MeV);
  G4double position = 0.5*(GammaRayTelDetector->GetWorldSizeZ());
  particleGun->SetParticlePosition(G4ThreeVector(0.*cm,0.*cm,position));
  particleSource = new G4GeneralParticleSource();
   
}

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GammaRayTelPrimaryGeneratorAction::~GammaRayTelPrimaryGeneratorAction()
{
 
  delete particleGun;
  delete particleSource;

  delete gunMessenger;
}

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void GammaRayTelPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
   if (sourceGun)
    {

      //this function is called at the begining of event
      // 
      G4double z0 = 0.5*(GammaRayTelDetector->GetWorldSizeZ());
      G4double x0 = 0.*cm, y0 = 0.*cm;
  
      G4ThreeVector pos0;
      G4ThreeVector dir0;
      G4ThreeVector vertex0 = G4ThreeVector(x0,y0,z0);
      
      dir0 = G4ThreeVector(0.,0.,-1.);
      
      G4double theta, phi, y, f;
      G4double theta0=0.;
      G4double phi0=0.;
      
      switch(nSourceType) {
      case 0:
        particleGun->SetParticlePosition(vertex0);
        particleGun->SetParticleMomentumDirection(dir0);
        break;
      case 1:
        // GS: Generate random position on the 4PIsphere to create a unif. distrib.
        // GS: on the sphere
        phi = G4UniformRand() * twopi;
        do {
          y = G4UniformRand()*1.0;
          theta = G4UniformRand() * pi;
          f = std::sin(theta);
        } while (y > f);
        vertex0 = G4ThreeVector(1.,0.,0.);
        vertex0.setMag(dVertexRadius);
        vertex0.setTheta(theta);
        vertex0.setPhi(phi);
        particleGun->SetParticlePosition(vertex0);
        
        dir0 = G4ThreeVector(1.,0.,0.);
        do {
          phi = G4UniformRand() * twopi;
          do {
            y = G4UniformRand()*1.0;
            theta = G4UniformRand() * pi;
            f = std::sin(theta);
          } while (y > f);
          dir0.setPhi(phi);
          dir0.setTheta(theta);
        } while (vertex0.dot(dir0) >= -0.7 * vertex0.mag());
        particleGun->SetParticleMomentumDirection((G4ParticleMomentum)dir0);
        
        break;
      case 2:
        // GS: Generate random position on the upper semi-sphere z>0 to create a unif. distrib.
        // GS: on a plane
        phi = G4UniformRand() * twopi;
        do {
          y = G4UniformRand()*1.0;
          theta = G4UniformRand() * halfpi;
          f = std::sin(theta) * std::cos(theta);
        } while (y > f);
        vertex0 = G4ThreeVector(1.,0.,0.);
        
        G4double xy = GammaRayTelDetector->GetWorldSizeXY();
        G4double z = GammaRayTelDetector->GetWorldSizeZ();
        
        if (dVertexRadius > xy*0.5)
          { 
            G4cout << "vertexRadius too big " << G4endl;
            G4cout << "vertexRadius setted to " << xy*0.45 << G4endl;
            dVertexRadius = xy*0.45;
          }
        
        if (dVertexRadius > z*0.5)
          { 
            G4cout << "vertexRadius too high " << G4endl;
            G4cout << "vertexRadius setted to " << z*0.45 << G4endl;
            dVertexRadius = z*0.45;
          }
        
        
        vertex0.setMag(dVertexRadius);
        vertex0.setTheta(theta);
        vertex0.setPhi(phi);
        
        // GS: Get the user defined direction for the primaries and
        // GS: Rotate the random position according to the user defined direction for the particle
        
        dir0 = particleGun->GetParticleMomentumDirection();
        if (dir0.mag() > 0.001) 
          {
            theta0 = dir0.theta();
            phi0   = dir0.phi();   
          }
        
        if (theta0!=0.) 
          {
            G4ThreeVector rotationAxis(1.,0.,0.);
            rotationAxis.setPhi(phi0+halfpi);
            vertex0.rotate(theta0+pi,rotationAxis);
          }
        particleGun->SetParticlePosition(vertex0);
        break;
      }
      
      
      G4double pEnergy;
      
      switch(nSpectrumType) {
      case 0:
        break;
      case 1:
        break;
      case 2:
        do {
          y = G4UniformRand()*100000.0;
          pEnergy = G4UniformRand() * 10. * GeV;
          f = std::pow(pEnergy * (1/GeV), -4.);
        } while (y > f);
        
        particleGun->SetParticleEnergy(pEnergy);
        
        break;
      case 3:
        break;
      }
      
      particleGun->GeneratePrimaryVertex(anEvent);
    }
   else
     {
       particleSource->GeneratePrimaryVertex(anEvent);
     }
   
}

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