fastAerosol/src/FAPrimaryGeneratorAction.cc

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0025 //
0026 // (adapted from B1PrimaryGeneratorAction)
0027 // Author: A.Knaian (ara@nklabs.com), N.MacFadden (natemacfadden@gmail.com)
0028
0029 #include "FAPrimaryGeneratorAction.hh"
0030 #include "G4LogicalVolumeStore.hh"
0031 #include "G4LogicalVolume.hh"
0032 #include "G4Box.hh"
0033 #include "G4RunManager.hh"
0034 #include "G4ParticleGun.hh"
0035 #include "G4ParticleTable.hh"
0036 #include "G4ParticleDefinition.hh"
0037 #include "G4SystemOfUnits.hh"
0038 #include "Randomize.hh"
0039
0040 PrimaryGeneratorAction::PrimaryGeneratorAction()
0041 : G4VUserPrimaryGeneratorAction(), fParticleGun(nullptr), fWorldBox(nullptr)
0042 {
0043  G4int n_particle = 1;
0044  fParticleGun  = new G4ParticleGun(n_particle);
0045
0046  // default particle kinematic
0047  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
0048  G4String particleName;
0049  G4ParticleDefinition* particle
0050         = particleTable->FindParticle(particleName="proton");
0051  fParticleGun->SetParticleDefinition(particle);
0052  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0.,0.,1.));
0053  fParticleGun->SetParticleEnergy(50.*MeV);
0054 }
0055
0056 PrimaryGeneratorAction::~PrimaryGeneratorAction()
0057 {
0058  delete fParticleGun;
0059 }
0060
0061 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
0062 {
0063  G4double worldSizeXY = 0;
0064  G4double worldSizeZ = 0;
0065
0066  if (!fWorldBox)
0067  {
0068   G4LogicalVolume* worldLV
0069         = G4LogicalVolumeStore::GetInstance()->GetVolume("World");
0070   if ( worldLV ) fWorldBox = dynamic_cast<G4Box*>(worldLV->GetSolid());
0071  }
0072  if ( fWorldBox )
0073   {
0074     worldSizeXY = fWorldBox->GetXHalfLength()*2.;
0075     worldSizeZ = fWorldBox->GetZHalfLength()*2.;
0076    }
0077   else
0078    {
0079    G4ExceptionDescription msg;
0080    msg << "World volume of box shape not found.\n";
0081    msg << "Perhaps you have changed geometry.\n";
0082    msg << "The gun will be place at the center.";
0083    G4Exception("PrimaryGeneratorAction::GeneratePrimaries()",
0084          "MyCode0002",JustWarning,msg);
0085    }
0086
0087    // shoot on XY disk centered on Z-axis behind the cloud
0088    G4double sigma = worldSizeXY/10.0;           // spread in x and y
0089    G4double x0 = G4RandGauss::shoot(0,sigma);
0090    G4double y0 = G4RandGauss::shoot(0,sigma);
0091    G4double z0 = 0.95 * (-0.5) * worldSizeZ;
0092
0093    fParticleGun->SetParticlePosition(G4ThreeVector(x0,y0,z0));
0094    fParticleGun->GeneratePrimaryVertex(anEvent);
0095 }
0096