particleGun/src/PrimaryGeneratorAction4.cc

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0025 //
0026 /// \file PrimaryGeneratorAction4.cc
0027 /// \brief Implementation of the PrimaryGeneratorAction4 class
0028
0029 #include "PrimaryGeneratorAction4.hh"
0030
0031 #include "PrimaryGeneratorAction.hh"
0032
0033 #include "G4Event.hh"
0034 #include "G4ParticleDefinition.hh"
0035 #include "G4ParticleGun.hh"
0036 #include "G4ParticleTable.hh"
0037 #include "G4PhysicalConstants.hh"
0038 #include "G4SystemOfUnits.hh"
0039 #include "Randomize.hh"
0040
0041 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0042
0043 PrimaryGeneratorAction4::PrimaryGeneratorAction4(G4ParticleGun* gun) : fParticleGun(gun)
0044 {
0045   // vertex volume
0046   //
0047   G4double Rmin = 2. * mm;
0048   G4double Rmax = 8. * mm;
0049   fRmin3 = Rmin * Rmin * Rmin;
0050   fRmax3 = Rmax * Rmax * Rmax;
0051
0052   // opening angle
0053   //
0054   G4double alphaMin = 0. * deg;
0055   G4double alphaMax = 60. * deg;
0056   fCosAlphaMin = std::cos(alphaMin);
0057   fCosAlphaMax = std::cos(alphaMax);
0058 }
0059
0060 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0061
0062 void PrimaryGeneratorAction4::GeneratePrimaries(G4Event* anEvent)
0063 {
0064   // vertex position uniform in spherical shell
0065   //
0066   G4double cosTheta = 2 * G4UniformRand() - 1;  // cosTheta uniform in [0, pi]
0067   G4double sinTheta = std::sqrt(1. - cosTheta * cosTheta);
0068   G4double phi = twopi * G4UniformRand();  // phi uniform in [0, 2*pi]
0069   G4ThreeVector ur(sinTheta * std::cos(phi), sinTheta * std::sin(phi), cosTheta);
0070
0071   G4double R3 = fRmin3 + G4UniformRand() * (fRmax3 - fRmin3);
0072   G4double R = std::pow(R3, 1. / 3);
0073
0074   fParticleGun->SetParticlePosition(R * ur);
0075
0076   // particle direction uniform around ur
0077   //
0078   // 1- in World frame
0079   // cosAlpha uniform in [cos(alphaMin), cos(alphaMax)]
0080   G4double cosAlpha = fCosAlphaMin - G4UniformRand() * (fCosAlphaMin - fCosAlphaMax);
0081   G4double sinAlpha = std::sqrt(1. - cosAlpha * cosAlpha);
0082   G4double psi = twopi * G4UniformRand();  // psi uniform in (0,2*pi)
0083   G4ThreeVector dir(sinAlpha * std::cos(psi), sinAlpha * std::sin(psi), cosAlpha);
0084
0085   // 2- rotate dir   (rotateUz transforms uz to ur)
0086   dir.rotateUz(ur);
0087
0088   fParticleGun->SetParticleMomentumDirection(dir);
0089
0090   // energy
0091   //
0092   fParticleGun->SetParticleEnergy(1 * MeV);
0093
0094   // create vertex
0095   //
0096   fParticleGun->GeneratePrimaryVertex(anEvent);
0097 }
0098 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......