particleGun/src/PrimaryGeneratorAction4.cc

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0025 //
0026 /// \file eventgenerator/particleGun/src/PrimaryGeneratorAction4.cc
0027 /// \brief Implementation of the PrimaryGeneratorAction4 class
0028 //
0029 //
0030 //
0031 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0032 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0033
0034 #include "PrimaryGeneratorAction4.hh"
0035
0036 #include "PrimaryGeneratorAction.hh"
0037
0038 #include "G4Event.hh"
0039 #include "G4ParticleDefinition.hh"
0040 #include "G4ParticleGun.hh"
0041 #include "G4ParticleTable.hh"
0042 #include "G4PhysicalConstants.hh"
0043 #include "G4SystemOfUnits.hh"
0044 #include "Randomize.hh"
0045
0046 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0047
0048 PrimaryGeneratorAction4::PrimaryGeneratorAction4(G4ParticleGun* gun) : fParticleGun(gun)
0049 {
0050   // vertex volume
0051   //
0052   G4double Rmin = 2. * mm;
0053   G4double Rmax = 8. * mm;
0054   fRmin3 = Rmin * Rmin * Rmin;
0055   fRmax3 = Rmax * Rmax * Rmax;
0056
0057   // opening angle
0058   //
0059   G4double alphaMin = 0. * deg;
0060   G4double alphaMax = 60. * deg;
0061   fCosAlphaMin = std::cos(alphaMin);
0062   fCosAlphaMax = std::cos(alphaMax);
0063 }
0064
0065 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0066
0067 void PrimaryGeneratorAction4::GeneratePrimaries(G4Event* anEvent)
0068 {
0069   // vertex position uniform in spherical shell
0070   //
0071   G4double cosTheta = 2 * G4UniformRand() - 1;  // cosTheta uniform in [0, pi]
0072   G4double sinTheta = std::sqrt(1. - cosTheta * cosTheta);
0073   G4double phi = twopi * G4UniformRand();  // phi uniform in [0, 2*pi]
0074   G4ThreeVector ur(sinTheta * std::cos(phi), sinTheta * std::sin(phi), cosTheta);
0075
0076   G4double R3 = fRmin3 + G4UniformRand() * (fRmax3 - fRmin3);
0077   G4double R = std::pow(R3, 1. / 3);
0078
0079   fParticleGun->SetParticlePosition(R * ur);
0080
0081   // particle direction uniform around ur
0082   //
0083   // 1- in World frame
0084   // cosAlpha uniform in [cos(alphaMin), cos(alphaMax)]
0085   G4double cosAlpha = fCosAlphaMin - G4UniformRand() * (fCosAlphaMin - fCosAlphaMax);
0086   G4double sinAlpha = std::sqrt(1. - cosAlpha * cosAlpha);
0087   G4double psi = twopi * G4UniformRand();  // psi uniform in (0,2*pi)
0088   G4ThreeVector dir(sinAlpha * std::cos(psi), sinAlpha * std::sin(psi), cosAlpha);
0089
0090   // 2- rotate dir   (rotateUz transforms uz to ur)
0091   dir.rotateUz(ur);
0092
0093   fParticleGun->SetParticleMomentumDirection(dir);
0094
0095   // energy
0096   //
0097   fParticleGun->SetParticleEnergy(1 * MeV);
0098
0099   // create vertex
0100   //
0101   fParticleGun->GeneratePrimaryVertex(anEvent);
0102 }
0103 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......