Geant4  10.03.p03
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PrimaryGeneratorAction0.cc
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30 // $Id: PrimaryGeneratorAction0.cc 83872 2014-09-20 22:23:50Z maire $
31 //
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34 
36 #include "PrimaryGeneratorAction.hh"
37 
38 #include "G4Event.hh"
39 #include "G4ParticleGun.hh"
40 #include "G4SystemOfUnits.hh"
41 #include "Randomize.hh"
42 
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44 
46 : fParticleGun(gun)
47 {
48  //solid angle
49  //
50  G4double alphaMin = 0*deg; //alpha in [0,pi]
51  G4double alphaMax = 60*deg;
52  fCosAlphaMin = std::cos(alphaMin);
53  fCosAlphaMax = std::cos(alphaMax);
54 
55  fPsiMin = 0*deg; //psi in [0, 2*pi]
56  fPsiMax = 360*deg;
57 }
58 
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62 { }
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65 
67 {
68  //vertex position fixed
69  //
70  G4double x0 = 0*mm, y0 = 0*mm, z0 = 0*mm;
71  fParticleGun->SetParticlePosition(G4ThreeVector(x0,y0,z0));
72 
73  //direction uniform in solid angle
74  //
75  G4double cosAlpha = fCosAlphaMin-G4UniformRand()*(fCosAlphaMin-fCosAlphaMax);
76  G4double sinAlpha = std::sqrt(1. - cosAlpha*cosAlpha);
77  G4double psi = fPsiMin + G4UniformRand()*(fPsiMax - fPsiMin);
78 
79  G4double ux = sinAlpha*std::cos(psi),
80  uy = sinAlpha*std::sin(psi),
81  uz = cosAlpha;
82 
83  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(ux,uy,uz));
84 
85  fParticleGun->GeneratePrimaryVertex(anEvent);
86 }
87 
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static constexpr double mm
Definition: G4SIunits.hh:115
CLHEP::Hep3Vector G4ThreeVector
void SetParticleMomentumDirection(G4ParticleMomentum aMomentumDirection)
virtual void GeneratePrimaryVertex(G4Event *evt)
void SetParticlePosition(G4ThreeVector aPosition)
#define G4UniformRand()
Definition: Randomize.hh:97
PrimaryGeneratorAction0(G4ParticleGun *)
Definition of the PrimaryGeneratorAction0 class.
double G4double
Definition: G4Types.hh:76
static constexpr double deg
Definition: G4SIunits.hh:152