Geant4  10.03.p03
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PrimaryGeneratorAction3.cc
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30 // $Id: PrimaryGeneratorAction3.cc 68024 2013-03-13 13:42:01Z gcosmo $
31 //
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34 
36 #include "PrimaryGeneratorAction.hh"
37 
38 #include "G4Event.hh"
39 #include "G4ParticleGun.hh"
40 #include "G4ParticleTable.hh"
41 #include "G4ParticleDefinition.hh"
42 #include "G4PhysicalConstants.hh"
43 #include "G4SystemOfUnits.hh"
44 #include "Randomize.hh"
45 
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47 
49 : fParticleGun(gun)
50 {
51  // direction
52  //
53  G4double theta = 90*deg, phi = 45*deg;
54  fNewUz = G4ThreeVector(std::sin(theta)*std::cos(phi),
55  std::sin(theta)*std::sin(phi),
56  std::cos(theta));
57 
58  fAlphaMax = 15*deg;
59 }
60 
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62 
64 { }
65 
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67 
69 {
70  //particle direction uniform around fNewUz axis
71  //
72  //1- in World frame
73  //cosAlpha uniform in [cos(0), cos(fAlphaMax)]
74  G4double cosAlpha = 1. - G4UniformRand()*(1.- std::cos(fAlphaMax));
75  G4double sinAlpha = std::sqrt(1. - cosAlpha*cosAlpha);
76  G4double psi = twopi*G4UniformRand(); //psi uniform in [0, 2*pi]
77  G4ThreeVector dir(sinAlpha*std::cos(psi),sinAlpha*std::sin(psi),cosAlpha);
78 
79  //2- rotate dir (rotateUz transforms uz to fNewUz)
80  dir.rotateUz(fNewUz);
81 
82  fParticleGun->SetParticleMomentumDirection(dir);
83 
84  //set energy
85  //
86  fParticleGun->SetParticleEnergy(1*MeV);
87 
88  //create vertex
89  //
90  fParticleGun->GeneratePrimaryVertex(anEvent);
91 }
92 
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CLHEP::Hep3Vector G4ThreeVector
void SetParticleMomentumDirection(G4ParticleMomentum aMomentumDirection)
virtual void GeneratePrimaryVertex(G4Event *evt)
static constexpr double twopi
Definition: G4SIunits.hh:76
PrimaryGeneratorAction3(G4ParticleGun *)
#define G4UniformRand()
Definition: Randomize.hh:97
Definition of the PrimaryGeneratorAction3 class.
Hep3Vector & rotateUz(const Hep3Vector &)
Definition: ThreeVector.cc:38
void SetParticleEnergy(G4double aKineticEnergy)
static constexpr double MeV
Definition: G4SIunits.hh:214
double G4double
Definition: G4Types.hh:76
static constexpr double deg
Definition: G4SIunits.hh:152