Geant4  10.03.p02
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PrimaryGeneratorGun2.cc
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30 // $Id: PrimaryGeneratorGun2.cc 68734 2013-04-05 09:47:02Z gcosmo $
31 //
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34 
35 #include "PrimaryGeneratorGun2.hh"
36 
37 #include "G4Event.hh"
38 #include "G4ParticleGun.hh"
39 #include "G4ParticleTable.hh"
40 #include "G4ParticleDefinition.hh"
41 #include "G4SystemOfUnits.hh"
42 #include "G4PhysicalConstants.hh"
43 #include "Randomize.hh"
44 
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46 
48  : G4VUserPrimaryGeneratorAction(), fParticleGun(0)
49 {
50  // default particle kinematic
51  //
52  G4int n_particle = 1;
53  fParticleGun = new G4ParticleGun(n_particle);
54 
55  G4ParticleDefinition* particle
57  fParticleGun->SetParticleDefinition(particle);
58  fParticleGun->SetParticleEnergy(1*eV);
59 
60  // vertex
61  //
62  fRadius = 8.*mm;
63 
64  //opening angle
65  //
66  G4double alphaMin = 91.*deg;
67  G4double alphaMax = 180.*deg;
68  fCosAlphaMin = std::cos(alphaMin);
69  fCosAlphaMax = std::cos(alphaMax);
70 }
71 
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73 
75 {
76  delete fParticleGun;
77 }
78 
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80 
82 {
83  //vertex position uniform in sphere
84  //
85  G4double cosTheta = 2*G4UniformRand() - 1; //cosTheta uniform in [0, pi]
86  G4double sinTheta = std::sqrt(1. - cosTheta*cosTheta);
87  G4double phi = twopi*G4UniformRand(); //phi uniform in [0, 2*pi]
88  G4ThreeVector ur(sinTheta*std::cos(phi),sinTheta*std::sin(phi),cosTheta);
89 
90  fParticleGun->SetParticlePosition(fRadius*ur);
91 
92  //particle direction uniform around ur
93  //
94  //1- in World frame
95  //cosAlpha uniform in [cos(alphaMin), cos(alphaMax)]
96  G4double cosAlpha = fCosAlphaMin-G4UniformRand()*(fCosAlphaMin-fCosAlphaMax);
97  G4double sinAlpha = std::sqrt(1. - cosAlpha*cosAlpha);
98  //psi uniform in (0,2*pi)
100  G4ThreeVector dir(sinAlpha*std::cos(psi),sinAlpha*std::sin(psi),cosAlpha);
101 
102  //2- rotate dir (rotateUz transforms uz to ur)
103  dir.rotateUz(ur);
104 
105  fParticleGun->SetParticleMomentumDirection(dir);
106 
107  //create vertex
108  //
109  fParticleGun->GeneratePrimaryVertex(anEvent);
110 }
111 
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G4ParticleDefinition * FindParticle(G4int PDGEncoding)
static constexpr double mm
Definition: G4SIunits.hh:115
void SetParticleMomentumDirection(G4ParticleMomentum aMomentumDirection)
int G4int
Definition: G4Types.hh:78
virtual void GeneratePrimaryVertex(G4Event *evt)
static constexpr double twopi
Definition: G4SIunits.hh:76
void SetParticlePosition(G4ThreeVector aPosition)
#define G4UniformRand()
Definition: Randomize.hh:97
Hep3Vector & rotateUz(const Hep3Vector &)
Definition: ThreeVector.cc:38
static constexpr double eV
Definition: G4SIunits.hh:215
void SetParticleEnergy(G4double aKineticEnergy)
static G4ParticleTable * GetParticleTable()
double G4double
Definition: G4Types.hh:76
static constexpr double deg
Definition: G4SIunits.hh:152
void SetParticleDefinition(G4ParticleDefinition *aParticleDefinition)
virtual void GeneratePrimaries(G4Event *)