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G4eeToPGammaModel.cc
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25 //
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27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class header file
30 //
31 //
32 // File name: G4eeToPGammaModel
33 //
34 // Author: Vladimir Ivanchenko
35 //
36 // Creation date: 25.10.2003
37 //
38 // Modifications:
39 //
40 //
41 // -------------------------------------------------------------------
42 //
43 
44 
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47 
48 #include "G4eeToPGammaModel.hh"
49 #include "Randomize.hh"
50 #include "G4PhysicalConstants.hh"
51 #include "G4SystemOfUnits.hh"
52 #include "G4PionZero.hh"
53 #include "G4Eta.hh"
54 #include "G4Gamma.hh"
55 #include "G4DynamicParticle.hh"
56 #include "G4PhysicsVector.hh"
57 #include "G4PhysicsLinearVector.hh"
58 #include "G4eeCrossSections.hh"
59 
60 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
61 
62 using namespace std;
63 
64 G4eeToPGammaModel::G4eeToPGammaModel(G4eeCrossSections* cr,
65  const G4String& npart,
66  G4double maxkinEnergy,
67  G4double binWidth)
68 : G4Vee2hadrons(cr,
69  npart=="pi0" ? 782.62*MeV:1019.46*MeV,
70  maxkinEnergy,
71  binWidth)
72 {
73  G4cout << "####G4eeToPGammaModel & particle:" << npart
74  << "####" << G4endl;
75 
76  pi0 = G4PionZero::PionZero();
77  if(npart == "pi0") {
78  massR = 782.62*MeV;
79  particle = pi0;
80  } else {
81  massR = 1019.46*MeV;
82  particle = G4Eta::Eta();
83  }
84  massP = particle->GetPDGMass();
85 
86 }
87 
88 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
89 
90 G4eeToPGammaModel::~G4eeToPGammaModel()
91 {}
92 
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94 
95 G4double G4eeToPGammaModel::PeakEnergy() const
96 {
97  return massR;
98 }
99 
100 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
101 
102 G4double G4eeToPGammaModel::ComputeCrossSection(G4double e) const
103 {
104  G4double xs;
105  if(particle == pi0) xs = cross->CrossSectionPi0G(e);
106  else xs = cross->CrossSectionEtaG(e);
107  return xs;
108 }
109 
110 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
111 
112 void G4eeToPGammaModel::SampleSecondaries(std::vector<G4DynamicParticle*>* newp,
113  G4double e, const G4ThreeVector& direction)
114 {
115  G4double egam = 0.5*e*(1.0 - massP*massP/(massR*massR));
116  G4double tkin = e - egam - massP;
117  if(tkin < 0.0) tkin = 0.0;
118  G4double cost;
119  do {
120  cost = 2.0*G4UniformRand() - 1.0;
121  // Loop checking, 07-Aug-2015, Vladimir Ivanchenko
122  } while( 2.0*G4UniformRand() > 1.0 + cost*cost );
123 
124  G4double sint = sqrt(1.0 - cost*cost);
125  G4double phi = twopi * G4UniformRand();
126 
127  G4ThreeVector dir(sint*cos(phi),sint*sin(phi), cost);
128  dir.rotateUz(direction);
129 
130  // create G4DynamicParticle objects
131  G4DynamicParticle* p1 =
132  new G4DynamicParticle(particle,dir,tkin);
133  G4DynamicParticle* p2 =
134  new G4DynamicParticle(G4Gamma::Gamma(),-dir,egam);
135  newp->push_back(p1);
136  newp->push_back(p2);
137 }
138 
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140