| Geant4 Cross Reference |
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 //
27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4ModifiedMephi
33 //
34 // Author: V. Ivanchenko
35 //
36 // Creation date: 27 October 2020
37 //
38 // Modifications:
39 //
40 //
41 // -------------------------------------------------------------------
42 //
43
44 #include "G4ModifiedMephi.hh"
45 #include "Randomize.hh"
46 #include "G4Log.hh"
47 #include <CLHEP/Units/PhysicalConstants.h>
48
49 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
50
51 G4ModifiedMephi::G4ModifiedMephi(const G4String&)
52 : G4VEmAngularDistribution("ModifiedMephi")
53 {}
54
55 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
56
57 G4ModifiedMephi::~G4ModifiedMephi()
58 {}
59
60 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
61
62 G4ThreeVector&
63 G4ModifiedMephi::SampleDirection(const G4DynamicParticle* dp,
64 G4double gEnergy, G4int,
65 const G4Material*)
66 {
67 // Sample gamma angle (Z - axis along the parent particle).
68 G4double cost = SampleCosTheta(dp->GetKineticEnergy(), gEnergy,
69 dp->GetDefinition()->GetPDGMass());
70 G4double sint = std::sqrt((1.0 - cost)*(1.0 + cost));
71 G4double phi = CLHEP::twopi*G4UniformRand();
72
73 fLocalDirection.set(sint*std::cos(phi), sint*std::sin(phi), cost);
74 fLocalDirection.rotateUz(dp->GetMomentumDirection());
75
76 return fLocalDirection;
77 }
78
79 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
80
81 G4double G4ModifiedMephi::SampleCosTheta(G4double primKinEnergy,
82 G4double gEnergy,
83 G4double mass)
84 {
85 G4double gam = 1.0 + primKinEnergy/mass;
86 G4double rmax = gam*CLHEP::halfpi*std::min(1.0, gam*mass/gEnergy - 1.0);
87 G4double rmax2= rmax*rmax;
88 G4double x = G4UniformRand()*rmax2/(1.0 + rmax2);
89
90 return std::cos(std::sqrt(x/(1.0 - x))/gam);
91 }
92
93 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
94
95 void G4ModifiedMephi::SamplePairDirections(const G4DynamicParticle* dp,
96 G4double elecKinEnergy,
97 G4double posiKinEnergy,
98 G4ThreeVector& dirElectron,
99 G4ThreeVector& dirPositron,
100 G4int, const G4Material*)
101 {
102 G4double phi = CLHEP::twopi * G4UniformRand();
103 G4double sinp = std::sin(phi);
104 G4double cosp = std::cos(phi);
105
106 G4double ekin = dp->GetKineticEnergy();
107 G4double etwo = elecKinEnergy + posiKinEnergy;
108 G4double mass = dp->GetDefinition()->GetPDGMass();
109
110 G4double cost = SampleCosTheta(ekin, etwo, mass);
111 G4double sint = std::sqrt((1.0 - cost)*(1.0 + cost));
112
113 dirElectron.set(sint*cosp, sint*sinp, cost);
114 dirElectron.rotateUz(dp->GetMomentumDirection());
115
116 cost = SampleCosTheta(ekin, etwo, mass);
117 sint = std::sqrt((1.0 - cost)*(1.0 + cost));
118
119 dirPositron.set(-sint*cosp, -sint*sinp, cost);
120 dirPositron.rotateUz(dp->GetMomentumDirection());
121 }
122
123 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
124
125 void G4ModifiedMephi::PrintGeneratorInformation() const
126 {
127 G4cout << "\n" << G4endl;
128 G4cout << "Angular Generator is Modified Mephi" << G4endl;
129 }
130
131 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
132