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G4RDPhotoElectricAngularGeneratorSauterGavrila.cc
Go to the documentation of this file. Or view the newest version in sPHENIX GitHub for file G4RDPhotoElectricAngularGeneratorSauterGavrila.cc
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25 //
26 //
27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4RDPhotoElectricAngularGeneratorSauterGavrila
33 //
34 // Creation date: 10 May 2004
35 //
36 // Modifications:
37 // 10 May 2003 P. Rodrigues First implementation acording with new design
38 //
39 // Class Description:
40 //
41 // Concrete class for PhotoElectric Electron Angular Distribution Generation
42 // This model is a re-implementation of the Photolectric angular distribution
43 // developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect
44 //
45 // Class Description: End
46 //
47 // -------------------------------------------------------------------
48 //
49 //
50 
52 #include "Randomize.hh"
53 #include "G4PhysicalConstants.hh"
54 
55 //
56 
58 {;}
59 
60 //
61 
63 {;}
64 
65 //
66 
68 {
69 
70  // Compute Theta distribution of the emitted electron, with respect to the
71  // incident Gamma.
72  // The Sauter-Gavrila distribution for the K-shell is used. (adapted from G4PhotoElectricEffect)
73 
74  G4double costeta = 1.;
75  G4double Phi = twopi * G4UniformRand();
76  G4double cosphi = std::cos(Phi);
77  G4double sinphi = std::sin(Phi);
78  G4double sinteta = 0;
79  G4double gamma = 1. + eKineticEnergy/electron_mass_c2;
80 
81  if (gamma > 5.) {
82  G4ThreeVector direction (sinteta*cosphi, sinteta*sinphi, costeta);
83  return direction;
84  }
85 
86  G4double beta = std::sqrt(gamma*gamma-1.)/gamma;
87  G4double b = 0.5*gamma*(gamma-1.)*(gamma-2);
88 
89  G4double rndm,term,greject,grejsup;
90  if (gamma < 2.) grejsup = gamma*gamma*(1.+b-beta*b);
91  else grejsup = gamma*gamma*(1.+b+beta*b);
92 
93  do { rndm = 1.-2*G4UniformRand();
94  costeta = (rndm+beta)/(rndm*beta+1.);
95  term = 1.-beta*costeta;
96  greject = (1.-costeta*costeta)*(1.+b*term)/(term*term);
97  } while(greject < G4UniformRand()*grejsup);
98 
99 
100  sinteta = std::sqrt(1.-costeta*costeta);
101  G4ThreeVector photoelectrondirection (sinteta*cosphi, sinteta*sinphi, costeta);
102  photoelectrondirection.rotateUz(direction);
103  return photoelectrondirection;
104 }
105 
106 //
107 
109 {
110  G4cout << "\n" << G4endl;
111  G4cout << "" << G4endl;
112  G4cout << "Re-implementation of the photolectric angular distribution" << G4endl;
113  G4cout << "developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect" << G4endl;
114  G4cout << "It computes the theta distribution of the emitted electron, with respect to the" << G4endl;
115  G4cout << "incident Gamma, using the Sauter-Gavrila distribution for the K-shell\n" << G4endl;
116 }