ECCE @ EIC Software
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Groups Pages
G4RDModifiedTsai.cc
Go to the documentation of this file. Or view the newest version in sPHENIX GitHub for file G4RDModifiedTsai.cc
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: G4RDModifiedTsai
33 //
34 // Author: Andreia Trindade (andreia@lip.pt)
35 // Pedro Rodrigues (psilva@lip.pt)
36 // Luis Peralta (luis@lip.pt)
37 //
38 // Creation date: 21 March 2003
39 //
40 // Modifications:
41 // 21 Mar 2003 A. Trindade First implementation acording with new design
42 // 24 Mar 2003 & Fix in Tsai generator in order to prevent theta generation above pi
43 //
44 // Class Description:
45 //
46 // Concrete base class for Bremsstrahlung Angular Distribution Generation - Tsai Model
47 //
48 // Class Description: End
49 //
50 // -------------------------------------------------------------------
51 //
52 //
53 
54 #include "G4RDModifiedTsai.hh"
55 #include "Randomize.hh"
56 #include "G4PhysicalConstants.hh"
57 //
58 
59 G4RDModifiedTsai::G4RDModifiedTsai(const G4String& name):G4RDVBremAngularDistribution(name)
60 {;}
61 
62 //
63 
64 G4RDModifiedTsai::~G4RDModifiedTsai()
65 {;}
66 
67 //
68 
69 G4double G4RDModifiedTsai::PolarAngle(const G4double initial_energy,
70  const G4double, // final_energy
71  const G4int ) // Z
72 {
73 
74  // Sample gamma angle (Z - axis along the parent particle).
75  // Universal distribution suggested by L. Urban (Geant3 manual (1993)
76  // Phys211) derived from Tsai distribution (Rev Mod Phys 49,421(1977))
77 
78  G4double totalEnergy = initial_energy + electron_mass_c2;
79 
80  const G4double a1 = 0.625, a2 = 3.*a1, d = 27.;
81  G4double u, theta = 0;
82 
83  do{
84  u = - std::log(G4UniformRand()*G4UniformRand());
85 
86  if (9./(9.+d) > G4UniformRand()) u /= a1;
87  else u /= a2;
88 
89  theta = u*electron_mass_c2/totalEnergy;
90  }while(u > (totalEnergy*pi/electron_mass_c2));
91 
92  return theta;
93 }
94 //
95 
96 void G4RDModifiedTsai::PrintGeneratorInformation() const
97 {
98 
99  G4cout << "\n" << G4endl;
100  G4cout << "Bremsstrahlung Angular Generator is Modified Tsai" << G4endl;
101  G4cout << "Universal distribution suggested by L. Urban (Geant3 manual (1993) Phys211)" << G4endl;
102  G4cout << "Derived from Tsai distribution (Rev Mod Phys 49,421(1977)) \n" << G4endl;
103 }