physics/src/G4RDModifiedTsai.cc

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0025 //
0026 //
0027 // -------------------------------------------------------------------
0028 //
0029 // GEANT4 Class file
0030 //
0031 //
0032 // File name:     G4RDModifiedTsai
0033 //
0034 // Author:        Andreia Trindade (andreia@lip.pt)
0035 //                Pedro Rodrigues  (psilva@lip.pt)
0036 //                Luis Peralta     (luis@lip.pt)
0037 //
0038 // Creation date: 21 March 2003
0039 //
0040 // Modifications:
0041 // 21 Mar 2003       A. Trindade    First implementation acording with new design
0042 // 24 Mar 2003                      & Fix in Tsai generator in order to prevent theta generation above pi
0043 //
0044 // Class Description:
0045 //
0046 // Concrete base class for Bremsstrahlung Angular Distribution Generation - Tsai Model
0047 //
0048 // Class Description: End
0049 //
0050 // -------------------------------------------------------------------
0051 //
0052 //
0053
0054 #include "G4RDModifiedTsai.hh"
0055 #include "Randomize.hh"
0056 #include "G4PhysicalConstants.hh"
0057 //
0058
0059 G4RDModifiedTsai::G4RDModifiedTsai(const G4String& name):G4RDVBremAngularDistribution(name)
0060 {;}
0061
0062 //
0063
0064 G4RDModifiedTsai::~G4RDModifiedTsai()
0065 {;}
0066
0067 //
0068
0069 G4double G4RDModifiedTsai::PolarAngle(const G4double initial_energy,
0070                     const G4double, // final_energy
0071                     const G4int ) // Z
0072 {
0073
0074   // Sample gamma angle (Z - axis along the parent particle).
0075   // Universal distribution suggested by L. Urban (Geant3 manual (1993)
0076   // Phys211) derived from Tsai distribution (Rev Mod Phys 49,421(1977))
0077
0078   G4double totalEnergy = initial_energy + electron_mass_c2;
0079
0080   const G4double a1 = 0.625, a2 = 3.*a1, d = 27.;
0081   G4double u, theta = 0;
0082
0083   do{
0084   u = - std::log(G4UniformRand()*G4UniformRand());
0085
0086   if (9./(9.+d) > G4UniformRand()) u /= a1;
0087   else                             u /= a2;
0088
0089   theta = u*electron_mass_c2/totalEnergy;
0090   }while(u > (totalEnergy*pi/electron_mass_c2));
0091
0092   return theta;
0093 }
0094 //
0095
0096 void G4RDModifiedTsai::PrintGeneratorInformation() const
0097 {
0098
0099   G4cout << "\n" << G4endl;
0100   G4cout << "Bremsstrahlung Angular Generator is Modified Tsai" << G4endl;
0101   G4cout << "Universal distribution suggested by L. Urban (Geant3 manual (1993) Phys211)" << G4endl;
0102   G4cout << "Derived from Tsai distribution (Rev Mod Phys 49,421(1977)) \n" << G4endl;
0103 }