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26 // 26 //
27 // ------------------------------------------- 27 // -------------------------------------------------------------------
28 // 28 //
29 // GEANT4 Class file 29 // GEANT4 Class file
30 // 30 //
31 // 31 //
32 // File name: G4Generator2BS 32 // File name: G4Generator2BS
33 // 33 //
34 // Author: Andreia Trindade (andreia@li 34 // Author: Andreia Trindade (andreia@lip.pt)
35 // Pedro Rodrigues (psilva@lip 35 // Pedro Rodrigues (psilva@lip.pt)
36 // Luis Peralta (luis@lip.p 36 // Luis Peralta (luis@lip.pt)
37 // 37 //
38 // Creation date: 2 June 2003 38 // Creation date: 2 June 2003
39 // 39 //
40 // Modifications: 40 // Modifications:
41 // 02 Jun 2003 First implementat << 41 // 02 Jun 2003 First implementation acording with new design
42 // 05 Nov 2003 MGP Fixed std namespa << 42 // 05 Nov 2003 MGP Fixed std namespace
43 // 17 Nov 2003 MGP Fixed compilation << 43 // 17 Nov 2003 MGP Fixed compilation problem on Windows
44 // 12 Oct 2010 V.Ivanchenko Moved RejectionFu <<
45 // 09 May 2011 L.Pandola Initialize privat <<
46 // 44 //
47 // Class Description: 45 // Class Description:
48 // 46 //
49 // Concrete base class for Bremsstrahlung Angu << 47 // Concrete base class for Bremsstrahlung Angular Distribution Generation - 2BS Distribution
50 // 2BS Distribution <<
51 // 48 //
52 // Class Description: End 49 // Class Description: End
53 // 50 //
54 // ------------------------------------------- 51 // -------------------------------------------------------------------
55 // 52 //
>> 53 //
56 54
57 #include "G4Generator2BS.hh" 55 #include "G4Generator2BS.hh"
58 #include "Randomize.hh" << 56 #include "Randomize.hh"
59 #include "G4PhysicalConstants.hh" << 57 //
60 #include "G4SystemOfUnits.hh" << 58
61 #include "G4Pow.hh" << 59 G4Generator2BS::G4Generator2BS(const G4String& name):G4VBremAngularDistribution(name)
62 << 60 {;}
63 G4Generator2BS::G4Generator2BS(const G4String& << 61
64 : G4VEmAngularDistribution("AngularGen2BS"), << 62 //
65 ratio1(1.),ratio2(1.),delta(0.) <<
66 { <<
67 g4pow = G4Pow::GetInstance(); <<
68 nwarn = 0; <<
69 } <<
70 63
71 G4Generator2BS::~G4Generator2BS() 64 G4Generator2BS::~G4Generator2BS()
72 {} << 65 {;}
>> 66
>> 67 //
73 68
74 G4ThreeVector& G4Generator2BS::SampleDirection << 69 G4double G4Generator2BS::PolarAngle(const G4double initial_energy,
75 G4double final_energy, << 70 const G4double final_energy,
76 G4int Z, << 71 const G4int Z)
77 const G4Material*) <<
78 { 72 {
>> 73
79 // Adapted from "Improved bremsstrahlung pho 74 // Adapted from "Improved bremsstrahlung photon angular sampling in the EGS4 code system"
80 // by Alex F. Bielajew, Rahde Mohan anc Chen 75 // by Alex F. Bielajew, Rahde Mohan anc Chen-Shou Chui, PIRS-0203
81 // Ionizing Radiation Standards 76 // Ionizing Radiation Standards
82 // Institute for National Measurement Standa 77 // Institute for National Measurement Standards
83 // National Research Council of Canada 78 // National Research Council of Canada
84 // Departement of Medical Physics, Memorial 79 // Departement of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York
85 80
86 G4double energy = dp->GetTotalEnergy(); <<
87 ratio = final_energy/energy; <<
88 ratio1 = (1 + ratio)*(1 + ratio); <<
89 ratio2 = 1 + ratio*ratio; <<
90 <<
91 G4double gamma = energy/electron_mass_c2; <<
92 G4double beta = std::sqrt((gamma - 1)*(gamm <<
93 <<
94 // VI speadup <<
95 fz = 0.00008116224*g4pow->Z13(Z)*g4pow->Z13( <<
96 <<
97 // majoranta <<
98 G4double ymax = 2*beta*(1 + beta)*gamma*gamm <<
99 G4double gMax = RejectionFunction(0.0); <<
100 gMax = std::max(gMax,RejectionFunction(ymax) <<
101 81
102 G4double y, gfun; << 82 G4double theta = 0;
>> 83
>> 84 G4double initialTotalEnergy = (initial_energy+electron_mass_c2)/electron_mass_c2;
>> 85 G4double finalTotalEnergy = (final_energy+electron_mass_c2)/electron_mass_c2;
>> 86 EnergyRatio = finalTotalEnergy/initialTotalEnergy;
>> 87 G4double gMaxEnergy = (pi*initialTotalEnergy)*(pi*initialTotalEnergy);
>> 88
>> 89 G4double Zeff = std::sqrt(static_cast<G4double>(Z) * (static_cast<G4double>(Z) + 1.0));
>> 90 z = (0.00008116224*(std::pow(Zeff,0.3333333)));
>> 91
>> 92 // Rejection arguments
>> 93 rejection_argument1 = (1.0+EnergyRatio*EnergyRatio);
>> 94 rejection_argument2 = - 2.0*EnergyRatio + 3.0*rejection_argument1;
>> 95 rejection_argument3 = ((1-EnergyRatio)/(2.0*initialTotalEnergy*EnergyRatio))*
>> 96 ((1-EnergyRatio)/(2.0*initialTotalEnergy*EnergyRatio));
>> 97
>> 98 // Calculate rejection function at 0, 1 and Emax
>> 99 G4double gfunction0 = RejectionFunction(0);
>> 100 G4double gfunction1 = RejectionFunction(1);
>> 101 G4double gfunctionEmax = RejectionFunction(gMaxEnergy);
>> 102
>> 103
>> 104 // Calculate Maximum value
>> 105 G4double gMaximum = std::max(gfunction0,gfunction1);
>> 106 gMaximum = std::max(gMaximum,gfunctionEmax);
>> 107
>> 108 G4double rand, gfunctionTest, randTest;
103 109
104 do{ 110 do{
105 G4double q = G4UniformRand(); << 111 rand = G4UniformRand();
106 y = q*ymax/(1 + ymax*(1 - q)); << 112 rand = rand/(1-rand+1.0/gMaxEnergy);
107 gfun = RejectionFunction(y); << 113 gfunctionTest = RejectionFunction(rand);
108 << 114 randTest = G4UniformRand();
109 // violation point << 115
110 if(gfun > gMax && nwarn >= 20) { << 116 }while(randTest > (gfunctionTest/gMaximum));
111 ++nwarn; << 117
112 G4cout << "### WARNING in G4Generator2BS << 118 theta = std::sqrt(rand)/initialTotalEnergy;
113 << " Egamma(MeV)" << (energy - final_e << 119
114 << " gMax= " << gMax << " < " << gfun << 120
115 << " results are not reliable!" << 121 return theta;
116 << G4endl; << 122 }
117 if(20 == nwarn) { << 123 //
118 G4cout << " WARNING in G4Generator2BS is c << 124
119 } << 125 G4double G4Generator2BS::RejectionFunction(G4double value) const
120 } << 126 {
121 << 127
122 } while(G4UniformRand()*gMax > gfun || y > y << 128 G4double argument = (1+value)*(1+value);
123 << 129
124 G4double cost = 1 - 2*y/ymax; << 130 G4double gfunction = (4+std::log(rejection_argument3+(z/argument)))*
125 G4double sint = std::sqrt((1 - cost)*(1 + co << 131 ((4*EnergyRatio*value/argument)-rejection_argument1)+rejection_argument2;
126 G4double phi = twopi*G4UniformRand(); <<
127 132
128 fLocalDirection.set(sint*std::cos(phi), sint << 133 return gfunction;
129 fLocalDirection.rotateUz(dp->GetMomentumDire <<
130 134
131 return fLocalDirection; <<
132 } 135 }
133 136
134 void G4Generator2BS::PrintGeneratorInformation 137 void G4Generator2BS::PrintGeneratorInformation() const
135 { 138 {
136 G4cout << "\n" << G4endl; 139 G4cout << "\n" << G4endl;
137 G4cout << "Bremsstrahlung Angular Generator << 140 G4cout << "Bremsstrahlung Angular Generator is 2BS Generator from 2BS Koch & Motz distribution (Rev Mod Phys 31(4), 920 (1959))" << G4endl;
138 << "from 2BS Koch & Motz distribution (Rev <<
139 G4cout << "Sampling algorithm adapted from P 141 G4cout << "Sampling algorithm adapted from PIRS-0203" << G4endl;
140 G4cout << "\n" << G4endl; 142 G4cout << "\n" << G4endl;
141 } 143 }
142 144
143 145