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27 //
28 // Geant4 class file
29 //
30 // File name: G4PolarizedBremsstrahlungXS
31 //
32 // Author: Andreas Schaelicke on the base of Karim Laihems code
33
34 #include "G4PolarizedBremsstrahlungXS.hh"
35
36 #include "G4PhysicalConstants.hh"
37
38 G4double G4PolarizedBremsstrahlungXS::SCRN[2][19] = {
39 { 0.5, 1.0, 2.0, 4.0, 8.0, 15.0, 20.0, 25.0, 30.0, 35.0, 40.0, 45.0, 50.0,
40 60.0, 70.0, 80.0, 90.0, 100.0, 120.0 },
41 { 0.0145, 0.0490, 0.1400, 0.3312, 0.6758, 1.126, 1.367, 1.564, 1.731, 1.875,
42 2.001, 2.114, 2.216, 2.393, 2.545, 2.676, 2.793, 2.897, 3.078 }
43 };
44
45 G4PolarizedBremsstrahlungXS::G4PolarizedBremsstrahlungXS()
46 {
47 fFinalLeptonPolarization = G4StokesVector::ZERO;
48 fFinalGammaPolarization = G4StokesVector::ZERO;
49 }
50
51 G4PolarizedBremsstrahlungXS::~G4PolarizedBremsstrahlungXS() {}
52
53 void G4PolarizedBremsstrahlungXS::Initialize(G4double aLept0E, G4double aGammaE,
54 G4double sintheta,
55 const G4StokesVector& beamPol,
56 const G4StokesVector& /*p1*/,
57 G4int /*flag*/)
58 {
59 G4double aLept1E = aLept0E - aGammaE;
60
61 G4double Stokes_S1 = beamPol.x();
62 G4double Stokes_S2 = beamPol.y();
63 G4double Stokes_S3 = beamPol.z();
64
65 G4double Lept0E = aLept0E / electron_mass_c2 + 1.;
66 G4double Lept0E2 = Lept0E * Lept0E;
67 G4double GammaE = aGammaE / electron_mass_c2;
68 G4double GammaE2 = GammaE * GammaE;
69 G4double Lept1E = aLept1E / electron_mass_c2 + 1.;
70 G4double Lept1E2 = Lept1E * Lept1E;
71
72 // ******* Gamma Transverse Momentum
73 G4double TMom = std::sqrt(Lept0E2 - 1.) * sintheta;
74 G4double u = TMom;
75 G4double u2 = u * u;
76 G4double Xsi = 1. / (1. + u2);
77 G4double Xsi2 = Xsi * Xsi;
78
79 G4double delta =
80 12. * std::pow(fZ, 1. / 3.) * Lept0E * Lept1E * Xsi / (121. * GammaE);
81
82 G4double GG = 0.;
83 if(delta < 0.5)
84 {
85 GG = std::log(2. * Lept0E * Lept1E / GammaE) - 2. - fCoul;
86 }
87 else if(delta < 120)
88 {
89 for(G4int j = 1; j < 19; ++j)
90 {
91 if(SCRN[0][j] >= delta)
92 {
93 GG = std::log(2 * Lept0E * Lept1E / GammaE) - 2 - fCoul -
94 (SCRN[1][j - 1] + (delta - SCRN[0][j - 1]) *
95 (SCRN[1][j] - SCRN[1][j - 1]) /
96 (SCRN[0][j] - SCRN[0][j - 1]));
97 break;
98 }
99 }
100 }
101 else
102 {
103 G4double alpha_sc = (111. * std::pow(fZ, -1. / 3.)) / Xsi;
104 GG = std::log(alpha_sc) - 2. - fCoul;
105 }
106
107 if(GG < -1.)
108 GG = -1.;
109
110 G4double I_Lept = (Lept0E2 + Lept1E2) * (3. + 2. * GG) -
111 2 * Lept0E * Lept1E * (1. + 4. * u2 * Xsi2 * GG);
112 G4double F_Lept =
113 Lept1E * 4. * GammaE * u * Xsi * (1. - 2 * Xsi) * GG / I_Lept;
114 G4double E_Lept =
115 Lept0E * 4. * GammaE * u * Xsi * (2. * Xsi - 1.) * GG / I_Lept;
116 G4double M_Lept =
117 4. * Lept0E * Lept1E * (1. + GG - 2. * Xsi2 * u2 * GG) / I_Lept;
118 G4double P_Lept =
119 GammaE2 * (1. + 8. * GG * (Xsi - 0.5) * (Xsi - 0.5)) / I_Lept;
120
121 G4double Stokes_SS1 = M_Lept * Stokes_S1 + E_Lept * Stokes_S3;
122 G4double Stokes_SS2 = M_Lept * Stokes_S2;
123 G4double Stokes_SS3 = (M_Lept + P_Lept) * Stokes_S3 + F_Lept * Stokes_S1;
124
125 fFinalLeptonPolarization.setX(Stokes_SS1);
126 fFinalLeptonPolarization.setY(Stokes_SS2);
127 fFinalLeptonPolarization.setZ(Stokes_SS3);
128
129 if(fFinalLeptonPolarization.mag2() > 1.)
130 {
131 G4ExceptionDescription ed;
132 ed << " WARNING in pol-brem fFinalLeptonPolarization \n";
133 ed << "\t" << fFinalLeptonPolarization << "\t GG\t" << GG << "\t delta\t"
134 << delta;
135 G4Exception("G4PolarizedBremsstrahlungXS::Initialize", "pol014",
136 JustWarning, ed);
137 fFinalLeptonPolarization.setX(0);
138 fFinalLeptonPolarization.setY(0);
139 fFinalLeptonPolarization.setZ(Stokes_SS3);
140 if(Stokes_SS3 > 1)
141 fFinalLeptonPolarization.setZ(1);
142 }
143
144 G4double I_Gamma = (Lept0E2 + Lept1E2) * (3. + 2. * GG) -
145 2. * Lept0E * Lept1E * (1. + 4. * u2 * Xsi2 * GG);
146 G4double D_Gamma = 8. * Lept0E * Lept1E * u2 * Xsi2 * GG / I_Gamma;
147 G4double L_Gamma = GammaE *
148 ((Lept0E + Lept1E) * (3. + 2. * GG) -
149 2. * Lept1E * (1. + 4. * u2 * Xsi2 * GG)) /
150 I_Gamma;
151 G4double T_Gamma =
152 4. * GammaE * Lept1E * Xsi * u * (2. * Xsi - 1.) * GG / I_Gamma;
153
154 G4double Stokes_P1 = D_Gamma;
155 G4double Stokes_P2 = 0.;
156 G4double Stokes_P3 = (Stokes_S3 * L_Gamma + Stokes_S1 * T_Gamma);
157
158 fFinalGammaPolarization.SetPhoton();
159
160 fFinalGammaPolarization.setX(Stokes_P1);
161 fFinalGammaPolarization.setY(Stokes_P2);
162 fFinalGammaPolarization.setZ(Stokes_P3);
163
164 if(fFinalGammaPolarization.mag2() > 1.)
165 {
166 G4ExceptionDescription ed;
167 ed << " WARNING in pol-brem fFinalGammaPolarization \n";
168 ed << "\t" << fFinalGammaPolarization << "\t GG\t" << GG << "\t delta\t"
169 << delta;
170 G4Exception("G4PolarizedBremsstrahlungXS::Initialize", "pol015",
171 JustWarning, ed);
172 }
173 }
174
175 G4double G4PolarizedBremsstrahlungXS::XSection(const G4StokesVector& /*pol2*/,
176 const G4StokesVector& /*pol3*/)
177 {
178 G4ExceptionDescription ed;
179 ed << "ERROR dummy routine G4PolarizedBremsstrahlungXS::XSection "
180 "called.\n";
181 G4Exception("G4PolarizedBremsstrahlungXS::XSection", "pol016", FatalException,
182 ed);
183
184 return 0.;
185 }
186
187 // return expected mean polarisation
188 G4StokesVector G4PolarizedBremsstrahlungXS::GetPol2()
189 {
190 // electron/positron
191 return fFinalLeptonPolarization;
192 }
193
194 G4StokesVector G4PolarizedBremsstrahlungXS::GetPol3()
195 {
196 // photon
197 return fFinalGammaPolarization;
198 }
199