source: trunk/source/processes/electromagnetic/polarisation/src/G4PolarizedPairProductionCrossSection.cc@ 1347

Last change on this file since 1347 was 1337, checked in by garnier, 15 years ago

tag geant4.9.4 beta 1 + modifs locales
File size: 7.4 KB
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25//
26// $Id: G4PolarizedPairProductionCrossSection.cc,v 1.5 2007/11/01 17:32:34 schaelic Exp $
27// GEANT4 tag $Name: geant4-09-04-beta-01 $
28//
29// -------------------------------------------------------------------
30//
31// GEANT4 Class file
32//
33//
34// File name: G4PolarizedPairProductionCrossSection
35//
36// Author: Andreas Schaelicke on the base of Karim Laihems code
37//
38// Creation date: 16.08.2006
39//
40
41#include "G4PolarizedPairProductionCrossSection.hh"
42// #include "G4PolarizedGammaConversionModel.hh"
43// #include "G4Element.hh"
44
45G4bool G4PolarizedPairProductionCrossSection::scrnInitialized=false;
46G4double G4PolarizedPairProductionCrossSection::SCRN [3][20];
47// screening function lookup table;
48
49void G4PolarizedPairProductionCrossSection::InitializeMe()
50{
51 if (!scrnInitialized) {
52 SCRN [1][1]= 0.5 ; SCRN [2][1] = 0.0145;
53 SCRN [1][2]= 1.0 ; SCRN [2][2] = 0.0490;
54 SCRN [1][3]= 2.0 ; SCRN [2][3] = 0.1400;
55 SCRN [1][4]= 4.0 ; SCRN [2][4] = 0.3312;
56 SCRN [1][5]= 8.0 ; SCRN [2][5] = 0.6758;
57 SCRN [1][6]= 15.0 ; SCRN [2][6] = 1.126;
58 SCRN [1][7]= 20.0 ; SCRN [2][7] = 1.367;
59 SCRN [1][8]= 25.0 ; SCRN [2][8] = 1.564;
60 SCRN [1][9]= 30.0 ; SCRN [2][9] = 1.731;
61 SCRN [1][10]= 35.0 ; SCRN [2][10]= 1.875;
62 SCRN [1][11]= 40.0 ; SCRN [2][11]= 2.001;
63 SCRN [1][12]= 45.0 ; SCRN [2][12]= 2.114;
64 SCRN [1][13]= 50.0 ; SCRN [2][13]= 2.216;
65 SCRN [1][14]= 60.0 ; SCRN [2][14]= 2.393;
66 SCRN [1][15]= 70.0 ; SCRN [2][15]= 2.545;
67 SCRN [1][16]= 80.0 ; SCRN [2][16]= 2.676;
68 SCRN [1][17]= 90.0 ; SCRN [2][17]= 2.793;
69 SCRN [1][18]= 100.0 ; SCRN [2][18]= 2.897;
70 SCRN [1][19]= 120.0 ; SCRN [2][19]= 3.078;
71
72 scrnInitialized=true;
73 }
74}
75
76G4PolarizedPairProductionCrossSection::G4PolarizedPairProductionCrossSection()
77{
78 InitializeMe();
79}
80
81
82void G4PolarizedPairProductionCrossSection::Initialize(G4double aGammaE,
83 G4double aLept0E,
84 G4double sintheta,
85 const G4StokesVector & beamPol,
86 const G4StokesVector & /*p1*/,
87 G4int /*flag*/)
88{
89 G4double aLept1E = aGammaE - aLept0E;
90
91 G4double Stokes_P3 = beamPol.z() ;
92 // **************************************************************************
93
94 G4double m0_c2 = electron_mass_c2;
95 G4double Lept0E = aLept0E/m0_c2+1., Lept0E2 = Lept0E * Lept0E ;
96 G4double GammaE = aGammaE/m0_c2;
97 G4double Lept1E = aLept1E/m0_c2-1., Lept1E2 = Lept1E * Lept1E ;
98
99
100 // const G4Element* theSelectedElement = theModel->SelectedAtom();
101
102 // ******* Gamma Transvers Momentum
103
104 G4double TMom = std::sqrt(Lept0E2 -1.)* sintheta, u = TMom , u2 =u * u ;
105 G4double Xsi = 1./(1.+u2) , Xsi2 = Xsi * Xsi ;
106
107 // G4double theZ = theSelectedElement->GetZ();
108
109 // G4double fCoul = theSelectedElement->GetfCoulomb();
110 G4double delta = 12. * std::pow(theZ, 1./3.) * Lept0E * Lept1E * Xsi / (121. * GammaE);
111 G4double GG=0.;
112
113 if(delta < 0.5) {
114 GG = std::log(2.* Lept0E * Lept1E / GammaE) - 2. - fCoul;
115 }
116 else if ( delta < 120) {
117 for (G4int j=2; j<=19; j++) {
118 if(SCRN[1][j] >= delta) {
119 GG =std::log(2 * Lept0E * Lept1E / GammaE) - 2 - fCoul
120 -(SCRN[2][j-1]+(delta-SCRN[1][j-1])*(SCRN[2][j]-SCRN[2][j-1])/(SCRN[1][j]-SCRN[1][j-1]));
121 break;
122 }
123 }
124 }
125 else {
126 G4double alpha_sc = (111 * std::pow(theZ, -1./3.)) / Xsi;
127 GG = std::log(alpha_sc)- 2 - fCoul;
128 }
129
130 if(GG<-1) GG=-1; // *KL* do we need this ?!
131
132
133 G4double I_Lepton = (Lept0E2 + Lept1E2)*(3+2*GG) + 2 * Lept0E * Lept1E * (1 + 4 * u2 * Xsi2 * GG);
134
135 // G4double D_Lepton1 = -8 * Lept0E * Lept1E * u2 * Xsi2 * GG / I_Lepton;
136
137 G4double L_Lepton1 = GammaE * ((Lept0E - Lept1E) * (3. + 2. * GG)+2 * Lept1E * (1 + 4 * u2 * Xsi2 * GG))/I_Lepton;
138
139 G4double T_Lepton1 = 4 * GammaE * Lept1E * Xsi * u * (1. - 2. * Xsi) * GG / I_Lepton ;
140
141
142 G4double Stokes_S1 = (Stokes_P3 * T_Lepton1) ;
143 G4double Stokes_S2 = 0;
144 G4double Stokes_S3 = (Stokes_P3 * L_Lepton1) ;
145
146
147 theFinalElectronPolarization.setX(Stokes_S1);
148 theFinalElectronPolarization.setY(Stokes_S2);
149 theFinalElectronPolarization.setZ(Stokes_S3);
150
151 if(theFinalElectronPolarization.mag2()>1) {
152 G4cout<<" WARNING in pol-conv theFinalElectronPolarization \n";
153 G4cout
154 <<"\t"<<theFinalElectronPolarization
155 <<"\t GG\t"<<GG
156 <<"\t delta\t"<<delta
157 <<G4endl;
158 theFinalElectronPolarization.setX(0);
159 theFinalElectronPolarization.setY(0);
160 theFinalElectronPolarization.setZ(Stokes_S3);
161 if(Stokes_S3>1) theFinalElectronPolarization.setZ(1);
162 }
163
164
165 G4double L_Lepton2 = GammaE * ((Lept1E - Lept0E) * (3. + 2. * GG)+2 * Lept0E * (1 + 4 * u2 * Xsi2 * GG))/I_Lepton;
166
167 G4double T_Lepton2 = 4 * GammaE * Lept0E * Xsi * u * (1. - 2. * Xsi) * GG / I_Lepton ;
168
169 G4double Stokes_SS1 = (Stokes_P3 * T_Lepton2) ;
170 G4double Stokes_SS2 = 0;
171 G4double Stokes_SS3 = (Stokes_P3 * L_Lepton2) ;
172
173 theFinalPositronPolarization.SetPhoton();
174
175 theFinalPositronPolarization.setX(Stokes_SS1);
176 theFinalPositronPolarization.setY(Stokes_SS2);
177 theFinalPositronPolarization.setZ(Stokes_SS3);
178
179 if(theFinalPositronPolarization.mag2()>1) {
180 G4cout<<" WARNING in pol-conv theFinalPositronPolarization \n";
181 G4cout
182 <<"\t"<<theFinalPositronPolarization
183 <<"\t GG\t"<<GG
184 <<"\t delta\t"<<delta
185 <<G4endl;
186 }
187}
188
189G4double G4PolarizedPairProductionCrossSection::XSection(const G4StokesVector & /*pol2*/,
190 const G4StokesVector & /*pol3*/)
191{
192 G4cout<<"ERROR dummy routine G4PolarizedPairProductionCrossSection::XSection called \n";
193 return 0;
194}
195
196 // return expected mean polarisation
197G4StokesVector G4PolarizedPairProductionCrossSection::GetPol2()
198{
199 // electron/positron
200 return theFinalElectronPolarization;
201}
202G4StokesVector G4PolarizedPairProductionCrossSection::GetPol3()
203{
204 // photon
205 return theFinalPositronPolarization;;
206}
207
208
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