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25 // 25 //
26 // Geant4 Class file << 26 //
>> 27 // GEANT4 Class file
>> 28 //
27 // 29 //
28 // File name: G4StokesVector 30 // File name: G4StokesVector
29 // 31 //
30 // Author: Andreas Schaelicke 32 // Author: Andreas Schaelicke
31 // 33 //
>> 34 // Creation date: 01.05.2005
>> 35 //
>> 36 // Modifications:
>> 37 //
32 // Class Description: 38 // Class Description:
33 // Provides Stokes vector representation emp << 39 //
34 << 40 // Provides Stokesvector representation employed in polarized
>> 41 // processes.
>> 42 //
35 #include "G4StokesVector.hh" 43 #include "G4StokesVector.hh"
36 <<
37 #include "G4PolarizationHelper.hh" 44 #include "G4PolarizationHelper.hh"
>> 45 #include "G4PhysicalConstants.hh"
38 #include "Randomize.hh" 46 #include "Randomize.hh"
39 47
40 const G4StokesVector G4StokesVector::ZERO = << 48 const G4StokesVector G4StokesVector::ZERO=G4ThreeVector(0.,0.,0.);
41 G4StokesVector(G4ThreeVector(0., 0., 0.)); << 49 const G4StokesVector G4StokesVector::P1=G4ThreeVector(1.,0.,0.);
42 const G4StokesVector G4StokesVector::P1 = << 50 const G4StokesVector G4StokesVector::P2=G4ThreeVector(0.,1.,0.);
43 G4StokesVector(G4ThreeVector(1., 0., 0.)); << 51 const G4StokesVector G4StokesVector::P3=G4ThreeVector(0.,0.,1.);
44 const G4StokesVector G4StokesVector::P2 = << 52 const G4StokesVector G4StokesVector::M1=G4ThreeVector(-1.,0.,0.);
45 G4StokesVector(G4ThreeVector(0., 1., 0.)); << 53 const G4StokesVector G4StokesVector::M2=G4ThreeVector(0.,-1.,0.);
46 const G4StokesVector G4StokesVector::P3 = << 54 const G4StokesVector G4StokesVector::M3=G4ThreeVector(0.,0.,-1.);
47 G4StokesVector(G4ThreeVector(0., 0., 1.)); <<
48 const G4StokesVector G4StokesVector::M1 = <<
49 G4StokesVector(G4ThreeVector(-1., 0., 0.)); <<
50 const G4StokesVector G4StokesVector::M2 = <<
51 G4StokesVector(G4ThreeVector(0., -1., 0.)); <<
52 const G4StokesVector G4StokesVector::M3 = <<
53 G4StokesVector(G4ThreeVector(0., 0., -1.)); <<
54 55
55 G4StokesVector::G4StokesVector() 56 G4StokesVector::G4StokesVector()
56 : G4ThreeVector() << 57 : G4ThreeVector(),isPhoton(false)
57 , fIsPhoton(false) << 58 {
58 {} << 59 }
59 60
60 G4StokesVector::G4StokesVector(const G4ThreeVe << 61 G4StokesVector::G4StokesVector(const G4ThreeVector & v)
61 : G4ThreeVector(v) << 62 : G4ThreeVector(v),isPhoton(false)
62 , fIsPhoton(false) << 63 {
63 {} << 64 }
64 65
65 G4bool G4StokesVector::IsZero() const { return << 66 G4bool G4StokesVector::IsZero() const
>> 67 {
>> 68 return *this==ZERO;
>> 69 }
66 70
67 void G4StokesVector::RotateAz(G4ThreeVector nI << 71 void G4StokesVector::RotateAz(G4ThreeVector nInteractionFrame,
68 G4ThreeVector pa << 72 G4ThreeVector particleDirection)
69 { 73 {
70 G4ThreeVector yParticleFrame = << 74 G4ThreeVector yParticleFrame =
71 G4PolarizationHelper::GetParticleFrameY(pa 75 G4PolarizationHelper::GetParticleFrameY(particleDirection);
72 76
73 G4double cosphi = yParticleFrame * nInteract << 77
74 if(cosphi > (1. + 1.e-8) || cosphi < (-1. - << 78 G4double cosphi=yParticleFrame*nInteractionFrame;
75 { << 79 if (cosphi>(1.+1.e-8) || cosphi<(-1.-1.e-8)) {
76 G4ExceptionDescription ed; << 80 G4cout<<" warning G4StokesVector::RotateAz cosphi>1 or cosphi<-1\n"
77 ed << " warning G4StokesVector::RotateAz << 81 <<" cosphi="<<cosphi<<"\n"
78 << " cosphi=" << cosphi << "\n" << 82 <<" zAxis="<<particleDirection<<" ("<<particleDirection.mag()<<")\n"
79 << " zAxis=" << particleDirection << " << 83 <<" yAxis="<<yParticleFrame<<" ("<<yParticleFrame.mag()<<")\n"
80 << ")\n" << 84 <<" nAxis="<<nInteractionFrame<<" ("
81 << " yAxis=" << yParticleFrame << " (" << 85 <<nInteractionFrame.mag()<<")"<<G4endl;
82 << " nAxis=" << nInteractionFrame << " <<
83 << ")\n"; <<
84 G4Exception("G4StokesVector::RotateAz", "p <<
85 } 86 }
86 if(cosphi > 1.) << 87 if (cosphi>1.) cosphi=1.;
87 cosphi = 1.; << 88 else if (cosphi<-1.) cosphi=-1.;
88 else if(cosphi < -1.) <<
89 cosphi = -1.; <<
90 89
91 G4double hel = << 90 // G4cout<<" cosphi="<<cosphi<<"\n"
92 (yParticleFrame.cross(nInteractionFrame) * << 91 // <<" zAxis="<<particleDirection<<" ("<<particleDirection.mag()<<")\n"
93 << 92 // <<" yAxis="<<yParticleFrame<<" ("<<yParticleFrame.mag()<<","<<(yParticleFrame*particleDirection)<<")\n"
>> 93 // <<" nAxis="<<nInteractionFrame<<" ("
>> 94 // <<nInteractionFrame.mag()<<")"<<G4endl;
94 95
95 G4double sinphi = hel * std::sqrt(1. - cosph << 96 // G4double hel=sgn(cross(yParticleFrame*nInteractionFrame)*zInteractionFrame);
>> 97 // Why not particleDirection instead of zInteractionFrame ???!!!
>> 98 // -> is the same, since SYSIN is called with p1, and p2 as first parameter!
>> 99 G4double hel=(yParticleFrame.cross(nInteractionFrame)*particleDirection)>0?1.:-1.;
96 100
97 RotateAz(cosphi, sinphi); << 101 G4double sinphi=hel*std::sqrt(1.-cosphi*cosphi);
>> 102 // G4cout<<" sin2 + cos2 -1 = "<<(sinphi*sinphi+cosphi*cosphi-1)<<"\n";
>> 103
>> 104 RotateAz(cosphi,sinphi);
98 } 105 }
99 106
100 void G4StokesVector::InvRotateAz(G4ThreeVector << 107
101 G4ThreeVector << 108 void G4StokesVector::InvRotateAz(G4ThreeVector nInteractionFrame,
>> 109 G4ThreeVector particleDirection)
102 { 110 {
103 // note if incoming particle is on z-axis, << 111 // note if incomming particle is on z-axis,
104 // we might encounter some nummerical proble 112 // we might encounter some nummerical problems, since
105 // nInteratonFrame and yParticleFrame are ac 113 // nInteratonFrame and yParticleFrame are actually (almost) the same momentum
106 // and the normalization is only good to 10^ 114 // and the normalization is only good to 10^-12 !
107 115
108 G4ThreeVector yParticleFrame = << 116 G4ThreeVector yParticleFrame =
109 G4PolarizationHelper::GetParticleFrameY(pa 117 G4PolarizationHelper::GetParticleFrameY(particleDirection);
110 G4double cosphi = yParticleFrame * nInteract << 118 G4double cosphi=yParticleFrame*nInteractionFrame;
111 119
112 if(cosphi > 1. + 1.e-8 || cosphi < -1. - 1.e << 120 if (cosphi>1.+1.e-8 || cosphi<-1.-1.e-8) {
113 { << 121 G4cout<<" warning G4StokesVector::RotateAz cosphi>1 or cosphi<-1\n";
114 G4ExceptionDescription ed; <<
115 ed << " warning G4StokesVector::RotateAz <<
116 G4Exception("G4StokesVector::InvRotateAz", <<
117 } 122 }
118 if(cosphi > 1.) << 123 if (cosphi>1.) cosphi=1.;
119 cosphi = 1.; << 124 else if (cosphi<-1.)cosphi=-1.;
120 else if(cosphi < -1.) <<
121 cosphi = -1.; <<
122 125
123 // check sign once more! 126 // check sign once more!
124 G4double hel = << 127 G4double hel=(yParticleFrame.cross(nInteractionFrame)*particleDirection)>0?1.:-1.;
125 (yParticleFrame.cross(nInteractionFrame) * << 128 G4double sinphi=hel*std::sqrt(std::fabs(1.-cosphi*cosphi));
126 << 129 RotateAz(cosphi,-sinphi);
127 G4double sinphi = hel * std::sqrt(std::fabs( <<
128 RotateAz(cosphi, -sinphi); <<
129 } 130 }
130 131
131 void G4StokesVector::RotateAz(G4double cosphi, << 132 void G4StokesVector::RotateAz(G4double cosphi, G4double sinphi)
132 { << 133 {
133 if(!fIsPhoton) << 134 if (!isPhoton) {
134 { << 135 G4double xsi1= cosphi*p1() + sinphi*p2();
135 G4double xsi1 = cosphi * p1() + sinphi * p << 136 G4double xsi2= -sinphi*p1() + cosphi*p2();
136 G4double xsi2 = -sinphi * p1() + cosphi * <<
137 setX(xsi1); 137 setX(xsi1);
138 setY(xsi2); 138 setY(xsi2);
139 return; 139 return;
140 } 140 }
141 141
142 G4double sin2phi = 2. * cosphi * sinphi; << 142 G4double sin2phi=2.*cosphi*sinphi;
143 G4double cos2phi = cosphi * cosphi - sinphi << 143 G4double cos2phi=cosphi*cosphi-sinphi*sinphi;
144 144
145 G4double xsi1 = cos2phi * p1() + sin2phi * p << 145 G4double xsi1= cos2phi*p1() + sin2phi*p2();
146 G4double xsi2 = -sin2phi * p1() + cos2phi * << 146 G4double xsi2= -sin2phi*p1() + cos2phi*p2();
147 setX(xsi1); 147 setX(xsi1);
148 setY(xsi2); 148 setY(xsi2);
149 } 149 }
150 150
151 G4double G4StokesVector::GetBeta() << 151 G4double G4StokesVector::GetBeta()
152 { 152 {
153 G4double bet = getPhi(); << 153 G4double bet=getPhi();
154 if(fIsPhoton) << 154 if (isPhoton) { bet *= 0.5; }
155 { <<
156 bet *= 0.5; <<
157 } <<
158 return bet; 155 return bet;
159 } 156 }
160 157
161 void G4StokesVector::DiceUniform() << 158 void G4StokesVector::DiceUniform()
162 { 159 {
163 G4double costheta = 2. * G4UniformRand() - 1 << 160 G4double costheta=2.*G4UniformRand()-1.;
164 G4double sintheta = std::sqrt(1. - costheta << 161 G4double sintheta=std::sqrt(1.-costheta*costheta);
165 G4double aphi = 2. * CLHEP::pi * G4Unifo << 162 G4double aphi =2.*pi*G4UniformRand();
166 setX(std::sin(aphi) * sintheta); << 163 setX(std::sin(aphi)*sintheta);
167 setY(std::cos(aphi) * sintheta); << 164 setY(std::cos(aphi)*sintheta);
168 setZ(costheta); 165 setZ(costheta);
169 } 166 }
170 167
171 void G4StokesVector::DiceP1() << 168 void G4StokesVector::DiceP1()
172 { 169 {
173 if(G4UniformRand() > 0.5) << 170 if (G4UniformRand()>0.5) setX(1.);
174 setX(1.); << 171 else setX(-1.);
175 else <<
176 setX(-1.); <<
177 setY(0.); 172 setY(0.);
178 setZ(0.); 173 setZ(0.);
179 } 174 }
180 175
181 void G4StokesVector::DiceP2() << 176 void G4StokesVector::DiceP2()
182 { 177 {
183 setX(0.); 178 setX(0.);
184 if(G4UniformRand() > 0.5) << 179 if (G4UniformRand()>0.5) setY(1.);
185 setY(1.); << 180 else setY(-1.);
186 else <<
187 setY(-1.); <<
188 setZ(0.); 181 setZ(0.);
189 } 182 }
190 183
191 void G4StokesVector::DiceP3() << 184 void G4StokesVector::DiceP3()
192 { 185 {
193 setX(0.); 186 setX(0.);
194 setY(0.); 187 setY(0.);
195 if(G4UniformRand() > 0.5) << 188 if (G4UniformRand()>0.5) setZ(1.);
196 setZ(1.); << 189 else setZ(-1.);
197 else <<
198 setZ(-1.); <<
199 } 190 }
200 191
201 void G4StokesVector::FlipP3() { setZ(-z()); } << 192 void G4StokesVector::FlipP3()
>> 193 {
>> 194 setZ(-z());
>> 195 }
202 196
203 G4ThreeVector G4StokesVector::PolError(const G << 197 G4ThreeVector G4StokesVector::PolError(const G4StokesVector & sum2, long n)
204 { 198 {
205 // delta x = sqrt[ ( <x^2> - <x>^2 )/(n-1) ] 199 // delta x = sqrt[ ( <x^2> - <x>^2 )/(n-1) ]
206 G4ThreeVector mean = (1. / n) * G4ThreeVec << 200 G4StokesVector mean=(1./n)*(*this);
207 G4ThreeVector polsqr = G4StokesVector(mean). << 201 return G4StokesVector((1./(n-1.)*((1./n)*sum2 - mean.PolSqr()))).PolSqrt();
208 G4ThreeVector result = <<
209 G4StokesVector((1. / (n - 1.) * ((1. / n) <<
210 return result; <<
211 } 202 }
212 203
213 G4ThreeVector G4StokesVector::PolDiv(const G4S << 204 G4ThreeVector G4StokesVector::PolDiv(const G4StokesVector & b)
214 { << 205 {return G4ThreeVector(b.x()!=0. ? x()/b.x() : 11111.,
215 return G4ThreeVector(b.x() != 0. ? x() / b.x << 206 b.y()!=0. ? y()/b.y() : 11111.,
216 b.y() != 0. ? y() / b.y << 207 b.z()!=0. ? z()/b.z() : 11111.);}
217 b.z() != 0. ? z() / b.z <<
218 } <<
219 208