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25 // 25 //
26 // Geant4 Class file << 26 // $Id: G4PolarizationHelper.cc 68046 2013-03-13 14:31:38Z gcosmo $
>> 27 //
>> 28 // GEANT4 Class file
>> 29 //
27 // 30 //
28 // File name: G4PolarizationHelper 31 // File name: G4PolarizationHelper
29 // 32 //
30 // Author: Andreas Schaelicke 33 // Author: Andreas Schaelicke
31 // 34 //
>> 35 // Creation date: 12.08.2006
>> 36 //
>> 37 // Modifications:
>> 38 //
32 // Class Description: 39 // Class Description:
33 // Provides some basic polarization transfor << 40 //
34 << 41 // Provides some basic polarization transformation routines.
>> 42 //
35 #include "G4PolarizationHelper.hh" 43 #include "G4PolarizationHelper.hh"
36 <<
37 #include "G4PhysicalConstants.hh" 44 #include "G4PhysicalConstants.hh"
38 #include "G4StokesVector.hh" 45 #include "G4StokesVector.hh"
39 #include "Randomize.hh" <<
40 46
41 G4ThreeVector G4PolarizationHelper::GetFrame(c << 47
42 c << 48 G4ThreeVector G4PolarizationHelper::GetFrame(const G4ThreeVector & mom1, const G4ThreeVector & mom2)
43 { 49 {
44 G4ThreeVector normal = (mom1.cross(mom2)).un 50 G4ThreeVector normal = (mom1.cross(mom2)).unit();
45 return normal; 51 return normal;
>> 52 // return 1./normal.mag()*normal;
46 } 53 }
47 54
48 G4ThreeVector G4PolarizationHelper::GetParticl << 55 G4ThreeVector G4PolarizationHelper::GetParticleFrameY(const G4ThreeVector &uZ)
49 { 56 {
50 if(uZ.x() == 0. && uZ.y() == 0.) << 57 // compare also G4ThreeVector::rotateUz()
51 { << 58
52 return G4ThreeVector(0., 1., 0.); << 59 if (uZ.x()==0. && uZ.y()==0.) {
>> 60 return G4ThreeVector(0.,1.,0.);
53 } 61 }
54 62
55 G4double invPerp = 1. / std::sqrt(sqr(uZ.x() << 63 G4double invPerp = 1./std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
56 return G4ThreeVector(-uZ.y() * invPerp, uZ.x << 64 return G4ThreeVector(-uZ.y()*invPerp,uZ.x()*invPerp,0);
57 } 65 }
58 66
59 G4ThreeVector G4PolarizationHelper::GetParticl << 67 G4ThreeVector G4PolarizationHelper::GetParticleFrameX(const G4ThreeVector &uZ)
60 { 68 {
61 if(uZ.x() == 0. && uZ.y() == 0.) << 69 // compare also G4ThreeVector::rotateUz()
62 { << 70
63 if(uZ.z() >= 0.) << 71 if (uZ.x()==0. && uZ.y()==0.) {
64 return G4ThreeVector(1., 0., 0.); << 72 if (uZ.z()>=0.) return G4ThreeVector(1.,0.,0.);
65 return G4ThreeVector(-1., 0., 0.); << 73 return G4ThreeVector(-1.,0.,0.);
66 } 74 }
67 75
68 G4double perp = std::sqrt(sqr(uZ.x()) + s << 76 G4double perp = std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
69 G4double invPerp = uZ.z() / perp; << 77 G4double invPerp = uZ.z()/perp;
70 return G4ThreeVector(uZ.x() * invPerp, uZ.y( << 78 return G4ThreeVector(uZ.x()*invPerp,uZ.y()*invPerp,-perp);
71 } 79 }
72 80
73 G4ThreeVector G4PolarizationHelper::GetRandomF << 81 G4ThreeVector G4PolarizationHelper::GetRandomFrame(const G4ThreeVector & mom1)
74 { 82 {
75 G4double phi = 2. * pi * G4UniformRand(); << 83 G4double phi =2.*pi*G4UniformRand();
76 G4ThreeVector normal = << 84 G4ThreeVector normal = std::cos(phi)*GetParticleFrameX(mom1)
77 std::cos(phi) * GetParticleFrameX(mom1) + << 85 + std::sin(phi)*G4PolarizationHelper::GetParticleFrameY(mom1);
78 std::sin(phi) * G4PolarizationHelper::GetP <<
79 return normal; 86 return normal;
80 } 87 }
81 88
82 G4ThreeVector G4PolarizationHelper::GetSpinInP << 89
83 << 90 G4ThreeVector G4PolarizationHelper::GetSpinInPRF(const G4ThreeVector &uZ, const G4ThreeVector & spin)
84 { 91 {
85 if(uZ.x() == 0. && uZ.y() == 0.) << 92 // compare also G4ThreeVector::rotateUz()
86 { <<
87 if(uZ.z() >= 0.) <<
88 return spin; <<
89 return G4ThreeVector(-spin.x(), spin.y(), <<
90 } <<
91 93
92 G4double perp = std::sqrt(sqr(uZ.x()) + s << 94 if (uZ.x()==0. && uZ.y()==0.) {
93 G4double invPerp = 1. / perp; << 95 if (uZ.z()>=0.) return spin;
>> 96 return G4ThreeVector(-spin.x(),spin.y(),-spin.z());
>> 97 }
94 98
95 G4ThreeVector uX(uZ.x() * uZ.z() * invPerp, << 99 G4double perp = std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
96 G4ThreeVector uY(-uZ.y() * invPerp, uZ.x() * << 100 G4double invPerp = 1./perp;
97 101
98 return G4ThreeVector(spin * uX, spin * uY, s << 102 G4ThreeVector uX(uZ.x()*uZ.z()*invPerp,uZ.y()*uZ.z()*invPerp,-perp);
>> 103 G4ThreeVector uY(-uZ.y()*invPerp,uZ.x()*invPerp,0);
>> 104
>> 105 return G4ThreeVector(spin*uX,spin*uY,spin*uZ);
99 } 106 }
100 107
101 void G4PolarizationHelper::TestPolarizationTra 108 void G4PolarizationHelper::TestPolarizationTransformations()
102 { 109 {
103 G4double theta = 0.; << 110 G4double theta=0.;
104 G4cout << "================================= << 111 G4cout<<"========================================\n\n";
105 for(G4int i = 0; i <= 10; ++i) << 112 for (G4int i=0; i<=10; ++i) {
106 { << 113 theta=pi*i/10.;
107 theta = pi * i / 10.; << 114 G4ThreeVector zAxis = G4ThreeVector(std::sin(theta),0.,std::cos(theta));
108 G4ThreeVector zAxis = G4ThreeVector(std::s << 115 if (i==5) zAxis = G4ThreeVector(1.,0.,0.);
109 if(i == 5) << 116 if (i==10) zAxis = G4ThreeVector(0.,0.,-1.);
110 zAxis = G4ThreeVector(1., 0., 0.); <<
111 if(i == 10) <<
112 zAxis = G4ThreeVector(0., 0., -1.); <<
113 G4ThreeVector yAxis = GetParticleFrameY(zA 117 G4ThreeVector yAxis = GetParticleFrameY(zAxis);
114 118
115 G4cout << zAxis << " " << zAxis.mag() << " << 119 G4cout<<zAxis<<" "<<zAxis.mag()<<"\n";
116 G4cout << yAxis << " " << yAxis.mag() << " << 120 G4cout<<yAxis<<" "<<yAxis.mag()<<"\n";
117 G4ThreeVector xAxis = yAxis.cross(zAxis); 121 G4ThreeVector xAxis = yAxis.cross(zAxis);
118 G4cout << xAxis << " " << xAxis.mag() << " << 122 G4cout<<xAxis<<" "<<xAxis.mag()<<"\n\n";
119 } 123 }
120 124
121 G4cout << "================================= << 125 G4cout<<"========================================\n\n";
122 126
123 for(G4int i = 0; i <= 10; ++i) << 127 for (G4int i=0; i<=10; ++i) {
124 { << 128 theta=pi*i/10.;
125 theta = pi * i / 10.; << 129 G4ThreeVector zAxis = G4ThreeVector(0.,std::sin(theta),std::cos(theta));
126 G4ThreeVector zAxis = G4ThreeVector(0., st << 130 if (i==5) zAxis = G4ThreeVector(0.,1.,0.);
127 if(i == 5) << 131 if (i==10) zAxis = G4ThreeVector(0.,0.,-1.);
128 zAxis = G4ThreeVector(0., 1., 0.); <<
129 if(i == 10) <<
130 zAxis = G4ThreeVector(0., 0., -1.); <<
131 G4ThreeVector yAxis = GetParticleFrameY(zA 132 G4ThreeVector yAxis = GetParticleFrameY(zAxis);
132 133
133 G4cout << zAxis << " " << zAxis.mag() << " << 134 G4cout<<zAxis<<" "<<zAxis.mag()<<"\n";
134 G4cout << yAxis << " " << yAxis.mag() << " << 135 G4cout<<yAxis<<" "<<yAxis.mag()<<"\n";
135 G4ThreeVector xAxis = yAxis.cross(zAxis); 136 G4ThreeVector xAxis = yAxis.cross(zAxis);
136 G4cout << xAxis << " " << xAxis.mag() << " << 137 G4cout<<xAxis<<" "<<xAxis.mag()<<"\n\n";
137 138
138 G4cout << "spat : " << xAxis * yAxis.cross << 139 G4cout<<"spat : "<<xAxis*yAxis.cross(zAxis)<<"\n\n";
139 } 140 }
140 G4cout << "================================= << 141 G4cout<<"========================================\n\n";
141 } 142 }
142 143
143 void G4PolarizationHelper::TestInteractionFram 144 void G4PolarizationHelper::TestInteractionFrame()
144 { 145 {
145 // check transformation procedure for polari << 146 // check transformation procedure for polarisation transfer
146 // calculation in scattering processes 147 // calculation in scattering processes
147 // a) transfer target polarisation in beam 148 // a) transfer target polarisation in beam particle reference frame (PRF)
148 // b) calc correct asymmetry w.r.t. scatter 149 // b) calc correct asymmetry w.r.t. scattering plane
149 // c) determine incoming polarisation in in << 150 // c) determine incomming polarisation in interaction frame (IF)
150 // d) transfer outgoing polarisation from I 151 // d) transfer outgoing polarisation from IF to PRF
151 G4cout << "================================= << 152 G4cout<<"========================================\n\n";
152 <<
153 G4double theta = 0.; <<
154 153
155 G4ThreeVector dir0 = G4ThreeVector(0., 0., 1 << 154 G4double theta=0.;
156 G4ThreeVector dir2 = G4ThreeVector(std::sin( <<
157 155
158 G4StokesVector pol0 = G4StokesVector::P3; << 156 G4ThreeVector dir0=G4ThreeVector(0.,0.,1.);
159 G4StokesVector pol1 = G4StokesVector::P3; << 157 G4ThreeVector dir2=G4ThreeVector(std::sin(theta),0.,std::cos(theta));
>> 158
>> 159 G4StokesVector pol0=G4ThreeVector(0.,0.,1.);
>> 160 G4StokesVector pol1=G4ThreeVector(0.,0.,1.);
160 161
161 pol1.rotateUz(dir0); 162 pol1.rotateUz(dir0);
162 163
163 G4cout << "================================= << 164 G4cout<<"========================================\n\n";
>> 165
>> 166
164 } 167 }
165 168