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