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26 // Geant4 Class file << 26 // $Id: G4PolarizationHelper.cc,v 1.3 2006/11/17 14:14:19 vnivanch Exp $
>> 27 // GEANT4 tag $Name: geant4-08-03-patch-02 $
>> 28 //
>> 29 // GEANT4 Class file
>> 30 //
27 // 31 //
28 // File name: G4PolarizationHelper 32 // File name: G4PolarizationHelper
29 // 33 //
30 // Author: Andreas Schaelicke 34 // Author: Andreas Schaelicke
31 // 35 //
>> 36 // Creation date: 12.08.2006
>> 37 //
>> 38 // Modifications:
>> 39 //
32 // Class Description: 40 // Class Description:
33 // Provides some basic polarization transfor << 41 //
34 << 42 // Provides polarization information for logical volumes, and some basic
>> 43 // transformation routines.
>> 44 //
35 #include "G4PolarizationHelper.hh" 45 #include "G4PolarizationHelper.hh"
36 <<
37 #include "G4PhysicalConstants.hh" <<
38 #include "G4StokesVector.hh" 46 #include "G4StokesVector.hh"
39 #include "Randomize.hh" <<
40 47
41 G4ThreeVector G4PolarizationHelper::GetFrame(c << 48
42 c << 49 G4ThreeVector G4PolarizationHelper::GetFrame(const G4ThreeVector & mom1, const G4ThreeVector & mom2)
43 { 50 {
44 G4ThreeVector normal = (mom1.cross(mom2)).un << 51 G4ThreeVector normal = mom1.cross(mom2);
45 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::GetSpinInPRF(const G4ThreeVector &uZ, const G4ThreeVector & spin)
74 { 82 {
75 G4double phi = 2. * pi * G4UniformRand(); << 83 // compare also G4ThreeVector::rotateUz()
76 G4ThreeVector normal = <<
77 std::cos(phi) * GetParticleFrameX(mom1) + <<
78 std::sin(phi) * G4PolarizationHelper::GetP <<
79 return normal; <<
80 } <<
81 84
82 G4ThreeVector G4PolarizationHelper::GetSpinInP << 85 if (uZ.x()==0. && uZ.y()==0.) {
83 << 86 if (uZ.z()>=0.) return spin;
84 { << 87 return G4ThreeVector(-spin.x(),spin.y(),-spin.z());
85 if(uZ.x() == 0. && uZ.y() == 0.) <<
86 { <<
87 if(uZ.z() >= 0.) <<
88 return spin; <<
89 return G4ThreeVector(-spin.x(), spin.y(), <<
90 } 88 }
91 89
92 G4double perp = std::sqrt(sqr(uZ.x()) + s << 90 G4double perp = std::sqrt(sqr(uZ.x())+sqr(uZ.y()));
93 G4double invPerp = 1. / perp; << 91 G4double invPerp = uZ.z()/perp;
94 <<
95 G4ThreeVector uX(uZ.x() * uZ.z() * invPerp, <<
96 G4ThreeVector uY(-uZ.y() * invPerp, uZ.x() * <<
97 92
98 return G4ThreeVector(spin * uX, spin * uY, s << 93 G4ThreeVector uX(uZ.x()*invPerp,uZ.y()*invPerp,-perp);
>> 94 G4ThreeVector uY(-uZ.y()*invPerp,uZ.x()*invPerp,0);
>> 95
>> 96 return G4ThreeVector(spin*uX,spin*uY,spin*uZ);
99 } 97 }
100 98
101 void G4PolarizationHelper::TestPolarizationTra 99 void G4PolarizationHelper::TestPolarizationTransformations()
102 { 100 {
103 G4double theta = 0.; << 101 G4double theta=0.;
104 G4cout << "================================= << 102 G4cout<<"========================================\n\n";
105 for(G4int i = 0; i <= 10; ++i) << 103 for (G4int i=0; i<=10; ++i) {
106 { << 104 theta=pi*i/10.;
107 theta = pi * i / 10.; << 105 G4ThreeVector zAxis = G4ThreeVector(std::sin(theta),0.,std::cos(theta));
108 G4ThreeVector zAxis = G4ThreeVector(std::s << 106 if (i==5) zAxis = G4ThreeVector(1.,0.,0.);
109 if(i == 5) << 107 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 108 G4ThreeVector yAxis = GetParticleFrameY(zAxis);
114 109
115 G4cout << zAxis << " " << zAxis.mag() << " << 110 G4cout<<zAxis<<" "<<zAxis.mag()<<"\n";
116 G4cout << yAxis << " " << yAxis.mag() << " << 111 G4cout<<yAxis<<" "<<yAxis.mag()<<"\n";
117 G4ThreeVector xAxis = yAxis.cross(zAxis); 112 G4ThreeVector xAxis = yAxis.cross(zAxis);
118 G4cout << xAxis << " " << xAxis.mag() << " << 113 G4cout<<xAxis<<" "<<xAxis.mag()<<"\n\n";
119 } 114 }
120 115
121 G4cout << "================================= << 116 G4cout<<"========================================\n\n";
122 117
123 for(G4int i = 0; i <= 10; ++i) << 118 for (G4int i=0; i<=10; ++i) {
124 { << 119 theta=pi*i/10.;
125 theta = pi * i / 10.; << 120 G4ThreeVector zAxis = G4ThreeVector(0.,std::sin(theta),std::cos(theta));
126 G4ThreeVector zAxis = G4ThreeVector(0., st << 121 if (i==5) zAxis = G4ThreeVector(0.,1.,0.);
127 if(i == 5) << 122 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 123 G4ThreeVector yAxis = GetParticleFrameY(zAxis);
132 124
133 G4cout << zAxis << " " << zAxis.mag() << " << 125 G4cout<<zAxis<<" "<<zAxis.mag()<<"\n";
134 G4cout << yAxis << " " << yAxis.mag() << " << 126 G4cout<<yAxis<<" "<<yAxis.mag()<<"\n";
135 G4ThreeVector xAxis = yAxis.cross(zAxis); 127 G4ThreeVector xAxis = yAxis.cross(zAxis);
136 G4cout << xAxis << " " << xAxis.mag() << " << 128 G4cout<<xAxis<<" "<<xAxis.mag()<<"\n\n";
137 <<
138 G4cout << "spat : " << xAxis * yAxis.cross <<
139 } 129 }
140 G4cout << "================================= << 130 G4cout<<"========================================\n\n";
141 } 131 }
142 132
143 void G4PolarizationHelper::TestInteractionFram 133 void G4PolarizationHelper::TestInteractionFrame()
144 { 134 {
145 // check transformation procedure for polari << 135 // check transformation procedure for polarisation transfer
146 // calculation in scattering processes 136 // calculation in scattering processes
147 // a) transfer target polarisation in beam 137 // a) transfer target polarisation in beam particle reference frame (PRF)
148 // b) calc correct asymmetry w.r.t. scatter 138 // b) calc correct asymmetry w.r.t. scattering plane
149 // c) determine incoming polarisation in in << 139 // c) determine incomming polarisation in interaction frame (IF)
150 // d) transfer outgoing polarisation from I 140 // d) transfer outgoing polarisation from IF to PRF
151 G4cout << "================================= << 141 G4cout<<"========================================\n\n";
152 <<
153 G4double theta = 0.; <<
154 142
155 G4ThreeVector dir0 = G4ThreeVector(0., 0., 1 << 143 G4double theta=0.;
156 G4ThreeVector dir2 = G4ThreeVector(std::sin( <<
157 144
158 G4StokesVector pol0 = G4StokesVector::P3; << 145 G4ThreeVector dir0=G4ThreeVector(0.,0.,1.);
159 G4StokesVector pol1 = G4StokesVector::P3; << 146 G4ThreeVector dir2=G4ThreeVector(std::sin(theta),0.,std::cos(theta));
>> 147
>> 148 G4StokesVector pol0=G4ThreeVector(0.,0.,1.);
>> 149 G4StokesVector pol1=G4ThreeVector(0.,0.,1.);
160 150
161 pol1.rotateUz(dir0); 151 pol1.rotateUz(dir0);
162 152
163 G4cout << "================================= << 153 G4cout<<"========================================\n\n";
>> 154
>> 155
164 } 156 }
165 157