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25 // 25 //
26 // G4Mag_SpinEqRhs implementation 26 // G4Mag_SpinEqRhs implementation
27 // 27 //
28 // Created: J.Apostolakis, P.Gumplinger - 08.0 28 // Created: J.Apostolakis, P.Gumplinger - 08.02.1999
29 // ------------------------------------------- 29 // --------------------------------------------------------------------
30 30
31 #include "G4Mag_SpinEqRhs.hh" 31 #include "G4Mag_SpinEqRhs.hh"
32 #include "G4PhysicalConstants.hh" 32 #include "G4PhysicalConstants.hh"
33 #include "G4SystemOfUnits.hh" 33 #include "G4SystemOfUnits.hh"
34 #include "G4MagneticField.hh" 34 #include "G4MagneticField.hh"
35 #include "G4ThreeVector.hh" 35 #include "G4ThreeVector.hh"
36 36
37 G4Mag_SpinEqRhs::G4Mag_SpinEqRhs( G4MagneticFi 37 G4Mag_SpinEqRhs::G4Mag_SpinEqRhs( G4MagneticField* MagField )
38 : G4Mag_EqRhs( MagField ) 38 : G4Mag_EqRhs( MagField )
39 { 39 {
40 } 40 }
41 41
42 G4Mag_SpinEqRhs::~G4Mag_SpinEqRhs() = default; << 42 G4Mag_SpinEqRhs::~G4Mag_SpinEqRhs()
>> 43 {
>> 44 }
43 45
44 void 46 void
45 G4Mag_SpinEqRhs::SetChargeMomentumMass(G4Charg 47 G4Mag_SpinEqRhs::SetChargeMomentumMass(G4ChargeState particleCharge,
46 G4doubl 48 G4double MomentumXc,
47 G4doubl 49 G4double particleMass)
48 { 50 {
49 G4Mag_EqRhs::SetChargeMomentumMass( particl 51 G4Mag_EqRhs::SetChargeMomentumMass( particleCharge, MomentumXc, mass);
50 52
51 charge = particleCharge.GetCharge(); 53 charge = particleCharge.GetCharge();
52 mass = particleMass; 54 mass = particleMass;
53 magMoment = particleCharge.GetMagneticDipol 55 magMoment = particleCharge.GetMagneticDipoleMoment();
54 spin = particleCharge.GetSpin(); 56 spin = particleCharge.GetSpin();
55 57
56 omegac = (eplus/mass)*c_light; 58 omegac = (eplus/mass)*c_light;
57 59
58 G4double muB = 0.5*eplus*hbar_Planck/(mass/ 60 G4double muB = 0.5*eplus*hbar_Planck/(mass/c_squared);
59 61
60 G4double g_BMT; 62 G4double g_BMT;
61 if ( spin != 0. ) << 63 if ( spin != 0. ) g_BMT = (std::abs(magMoment)/muB)/spin;
62 { << 64 else g_BMT = 2.;
63 g_BMT = (std::abs(magMoment)/muB)/spin; <<
64 } <<
65 else <<
66 { <<
67 g_BMT = 2.; <<
68 } <<
69 65
70 anomaly = (g_BMT - 2.)/2.; 66 anomaly = (g_BMT - 2.)/2.;
71 67
72 G4double E = std::sqrt(sqr(MomentumXc)+sqr( 68 G4double E = std::sqrt(sqr(MomentumXc)+sqr(mass));
73 beta = MomentumXc/E; 69 beta = MomentumXc/E;
74 gamma = E/mass; 70 gamma = E/mass;
75 } 71 }
76 72
77 void 73 void
78 G4Mag_SpinEqRhs::EvaluateRhsGivenB( const G4do 74 G4Mag_SpinEqRhs::EvaluateRhsGivenB( const G4double y[],
79 const G4do 75 const G4double B[3],
80 G4do 76 G4double dydx[] ) const
81 { 77 {
82 G4double momentum_mag_square = sqr(y[3]) + 78 G4double momentum_mag_square = sqr(y[3]) + sqr(y[4]) + sqr(y[5]);
83 G4double inv_momentum_magnitude = 1.0 / std 79 G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
84 G4double cof = FCof()*inv_momentum_magnitud 80 G4double cof = FCof()*inv_momentum_magnitude;
85 81
86 dydx[0] = y[3] * inv_momentum_magnitude; 82 dydx[0] = y[3] * inv_momentum_magnitude; // (d/ds)x = Vx/V
87 dydx[1] = y[4] * inv_momentum_magnitude; 83 dydx[1] = y[4] * inv_momentum_magnitude; // (d/ds)y = Vy/V
88 dydx[2] = y[5] * inv_momentum_magnitude; 84 dydx[2] = y[5] * inv_momentum_magnitude; // (d/ds)z = Vz/V
89 85
90 if (charge == 0.) 86 if (charge == 0.)
91 { 87 {
92 dydx[3] = 0.; 88 dydx[3] = 0.;
93 dydx[4] = 0.; 89 dydx[4] = 0.;
94 dydx[5] = 0.; 90 dydx[5] = 0.;
95 } 91 }
96 else 92 else
97 { 93 {
98 dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; 94 dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ; // Ax = a*(Vy*Bz - Vz*By)
99 dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; 95 dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ; // Ay = a*(Vz*Bx - Vx*Bz)
100 dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; 96 dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ; // Az = a*(Vx*By - Vy*Bx)
101 } 97 }
102 98
103 G4ThreeVector u(y[3], y[4], y[5]); 99 G4ThreeVector u(y[3], y[4], y[5]);
104 u *= inv_momentum_magnitude; 100 u *= inv_momentum_magnitude;
105 101
106 G4ThreeVector BField(B[0],B[1],B[2]); 102 G4ThreeVector BField(B[0],B[1],B[2]);
107 103
108 G4double udb = anomaly*beta*gamma/(1.+gamma 104 G4double udb = anomaly*beta*gamma/(1.+gamma) * (BField * u);
109 G4double ucb = (anomaly+1./gamma)/beta; 105 G4double ucb = (anomaly+1./gamma)/beta;
110 106
111 // Initialise the values of dydx that we do 107 // Initialise the values of dydx that we do not update.
112 dydx[6] = dydx[7] = dydx[8] = 0.0; 108 dydx[6] = dydx[7] = dydx[8] = 0.0;
113 109
114 G4ThreeVector Spin(y[9],y[10],y[11]); 110 G4ThreeVector Spin(y[9],y[10],y[11]);
115 111
116 G4double pcharge; 112 G4double pcharge;
117 if (charge == 0.) 113 if (charge == 0.)
118 { 114 {
119 pcharge = 1.; 115 pcharge = 1.;
120 } 116 }
121 else 117 else
122 { 118 {
123 pcharge = charge; 119 pcharge = charge;
124 } 120 }
125 121
126 G4ThreeVector dSpin(0.,0.,0.); 122 G4ThreeVector dSpin(0.,0.,0.);
127 if (Spin.mag2() != 0.) 123 if (Spin.mag2() != 0.)
128 { 124 {
129 dSpin = pcharge*omegac*(ucb*(Spin.cross(B 125 dSpin = pcharge*omegac*(ucb*(Spin.cross(BField))-udb*(Spin.cross(u)));
130 } 126 }
131 127
132 dydx[9] = dSpin.x(); 128 dydx[9] = dSpin.x();
133 dydx[10] = dSpin.y(); 129 dydx[10] = dSpin.y();
134 dydx[11] = dSpin.z(); 130 dydx[11] = dSpin.z();
135 131
136 return; 132 return;
137 } 133 }
138 134