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G4MonopoleEquation.cc
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25 //
28 //
29 //
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32 //
33 //
34 // class G4MonopoleEquation
35 //
36 // Class description:
37 //
38 //
39 // This is the standard right-hand side for equation of motion.
40 //
41 // The only case another is required is when using a moving reference
42 // frame ... or extending the class to include additional Forces,
43 // eg an electric field
44 //
45 // 10.11.98 V.Grichine
46 //
47 // 30.04.10 S.Burdin (modified to use for the monopole trajectories).
48 //
49 // 15.06.10 B.Bozsogi (replaced the hardcoded magnetic charge with
50 // the one passed by G4MonopoleTransportation)
51 // +workaround to pass the electric charge.
52 //
53 // 12.07.10 S.Burdin (added equations for the electric charges)
54 // -------------------------------------------------------------------
55 
56 #include "G4MonopoleEquation.hh"
57 #include "globals.hh"
58 #include "G4PhysicalConstants.hh"
59 #include "G4SystemOfUnits.hh"
60 #include <iomanip>
61 
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63 
64 G4MonopoleEquation::G4MonopoleEquation(G4MagneticField *emField )
65  : G4EquationOfMotion( emField )
66 {
67  G4cout << "G4MonopoleEquation::G4MonopoleEquation" << G4endl;
68 }
69 
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71 
72 G4MonopoleEquation::~G4MonopoleEquation()
73 {}
74 
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76 
77 void
78 G4MonopoleEquation::SetChargeMomentumMass( G4ChargeState particleChargeState,
79  G4double , // momentum,
80  G4double particleMass)
81 {
82  G4double particleMagneticCharge= particleChargeState.MagneticCharge();
83  G4double particleElectricCharge= particleChargeState.GetCharge();
84 
85  // fElCharge = particleElectricCharge;
86  fElCharge =eplus* particleElectricCharge*c_light;
87 
88  fMagCharge = eplus*particleMagneticCharge*c_light ;
89 
90  // G4cout << " G4MonopoleEquation: ElectricCharge=" << particleElectricCharge
91  // << "; MagneticCharge=" << particleMagneticCharge
92  // << G4endl;
93 
94  fMassCof = particleMass*particleMass ;
95 }
96 
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98 
99 void
100 G4MonopoleEquation::EvaluateRhsGivenB(const G4double y[],
101  const G4double Field[],
102  G4double dydx[] ) const
103 {
104  // Components of y:
105  // 0-2 dr/ds,
106  // 3-5 dp/ds - momentum derivatives
107 
108  G4double pSquared = y[3]*y[3] + y[4]*y[4] + y[5]*y[5] ;
109 
110  G4double Energy = std::sqrt( pSquared + fMassCof );
111 
112  G4double pModuleInverse = 1.0/std::sqrt(pSquared);
113 
114  G4double inverse_velocity = Energy * pModuleInverse / c_light;
115 
116  G4double cofEl = fElCharge * pModuleInverse ;
117  G4double cofMag = fMagCharge * Energy * pModuleInverse;
118 
119  dydx[0] = y[3]*pModuleInverse ;
120  dydx[1] = y[4]*pModuleInverse ;
121  dydx[2] = y[5]*pModuleInverse ;
122 
123  // G4double magCharge = twopi * hbar_Planck / (eplus * mu0);
124  // magnetic charge in SI units A*m convention
125  // see http://en.wikipedia.org/wiki/Magnetic_monopole
126  // G4cout << "Magnetic charge: " << magCharge << G4endl;
127  // dp/ds = dp/dt * dt/ds = dp/dt / v = Force / velocity
128  // dydx[3] = fMagCharge * Field[0] * inverse_velocity * c_light;
129  // multiplied by c_light to convert to MeV/mm
130  // dydx[4] = fMagCharge * Field[1] * inverse_velocity * c_light;
131  // dydx[5] = fMagCharge * Field[2] * inverse_velocity * c_light;
132 
133  dydx[3] = cofMag * Field[0] + cofEl * (y[4]*Field[2] - y[5]*Field[1]);
134  dydx[4] = cofMag * Field[1] + cofEl * (y[5]*Field[0] - y[3]*Field[2]);
135  dydx[5] = cofMag * Field[2] + cofEl * (y[3]*Field[1] - y[4]*Field[0]);
136 
137  // G4cout << std::setprecision(5)<< "E=" << Energy
138  // << "; p="<< 1/pModuleInverse
139  // << "; mC="<< magCharge
140  // <<"; x=" << y[0]
141  // <<"; y=" << y[1]
142  // <<"; z=" << y[2]
143  // <<"; dydx[3]=" << dydx[3]
144  // <<"; dydx[4]=" << dydx[4]
145  // <<"; dydx[5]=" << dydx[5]
146  // << G4endl;
147 
148  dydx[6] = 0.;//not used
149 
150  // Lab Time of flight
151  dydx[7] = inverse_velocity;
152  return;
153 }
154 
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