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G4MonopoleEquation.cc
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29 // $Id: G4MonopoleEquation.cc 66994 2013-01-29 14:34:08Z gcosmo $
30 //
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33 //
34 //
35 // class G4MonopoleEquation
36 //
37 // Class description:
38 //
39 //
40 // This is the standard right-hand side for equation of motion.
41 //
42 // The only case another is required is when using a moving reference
43 // frame ... or extending the class to include additional Forces,
44 // eg an electric field
45 //
46 // 10.11.98 V.Grichine
47 //
48 // 30.04.10 S.Burdin (modified to use for the monopole trajectories).
49 //
50 // 15.06.10 B.Bozsogi (replaced the hardcoded magnetic charge with
51 // the one passed by G4MonopoleTransportation)
52 // +workaround to pass the electric charge.
53 //
54 // 12.07.10 S.Burdin (added equations for the electric charges)
55 // -------------------------------------------------------------------
56 
57 #include "G4MonopoleEquation.hh"
58 #include "globals.hh"
59 #include "G4PhysicalConstants.hh"
60 #include "G4SystemOfUnits.hh"
61 #include <iomanip>
62 
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64 
65 G4MonopoleEquation::G4MonopoleEquation(G4ElectroMagneticField *emField )
66  : G4EquationOfMotion( emField )
67 {}
68 
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70 
71 G4MonopoleEquation::~G4MonopoleEquation()
72 {}
73 
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75 
76 void
77 G4MonopoleEquation::SetChargeMomentumMass(G4double particleMagneticCharge,
78  G4double particleElectricCharge,
79  G4double particleMass)
80 {
81  // fElCharge = particleElectricCharge;
82  fElCharge =eplus* particleElectricCharge*c_light;
83 
84  fMagCharge = eplus*particleMagneticCharge*c_light ;
85 
86  // G4cout << " G4MonopoleEquation: ElectricCharge=" << particleElectricCharge
87  // << "; MagneticCharge=" << particleMagneticCharge
88  // << G4endl;
89 
90  fMassCof = particleMass*particleMass ;
91 }
92 
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94 
95 void
96 G4MonopoleEquation::EvaluateRhsGivenB(const G4double y[],
97  const G4double Field[],
98  G4double dydx[] ) const
99 {
100  // Components of y:
101  // 0-2 dr/ds,
102  // 3-5 dp/ds - momentum derivatives
103 
104  G4double pSquared = y[3]*y[3] + y[4]*y[4] + y[5]*y[5] ;
105 
106  G4double Energy = std::sqrt( pSquared + fMassCof );
107 
108  G4double pModuleInverse = 1.0/std::sqrt(pSquared);
109 
110  G4double inverse_velocity = Energy * pModuleInverse / c_light;
111 
112  G4double cofEl = fElCharge * pModuleInverse ;
113  G4double cofMag = fMagCharge * Energy * pModuleInverse;
114 
115 
116  dydx[0] = y[3]*pModuleInverse ;
117  dydx[1] = y[4]*pModuleInverse ;
118  dydx[2] = y[5]*pModuleInverse ;
119 
120  // G4double magCharge = twopi * hbar_Planck / (eplus * mu0);
121  // magnetic charge in SI units A*m convention
122  // see http://en.wikipedia.org/wiki/Magnetic_monopole
123  // G4cout << "Magnetic charge: " << magCharge << G4endl;
124  // dp/ds = dp/dt * dt/ds = dp/dt / v = Force / velocity
125  // dydx[3] = fMagCharge * Field[0] * inverse_velocity * c_light;
126  // multiplied by c_light to convert to MeV/mm
127  // dydx[4] = fMagCharge * Field[1] * inverse_velocity * c_light;
128  // dydx[5] = fMagCharge * Field[2] * inverse_velocity * c_light;
129 
130  dydx[3] = cofMag * Field[0] + cofEl * (y[4]*Field[2] - y[5]*Field[1]);
131  dydx[4] = cofMag * Field[1] + cofEl * (y[5]*Field[0] - y[3]*Field[2]);
132  dydx[5] = cofMag * Field[2] + cofEl * (y[3]*Field[1] - y[4]*Field[0]);
133 
134  // G4cout << std::setprecision(5)<< "E=" << Energy
135  // << "; p="<< 1/pModuleInverse
136  // << "; mC="<< magCharge
137  // <<"; x=" << y[0]
138  // <<"; y=" << y[1]
139  // <<"; z=" << y[2]
140  // <<"; dydx[3]=" << dydx[3]
141  // <<"; dydx[4]=" << dydx[4]
142  // <<"; dydx[5]=" << dydx[5]
143  // << G4endl;
144 
145  dydx[6] = 0.;//not used
146 
147  // Lab Time of flight
148  dydx[7] = inverse_velocity;
149  return;
150 }
151 
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