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G4EqMagElectricField.cc
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25 //
26 // G4EqMagElectricField implementation
27 //
28 // This is the standard right-hand side for equation of motion.
29 //
30 // The only case another is required is when using a moving reference
31 // frame ... or extending the class to include additional forces,
32 // e.g., an electric field
33 //
34 // Created: V.Grichine, 10.11.1998
35 // -------------------------------------------------------------------
36 
37 #include "G4EqMagElectricField.hh"
38 #include "globals.hh"
39 #include "G4PhysicalConstants.hh"
40 #include "G4SystemOfUnits.hh"
41 
43  : G4EquationOfMotion( emField )
44 {
45 }
46 
48 {
49 }
50 
51 void
53  G4double,
54  G4double particleMass)
55 {
56  G4double pcharge = particleCharge.GetCharge();
57  fElectroMagCof = eplus*pcharge*c_light ;
58  fMassCof = particleMass*particleMass ;
59 }
60 
61 void
63  const G4double Field[],
64  G4double dydx[] ) const
65 {
66  // Components of y:
67  // 0-2 dr/ds,
68  // 3-5 dp/ds - momentum derivatives
69 
70  G4double pSquared = y[3]*y[3] + y[4]*y[4] + y[5]*y[5] ;
71 
72  G4double Energy = std::sqrt( pSquared + fMassCof );
73  G4double cof2 = Energy/c_light ;
74 
75  G4double pModuleInverse = 1.0/std::sqrt(pSquared) ;
76 
77  G4double inverse_velocity = Energy * pModuleInverse / c_light;
78 
79  G4double cof1 = fElectroMagCof*pModuleInverse ;
80 
81  dydx[0] = y[3]*pModuleInverse ;
82  dydx[1] = y[4]*pModuleInverse ;
83  dydx[2] = y[5]*pModuleInverse ;
84 
85  dydx[3] = cof1*(cof2*Field[3] + (y[4]*Field[2] - y[5]*Field[1])) ;
86 
87  dydx[4] = cof1*(cof2*Field[4] + (y[5]*Field[0] - y[3]*Field[2])) ;
88 
89  dydx[5] = cof1*(cof2*Field[5] + (y[3]*Field[1] - y[4]*Field[0])) ;
90 
91  dydx[6] = 0.;//not used
92 
93  // Lab Time of flight
94  //
95  dydx[7] = inverse_velocity;
96 
97  return;
98 }