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25 // 25 //
26 // G4EqGravityField implementation 26 // G4EqGravityField implementation
27 // 27 //
28 // This is the right-hand side for equation of 28 // This is the right-hand side for equation of motion for a
29 // massive particle in a gravitational field. 29 // massive particle in a gravitational field.
30 // 30 //
31 // Created: P.Gumplinger, 14.06.11 - Adopted f 31 // Created: P.Gumplinger, 14.06.11 - Adopted from G4EqMagElectricField
32 // Thanks to P.Fierlinger (PSI) and A 32 // Thanks to P.Fierlinger (PSI) and A.Capra and A.Fontana (INFN Pavia)
33 // ------------------------------------------- 33 // -------------------------------------------------------------------
34 34
35 #include "G4EqGravityField.hh" 35 #include "G4EqGravityField.hh"
36 #include "globals.hh" 36 #include "globals.hh"
37 #include "G4PhysicalConstants.hh" 37 #include "G4PhysicalConstants.hh"
38 38
39 G4EqGravityField::G4EqGravityField(G4UniformGr 39 G4EqGravityField::G4EqGravityField(G4UniformGravityField* gField)
40 : G4EquationOfMotion( gField ) 40 : G4EquationOfMotion( gField )
41 { 41 {
42 } 42 }
43 43
44 G4EqGravityField::~G4EqGravityField() = defaul << 44 G4EqGravityField::~G4EqGravityField()
>> 45 {
>> 46 }
45 47
46 void 48 void
47 G4EqGravityField::SetChargeMomentumMass(G4Char 49 G4EqGravityField::SetChargeMomentumMass(G4ChargeState,
48 G4doub 50 G4double,
49 G4doub 51 G4double particleMass )
50 { 52 {
51 fMass = particleMass; 53 fMass = particleMass;
52 } 54 }
53 55
54 void 56 void
55 G4EqGravityField::EvaluateRhsGivenB(const G4do 57 G4EqGravityField::EvaluateRhsGivenB(const G4double y[],
56 const G4do 58 const G4double G[],
57 G4do 59 G4double dydx[] ) const
58 { 60 {
59 61
60 // Components of y: 62 // Components of y:
61 // 0-2 dr/ds, 63 // 0-2 dr/ds,
62 // 3-5 dp/ds - momentum derivatives 64 // 3-5 dp/ds - momentum derivatives
63 65
64 G4double momentum_mag_square = y[3]*y[3] + y 66 G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5];
65 G4double inv_momentum_magnitude = 1.0 / std: 67 G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
66 68
67 G4double Energy = std::sqrt(momentum_mag_squ 69 G4double Energy = std::sqrt(momentum_mag_square + fMass*fMass);
68 G4double cof2 = Energy/c_light; 70 G4double cof2 = Energy/c_light;
69 G4double cof1 = inv_momentum_magnitude*fMass 71 G4double cof1 = inv_momentum_magnitude*fMass;
70 G4double inverse_velocity = Energy*inv_momen 72 G4double inverse_velocity = Energy*inv_momentum_magnitude/c_light;
71 73
72 dydx[0] = y[3]*inv_momentum_magnitude; 74 dydx[0] = y[3]*inv_momentum_magnitude; // (d/ds)x = Vx/V
73 dydx[1] = y[4]*inv_momentum_magnitude; 75 dydx[1] = y[4]*inv_momentum_magnitude; // (d/ds)y = Vy/V
74 dydx[2] = y[5]*inv_momentum_magnitude; 76 dydx[2] = y[5]*inv_momentum_magnitude; // (d/ds)z = Vz/V
75 77
76 dydx[3] = G[0]*cof1*cof2/c_light; 78 dydx[3] = G[0]*cof1*cof2/c_light;
77 dydx[4] = G[1]*cof1*cof2/c_light; 79 dydx[4] = G[1]*cof1*cof2/c_light; // m*g
78 dydx[5] = G[2]*cof1*cof2/c_light; 80 dydx[5] = G[2]*cof1*cof2/c_light;
79 81
80 // Lab Time of flight 82 // Lab Time of flight
81 // 83 //
82 dydx[7] = inverse_velocity; 84 dydx[7] = inverse_velocity;
83 85
84 return; 86 return;
85 } 87 }
86 88