include/Geant4/G4Mag_EqRhs.hh

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0025 //
0026 // G4Mag_EqRhs
0027 //
0028 // Class description:
0029 //
0030 // The "standard" equation of motion of a particle in a pure magnetic field.
0031 // Other that might be required are:
0032 //     i) is when using a moving reference frame ... or
0033 //    ii) extending for other forces, e.g. an electric field
0034
0035 // Author: John Apostolakis (CERN), 13.01.1997
0036 // --------------------------------------------------------------------
0037 #ifndef G4MAG_EQRHS_HH
0038 #define G4MAG_EQRHS_HH
0039
0040 #include "G4Types.hh"
0041 #include "G4ChargeState.hh"
0042 #include "G4EquationOfMotion.hh"
0043
0044 class G4MagneticField;
0045
0046 /**
0047  * @brief G4Mag_EqRhs is the "standard" equation of motion of a particle
0048  * in a pure magnetic field.
0049  */
0050
0051 class G4Mag_EqRhs : public G4EquationOfMotion
0052 {
0053   public:
0054
0055     /**
0056      * Constructor for G4Mag_EqRhs.
0057      *  @param[in] magField Pointer to the associated magnetic field.
0058      */
0059     G4Mag_EqRhs(G4MagneticField* magField);
0060
0061     /**
0062      * Default Destructor.
0063      */
0064     ~G4Mag_EqRhs() override = default;
0065
0066     /**
0067      * Calculates the value of the derivative, given the value of the field.
0068      *  @param[in] y Coefficients array.
0069      *  @param[in] B Field value.
0070      *  @param[out] dydx Derivatives array.
0071      */
0072     void EvaluateRhsGivenB( const G4double y[],
0073                             const G4double B[3],
0074                                   G4double dydx[] ) const override = 0;
0075
0076     /**
0077      * Returns and sets the charge momentum mass value.
0078      */
0079     inline G4double FCof() const { return fCof_val; }
0080     void SetChargeMomentumMass( G4ChargeState particleCharge,
0081                                 G4double MomentumXc,
0082                                 G4double mass ) override;
0083   private:
0084
0085     /** Charge momentum mass. */
0086     G4double fCof_val = 0.0;
0087
0088     /** Coefficient in the Lorentz motion equation (Lorentz force), if the
0089         magnetic field B is in Tesla, the particle charge in units of the
0090         elementary charge, the momentum P in MeV/c, and the space coordinates
0091         and path along the trajectory in mm. */
0092     static const G4double fUnitConstant;     // Set to 0.299792458
0093 };
0094
0095 #endif