| Geant4 Cross Reference |
1 //
2 // ********************************************************************
3 // * License and Disclaimer *
4 // * *
5 // * The Geant4 software is copyright of the Copyright Holders of *
6 // * the Geant4 Collaboration. It is provided under the terms and *
7 // * conditions of the Geant4 Software License, included in the file *
8 // * LICENSE and available at http://cern.ch/geant4/license . These *
9 // * include a list of copyright holders. *
10 // * *
11 // * Neither the authors of this software system, nor their employing *
12 // * institutes,nor the agencies providing financial support for this *
13 // * work make any representation or warranty, express or implied, *
14 // * regarding this software system or assume any liability for its *
15 // * use. Please see the license in the file LICENSE and URL above *
16 // * for the full disclaimer and the limitation of liability. *
17 // * *
18 // * This code implementation is the result of the scientific and *
19 // * technical work of the GEANT4 collaboration. *
20 // * By using, copying, modifying or distributing the software (or *
21 // * any work based on the software) you agree to acknowledge its *
22 // * use in resulting scientific publications, and indicate your *
23 // * acceptance of all terms of the Geant4 Software license. *
24 // ********************************************************************
25 //
26 // G4MagHelicalStepper
27 //
28 // Class description:
29 //
30 // Abstract base class for integrator of particle's equation of motion,
31 // used in tracking in space dependent magnetic field
32 //
33 // It is used for a set of steppers which use the helix as a sort of
34 // 'first order' solution.
35 // - Most obtain an error by breaking up the step in two
36 // - G4ExactHelicalStepper does not provide an error estimate
37
38 // Created: J.Apostolakis, CERN - 05.11.1998
39 // --------------------------------------------------------------------
40 #ifndef G4MAGHELICALSTEPPER_HH
41 #define G4MAGHELICALSTEPPER_HH
42
43 #include <CLHEP/Units/PhysicalConstants.h>
44
45 #include "G4Types.hh"
46 #include "G4MagIntegratorStepper.hh"
47 #include "G4Mag_EqRhs.hh"
48 #include "G4ThreeVector.hh"
49
50 class G4MagHelicalStepper : public G4MagIntegratorStepper
51 {
52 public:
53
54 G4MagHelicalStepper(G4Mag_EqRhs *EqRhs);
55 ~G4MagHelicalStepper() override;
56
57 G4MagHelicalStepper(const G4MagHelicalStepper&) = delete;
58 G4MagHelicalStepper& operator=(const G4MagHelicalStepper&) = delete;
59
60 void Stepper( const G4double y[], // VIRTUAL for ExactHelix
61 const G4double dydx[],
62 G4double h,
63 G4double yout[],
64 G4double yerr[] ) override;
65 // The stepper for the Runge Kutta integration.
66 // The stepsize is fixed, equal to h.
67 // Integrates ODE starting values y[0 to 6]
68 // Outputs yout[] and its estimated error yerr[].
69
70 virtual void DumbStepper( const G4double y[],
71 G4ThreeVector Bfld,
72 G4double h,
73 G4double yout[] ) = 0;
74 // Performs a 'dump' Step without error calculation.
75
76 G4double DistChord()const override ;
77 // Estimate maximum distance of curved solution and chord ...
78
79 protected:
80
81 inline void LinearStep( const G4double yIn[],
82 G4double h,
83 G4double yHelix[]) const;
84 // A linear Step in regions without magnetic field.
85
86 void AdvanceHelix( const G4double yIn[],
87 const G4ThreeVector& Bfld,
88 G4double h,
89 G4double yHelix[], G4double yHelix2[] = nullptr);
90 // A first order Step along a helix inside the field.
91
92 inline void MagFieldEvaluate( const G4double y[], G4ThreeVector& Bfield );
93 // Evaluate the field at a certain point.
94
95 inline G4double GetInverseCurve( const G4double Momentum,
96 const G4double Bmag );
97 // Evaluate Inverse of Curvature of Track
98
99 // Store and use the parameters of track :
100 // radius of curve, Stepping angle, Radius of projected helix
101
102 inline void SetAngCurve(const G4double Ang);
103 inline G4double GetAngCurve()const;
104
105 inline void SetCurve(const G4double Curve);
106 inline G4double GetCurve()const;
107
108 inline void SetRadHelix(const G4double Rad);
109 inline G4double GetRadHelix()const;
110
111 private:
112
113 static const G4double fUnitConstant;
114 // As in G4Mag_EqRhs.hh/cc where it is not used.
115
116 G4Mag_EqRhs* fPtrMagEqOfMot = nullptr;
117
118 // Data stored in order to find the chord
119 //
120 G4double fAngCurve = 0.0;
121 G4double frCurve = 0.0;
122 G4double frHelix = 0.0;
123 G4ThreeVector yInitial, yMidPoint, yFinal;
124 };
125
126 #include "G4MagHelicalStepper.icc"
127
128 #endif
129