Gabriele Cosmo
168 lines
6.1 KiB
C++
168 lines
6.1 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// G4MagHelicalStepper
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//
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// Class description:
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//
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// Abstract base class for integrator of particle's equation of motion,
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// used in tracking in space dependent magnetic field
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//
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// It is used for a set of steppers which use the helix as a sort of
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// 'first order' solution.
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// - Most obtain an error by breaking up the step in two
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// - G4ExactHelicalStepper does not provide an error estimate
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// Author: John Apostolakis (CERN), 05.11.1998
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// --------------------------------------------------------------------
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#ifndef G4MAGHELICALSTEPPER_HH
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#define G4MAGHELICALSTEPPER_HH
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#include <CLHEP/Units/PhysicalConstants.h>
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#include "G4Types.hh"
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#include "G4MagIntegratorStepper.hh"
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#include "G4Mag_EqRhs.hh"
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#include "G4ThreeVector.hh"
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/**
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* @brief G4MagHelicalStepper is an abstract base class for integrator of
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* particle's equation of motion, used in tracking in space dependent magnetic
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* field, and for a set of steppers which use the helix as 'first order'
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* solution.
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*/
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class G4MagHelicalStepper : public G4MagIntegratorStepper
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{
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public:
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/**
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* Constructor for G4MagHelicalStepper.
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* @param[in] EqRhs Pointer to the provided equation of motion.
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*/
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G4MagHelicalStepper(G4Mag_EqRhs *EqRhs);
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/**
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* Default Destructor.
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*/
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~G4MagHelicalStepper() override = default;
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/**
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* Copy constructor and assignment operator not allowed.
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*/
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G4MagHelicalStepper(const G4MagHelicalStepper&) = delete;
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G4MagHelicalStepper& operator=(const G4MagHelicalStepper&) = delete;
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/**
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* The stepper for the Runge Kutta integration.
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* The stepsize is fixed, with the step size given by 'h'.
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* Integrates ODE starting values y[0 to 6].
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* Outputs yout[] and its estimated error yerr[].
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* @param[in] y Starting values array of integration variables.
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* @param[in] dydx Derivatives array.
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* @param[in] h The given step size.
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* @param[out] yout Integration output.
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* @param[out] yerr The estimated error.
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*/
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void Stepper( const G4double y[], // VIRTUAL for ExactHelix
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const G4double dydx[],
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G4double h,
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G4double yout[],
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G4double yerr[] ) override;
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/**
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* Same as Stepper() function above, but should perform a 'dump' step
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* without error calculation. To be implemented in concrete derived classes.
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*/
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virtual void DumbStepper( const G4double y[],
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G4ThreeVector Bfld,
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G4double h,
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G4double yout[] ) = 0;
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/**
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* Estimates the maximum distance of curved solution and chord.
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*/
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G4double DistChord()const override ;
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protected:
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/**
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* Performs a linear Step in regions without magnetic field.
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*/
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inline void LinearStep( const G4double yIn[],
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G4double h,
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G4double yHelix[]) const;
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/**
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* A first order Step along a helix inside the field.
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*/
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void AdvanceHelix( const G4double yIn[],
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const G4ThreeVector& Bfld,
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G4double h,
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G4double yHelix[], G4double yHelix2[] = nullptr);
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/**
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* Evaluates the field at a certain point.
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*/
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inline void MagFieldEvaluate( const G4double y[], G4ThreeVector& Bfield );
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/**
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* Evaluates inverse of Curvature of Track.
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*/
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inline G4double GetInverseCurve( const G4double Momentum,
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const G4double Bmag );
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// Store and use the parameters of track :
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// radius of curve, Stepping angle, Radius of projected helix
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/**
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* Modifiers and accessors for storing and using the parameters of a track:
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* radius of curve, Stepping angle, Radius of projected helix.
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*/
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inline void SetAngCurve(const G4double Ang);
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inline G4double GetAngCurve()const;
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inline void SetCurve(const G4double Curve);
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inline G4double GetCurve()const;
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inline void SetRadHelix(const G4double Rad);
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inline G4double GetRadHelix()const;
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private:
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/** As in G4Mag_EqRhs.hh/cc where it is not used. */
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static const G4double fUnitConstant;
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G4Mag_EqRhs* fPtrMagEqOfMot = nullptr;
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/** Data stored in order to find the chord. */
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G4double fAngCurve = 0.0;
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G4double frCurve = 0.0;
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G4double frHelix = 0.0;
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G4ThreeVector yInitial, yMidPoint, yFinal;
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};
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#include "G4MagHelicalStepper.icc"
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#endif
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