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// $Id: G4FieldManager.hh 69786 2013-05-15 09:38:51Z gcosmo $
//
//
// class G4FieldManager
//
// Class description:
//
// A class to manage (Store) a pointer to the Field subclass that
// describes the field of a detector (magnetic, electric or other).
// Also stores a reference to the chord finder.
//
// The G4FieldManager class exists to allow the user program to specify
// the electric, magnetic and/or other field(s) of the detector.
//
// A field manager can be set to a logical volume (or to more than one),
// in order to vary its field from that of the world. In this manner
// a zero or constant field can override a global field, a more or
// less exact version can override the external approximation, lower
// or higher precision for tracking can be specified, a different
// stepper can be chosen for different volumes, ...
//
// It also stores a pointer to the ChordFinder object that can do the
// propagation in this field. All geometrical track "advancement"
// in the field is handled by this ChordFinder object.
//
// G4FieldManager allows the other classes/object (of the MagneticField
// & other class categories) to find out whether a detector field object
// exists and what that object is.
//
// The Chord Finder must be created either by calling CreateChordFinder
// for a Magnetic Field or by the user creating a a Chord Finder object
// "manually" and setting this pointer.
//
// A default FieldManager is created by the singleton class
// G4NavigatorForTracking and exists before main is called.
// However a new one can be created and given to G4NavigatorForTracking.
//
// Our current design envisions that one Field manager is
// valid for each region detector.
// History:
// - 05.11.03 John Apostolakis, Added Min/MaximumEpsilonStep
// - 20.06.03 John Apostolakis, Abstract & ability to ConfigureForTrack
// - 10.03.97 John Apostolakis, design and implementation.
// -------------------------------------------------------------------
#ifndef G4FIELDMANAGER_HH
#define G4FIELDMANAGER_HH 1
#include "globals.hh"
class G4Field;
class G4MagneticField;
class G4ChordFinder;
class G4Track; // Forward reference for parameter configuration
class G4FieldManager
{
public: // with description
G4FieldManager(G4Field *detectorField=0,
G4ChordFinder *pChordFinder=0,
G4bool b=true ); // fieldChangesEnergy is taken from field
// General constructor for any field.
// -> Must be set with field and chordfinder for use.
G4FieldManager(G4MagneticField *detectorMagneticField);
// Creates ChordFinder
// - assumes pure magnetic field (so Energy constant)
virtual ~G4FieldManager();
G4bool SetDetectorField(G4Field *detectorField);
inline const G4Field* GetDetectorField() const;
inline G4bool DoesFieldExist() const;
// Set, get and check the field object
void CreateChordFinder(G4MagneticField *detectorMagField);
inline void SetChordFinder(G4ChordFinder *aChordFinder);
inline G4ChordFinder* GetChordFinder();
inline const G4ChordFinder* GetChordFinder() const;
// Create, set or get the associated Chord Finder
virtual void ConfigureForTrack( const G4Track * );
// Setup the choice of the configurable parameters
// relying on the current track's energy, particle identity, ..
// Note: In addition to the values of member variables,
// a user can use this to change the ChordFinder, the field, ...
public: // with description
inline G4double GetDeltaIntersection() const; // virtual ?
// Accuracy for boundary intersection.
inline G4double GetDeltaOneStep() const; // virtual ?
// Accuracy for one tracking/physics step.
inline void SetAccuraciesWithDeltaOneStep(G4double valDeltaOneStep);
// Sets both accuracies, maintaining a fixed ratio for accuracties
// of volume Intersection and Integration (in One Step)
inline void SetDeltaOneStep(G4double valueD1step);
// Set accuracy for integration of one step. (only)
inline void SetDeltaIntersection(G4double valueDintersection);
// Set accuracy of intersection of a volume. (only)
inline G4double GetMinimumEpsilonStep() const;
inline void SetMinimumEpsilonStep( G4double newEpsMin );
// Minimum for Relative accuracy of a Step
inline G4double GetMaximumEpsilonStep() const;
inline void SetMaximumEpsilonStep( G4double newEpsMax );
// Maximum for Relative accuracy of a Step
inline G4bool DoesFieldChangeEnergy() const;
inline void SetFieldChangesEnergy(G4bool value);
// For electric field this should be true
// For magnetic field this should be false
private:
G4FieldManager(const G4FieldManager&);
G4FieldManager& operator=(const G4FieldManager&);
// Private copy constructor and assignment operator.
private:
// Dependent objects -- with state that depends on tracking
G4Field* fDetectorField;
G4ChordFinder* fChordFinder;
G4bool fAllocatedChordFinder; // Did we used "new" to
// create fChordFinder ?
// INVARIANTS of tracking ---------------------------------------
//
// 1. CONSTANTS
const G4double fEpsilonMinDefault; // Can be 1.0e-5 to 1.0e-10 ...
const G4double fEpsilonMaxDefault; // Can be 1.0e-3 to 1.0e-8 ...
// 2. CHARACTERISTIC of field
G4bool fFieldChangesEnergy;
// 3. PARAMETERS
//
// Values for the required accuracies
G4double fDelta_One_Step_Value; // for one tracking/physics step
G4double fDelta_Intersection_Val; // for boundary intersection
G4double fDefault_Delta_One_Step_Value; // = 0.25 * mm;
G4double fDefault_Delta_Intersection_Val; // = 0.1 * mm;
// Values for the small possible relative accuracy of a step
// (corresponding to the greatest possible integration accuracy)
G4double fEpsilonMin;
G4double fEpsilonMax;
};
// Our current design and implementation expect that a particular
// geometrical region has a Field manager.
// By default a Field Manager is created for the world volume, and
// will be utilised for all volumes unless it is overridden by a 'local'
// field manager.
// Note also that a region with both electric E and magnetic B field will
// have these treated as one field.
// Similarly it could be extended to treat other fields as additional components
// of a single field type.
// Implementation of inline functions
#include "G4FieldManager.icc"
#endif /* G4FIELDMANAGER_HH */