1 #ifndef ALIMUONTRACKEXTRAP_H
2 #define ALIMUONTRACKEXTRAP_H
3 /* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * See cxx source for full Copyright notice */
7 // Revision of includes 07/05/2004
10 /// \class AliMUONTrackExtrap
11 /// \brief Track parameters in ALICE dimuon spectrometer
13 //////////////////////////////////////////////////////////////
14 /// Tools for track extrapolation in ALICE dimuon spectrometer
15 //////////////////////////////////////////////////////////////
20 class AliMUONTrackParam;
22 class AliMUONTrackExtrap : public TObject
26 AliMUONTrackExtrap() : TObject(){};
28 virtual ~AliMUONTrackExtrap(){};
31 static void SetField(const AliMagF* magField) {fgkField = magField;}
33 static Double_t GetImpactParamFromBendingMomentum(Double_t bendingMomentum);
34 static Double_t GetBendingMomentumFromImpactParam(Double_t impactParam);
36 static void ExtrapToZ(AliMUONTrackParam *trackParam, Double_t Z);
37 static void ExtrapToZCov(AliMUONTrackParam* trackParam, Double_t zEnd, Bool_t updatePropagator = kFALSE);
38 static void ExtrapToStation(AliMUONTrackParam *trackParamIn, Int_t station, AliMUONTrackParam *trackParamOut);
39 static void ExtrapToVertexUncorrected(AliMUONTrackParam* trackParam, Double_t zVtx);
40 static void ExtrapToVertex(AliMUONTrackParam *trackParam, Double_t xVtx, Double_t yVtx, Double_t zVtx,
41 Bool_t CorrectForMCS = kTRUE, Bool_t CorrectForEnergyLoss = kTRUE);
43 static Double_t TotalMomentumEnergyLoss(AliMUONTrackParam* trackParam, Double_t xVtx, Double_t yVtx, Double_t zVtx);
45 static Double_t GetMCSAngle2(const AliMUONTrackParam& param, Double_t dZ, Double_t x0);
46 static void AddMCSEffect(AliMUONTrackParam *param, Double_t dZ, Double_t x0);
48 static void ExtrapOneStepRungekutta(Double_t charge, Double_t step, Double_t* vect, Double_t* vout);
52 static const AliMagF* fgkField; //!< field map
53 static const Bool_t fgkUseHelix; //!< Tell whether to use Helix or not (default is Runge-Kutta)
54 static const Int_t fgkMaxStepNumber; //!< Maximum number of steps for track extrapolation
55 static const Double_t fgkHelixStepLength; //!< Step lenght for track extrapolation (used in Helix)
56 static const Double_t fgkRungeKuttaMaxResidue;//!< Maximal distance (in Z) to destination to stop the track extrapolation (used in Runge-Kutta)
61 AliMUONTrackExtrap(const AliMUONTrackExtrap& trackExtrap);
63 AliMUONTrackExtrap& operator=(const AliMUONTrackExtrap& trackExtrap);
65 static void ExtrapToZHelix(AliMUONTrackParam *trackParam, Double_t Z);
66 static void ExtrapToZRungekutta(AliMUONTrackParam *trackParam, Double_t Z);
68 static void ConvertTrackParamForExtrap(AliMUONTrackParam* trackParam, Double_t forwardBackward, Double_t *v3);
69 static void RecoverTrackParam(Double_t *v3, Double_t Charge, AliMUONTrackParam* trackParam);
71 static void AddMCSEffectInAbsorber(AliMUONTrackParam* trackParam, Double_t pathLength, Double_t f0, Double_t f1, Double_t f2);
72 static void GetAbsorberCorrectionParam(Double_t trackXYZIn[3], Double_t trackXYZOut[3], Double_t &pathLength,
73 Double_t &f0, Double_t &f1, Double_t &f2, Double_t &meanRho);
75 static Double_t TotalMomentumEnergyLoss(Double_t pTotal, Double_t pathLength, Double_t rho);
76 static Double_t ApproximateBetheBloch(Double_t beta2);
78 static void ExtrapOneStepHelix(Double_t charge, Double_t step, Double_t *vect, Double_t *vout);
79 static void ExtrapOneStepHelix3(Double_t field, Double_t step, Double_t *vect, Double_t *vout);
81 static void GetField(Double_t *Position, Double_t *Field);
83 ClassDef(AliMUONTrackExtrap, 0) // Tools for track extrapolation in ALICE dimuon spectrometer