Line data Source code
1 : #ifndef AliMFTTrackExtrap_H
2 : #define AliMFTTrackExtrap_H
3 : /* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 : * See cxx source for full Copyright notice */
5 :
6 : /*$Id$*/
7 : // Revision of includes 07/05/2004
8 :
9 : /// \ingroup rec
10 : /// \class AliMFTTrackExtrap
11 : /// \brief Track parameters in ALICE dimuon spectrometer
12 : ///
13 : //////////////////////////////////////////////////////////////
14 : /// Tools for track extrapolation in ALICE dimuon spectrometer
15 : //////////////////////////////////////////////////////////////
16 :
17 : #include <TObject.h>
18 : #include <TMatrixD.h>
19 :
20 : class AliMagF;
21 : class AliMFTTrackParam;
22 :
23 : class AliMFTTrackExtrap : public TObject
24 : {
25 : public:
26 : /// Constructor
27 0 : AliMFTTrackExtrap() : TObject(){};
28 : /// Destructor
29 0 : virtual ~AliMFTTrackExtrap(){};
30 :
31 : static void SetField();
32 :
33 : /// return kTRUE if the field is switched ON
34 0 : static Bool_t IsFieldON() {return fgFieldON;}
35 :
36 : static Double_t GetImpactParamFromBendingMomentum(Double_t bendingMomentum);
37 : static Double_t GetBendingMomentumFromImpactParam(Double_t impactParam);
38 :
39 : // Linearly extrapolate track parameters
40 : static void LinearExtrapToZ(AliMFTTrackParam* trackParam, Double_t zEnd);
41 :
42 : // Linearly extrapolate track parameters and covariances
43 : static void LinearExtrapToZCov(AliMFTTrackParam* trackParam, Double_t zEnd, Bool_t updatePropagator = kFALSE);
44 :
45 : // Extrapolate track parameters in magnetic field
46 : static Bool_t ExtrapToZ(AliMFTTrackParam *trackParam, Double_t zEnd);
47 :
48 : // Extrapolate track parameters and covariances in magnetic field
49 : static Bool_t ExtrapToZCov(AliMFTTrackParam* trackParam, Double_t zEnd, Bool_t updatePropagator = kFALSE);
50 :
51 : // Extrapolate track parameters to vertex, corrected for multiple scattering and energy loss effects
52 : // Add branson correction resolution and energy loss fluctuation to parameter covariances
53 : static void ExtrapToVertex(AliMFTTrackParam* trackParam,
54 : Double_t xVtx, Double_t yVtx, Double_t zVtx,
55 : Double_t errXVtx, Double_t errYVtx);
56 :
57 : // Extrapolate track parameters to vertex, corrected for multiple scattering effects only
58 : // Add branson correction resolution to parameter covariances
59 : static void ExtrapToVertexWithoutELoss(AliMFTTrackParam* trackParam,
60 : Double_t xVtx, Double_t yVtx, Double_t zVtx,
61 : Double_t errXVtx, Double_t errYVtx);
62 :
63 : // Extrapolate track parameters to vertex, corrected for energy loss effects only
64 : // Add dispersion due to multiple scattering and energy loss fluctuation to parameter covariances
65 : static void ExtrapToVertexWithoutBranson(AliMFTTrackParam* trackParam, Double_t zVtx);
66 :
67 : // Extrapolate track parameters to vertex without multiple scattering and energy loss corrections
68 : // Add dispersion due to multiple scattering to parameter covariances
69 : static void ExtrapToVertexUncorrected(AliMFTTrackParam* trackParam, Double_t zVtx);
70 :
71 : static Double_t TotalMomentumEnergyLoss(AliMFTTrackParam* trackParam, Double_t xVtx, Double_t yVtx, Double_t zVtx);
72 :
73 : static Double_t GetMCSAngle2(const AliMFTTrackParam& param, Double_t dZ, Double_t x0);
74 : static void AddMCSEffect(AliMFTTrackParam *param, Double_t dZ, Double_t x0);
75 :
76 : static Bool_t ExtrapOneStepRungekutta(Double_t charge, Double_t step, const Double_t* vect, Double_t* vout);
77 :
78 : static Double_t LinearRegression(Int_t nVal, Double_t *xVal, Double_t *yVal, Double_t &p0, Double_t &p1);
79 : static Double_t Sagitta(Int_t nVal, Double_t *xVal, Double_t *yVal, Double_t &distL, Double_t &q2);
80 : static Double_t QuadraticRegression(Int_t nVal, Double_t *xVal, Double_t *yVal, Double_t &p0, Double_t &p1, Double_t &p2);
81 : static Double_t CircleRegression(Int_t nVal, Double_t *xVal, Double_t *yVal);
82 :
83 : private:
84 : static const Double_t fgkSimpleBPosition; //!<! position of the dipole
85 : static const Double_t fgkSimpleBLength; //!<! length of the dipole
86 : static Double_t fgSimpleBValue; //!<! magnetic field value at the centre
87 : static Bool_t fgFieldON; //!<! kTRUE if the field is switched ON
88 : static const Bool_t fgkUseHelix; //!<! Tell whether to use Helix or not (default is Runge-Kutta)
89 : static const Int_t fgkMaxStepNumber; //!<! Maximum number of steps for track extrapolation
90 : static const Double_t fgkHelixStepLength; //!<! Step lenght for track extrapolation (used in Helix)
91 : static const Double_t fgkRungeKuttaMaxResidue;//!<! Maximal distance (in Z) to destination to stop the track extrapolation (used in Runge-Kutta)
92 :
93 : // Functions
94 :
95 : /// Not implemented
96 : AliMFTTrackExtrap(const AliMFTTrackExtrap& trackExtrap);
97 : /// Not implemented
98 : AliMFTTrackExtrap& operator=(const AliMFTTrackExtrap& trackExtrap);
99 :
100 : static Bool_t ExtrapToZHelix(AliMFTTrackParam *trackParam, Double_t Z);
101 : static Bool_t ExtrapToZRungekutta(AliMFTTrackParam *trackParam, Double_t Z);
102 :
103 : static void ConvertTrackParamForExtrap(AliMFTTrackParam* trackParam, Double_t forwardBackward, Double_t *v3);
104 : static void RecoverTrackParam(Double_t *v3, Double_t Charge, AliMFTTrackParam* trackParam);
105 :
106 : static void ExtrapToVertex(AliMFTTrackParam* trackParam,
107 : Double_t xVtx, Double_t yVtx, Double_t zVtx,
108 : Double_t errXVtx, Double_t errYVtx,
109 : Bool_t correctForMCS, Bool_t correctForEnergyLoss);
110 :
111 : static void AddMCSEffectInAbsorber(AliMFTTrackParam* trackParam, Double_t signedPathLength, Double_t f0, Double_t f1, Double_t f2);
112 : static void CorrectMCSEffectInAbsorber(AliMFTTrackParam* param,
113 : Double_t xVtx, Double_t yVtx, Double_t zVtx,
114 : Double_t errXVtx, Double_t errYVtx,
115 : Double_t absZBeg, Double_t pathLength, Double_t f0, Double_t f1, Double_t f2);
116 : static void CorrectELossEffectInAbsorber(AliMFTTrackParam* param, Double_t eLoss, Double_t sigmaELoss2);
117 : static Bool_t GetAbsorberCorrectionParam(Double_t trackXYZIn[3], Double_t trackXYZOut[3], Double_t pTotal,
118 : Double_t &pathLength, Double_t &f0, Double_t &f1, Double_t &f2,
119 : Double_t &meanRho, Double_t &totalELoss, Double_t &sigmaELoss2);
120 :
121 : static Double_t BetheBloch(Double_t pTotal, Double_t pathLength, Double_t rho, Double_t atomicZ, Double_t atomicZoverA);
122 : static Double_t EnergyLossFluctuation(Double_t pTotal, Double_t pathLength, Double_t rho, Double_t atomicZoverA);
123 :
124 : static void Cov2CovP(const TMatrixD ¶m, TMatrixD &cov);
125 : static void CovP2Cov(const TMatrixD ¶m, TMatrixD &cov);
126 :
127 : static void ExtrapOneStepHelix(Double_t charge, Double_t step, const Double_t *vect, Double_t *vout);
128 : static void ExtrapOneStepHelix3(Double_t field, Double_t step, const Double_t *vect, Double_t *vout);
129 :
130 12 : ClassDef(AliMFTTrackExtrap, 0) // Tools for track extrapolation in ALICE dimuon spectrometer
131 : };
132 :
133 : #endif
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