1 #ifndef ALI_TPC_EX_B_TWIST_H
2 #define ALI_TPC_EX_B_TWIST_H
4 /* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
5 * See cxx source for full Copyright notice */
7 /// \class AliTPCExBTwist
8 /// \brief AliTPCExBTwist class
10 /// The class calculates the space point distortions due to a mismatch
11 /// of the E and B field axis (original code from STAR)
13 /// It assumes a homogeneous magnetic and electric field. The calculations performed
14 /// within this class can be written in a compact form as well (compare notes of Jim Thomas)
16 /// The inputs to this class are the twist angles in the x and y plane ($\theta_x,\theta_y$)
17 /// in cartesian coordinates. They can be set via the member functions SetXTwist and SetYTwist.
19 /// ![Picture from ROOT macro](AliTPCExBTwist_h_76e03fd.png)
21 /// Support since 2010: mrain.ivanov@cern.ch
23 /// \author Jim Thomas, Magnus Mager, Stefan Rossegger
26 #include "AliTPCCorrection.h"
28 class AliTPCExBTwist : public AliTPCCorrection {
31 virtual ~AliTPCExBTwist();
32 virtual Bool_t AddCorrectionCompact(AliTPCCorrection* corr, Double_t weight);
33 // initialization and update functions
35 virtual void Update(const TTimeStamp &timeStamp);
38 // common setters and getters for ExB
39 virtual void SetOmegaTauT1T2(Float_t omegaTau,Float_t t1,Float_t t2) {
41 const Float_t wt1=t1*omegaTau; fC1=wt1/(1.+wt1*wt1);
42 const Float_t wt2=t2*omegaTau; fC2=wt2*wt2/(1.+wt2*wt2);
44 void SetC1C2(Float_t c1,Float_t c2) {fC1=c1;fC2=c2;} // CAUTION: USE WITH CARE
45 Float_t GetC1() const {return fC1;}
46 Float_t GetC2() const {return fC2;}
48 // setters and getters for twist
49 void SetXTwist(Float_t xTwist) {fXTwist=xTwist;}
50 void SetYTwist(Float_t yTwist) {fYTwist=yTwist;}
51 Float_t GetXTwist() const {return fXTwist;}
52 Float_t GetYTwist() const {return fYTwist;}
54 virtual void Print(const Option_t* option="") const;
57 virtual void GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]);
60 Float_t fC1; ///< coefficient C1 (compare Jim Thomas's notes for definitions)
61 Float_t fC2; ///< coefficient C2 (compare Jim Thomas's notes for definitions)
63 Float_t fXTwist; ///< Twist of E to B field in X-Z [rad]
64 Float_t fYTwist; ///< Twist of E to B field in Y-Z [rad]
67 ClassDef(AliTPCExBTwist,1);