Line data    Source code

       1             : #ifndef ALI_TPC_EX_B_TWIST_H
       2             : #define ALI_TPC_EX_B_TWIST_H
       3             : 
       4             : /* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
       5             :  * See cxx source for full Copyright notice                               */
       6             : 
       7             : /// \class AliTPCExBTwist
       8             : /// \brief AliTPCExBTwist class
       9             : ///
      10             : /// The class calculates the space point distortions due to a mismatch
      11             : /// of the E and B field axis (original code from STAR)
      12             : ///
      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)
      15             : ///
      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.
      18             : ///
      19             : /// ![Picture from ROOT macro](AliTPCExBTwist_h_76e03fd.png)
      20             : ///
      21             : /// Support since 2010: mrain.ivanov@cern.ch
      22             : ///
      23             : /// \author Jim Thomas, Magnus Mager, Stefan Rossegger
      24             : /// \date 27/04/2010
      25             : 
      26             : #include "AliTPCCorrection.h"
      27             : 
      28             : class AliTPCExBTwist : public AliTPCCorrection {
      29             : public:
      30             :   AliTPCExBTwist();
      31             :   virtual ~AliTPCExBTwist();
      32             :   virtual Bool_t AddCorrectionCompact(AliTPCCorrection* corr, Double_t weight);
      33             :   // initialization and update functions
      34             :   virtual void Init();
      35             :   virtual void Update(const TTimeStamp &timeStamp);
      36             : 
      37             : 
      38             :   // common setters and getters for ExB
      39             :   virtual void SetOmegaTauT1T2(Float_t omegaTau,Float_t t1,Float_t t2) {
      40          12 :     fT1=t1; fT2=t2;
      41           6 :     const Float_t wt1=t1*omegaTau;     fC1=wt1/(1.+wt1*wt1);
      42           6 :     const Float_t wt2=t2*omegaTau;     fC2=wt2*wt2/(1.+wt2*wt2);
      43           6 :   };
      44           0 :   void SetC1C2(Float_t c1,Float_t c2) {fC1=c1;fC2=c2;} // CAUTION: USE WITH CARE
      45           0 :   Float_t GetC1() const {return fC1;}
      46           0 :   Float_t GetC2() const {return fC2;}
      47             : 
      48             :   // setters and getters for twist
      49           0 :   void SetXTwist(Float_t xTwist) {fXTwist=xTwist;}
      50           0 :   void SetYTwist(Float_t yTwist) {fYTwist=yTwist;}
      51           0 :   Float_t GetXTwist() const {return fXTwist;}
      52           0 :   Float_t GetYTwist() const {return fYTwist;}
      53             : 
      54             :   virtual void Print(const Option_t* option="") const;
      55             : 
      56             : protected:
      57             :   virtual void GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]);
      58             : 
      59             : private:
      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)
      62             : 
      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]
      65             : 
      66             :   /// \cond CLASSIMP
      67          42 :   ClassDef(AliTPCExBTwist,1);
      68             :   /// \endcond
      69             : };
      70             : 
      71             : #endif