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 // _________________________________________________________________
10 // <h2> AliTPCExBTwist class </h2>
11 // The class calculates the space point distortions due to a mismatch
12 // of the E and B field axis (original code from STAR)
14 // It assumes a homogeneous magnetic and electric field. The calculations performed
15 // within this class can be written in a compact form as well (compare notes of Jim Thomas)
17 // The inputs to this class are the twist angles in the x and y plane ($\theta_x,\theta_y$)
18 // in cartesian coordinates. They can be set via the member functions SetXTwist and SetYTwist.
21 // Begin_Macro(source)
23 // gROOT->SetStyle("Plain"); gStyle->SetPalette(1);
24 // TCanvas *c2 = new TCanvas("cAliTPCExBTwist","cAliTPCExBTwist",500,300);
25 // AliTPCExBTwist twist;
26 // twist.SetXTwist(0.001); // x angle in [rad]
27 // twist.SetXTwist(0.0005); // y angle in [rad]
28 // twist.SetOmegaTauT1T2(0.32,1,1);
29 // twist.CreateHistoDRPhiinXY(1.)->Draw("surf2"); // A side
36 // Date: 27/04/2010 <br>
37 // Authors: Jim Thomas, Magnus Mager, Stefan Rossegger
39 // _________________________________________________________________
41 #include "AliTPCCorrection.h"
43 class AliTPCExBTwist : public AliTPCCorrection {
46 virtual ~AliTPCExBTwist();
48 // initialization and update functions
50 virtual void Update(const TTimeStamp &timeStamp);
53 // common setters and getters for ExB
54 virtual void SetOmegaTauT1T2(Float_t omegaTau,Float_t t1,Float_t t2) {
56 const Float_t wt1=t1*omegaTau; fC1=wt1/(1.+wt1*wt1);
57 const Float_t wt2=t2*omegaTau; fC2=wt2*wt2/(1.+wt2*wt2);
59 void SetC1C2(Float_t c1,Float_t c2) {fC1=c1;fC2=c2;} // CAUTION: USE WITH CARE
60 Float_t GetC1() const {return fC1;}
61 Float_t GetC2() const {return fC2;}
63 // setters and getters for twist
64 void SetXTwist(Float_t xTwist) {fXTwist=xTwist;}
65 void SetYTwist(Float_t yTwist) {fYTwist=yTwist;}
66 Float_t GetXTwist() const {return fXTwist;}
67 Float_t GetYTwist() const {return fYTwist;}
69 virtual void Print(const Option_t* option="") const;
72 virtual void GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]);
75 Float_t fC1; // coefficient C1 (compare Jim Thomas's notes for definitions)
76 Float_t fC2; // coefficient C2 (compare Jim Thomas's notes for definitions)
78 Float_t fXTwist; // Twist of E to B field in X-Z [rad]
79 Float_t fYTwist; // Twist of E to B field in Y-Z [rad]
81 ClassDef(AliTPCExBTwist,1);