1 #ifndef ALI_TPCGG_VOLT_ERROR_H
2 #define ALI_TPCGG_VOLT_ERROR_H
4 /* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
5 * See cxx source for full Copyright notice */
7 // _________________________________________________________________
10 // <h2> AliTPCGGVoltError class </h2>
11 // The class calculates the electric field and the resulting space point distortions
12 // due a Gating Grid (GG) voltage error. It uses the analytical solution for such a problem.
14 // The input is the effective GG voltage residual in respect to the ideal setting. The effective
15 // residual voltage can be set via the functions SetDeltaVGGx. Note that this effective
16 // voltage-residuals are approx. a factor 0.9 lower than the actual difference in the setting
17 // of the GG due to the fact that the voltage on the GG is partially screened by the wire
18 // structure. The calculation has to be performed with the observable effective voltage difference.
20 // Unfortunately, the class is not capable of calculation the $dz$ offset due to possible changes
21 // of the drift velocity in dependence of the electric field. The special case of the numerical
22 // approximation (AliTPCBoundaryVoltError), which is capable of calculating the same effect, should
23 // be used for this purpose.
26 // Begin_Macro(source)
28 // gROOT->SetStyle("Plain"); gStyle->SetPalette(1);
29 // TCanvas *c2 = new TCanvas("cAliTPCGGVoltError","cAliTPCGGVoltError",500,300);
30 // AliTPCGGVoltError gg;
31 // gg.SetDeltaVGGA(-40); gg.SetDeltaVGGC(-40); // 40 Volt offset
32 // gg.InitGGVoltErrorDistortion();
33 // gg.SetOmegaTauT1T2(0,1,1); // B=0
34 // gg.CreateHistoDRinZR(0)->Draw("surf2");
41 // Date: 27/04/2010 <br>
42 // Authors: Jim Thomas, Stefan Rossegger, Magnus Mager
44 // _________________________________________________________________
47 #include "AliTPCCorrection.h"
49 class AliTPCGGVoltError : public AliTPCCorrection {
52 virtual ~AliTPCGGVoltError();
54 // initialization and update functions
56 virtual void Update(const TTimeStamp &timeStamp);
58 // common setters and getters for ExB
59 virtual void SetOmegaTauT1T2(Float_t omegaTau,Float_t t1,Float_t t2) {
61 const Double_t wt0=t2*omegaTau; fC0=1./(1.+wt0*wt0);
62 const Double_t wt1=t1*omegaTau; fC1=wt1/(1.+wt1*wt1);
65 void SetC0C1(Double_t c0,Double_t c1) {fC0=c0;fC1=c1;} // CAUTION: USE WITH CARE
66 Float_t GetC0() const {return fC0;}
67 Float_t GetC1() const {return fC1;}
69 // setters and getters for GG
70 void SetDeltaVGGA(Double_t deltaVGGA) {fDeltaVGGA=deltaVGGA;}
71 void SetDeltaVGGC(Double_t deltaVGGC) {fDeltaVGGC=deltaVGGC;}
72 Double_t GetDeltaVGGA() const {return fDeltaVGGA;}
73 Double_t GetDeltaVGGC() const {return fDeltaVGGC;}
75 void InitGGVoltErrorDistortion();
77 Float_t GetIntErOverEz(const Float_t x[],const Short_t roc);
79 virtual void Print(const Option_t* option="") const;
82 virtual void GetCorrection(const Float_t x[],const Short_t roc, Float_t dx[]);
85 Float_t fC0; // coefficient C0 (compare Jim Thomas's notes for definitions)
86 Float_t fC1; // coefficient C1 (compare Jim Thomas's notes for definitions)
88 Double_t fDeltaVGGA; // Missmatch of gating grid voltage on A-side [V]
89 Double_t fDeltaVGGC; // Missmatch of gating grid voltage on C-side [V]
90 Double_t fGGVoltErrorER[kNZ][kNR]; // Array to store electric field for GGVoltError calculation
92 Bool_t fInitLookUp; // flag to check it the Look Up table was created
94 ClassDef(AliTPCGGVoltError,1);