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 /// \class AliTPCGGVoltError
8 /// \brief AliTPCGGVoltError class
10 /// The class calculates the electric field and the resulting space point distortions
11 /// due a Gating Grid (GG) voltage error. It uses the analytical solution for such a problem.
13 /// The input is the effective GG voltage residual in respect to the ideal setting. The effective
14 /// residual voltage can be set via the functions SetDeltaVGGx. Note that this effective
15 /// voltage-residuals are approx. a factor 0.9 lower than the actual difference in the setting
16 /// of the GG due to the fact that the voltage on the GG is partially screened by the wire
17 /// structure. The calculation has to be performed with the observable effective voltage difference.
19 /// Unfortunately, the class is not capable of calculation the $dz$ offset due to possible changes
20 /// of the drift velocity in dependence of the electric field. The special case of the numerical
21 /// approximation (AliTPCBoundaryVoltError), which is capable of calculating the same effect, should
22 /// be used for this purpose.
23 /// ![Picture from ROOT macro](AliTPCGGVoltError_h_359f7ec.png)
25 /// \author Jim Thomas, Stefan Rossegger, Magnus Mager
29 #include "AliTPCCorrection.h"
31 class AliTPCGGVoltError : public AliTPCCorrection {
34 virtual ~AliTPCGGVoltError();
36 // initialization and update functions
38 virtual void Update(const TTimeStamp &timeStamp);
40 // common setters and getters for ExB
41 virtual void SetOmegaTauT1T2(Float_t omegaTau,Float_t t1,Float_t t2) {
43 const Double_t wt0=t2*omegaTau; fC0=1./(1.+wt0*wt0);
44 const Double_t wt1=t1*omegaTau; fC1=wt1/(1.+wt1*wt1);
47 void SetC0C1(Double_t c0,Double_t c1) {fC0=c0;fC1=c1;} // CAUTION: USE WITH CARE
48 Float_t GetC0() const {return fC0;}
49 Float_t GetC1() const {return fC1;}
51 // setters and getters for GG
52 void SetDeltaVGGA(Double_t deltaVGGA) {fDeltaVGGA=deltaVGGA;}
53 void SetDeltaVGGC(Double_t deltaVGGC) {fDeltaVGGC=deltaVGGC;}
54 Double_t GetDeltaVGGA() const {return fDeltaVGGA;}
55 Double_t GetDeltaVGGC() const {return fDeltaVGGC;}
57 void InitGGVoltErrorDistortion();
59 Float_t GetIntErOverEz(const Float_t x[],const Short_t roc);
61 virtual void Print(const Option_t* option="") const;
64 virtual void GetCorrection(const Float_t x[],const Short_t roc, Float_t dx[]);
67 Float_t fC0; ///< coefficient C0 (compare Jim Thomas's notes for definitions)
68 Float_t fC1; ///< coefficient C1 (compare Jim Thomas's notes for definitions)
70 Double_t fDeltaVGGA; ///< Missmatch of gating grid voltage on A-side [V]
71 Double_t fDeltaVGGC; ///< Missmatch of gating grid voltage on C-side [V]
72 Double_t fGGVoltErrorER[kNZ][kNR]; ///< Array to store electric field for GGVoltError calculation
74 Bool_t fInitLookUp; ///< flag to check it the Look Up table was created
77 ClassDef(AliTPCGGVoltError,1);