1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
16 ////////////////////////////////////////////////////////////////////////////
17 // AliTPCExBBShape class //
18 ////////////////////////////////////////////////////////////////////////////
21 #include "TGeoGlobalMagField.h"
22 #include "AliTPCcalibDB.h"
23 #include "AliTPCParam.h"
26 #include "AliTPCExBBShape.h"
28 AliTPCExBBShape::AliTPCExBBShape()
29 : AliTPCCorrection("exb_bshape","ExB B-shape"),
34 // default constructor
38 AliTPCExBBShape::~AliTPCExBBShape() {
44 void AliTPCExBBShape::Init() {
46 // Initialization funtion
49 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
50 if (!magF) AliError("Magneticd field - not initialized");
51 Double_t bzField = magF->SolenoidField()/10.; //field in T
53 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
54 if (!param) AliError("Parameters - not initialized");
55 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
56 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
57 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
58 // Correction Terms for effective omegaTau; obtained by a laser calibration run
59 SetOmegaTauT1T2(wt,fT1,fT2);
64 void AliTPCExBBShape::Update(const TTimeStamp &/*timeStamp*/) {
68 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
69 if (!magF) AliError("Magneticd field - not initialized");
70 Double_t bzField = magF->SolenoidField()/10.; //field in T
72 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
73 if (!param) AliError("Parameters - not initialized");
74 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
75 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
76 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
77 // Correction Terms for effective omegaTau; obtained by a laser calibration run
78 SetOmegaTauT1T2(wt,fT1,fT2);
85 void AliTPCExBBShape::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
87 // Calculates the space point corrections of the B field inperfections (B field shape)
91 for (Int_t j=0;j<3;++j) dx[j]=0.;
95 const Double_t xStart[3]={ x[0], x[1], x[2] };
96 const Double_t xEnd[3]={ x[0], x[1], roc%36<18?fgkTPCZ0:-fgkTPCZ0 };
98 Double_t intBStart[3];
101 fBField->GetTPCRatInt(xStart,intBStart);
102 fBField->GetTPCRatInt(xEnd, intBEnd );
104 const Float_t intBxOverBz=(intBEnd[0]-intBStart[0]);
105 const Float_t intByOverBz=(intBEnd[1]-intBStart[1]);
107 dx[0]=fC2*intBxOverBz-fC1*intByOverBz;
108 dx[1]=fC1*intBxOverBz+fC2*intByOverBz;
114 void AliTPCExBBShape::GetBxAndByOverBz(const Float_t x[],const Short_t roc,Float_t BxByOverBz[]) {
116 // This function is purely for calibration purposes
117 // Returns the via AliMagF obtaind B field integrals
121 for (Int_t j=0;j<3;++j) BxByOverBz[j]=0.;
125 const Double_t xStart[3]={ x[0], x[1], x[2] };
126 const Double_t xEnd[3]={ x[0], x[1], roc%36<18?fgkTPCZ0:-fgkTPCZ0 };
128 Double_t intBStart[3];
131 fBField->GetTPCRatInt(xStart,intBStart);
132 fBField->GetTPCRatInt(xEnd, intBEnd );
134 const Float_t intBxOverBz=(intBEnd[0]-intBStart[0]);
135 const Float_t intByOverBz=(intBEnd[1]-intBStart[1]);
137 BxByOverBz[0]=intBxOverBz;
138 BxByOverBz[1]=intByOverBz;
142 void AliTPCExBBShape::Print(Option_t* option) const {
144 // Print function to check the settings (e.g. voltage offsets)
145 // option=="a" prints details of the B field settings and the
146 // C0 and C1 coefficents (for calibration purposes)
148 TString opt = option; opt.ToLower();
149 printf("%s\t%s\n - B field settings:\n",GetTitle(),GetName());
150 fBField->Print(option);
151 // printf(" - B field: X-Twist: %1.5lf rad, Y-Twist: %1.5lf rad \n",fBField->Print(option));
152 if (opt.Contains("a")) { // Print all details
153 printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2);
154 printf(" - C1: %1.4f, C2: %1.4f \n",fC1,fC2);
158 Double_t AliTPCExBBShape::GetBFieldXYZ(Double_t gx, Double_t gy, Double_t gz, Int_t axisType){
160 // return B field at given x,y,z
162 AliMagF* field = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
163 if (!field) return 0;
164 Double_t xyz[3]={gx,gy,gz};
165 Double_t bxyz[3]={0};
166 field->Field(xyz,bxyz);
168 Double_t r=TMath::Sqrt(gx*gx+gy*gy);
169 // Double_t b=TMath::Sqrt(bxyz[0]*bxyz[0]+bxyz[1]*bxyz[1]);
171 return (xyz[0]*bxyz[1]-xyz[1]*bxyz[0])/(bxyz[2]*r);
174 return (xyz[0]*bxyz[0]+xyz[1]*bxyz[1])/(bxyz[2]*r);
176 if (axisType==2) return bxyz[2];
177 if (axisType==3) return bxyz[0];
178 if (axisType==4) return bxyz[1];
179 if (axisType==5) return bxyz[2];