Split task for ITS tracks: 1. ITS tracks with TPC partner, 2. pure ITS standalone
[u/mrichter/AliRoot.git] / TPC / AliTPCExBBShape.cxx
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0116859c 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
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 **************************************************************************/
15
16////////////////////////////////////////////////////////////////////////////
17// //
18// AliExBBShape class //
19// The class calculates the space point distortions due to the B field //
20// shape imperfections using a second order technique based on integrals //
21// over Bz (e.g. int By/Bz) obtained via the AliMagF class //
22// The class allows "effective Omega Tau" corrections. //
23// //
24// date: 27/04/2010 //
25// Authors: Magnus Mager, Jim Thomas, Stefan Rossegger //
26// //
27// Example usage: //
28// AliMagF mag("mag","mag"); //
29// AliTPCExBBShape exb; //
30// exb.SetBField(&mag); // use Bfield from AliMagF //
31// exb.SetOmegaTauT1T2(0.32,1.,1.); // values ideally from OCDB //
32// // plot dRPhi distortions ... //
33// exb.CreateHistoDRPhiinZR(0,100,100)->Draw("surf2"); //
34////////////////////////////////////////////////////////////////////////////
35
36#include <AliMagF.h>
534fd34a 37#include "TGeoGlobalMagField.h"
38#include "AliTPCcalibDB.h"
39#include "AliTPCParam.h"
40#include "AliLog.h"
0116859c 41
42#include "AliTPCExBBShape.h"
43
44AliTPCExBBShape::AliTPCExBBShape()
45 : AliTPCCorrection("exb_bshape","ExB B-shape"),
46 fC1(0.),fC2(0.),
47 fBField(0)
48{
49 //
50 // default constructor
51 //
52}
53
54AliTPCExBBShape::~AliTPCExBBShape() {
55 //
56 // virtual destructor
57 //
58}
59
e527a1b9 60void AliTPCExBBShape::Init() {
61 //
534fd34a 62 // Initialization funtion
e527a1b9 63 //
64
534fd34a 65 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
66 if (!magF) AliError("Magneticd field - not initialized");
67 Double_t bzField = magF->SolenoidField()/10.; //field in T
68 SetBField(magF);
69 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
70 if (!param) AliError("Parameters - not initialized");
71 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
e527a1b9 72 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
73 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
e527a1b9 74 // Correction Terms for effective omegaTau; obtained by a laser calibration run
534fd34a 75 SetOmegaTauT1T2(wt,fT1,fT2);
e527a1b9 76
77
78}
79
80void AliTPCExBBShape::Update(const TTimeStamp &/*timeStamp*/) {
81 //
82 // Update function
83 //
534fd34a 84 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
85 if (!magF) AliError("Magneticd field - not initialized");
86 Double_t bzField = magF->SolenoidField()/10.; //field in T
87 SetBField(magF);
88 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
89 if (!param) AliError("Parameters - not initialized");
90 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
e527a1b9 91 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
92 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
e527a1b9 93 // Correction Terms for effective omegaTau; obtained by a laser calibration run
534fd34a 94 SetOmegaTauT1T2(wt,fT1,fT2);
e527a1b9 95
96
97}
98
99
100
0116859c 101void AliTPCExBBShape::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
102 //
103 // Calculates the space point corrections of the B field inperfections (B field shape)
104 //
105
106 if (!fBField) {
107 for (Int_t j=0;j<3;++j) dx[j]=0.;
108 return;
109 }
110
111 const Double_t xStart[3]={ x[0], x[1], x[2] };
112 const Double_t xEnd[3]={ x[0], x[1], roc%36<18?fgkTPC_Z0:-fgkTPC_Z0 };
113
114 Double_t intBStart[3];
115 Double_t intBEnd[3];
116
117 fBField->GetTPCRatInt(xStart,intBStart);
118 fBField->GetTPCRatInt(xEnd, intBEnd );
119
120 const Float_t intBxOverBz=(intBEnd[0]-intBStart[0]);
121 const Float_t intByOverBz=(intBEnd[1]-intBStart[1]);
122
123 dx[0]=fC2*intBxOverBz-fC1*intByOverBz;
124 dx[1]=fC1*intBxOverBz+fC2*intByOverBz;
125 dx[2]=0.;
126
127
128}
129
130void AliTPCExBBShape::GetBxAndByOverBz(const Float_t x[],const Short_t roc,Float_t BxByOverBz[]) {
131 //
132 // This function is purely for calibration purposes
133 // Returns the via AliMagF obtaind B field integrals
134 //
135
136 if (!fBField) {
137 for (Int_t j=0;j<3;++j) BxByOverBz[j]=0.;
138 return;
139 }
140
141 const Double_t xStart[3]={ x[0], x[1], x[2] };
142 const Double_t xEnd[3]={ x[0], x[1], roc%36<18?fgkTPC_Z0:-fgkTPC_Z0 };
143
144 Double_t intBStart[3];
145 Double_t intBEnd[3];
146
147 fBField->GetTPCRatInt(xStart,intBStart);
148 fBField->GetTPCRatInt(xEnd, intBEnd );
149
150 const Float_t intBxOverBz=(intBEnd[0]-intBStart[0]);
151 const Float_t intByOverBz=(intBEnd[1]-intBStart[1]);
152
153 BxByOverBz[0]=intBxOverBz;
154 BxByOverBz[1]=intByOverBz;
155
156}
157
158void AliTPCExBBShape::Print(Option_t* option) const {
159 //
160 // Print function to check the settings (e.g. voltage offsets)
161 // option=="a" prints details of the B field settings and the
162 // C0 and C1 coefficents (for calibration purposes)
163 //
164 TString opt = option; opt.ToLower();
534fd34a 165 printf("%s\t%s\n - B field settings:\n",GetTitle(),GetName());
0116859c 166 fBField->Print(option);
167 // printf(" - B field: X-Twist: %1.5lf rad, Y-Twist: %1.5lf rad \n",fBField->Print(option));
534fd34a 168 if (opt.Contains("a")) { // Print all details
169 printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2);
0116859c 170 printf(" - C1: %1.4f, C2: %1.4f \n",fC1,fC2);
171 }
0116859c 172}