Correction classes + the Demo
[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>
37
38#include "AliTPCExBBShape.h"
39
40AliTPCExBBShape::AliTPCExBBShape()
41 : AliTPCCorrection("exb_bshape","ExB B-shape"),
42 fC1(0.),fC2(0.),
43 fBField(0)
44{
45 //
46 // default constructor
47 //
48}
49
50AliTPCExBBShape::~AliTPCExBBShape() {
51 //
52 // virtual destructor
53 //
54}
55
56void AliTPCExBBShape::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
57 //
58 // Calculates the space point corrections of the B field inperfections (B field shape)
59 //
60
61 if (!fBField) {
62 for (Int_t j=0;j<3;++j) dx[j]=0.;
63 return;
64 }
65
66 const Double_t xStart[3]={ x[0], x[1], x[2] };
67 const Double_t xEnd[3]={ x[0], x[1], roc%36<18?fgkTPC_Z0:-fgkTPC_Z0 };
68
69 Double_t intBStart[3];
70 Double_t intBEnd[3];
71
72 fBField->GetTPCRatInt(xStart,intBStart);
73 fBField->GetTPCRatInt(xEnd, intBEnd );
74
75 const Float_t intBxOverBz=(intBEnd[0]-intBStart[0]);
76 const Float_t intByOverBz=(intBEnd[1]-intBStart[1]);
77
78 dx[0]=fC2*intBxOverBz-fC1*intByOverBz;
79 dx[1]=fC1*intBxOverBz+fC2*intByOverBz;
80 dx[2]=0.;
81
82
83}
84
85void AliTPCExBBShape::GetBxAndByOverBz(const Float_t x[],const Short_t roc,Float_t BxByOverBz[]) {
86 //
87 // This function is purely for calibration purposes
88 // Returns the via AliMagF obtaind B field integrals
89 //
90
91 if (!fBField) {
92 for (Int_t j=0;j<3;++j) BxByOverBz[j]=0.;
93 return;
94 }
95
96 const Double_t xStart[3]={ x[0], x[1], x[2] };
97 const Double_t xEnd[3]={ x[0], x[1], roc%36<18?fgkTPC_Z0:-fgkTPC_Z0 };
98
99 Double_t intBStart[3];
100 Double_t intBEnd[3];
101
102 fBField->GetTPCRatInt(xStart,intBStart);
103 fBField->GetTPCRatInt(xEnd, intBEnd );
104
105 const Float_t intBxOverBz=(intBEnd[0]-intBStart[0]);
106 const Float_t intByOverBz=(intBEnd[1]-intBStart[1]);
107
108 BxByOverBz[0]=intBxOverBz;
109 BxByOverBz[1]=intByOverBz;
110
111}
112
113void AliTPCExBBShape::Print(Option_t* option) const {
114 //
115 // Print function to check the settings (e.g. voltage offsets)
116 // option=="a" prints details of the B field settings and the
117 // C0 and C1 coefficents (for calibration purposes)
118 //
119 TString opt = option; opt.ToLower();
120 printf("%s\n - B field settings:\n",GetTitle());
121 fBField->Print(option);
122 // printf(" - B field: X-Twist: %1.5lf rad, Y-Twist: %1.5lf rad \n",fBField->Print(option));
123 if (opt.Contains("a")) { // Print all details
124 printf(" - C1: %1.4f, C2: %1.4f \n",fC1,fC2);
125 }
126
127}