M AliTPCcalibDB.h - GetDistortion not inline function
[u/mrichter/AliRoot.git] / TPC / AliTPCGGVoltError.cxx
CommitLineData
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// AliTPCGGVoltError class //
19// The class calculates the electric field and space point distortions //
20// due a Gating Grid (GG) Error voltage. It uses the exact calculation //
21// technique based on bessel functions. (original code from STAR) //
22// The class allows "effective Omega Tau" corrections. //
23// //
24// date: 27/04/2010 //
25// Authors: Jim Thomas, Stefan Rossegger, Magnus Mager //
26// //
27// Example usage: //
28// AliTPCGGVoltError GGerror; //
29// GGerror.SetOmegaTauT1T2(0.32,1.,1.); // values ideally from OCDB //
30// GGerror.SetDeltaVGGA(50.); // voltage offset A-side //
31// GGerror.SetDeltaVGGC(50.); // voltage offset C-side //
32// GGerror.InitGGVoltErrorDistortion(); // initialization of the look up //
33// // plot dRPhi distortions ... //
34// GGerror.CreateHistoDRPhiinZR(1.,100,100)->Draw("surf2"); //
35////////////////////////////////////////////////////////////////////////////
36
37
534fd34a 38#include "AliMagF.h"
39#include "TGeoGlobalMagField.h"
40#include "AliTPCcalibDB.h"
41#include "AliTPCParam.h"
42#include "AliLog.h"
0116859c 43
44#include "AliTPCGGVoltError.h"
45#include <TMath.h>
46
47AliTPCGGVoltError::AliTPCGGVoltError()
48 : AliTPCCorrection("GGVoltError","GatingGrid (GG) Voltage Error"),
49 fC0(0.),fC1(0.),
50 fDeltaVGGA(0.),fDeltaVGGC(0.)
51{
52 //
53 // default constructor
54 //
55}
56
57AliTPCGGVoltError::~AliTPCGGVoltError() {
58 //
59 // default destructor
60 //
61}
62
e527a1b9 63void AliTPCGGVoltError::Init() {
64 //
e527a1b9 65 //
534fd34a 66 //
67 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
68 if (!magF) AliError("Magneticd field - not initialized");
69 Double_t bzField = magF->SolenoidField()/10.; //field in T
70 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
71 if (!param) AliError("Parameters - not initialized");
72 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
e527a1b9 73 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
74 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
534fd34a 75 //
76 SetOmegaTauT1T2(wt,fT1,fT2);
8b63d99c 77 InitGGVoltErrorDistortion();
534fd34a 78 //SetDeltaVGGA(0.0);// ideally from the database
79 //SetDeltaVGGC(0.0);// ideally from the database
e527a1b9 80}
81
82void AliTPCGGVoltError::Update(const TTimeStamp &/*timeStamp*/) {
83 //
534fd34a 84 // Update function
e527a1b9 85 //
534fd34a 86 AliMagF* magF= (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
87 if (!magF) AliError("Magneticd field - not initialized");
88 Double_t bzField = magF->SolenoidField()/10.; //field in T
89 AliTPCParam *param= AliTPCcalibDB::Instance()->GetParameters();
90 if (!param) AliError("Parameters - not initialized");
91 Double_t vdrift = param->GetDriftV()/1000000.; // [cm/us] // From dataBase: to be updated: per second (ideally)
e527a1b9 92 Double_t ezField = 400; // [V/cm] // to be updated: never (hopefully)
93 Double_t wt = -10.0 * (bzField*10) * vdrift / ezField ;
94
534fd34a 95 SetOmegaTauT1T2(wt,fT1,fT2);
8b63d99c 96 InitGGVoltErrorDistortion();
e527a1b9 97}
98
99
100
0116859c 101void AliTPCGGVoltError::GetCorrection(const Float_t x[],const Short_t roc,Float_t dx[]) {
102
103 //
104 // Gated Grid Voltage Error
105 //
106 // Calculates the effect of having an incorrect voltage on the A or C end plate Gated Grids.
107 //
108 // Electrostatic Equations from StarNote SN0253 by Howard Wieman.
109 //
110
111 Int_t order = 1 ; // FIXME: hardcoded? Linear interpolation = 1, Quadratic = 2
112
113 Double_t intEr, intEphi ;
114 Double_t r, phi, z ;
115 Int_t sign ;
116
117 Double_t deltaVGG;
118
119 r = TMath::Sqrt( x[0]*x[0] + x[1]*x[1] );
120 phi = TMath::ATan2(x[1],x[0]);
121 if ( phi < 0 ) phi += TMath::TwoPi(); // Table uses phi from 0 to 2*Pi
122 z = x[2] ;
123
124 if ( (roc%36) < 18 ) {
125 sign = 1;
126 deltaVGG = fDeltaVGGA; // (TPC End A)
127 } else {
128 sign = -1; // (TPC End C)
129 deltaVGG = fDeltaVGGC;
130 }
131
132 if ( sign==1 && z < fgkZOffSet ) z = fgkZOffSet; // Protect against discontinuity at CE
133 if ( sign==-1 && z > -fgkZOffSet ) z = -fgkZOffSet; // Protect against discontinuity at CE
134
135 Interpolate2DEdistortion( order, r, z, fGGVoltErrorER, intEr );
136 intEphi = 0.0; // Efield is symmetric in phi
137
138 // Calculate distorted position
139 if ( r > 0.0 ) {
140 phi = phi + deltaVGG*( fC0*intEphi - fC1*intEr ) / r;
141 r = r + deltaVGG*( fC0*intEr + fC1*intEphi );
142 }
143
144 // Calculate correction in cartesian coordinates
145 dx[0] = r * TMath::Cos(phi) - x[0];
146 dx[1] = r * TMath::Sin(phi) - x[1];
147 dx[2] = 0.; // z distortion not implemented (1st order distortions)
148
149}
150
151
152Float_t AliTPCGGVoltError::GetIntErOverEz(const Float_t x[],const Short_t roc) {
153 //
154 // This function is purely for calibration purposes
155 // Calculates the integral (int Er/Ez dz) for the setted GG voltage offset
156 //
157
158 Int_t order = 1 ; // FIXME: so far hardcoded? Linear interpolation = 1, Quadratic = 2
159
160 Double_t intEr;
161 Double_t r, phi, z ;
162 Int_t sign ;
163
164 Double_t deltaVGG;
165
166 r = TMath::Sqrt( x[0]*x[0] + x[1]*x[1] );
167 phi = TMath::ATan2(x[1],x[0]);
168 if ( phi < 0 ) phi += TMath::TwoPi(); // Table uses phi from 0 to 2*Pi
169 z = x[2] ;
170
171 if ( (roc%36) < 18 ) {
172 sign = 1;
173 deltaVGG = fDeltaVGGA; // (TPC End A)
174 } else {
175 sign = -1; // (TPC End C)
176 deltaVGG = fDeltaVGGC;
177 }
178
179 if ( sign==1 && z < fgkZOffSet ) z = fgkZOffSet; // Protect against discontinuity at CE
180 if ( sign==-1 && z > -fgkZOffSet ) z = -fgkZOffSet; // Protect against discontinuity at CE
181
182 Interpolate2DEdistortion(order, r, z, fGGVoltErrorER, intEr );
183
184 return (intEr*deltaVGG);
185
186}
187
188void AliTPCGGVoltError::InitGGVoltErrorDistortion() {
189 //
190 // Initialization of the Lookup table which contains the solutions of the GG Error problem
191 //
192
193 Double_t r,z;
194 Int_t nterms = 100 ;
195 for ( Int_t i = 0 ; i < kNZ ; ++i ) {
196 z = fgkZList[i] ;
197 for ( Int_t j = 0 ; j < kNR ; ++j ) {
198 r = fgkRList[j] ;
199 fGGVoltErrorER[i][j] = 0.0 ;
200 Double_t intz = 0.0 ;
201 for ( Int_t n = 1 ; n < nterms ; ++n ) {
202 Double_t k = n * TMath::Pi() / fgkTPC_Z0 ;
203 Double_t ein = 0 ; // Error potential on the IFC
204 Double_t eout = 0 ; // Error potential on the OFC
205 if ( z < 0 ) {
206 ein = -2.0 / ( k * (fgkCathodeV - fgkGG) ) ;
207 eout = -2.0 / ( k * (fgkCathodeV - fgkGG) ) ;
208 }
209 if ( z == 0 ) continue ;
210 if ( z > 0 ) {
211 ein = -2.0 / ( k * (fgkCathodeV - fgkGG) ) ;
212 eout = -2.0 / ( k * (fgkCathodeV - fgkGG) ) ;
213 }
214 Double_t an = ein * TMath::BesselK0( k*fgkOFCRadius ) - eout * TMath::BesselK0( k*fgkIFCRadius ) ;
215 Double_t bn = eout * TMath::BesselI0( k*fgkIFCRadius ) - ein * TMath::BesselI0( k*fgkOFCRadius ) ;
216 Double_t numerator =
217 an * TMath::BesselI1( k*r ) - bn * TMath::BesselK1( k*r ) ;
218 Double_t denominator =
219 TMath::BesselK0( k*fgkOFCRadius ) * TMath::BesselI0( k*fgkIFCRadius ) -
220 TMath::BesselK0( k*fgkIFCRadius ) * TMath::BesselI0( k*fgkOFCRadius ) ;
221 Double_t zterm = TMath::Cos( k*(fgkTPC_Z0-TMath::Abs(z)) ) - 1 ;
222 intz += zterm * numerator / denominator ;
223 // Assume series converges, break if small terms
b9f518ba 224 if ( n>10 && TMath::Abs(intz)*1.e-10 > TMath::Abs(numerator/denominator) ) break;
0116859c 225 }
226 fGGVoltErrorER[i][j] = (Double_t) intz ;
227
228 }
229 }
230}
231
232
233
234void AliTPCGGVoltError::Print(Option_t* option) const {
235 //
236 // Print function to check the settings (e.g. voltage offsets)
237 // option=="a" prints the C0 and C1 coefficents for calibration purposes
238 //
239
240 TString opt = option; opt.ToLower();
241 printf("%s\n",GetTitle());
242 printf(" - GG Voltage offset: A-side: %3.1f V, C-side: %3.1f V \n",fDeltaVGGA,fDeltaVGGC);
243 if (opt.Contains("a")) { // Print all details
534fd34a 244 printf(" - T1: %1.4f, T2: %1.4f \n",fT1,fT2);
0116859c 245 printf(" - C1: %1.4f, C0: %1.4f \n",fC1,fC0);
246 }
247
248
249
250}