1 /**************************************************************************
2 * Copyright(c) 2006-07, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
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14 **************************************************************************/
17 ///////////////////////////////////////////////////////////////////////////////
19 // Class describing the Vdrift dependencies on E,T,P and GasComposition //
20 // Authors: Stefan Rossegger, Haavard Helstrup //
22 ///////////////////////////////////////////////////////////////////////////////
27 #include "AliTPCTempMap.h"
28 #include "AliTPCSensorTempArray.h"
30 #include "AliTPCCalibVdrift.h"
32 ClassImp(AliTPCCalibVdrift)
34 namespace paramDefinitions {
36 // Standard Conditions used as origin in the Magbolz simulations
37 // Dimesions E [kV/cm], T [K], P [TORR], Cco2 [%], Cn2 [%]
38 const Double_t kstdE = 400;
39 const Double_t kstdT = 293;
40 const Double_t kstdP = 744;
41 const Double_t kstdCco2 = 9.52;
42 const Double_t kstdCn2 = 4.76;
43 // Driftvelocity at Standardcontitions [cm/microSec]
44 const Double_t kstdVdrift = 2.57563;
46 // Vdrift dependencies simulated with Magbolz [%(Vdrift)/[unit]]
47 const Double_t kdvdE = 0.24;
48 const Double_t kdvdT = 0.30;
49 const Double_t kdvdP = -0.13;
50 const Double_t kdvdCco2 = -6.60;
51 const Double_t kdvdCn2 = -1.74;
52 // 2nd order effect Taylor expansion
53 const Double_t kdvdE2nd = -0.00107628;
54 const Double_t kdvdT2nd = -0.00134441;
55 const Double_t kdvdP2nd = 0.000135325;
56 const Double_t kdvdCco22nd = 0.328761;
57 const Double_t kdvdCn22nd = 0.151605;
59 const Double_t torrTokPascal = 0.750061683;
61 Double_t krho = 0.934246; // density of TPC-Gas [kg/m^3]
62 // method of calculation: weighted average
66 // Nominal value obtained from 2008 data
68 const Double_t kKelvin =273.15; // degree to Kelvin
69 const Double_t kNominalTemp =19.03; // mean between A and C side in degree
70 const Double_t kNominalPress =973.9; // pressure sensor - in mbar-
71 // calibDB->GetPressure(tstamp,irun,1)
75 using namespace paramDefinitions;
77 AliTPCCalibVdrift::AliTPCCalibVdrift(AliTPCSensorTempArray *SensTemp, AliDCSSensor *SensPres, TObject *SensGasComp):
83 fNominalTemp(0), // nominal temperature in Kelvin
84 fNominalPress(0) // nominal pressure in mbar
87 // Standard constructor
93 fTempMap = new AliTPCTempMap(fSensTemp);
97 fSensGasComp = SensGasComp;
98 fNominalTemp = kNominalTemp;
99 fNominalPress= kNominalPress;
102 //_____________________________________________________________________________
103 AliTPCCalibVdrift::AliTPCCalibVdrift(const AliTPCCalibVdrift& source) :
105 fSensTemp(source.fSensTemp),
106 fSensPres(source.fSensPres),
107 fTempMap(source.fTempMap),
108 fSensGasComp(source.fSensGasComp),
109 fNominalTemp(source.fNominalTemp), // nominal temperature in Kelvin
110 fNominalPress(source.fNominalPress) // nominal pressure in mbar
118 //_____________________________________________________________________________
119 AliTPCCalibVdrift& AliTPCCalibVdrift::operator=(const AliTPCCalibVdrift& source){
121 // assignment operator
123 if (&source == this) return *this;
124 new (this) AliTPCCalibVdrift(source);
129 //_____________________________________________________________________________
130 AliTPCCalibVdrift::~AliTPCCalibVdrift()
133 // AliTPCCalibVdrift destructor
138 //_____________________________________________________________________________
139 Double_t AliTPCCalibVdrift::GetPTRelative(UInt_t absTimeSec, Int_t side){
141 // Get Relative difference of p/T for given time stamp
142 // absTimeSec - absolute time in secounds
143 // side: 0 - A side | 1 - C side
146 TTimeStamp tstamp(absTimeSec);
148 if (!fSensPres||!fSensTemp) return 0;
149 Double_t pressure = fSensPres->GetValue(tstamp);
150 TLinearFitter * fitter = fTempMap->GetLinearFitter(3,side,tstamp);
151 if (!fitter) return 0;
153 fitter->GetParameters(vec);
155 if (vec[0]<10) return 0;
159 Double_t temperature = vec[0]; //vec[0] temeperature
160 Double_t tpnom = (fNominalTemp+kKelvin)/(fNominalPress);
161 Double_t tpmeasured = (temperature+kKelvin)/(pressure);
162 Double_t result = (tpmeasured-tpnom)/tpnom;
169 //_____________________________________________________________________________
170 Double_t AliTPCCalibVdrift::VdriftLinearHyperplaneApprox(Double_t dE, Double_t dT, Double_t dP, Double_t dCco2, Double_t dCn2)
173 // Returns approximated value for the driftvelocity change (in percent)
174 // based on a Hyperplane approximation (~ Taylorapproximation of 2nd order)
177 Double_t termE = dE*kdvdE + TMath::Power(dE,2)*kdvdE2nd;
178 Double_t termT = dT*kdvdT + TMath::Power(dT,2)*kdvdT2nd;
179 Double_t termP = dP*kdvdP + TMath::Power(dP,2)*kdvdP2nd;
180 Double_t termCo2 = dCco2*kdvdCco2 + TMath::Power(dCco2,2)*kdvdCco22nd;
181 Double_t termN2 = dCn2*kdvdCn2 + TMath::Power(dCn2,2)*kdvdCn22nd;
183 Double_t vdChange = termE+termT+termP+termCo2+termN2;
189 //_____________________________________________________________________________
191 Double_t AliTPCCalibVdrift::GetVdriftNominal()
193 // returns nominal Driftvelocity at StandardConditions
197 //_____________________________________________________________________________
199 Double_t AliTPCCalibVdrift::GetVdriftChange(Double_t x, Double_t y, Double_t z, UInt_t absTimeSec)
202 // Calculates Vdrift change in percent of Vdrift_nominal
203 // (under nominal conditions) at x,y,z at absolute time (in sec)
206 TTimeStamp tstamp(absTimeSec);
208 // Get E-field Value --------------------------
209 Double_t dE = 0.23; // StandardOffset if CE is set to 100kV
211 // Get Temperature Value ----------------------
212 AliTPCTempMap *tempMap = fTempMap;
215 Double_t tempValue = tempMap->GetTemperature(x, y, z, tstamp);
216 dT = tempValue + 273.15 - kstdT;
219 // Get Main Pressure Value ---------------------
222 // Just the pressure drop over the TPC height
223 dP = - krho*kg*y/10000*torrTokPascal;
225 // pressure sensors plus additional 0.4mbar overpressure within the TPC
226 Double_t pressure = fSensPres->GetValue(tstamp) + 0.4;
227 // calculate pressure drop according to height in TPC and transform to
228 // TORR (with simplified hydrostatic formula)
229 dP = (pressure - krho*kg*y/10000) * torrTokPascal - kstdP;
232 // Get GasComposition
233 // FIXME: include Goofy values for CO2 and N2 conzentration out of OCDB
234 // Goofy not yet reliable ...
238 // Calculate change in drift velocity in terms of Vdrift_nominal
239 Double_t vdChange = VdriftLinearHyperplaneApprox(dE, dT, dP, dCco2, dCn2);
245 //_____________________________________________________________________________
247 Double_t AliTPCCalibVdrift::GetMeanZVdriftChange(Double_t x, Double_t y, UInt_t absTimeSec)
250 // Calculates Meanvalue in z direction of Vdrift change in percent
251 // of Vdrift_nominal (under standard conditions) at position x,y,absTimeSec
252 // with help of 'nPopints' base points
257 Double_t vdriftSum = 0;
259 for (Int_t i = 0; i<nPoints; i++) {
260 Double_t z = (Double_t)i/(nPoints-1)*500-250;
261 vdriftSum = vdriftSum + GetVdriftChange(x, y, z, absTimeSec);
264 Double_t meanZVdrift = vdriftSum/nPoints;
270 //_____________________________________________________________________________
272 TGraph *AliTPCCalibVdrift::MakeGraphMeanZVdriftChange(Double_t x, Double_t y, Int_t nPoints)
275 // Make graph from start time to end time of Mean Drift Velocity in
276 // Z direction at given x and y position
279 UInt_t startTime = fSensTemp->GetStartTime();
280 UInt_t endTime = fSensTemp->GetEndTime();
282 UInt_t stepTime = (endTime - startTime)/nPoints;
285 Double_t *xvec = new Double_t[nPoints];
286 Double_t *yvec = new Double_t[nPoints];
288 for (Int_t ip=0; ip<nPoints; ip++) {
289 xvec[ip] = startTime+ip*stepTime;
290 yvec[ip] = GetMeanZVdriftChange(x, y, fSensTemp->GetStartTime().GetSec() + ip*stepTime);
293 TGraph *graph = new TGraph(nPoints,xvec,yvec);
298 graph->GetXaxis()->SetTimeDisplay(1);
299 graph->GetXaxis()->SetLabelOffset(0.02);
300 graph->GetXaxis()->SetTimeFormat("#splitline{%d/%m}{%H:%M}");