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. *
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 **************************************************************************/
17 /// \class AliTPCCalibVdrift
19 /// Class describing the Vdrift dependencies on E,T,P and GasComposition
21 /// \author Stefan Rossegger, Haavard Helstrup
26 #include "AliTPCTempMap.h"
27 #include "AliTPCSensorTempArray.h"
29 #include "AliTPCCalibVdrift.h"
32 ClassImp(AliTPCCalibVdrift)
35 namespace paramDefinitions {
37 // Standard Conditions used as origin in the Magbolz simulations
38 // Dimesions E [kV/cm], T [K], P [TORR], Cco2 [%], Cn2 [%]
39 const Double_t kstdE = 400;
40 const Double_t kstdT = 293;
41 const Double_t kstdP = 744;
42 const Double_t kstdCco2 = 9.52;
43 const Double_t kstdCn2 = 4.76;
44 // Driftvelocity at Standardcontitions [cm/microSec]
45 const Double_t kstdVdrift = 2.57563;
47 // Vdrift dependencies simulated with Magbolz [%(Vdrift)/[unit]]
48 const Double_t kdvdE = 0.24;
49 const Double_t kdvdT = 0.30;
50 const Double_t kdvdP = -0.13;
51 const Double_t kdvdCco2 = -6.60;
52 const Double_t kdvdCn2 = -1.74;
53 // 2nd order effect Taylor expansion
54 const Double_t kdvdE2nd = -0.00107628;
55 const Double_t kdvdT2nd = -0.00134441;
56 const Double_t kdvdP2nd = 0.000135325;
57 const Double_t kdvdCco22nd = 0.328761;
58 const Double_t kdvdCn22nd = 0.151605;
60 const Double_t torrTokPascal = 0.750061683;
62 Double_t krho = 0.934246; // density of TPC-Gas [kg/m^3]
63 // method of calculation: weighted average
67 // Nominal value obtained from 2008 data
69 const Double_t kKelvin =273.15; // degree to Kelvin
70 const Double_t kNominalTemp =19.03; // mean between A and C side in degree
71 const Double_t kNominalPress =973.9; // pressure sensor - in mbar-
72 // calibDB->GetPressure(tstamp,irun,1)
76 using namespace paramDefinitions;
78 AliTPCCalibVdrift::AliTPCCalibVdrift():
84 fNominalTemp(0), // nominal temperature in Kelvin
85 fNominalPress(0) // nominal pressure in mbar
87 /// default constructor
91 AliTPCCalibVdrift::AliTPCCalibVdrift(AliTPCSensorTempArray *SensTemp, AliDCSSensor *SensPres, TObject *SensGasComp):
97 fNominalTemp(0), // nominal temperature in Kelvin
98 fNominalPress(0) // nominal pressure in mbar
100 /// Standard constructor
102 fSensTemp = SensTemp;
103 fSensPres = SensPres;
105 fTempMap = new AliTPCTempMap(fSensTemp);
109 fSensGasComp = SensGasComp;
110 fNominalTemp = kNominalTemp;
111 fNominalPress= kNominalPress;
114 //_____________________________________________________________________________
115 AliTPCCalibVdrift::AliTPCCalibVdrift(const AliTPCCalibVdrift& source) :
117 fSensTemp(source.fSensTemp),
118 fSensPres(source.fSensPres),
119 fTempMap(source.fTempMap),
120 fSensGasComp(source.fSensGasComp),
121 fNominalTemp(source.fNominalTemp), // nominal temperature in Kelvin
122 fNominalPress(source.fNominalPress) // nominal pressure in mbar
129 //_____________________________________________________________________________
130 AliTPCCalibVdrift& AliTPCCalibVdrift::operator=(const AliTPCCalibVdrift& source){
131 /// assignment operator
133 if (&source == this) return *this;
134 new (this) AliTPCCalibVdrift(source);
139 //_____________________________________________________________________________
140 AliTPCCalibVdrift::~AliTPCCalibVdrift()
142 /// AliTPCCalibVdrift destructor
146 //_____________________________________________________________________________
147 Double_t AliTPCCalibVdrift::GetPTRelative(UInt_t absTimeSec, Int_t side){
148 /// Get Relative difference of p/T for given time stamp
149 /// absTimeSec - absolute time in secounds
150 /// side: 0 - A side | 1 - C side
152 TTimeStamp tstamp(absTimeSec);
154 if (!fSensPres||!fSensTemp) return 0;
155 Double_t pressure = fSensPres->GetValue(tstamp);
156 TLinearFitter * fitter = fTempMap->GetLinearFitter(3,side,tstamp);
157 if (!fitter) return 0;
159 fitter->GetParameters(vec);
161 if (vec[0]<10) return 0;
165 Double_t temperature = vec[0]; //vec[0] temeperature
166 Double_t tpnom = (fNominalTemp+kKelvin)/(fNominalPress);
167 Double_t tpmeasured = (temperature+kKelvin)/(pressure);
168 Double_t result = (tpmeasured-tpnom)/tpnom;
175 //_____________________________________________________________________________
176 Double_t AliTPCCalibVdrift::VdriftLinearHyperplaneApprox(Double_t dE, Double_t dT, Double_t dP, Double_t dCco2, Double_t dCn2)
178 /// Returns approximated value for the driftvelocity change (in percent)
179 /// based on a Hyperplane approximation (~ Taylorapproximation of 2nd order)
181 Double_t termE = dE*kdvdE + TMath::Power(dE,2)*kdvdE2nd;
182 Double_t termT = dT*kdvdT + TMath::Power(dT,2)*kdvdT2nd;
183 Double_t termP = dP*kdvdP + TMath::Power(dP,2)*kdvdP2nd;
184 Double_t termCo2 = dCco2*kdvdCco2 + TMath::Power(dCco2,2)*kdvdCco22nd;
185 Double_t termN2 = dCn2*kdvdCn2 + TMath::Power(dCn2,2)*kdvdCn22nd;
187 Double_t vdChange = termE+termT+termP+termCo2+termN2;
193 //_____________________________________________________________________________
195 Double_t AliTPCCalibVdrift::GetVdriftNominal()
197 /// returns nominal Driftvelocity at StandardConditions
202 //_____________________________________________________________________________
204 Double_t AliTPCCalibVdrift::GetVdriftChange(Double_t x, Double_t y, Double_t z, UInt_t absTimeSec)
206 /// Calculates Vdrift change in percent of Vdrift_nominal
207 /// (under nominal conditions) at x,y,z at absolute time (in sec)
209 TTimeStamp tstamp(absTimeSec);
211 // Get E-field Value --------------------------
212 Double_t dE = 0.23; // StandardOffset if CE is set to 100kV
214 // Get Temperature Value ----------------------
215 AliTPCTempMap *tempMap = fTempMap;
218 Double_t tempValue = tempMap->GetTemperature(x, y, z, tstamp);
219 dT = tempValue + 273.15 - kstdT;
222 // Get Main Pressure Value ---------------------
225 // Just the pressure drop over the TPC height
226 dP = - krho*kg*y/10000*torrTokPascal;
228 // pressure sensors plus additional 0.4mbar overpressure within the TPC
229 Double_t pressure = fSensPres->GetValue(tstamp) + 0.4;
230 // calculate pressure drop according to height in TPC and transform to
231 // TORR (with simplified hydrostatic formula)
232 dP = (pressure - krho*kg*y/10000) * torrTokPascal - kstdP;
235 // Get GasComposition
236 // FIXME: include Goofy values for CO2 and N2 conzentration out of OCDB
237 // Goofy not yet reliable ...
241 // Calculate change in drift velocity in terms of Vdrift_nominal
242 Double_t vdChange = VdriftLinearHyperplaneApprox(dE, dT, dP, dCco2, dCn2);
248 //_____________________________________________________________________________
250 Double_t AliTPCCalibVdrift::GetMeanZVdriftChange(Double_t x, Double_t y, UInt_t absTimeSec)
252 /// Calculates Meanvalue in z direction of Vdrift change in percent
253 /// of Vdrift_nominal (under standard conditions) at position x,y,absTimeSec
254 /// with help of 'nPopints' base points
258 Double_t vdriftSum = 0;
260 for (Int_t i = 0; i<nPoints; i++) {
261 Double_t z = (Double_t)i/(nPoints-1)*500-250;
262 vdriftSum = vdriftSum + GetVdriftChange(x, y, z, absTimeSec);
265 Double_t meanZVdrift = vdriftSum/nPoints;
271 //_____________________________________________________________________________
273 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
278 UInt_t startTime = fSensTemp->GetStartTime();
279 UInt_t endTime = fSensTemp->GetEndTime();
281 UInt_t stepTime = (endTime - startTime)/nPoints;
284 Double_t *xvec = new Double_t[nPoints];
285 Double_t *yvec = new Double_t[nPoints];
287 for (Int_t ip=0; ip<nPoints; ip++) {
288 xvec[ip] = startTime+ip*stepTime;
289 yvec[ip] = GetMeanZVdriftChange(x, y, fSensTemp->GetStartTime().GetSec() + ip*stepTime);
292 TGraph *graph = new TGraph(nPoints,xvec,yvec);
297 graph->GetXaxis()->SetTimeDisplay(1);
298 graph->GetXaxis()->SetLabelOffset(0.02);
299 graph->GetXaxis()->SetTimeFormat("#splitline{%d/%m}{%H:%M}");