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70ae41ca 1
35d4a90a 2/////////////////////////////////////////////////////////////////////////////
3// //
4// This is a macro which measures the time delay of L1 trigger in TPC //
5// //
6// It reads the ESD tracks and fills histograms with the distance //
7// between the primary vertex and the Z position //
8// of the point of closest approach between the track and the beam axis. //
9// The processing of forward and backward tracks is done separately. //
10// The corresponding histograms are fitted with gaussian and the //
11// shifts of the Z positions are extracted. //
12// The L1 time delay is taken as an average of the forward and backward //
13// (with opposite sign) shifts divided by the drift velocity. //
14// We assume that the ESD tracks are obtained by the TPC tracking stand //
15// alone. //
16// The propagation to the vertex can be done either with or without //
17// TGeoManager. //
18// //
19// Cvetan.Cheshkov@cern.ch //
20// //
21/////////////////////////////////////////////////////////////////////////////
22
23#if !defined(__CINT__) || defined(__MAKECINT__)
24 #include <TMath.h>
25 #include <TError.h>
26 #include <Riostream.h>
27 #include <TH1F.h>
28 #include <TF1.h>
29 #include <TTree.h>
30 #include <TCanvas.h>
31 #include <TFile.h>
32 #include <TStyle.h>
33 #include <TGeoManager.h>
34 #include "AliRunLoader.h"
35 #include "AliRun.h"
36 #include "AliESD.h"
37 #include "AliTracker.h"
38 #include "AliTPCParam.h"
f7a1cc68 39 #include "AliMagF.h"
35d4a90a 40 #include "AliITStrackV2.h"
41#endif
42
43Int_t CorrectForDeadZoneMaterial(AliITStrackV2 *t);
44Bool_t PropagateToVertex(AliESDtrack *track, Float_t *vtxXYZ);
45Bool_t PropagateToVertexG(AliESDtrack *track, Float_t *vtxXYZ);
46
47void AliL1Delay(const Char_t *esdfilename = "./AliESDs.root", const Char_t *galicefilename = "./galice.root", Bool_t withTGeo = kFALSE, const Char_t *geomfilename = "./geometry.root")
48{
49 const Int_t kMinNClusters = 0;
50 const Double_t kPtMin = 0.5;
51 const Double_t kMaxImpact = 0.3;
52 const Double_t kDeltaZRes = 0.3;
53 const Double_t kZRange = 20.;
54
55 // Book histograms
56 Int_t NBins = (Int_t)(2.*kZRange/(0.5*kDeltaZRes));
57 TH1F *hDeltaZForward = new TH1F("hDeltaZForward","Longitudinal distance to the vertex (forward tracks)",NBins,-kZRange,kZRange);
58 TH1F *hDeltaZBackward = new TH1F("hDeltaZBackward","Longitudinal distance to the vertex (backward tracks)",NBins,-kZRange,kZRange);
59 TH1F *hTrImpact = new TH1F("hTrImpact","Transverse impact parameter (all tracks)",100,0,30.*kMaxImpact);
60
61 // Open RunLoader
62 AliRunLoader *rl = AliRunLoader::Open(galicefilename);
63 if (!rl) {
64 ::Error("AliL1Delay.C","Can't start session !");
65 return;
66 }
67 rl->LoadgAlice();
68 gAlice = rl->GetAliRun();
69
70 // Set magnetic field
f7a1cc68 71 AliMagF* field = TGeoGlobalMagField::Instance()->GetField();
35d4a90a 72 AliExternalTrackParam::SetNonuniformFieldTracking();
73 const Float_t sfield = field->SolenoidField();
74
75 // GetGeo manager
76 if(withTGeo)
77 {
78 TFile *geoFile = TFile::Open(geomfilename);
79 if (!geoFile || !geoFile->IsOpen()) {
80 ::Error("AliL1Delay.C","Can't open %s !",geomfilename);
81 return;
82 }
83 gGeoManager = (TGeoManager *)geoFile->Get("Geo");
84 if(!gGeoManager) {
85 ::Error("AliL1Delay.C","Can't find TGeoManager !");
86 return;
87 }
88 }
89
90 // Get X positions of the pad-rows
91 TDirectory* saveDir = gDirectory;
92 rl->CdGAFile();
93 AliTPCParam* param = (AliTPCParam*) gDirectory->Get("75x40_100x60_150x60");
94 if (!param) {
95 ::Error("AliL1Delay.C","No TPC parameters found !");
96 return;
97 }
98 Int_t nRowLow = param->GetNRowLow();
99 Int_t nRowUp = param->GetNRowUp();
100 Float_t xRow[159];
101 for (Int_t i=0;i<nRowLow;i++){
102 xRow[i] = param->GetPadRowRadiiLow(i);
103 }
104 for (Int_t i=0;i<nRowUp;i++){
105 xRow[i+nRowLow] = param->GetPadRowRadiiUp(i);
106 }
107 saveDir->cd();
108
109 // Open file with ESDs
110 TFile *esdFile = TFile::Open(esdfilename);
111 if (!esdFile || !esdFile->IsOpen()) {
112 ::Error("AliL1Delay.C","Can't open %s !",esdfilename);
113 return;
114 }
115 AliESD* event = new AliESD;
116 TTree* esdTree = (TTree*) esdFile->Get("esdTree");
117 if (!esdTree) {
118 ::Error("AliL1Delay.C","No ESD tree found !");
119 return;
120 }
121 esdTree->SetBranchAddress("ESD", &event);
122
123 // Init PID
124 AliPID pid;
125
126 Int_t nEvent = esdTree->GetEntries();
127
128 // Loop over events
129 for(Int_t iEvent = 0; iEvent<nEvent; iEvent++)
130 {
131 esdTree->GetEvent(iEvent);
132 const AliESDVertex *esdVtx = event->GetVertex();
133 Double_t zVtx = esdVtx->GetZv();
134 if(zVtx == 0.) continue; // Vertex is not found. Skip the event.
135 Int_t nTrk=event->GetNumberOfTracks();
136
137 ::Info("AliL1Delay.C","Event %d : Z vertex = %f | Number of tracks = %d",iEvent,zVtx,nTrk);
138
139 for(Int_t iTrk=0; iTrk<nTrk; iTrk++)
140 {
141 AliESDtrack *track = event->GetTrack(iTrk);
142 if(!track) continue;
143
144 // Track selection
145 if((track->GetStatus()&AliESDtrack::kTPCrefit)==0) continue;
146 if(track->GetTPCclusters((Int_t)0x0)<(kMinNClusters*3)) continue;
147 if(track->GetP()<kPtMin) continue;
148
149 Int_t firstRow = (Int_t)(track->GetTPCPoints(0)+0.5);
150 Int_t lastRow = (Int_t)(track->GetTPCPoints(2)+0.5);
151 Double_t firstXYZ[3];
152 Double_t lastXYZ[3];
153 track->GetXYZAt(xRow[firstRow], sfield, firstXYZ);
154 track->GetXYZAt(xRow[lastRow], sfield, lastXYZ);
155
156 // Select if the track is forward or backward one
157 Bool_t IsForward;
158 if(firstXYZ[2] > 0 && lastXYZ[2] > 0)
159 IsForward = kTRUE;
160 else if(firstXYZ[2] < 0 && lastXYZ[2] < 0)
161 IsForward = kFALSE;
162 else
163 continue;
164
165 // Propagate the track to the vertex
166 Float_t vtxXYZ[3];
167 if(withTGeo) {
168 if(PropagateToVertexG(track,vtxXYZ) == 0) continue;
169 }
170 else {
171 if(PropagateToVertex(track,vtxXYZ) == 0) continue;
172 }
173
174 // Get the position at point of closest approach to the vertex
175 Float_t impact = TMath::Sqrt(vtxXYZ[0]*vtxXYZ[0]+vtxXYZ[1]*vtxXYZ[1]);
176 hTrImpact->Fill(impact);
177 // Select primary tracks
178 if(impact > kMaxImpact) continue;
179
180 if (IsForward)
181 hDeltaZForward->Fill(vtxXYZ[2]-zVtx);
182 else
183 hDeltaZBackward->Fill(vtxXYZ[2]-zVtx);
184 }
185 }
186
187 // delete event;
188 // esdFile->Close();
189
190 // Check track propagation
191 TF1 *fexpo = new TF1("fexpo","expo");
192 hTrImpact->Fit("fexpo","E");
193 Double_t slope = fexpo->GetParameter(1);
194 if(slope > 3.*kMaxImpact)
195 ::Warning("AliL1Delay.C","The transverse impact parameter distribution is too broad: %f +- %f",slope,fexpo->GetParError(1));
196 delete fexpo;
197
198 // Fit histograms and extract L1 time delay
199 Double_t shifts[2],shifterrs2[2];
200 {
201 Double_t params[3];
202 params[0] = hDeltaZForward->GetMaximumBin();
203 params[1] = hDeltaZForward->GetBinCenter(hDeltaZForward->GetMaximumBin());
204 params[2] = kDeltaZRes;
205 TF1 *fgaus = new TF1("fgaus","gaus");
206 fgaus->SetParameters(params);
207 hDeltaZForward->Fit("fgaus","E");
208 shifts[0] = fgaus->GetParameter(1);
209 shifterrs2[0] = fgaus->GetParError(1)*fgaus->GetParError(1);
210 delete fgaus;
211 }
212 {
213 Double_t params[3];
214 params[0] = hDeltaZBackward->GetMaximumBin();
215 params[1] = hDeltaZBackward->GetBinCenter(hDeltaZBackward->GetMaximumBin());
216 params[2] = kDeltaZRes;
217 TF1 *fgaus = new TF1("fgaus","gaus");
218 fgaus->SetParameters(params);
219 hDeltaZBackward->Fit("fgaus","E");
220 shifts[1] = -fgaus->GetParameter(1);
221 shifterrs2[1] = fgaus->GetParError(1)*fgaus->GetParError(1);
222 delete fgaus;
223 }
224
225 // Check the consistency of the two time delays
226 if(TMath::Abs(shifts[0]-shifts[1])>3.*TMath::Sqrt(shifterrs2[0]+shifterrs2[1]))
227 ::Warning("AliL1Delay.C","The extracted delays are more than 3 sigma away from each other: %f %f",shifts[0],shifts[1]);
228
229 // Calculated the overall time delay
230 Double_t shifterr = 1./TMath::Sqrt(1./shifterrs2[0]+1./shifterrs2[1]);
231 Double_t shift = (shifts[0]/shifterrs2[0]+shifts[1]/shifterrs2[1])*shifterr*shifterr;
232
233 ::Info("AliL1Delay.C","");
234 ::Info("AliL1Delay.C","=====================================================");
235 ::Info("AliL1Delay.C","The measured L1 delay is (%f +- %f) cm",shift,shifterr);
236 ::Info("AliL1Delay.C","The measured L1 delay is (%f +- %f) ns",shift*1.e9/param->GetDriftV(),shifterr*1.e9/param->GetDriftV());
237 ::Info("AliL1Delay.C","=====================================================");
238
239 delete event;
240 esdFile->Close();
241
242 gStyle->SetOptFit(1);
243
244 TCanvas *c1 = new TCanvas("c1","",0,0,700,850);
245
246 TPad *p1 = new TPad("p1","",0,0,1,0.5); p1->Draw();
247 p1->cd(); p1->SetFillColor(42); p1->SetFrameFillColor(10);
248 p1->SetLogy(1);
249 hTrImpact->SetFillColor(4); hTrImpact->SetXTitle("(cm)");
250 hTrImpact->SetStats(kTRUE); hTrImpact->Draw(); c1->cd();
251
252 TPad *p2 = new TPad("p2","",0,0.5,0.5,1); p2->Draw();
253 p2->cd(); p2->SetFillColor(42); p2->SetFrameFillColor(10);
254 hDeltaZForward->SetFillColor(4); hDeltaZForward->SetXTitle("(cm)");
255 hDeltaZForward->SetStats(kTRUE); hDeltaZForward->Draw(); c1->cd();
256
257 TPad *p3 = new TPad("p3","",0.5,0.5,1,1); p3->Draw();
258 p3->cd(); p3->SetFillColor(42); p3->SetFrameFillColor(10);
259 hDeltaZBackward->SetFillColor(4); hDeltaZBackward->SetXTitle("(cm)");
260 hDeltaZBackward->SetStats(kTRUE); hDeltaZBackward->Draw(); c1->cd();
261
262 TFile f("AliL1Delay.root","RECREATE");
263 c1->Write();
264 f.Close();
265
266 delete rl;
267}
268
269Int_t CorrectForDeadZoneMaterial(AliITStrackV2 *t) {
270 //--------------------------------------------------------------------
271 // Correction for the material between the TPC and the ITS
272 // (should it belong to the TPC code ?)
273 //--------------------------------------------------------------------
274 Double_t riw=80., diw=0.0053, x0iw=30; // TPC inner wall ?
275 Double_t rcd=61., dcd=0.0053, x0cd=30; // TPC "central drum" ?
276 Double_t yr=12.8, dr=0.03; // rods ?
277 Double_t zm=0.2, dm=0.40; // membrane
278 //Double_t rr=52., dr=0.19, x0r=24., yyr=7.77; //rails
279 Double_t rs=50., ds=0.001; // something belonging to the ITS (screen ?)
280
281 if (t->GetX() > riw) {
282 if (!t->PropagateTo(riw,diw,x0iw)) return 1;
283 if (TMath::Abs(t->GetY())>yr) t->CorrectForMaterial(dr);
284 if (TMath::Abs(t->GetZ())<zm) t->CorrectForMaterial(dm);
285 if (!t->PropagateTo(rcd,dcd,x0cd)) return 1;
286 //Double_t x,y,z; t->GetGlobalXYZat(rr,x,y,z);
287 //if (TMath::Abs(y)<yyr) t->PropagateTo(rr,dr,x0r);
288 if (!t->PropagateTo(rs,ds)) return 1;
289 } else if (t->GetX() < rs) {
290 if (!t->PropagateTo(rs,-ds)) return 1;
291 //Double_t x,y,z; t->GetGlobalXYZat(rr,x,y,z);
292 //if (TMath::Abs(y)<yyr) t->PropagateTo(rr,-dr,x0r);
293 if (!t->PropagateTo(rcd,-dcd,x0cd)) return 1;
294 if (!t->PropagateTo(riw+0.001,-diw,x0iw)) return 1;
295 } else {
296 ::Error("CorrectForDeadZoneMaterial","track is already in the dead zone !");
297 return 1;
298 }
299
300 return 0;
301}
302
303Bool_t PropagateToVertex(AliESDtrack *track, Float_t *vtxXYZ)
304{
305 // Make an ITS track and propagate it to the vertex
306 AliITStrackV2 itstrack(*track);
307 if (CorrectForDeadZoneMaterial(&itstrack) != 0) return 0;
308 if (!itstrack.PropagateTo(3.,0.0028,65.19)) return 0;
309 if (!itstrack.PropagateToVertex()) return 0;
310
311 itstrack.GetXYZ(vtxXYZ);
312
313 return 1;
314}
315
316Bool_t PropagateToVertexG(AliESDtrack *track, Float_t *vtxXYZ)
317{
318 // Make an ITS track and propagate it to the vertex using TGeoManager
319 AliITStrackV2 itstrack(*track);
320 AliExternalTrackParam etrack(itstrack);
321 Double_t r = 3.;
322 Double_t xyz0[3],xyz1[3],y,z;
323 Double_t param[7];
324 Double_t step = 2.;
325 for (Double_t x = etrack.X()-step; x > r; x -= step) {
326 etrack.GetGlobalXYZ(xyz0[0],xyz0[1],xyz0[2]);
327 Double_t alpha = TMath::ATan2(xyz0[1],xyz0[0]);
328 etrack.RotateTo(alpha);
329 etrack.GetGlobalXYZ(xyz0[0],xyz0[1],xyz0[2]);
330 if (!etrack.GetProlongationAt(x,y,z)) return 0;
331 xyz1[0] = x*TMath::Cos(alpha)-y*TMath::Sin(alpha);
332 xyz1[1] = x*TMath::Sin(alpha)+y*TMath::Cos(alpha);
333 xyz1[2] = z;
70ae41ca 334 AliTracker::MeanMaterialBudget(xyz0,xyz1,param);
35d4a90a 335 if (!etrack.PropagateTo(x,param[1],param[0])) return 0;
336 }
337 etrack.PropagateTo(r,1,0);
338 if (!etrack.PropagateToDCA(0,0,param[1],0)) return 0;
339
340 etrack.GetXYZ(vtxXYZ);
341
342 return 1;
343}