TPC/AliTPCtrackerParam.cxx

   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  * This class builds AliTPCtrack objects from generated tracks to feed    *
  18  * ITS tracking (V2). The AliTPCtrack is built from its first hit in      *
  19  * the TPC. The track is assigned a Kalman-like covariance matrix         *
  20  * depending on its pT and pseudorapidity and track parameters are        *
  21  * smeared according to this covariance matrix.                           *
  22  * Output file contains sorted tracks, ready for matching with ITS        *
  23  *                                                                        *
  24  * Test macro is: AliBarrelRec_TPCparam.C                                 *
  25  *                                                                        *
  26  *  Origin: Andrea Dainese, Padova - e-mail: andrea.dainese@pd.infn.it    *
  27  *                                                                        *
  28  **************************************************************************/
  29 #include "AliTPCtrackerParam.h"
  30 #include "alles.h"
  31 #include "AliMagF.h"
  32 #include "AliTPCtrack.h"
  33 #include "TMatrixD.h"
  34 #include "AliKalmanTrack.h"
  35 #include "AliMagFCM.h"
  36 #include "AliGausCorr.h"
  37
  38
  39
  40
  41 ClassImp(AliTPCtrackerParam)
  42
  43 //-----------------------------------------------------------------
  44 AliTPCtrackerParam::AliTPCtrackerParam(const Int_t coll,const Double_t Bz)
  45 {
  46   fColl = coll; // collision code (0: PbPb6000)
  47   fBz = Bz;     // value of the z component of L3 field (Tesla)
  48
  49 }
  50 //-----------------------------------------------------------------
  51 AliTPCtrackerParam::~AliTPCtrackerParam()
  52 {}
  53 //-----------------------------------------------------------------
  54
  55 Int_t AliTPCtrackerParam::BuildTPCtracks(const TFile *inp, TFile *out, Int_t n)
  56 {
  57
  58   if(fColl!=0) {
  59     cerr<<"AliTPCtrackerParam::BuildTPCtracks:  Invalid collision!\n";
  60     cerr<<"      Available:  0   ->   PbPb6000"<<endl; return 0;
  61   }
  62   if(fBz!=0.4) {
  63     cerr<<"AliTPCtrackerParam::BuildTPCtracks:  Invalid field!\n";
  64     cerr<<"      Available:  0.4"<<endl; return 0;
  65   }
  66
  67   TFile *infile=(TFile*)inp;
  68
  69   // Get gAlice object from file
  70   if(!(gAlice=(AliRun*)infile->Get("gAlice"))) {
  71     cerr<<"gAlice has not been found on galice.root !\n";
  72     return 1;
  73   }
  74
  75   AliMagFCM *fiel = (AliMagFCM*)gAlice->Field();
  76   Double_t fieval=(Double_t)fiel->SolenoidField()/10.;
  77   printf("Magnetic field is %6.2f Tesla\n",fieval);
  78   if(fBz!=fieval) {
  79     cerr<<"AliTPCtrackerParam::BuildTPCtracks:  Invalid field!"<<endl;
  80     cerr<<"Field selected is: "<<fBz<<" T\n";
  81     cerr<<"Field found on file is: "<<fieval<<" T\n";
  82     return 0;
  83   }
  84
  85   AliKalmanTrack::SetConvConst(100/0.299792458/fBz);
  86
  87
  88   // loop over first n events in file
  89   for(Int_t evt=0; evt<n; evt++){
  90     cerr<<"+++\n+++ Processing event "<<evt<<"\n+++\n";
  91
  92     AliTPCtrack *tpctrack=0;
  93
  94     // tree for TPC tracks
  95     Char_t tname[100];
  96     sprintf(tname,"TreeT_TPC_%d",evt);
  97     TTree *tracktree = new TTree(tname,"Tree with TPC tracks");
  98     tracktree->Branch("tracks","AliTPCtrack",&tpctrack,20000,0);
  99
 100     // array for TPC tracks
 101     TObjArray tarray(20000);
 102
 103
 104     Int_t nparticles=gAlice->GetEvent(evt);
 105
 106     Bool_t done[500000];
 107     for(Int_t l=0; l<500000; l++) { done[l]=kFALSE; }
 108
 109
 110     // Get TPC detector
 111     AliTPC *TPC=(AliTPC*)gAlice->GetDetector("TPC");
 112     Int_t ver = TPC->IsVersion();
 113     cerr<<"+++ TPC version "<<ver<<" has been found !\n";
 114     AliTPCParam *digp=(AliTPCParam*)infile->Get("75x40_100x60");
 115     if(!digp) { cerr<<"TPC parameters have not been found !\n"; return 1; }
 116     TPC->SetParam(digp);
 117
 118     // Get TreeH with hits
 119     TTree *TH=gAlice->TreeH();
 120     Int_t ntracks=(Int_t)TH->GetEntries();
 121     cerr<<"+++\n+++ Number of particles in event "<<evt<<":  "<<nparticles<<"\n+++\n+++ Number of \"primary tracks\" (entries in TreeH): "<<ntracks<<"\n+++\n\n";
 122
 123     TParticle* Part;
 124     AliTPChit* tpcHit;
 125     Double_t hPx,hPy,hPz,hPt,xg,yg,zg,xl,yl,zl;
 126     Double_t Alpha;
 127     Float_t cosAlpha,sinAlpha;
 128     Int_t label,Pdg,charge,bin;
 129     Int_t tracks=0;
 130     //Int_t N1=0,N2=0;
 131
 132     // loop over entries in TreeH
 133     for(Int_t i=0; i<ntracks; i++) {
 134       if(i%1000==0) cerr<<"  --- Processing primary track "<<i<<" of "<<ntracks<<" ---\r";
 135       TPC->ResetHits();
 136       TH->GetEvent(i);
 137       // Get FirstHit
 138       tpcHit=(AliTPChit*)TPC->FirstHit(-1);
 139       for( ; tpcHit; tpcHit=(AliTPChit*)TPC->NextHit() ) {
 140         if(tpcHit->fQ !=0.) continue;
 141         // Get particle momentum at hit
 142         hPx=tpcHit->X(); hPy=tpcHit->Y(); hPz=tpcHit->Z();
 143         hPt=TMath::Sqrt(hPx*hPx+hPy*hPy);
 144         // reject hits with Pt<mag*0.45 GeV/c
 145         if(hPt<(fBz*0.45)) continue;
 146
 147         // Get track label
 148         label=tpcHit->Track();
 149         // check if this track has already been processed
 150         if(done[label]) continue;
 151         // electric charge
 152         Part = gAlice->Particle(label);
 153         Pdg = Part->GetPdgCode();
 154         if(Pdg>200 || Pdg==-11 || Pdg==-13) { charge=1; }
 155         else if(Pdg<-200 || Pdg==11 || Pdg==13) { charge=-1; }
 156         else continue;
 157
 158
 159         if((tpcHit=(AliTPChit*)TPC->NextHit())==0) break;
 160         if(tpcHit->fQ != 0.) continue;
 161         // Get global coordinates of hit
 162         xg=tpcHit->X(); yg=tpcHit->Y(); zg=tpcHit->Z();
 163         if(TMath::Sqrt(xg*xg+yg*yg)>90.) continue;
 164
 165         // Get TPC sector, Alpha angle and local coordinates
 166         // printf("Sector %d\n",tpcHit->fSector);
 167         digp->AdjustCosSin(tpcHit->fSector,cosAlpha,sinAlpha);
 168         Alpha = TMath::ATan2(sinAlpha,cosAlpha);
 169         xl = xg*cosAlpha + yg*sinAlpha;
 170         yl =-xg*sinAlpha + yg*cosAlpha;
 171         zl = zg;
 172         //printf("Alpha %f   xl %f  yl %f  zl %f\n",Alpha,xl,yl,zl);
 173
 174         // reject tracks which are not in the TPC acceptance
 175         if(TMath::Abs(zl+(244.-xl)*hPz/hPt)>252.) continue;
 176
 177         // Get bin in pT,eta
 178         bin = GetBin(hPt,Part->Eta());
 179
 180         // Apply selection according to TPC efficiency
 181         //if(abs(Pdg)==211) N1++;
 182         if(!SelectedTrack(Pdg,hPt,Part->Eta())) continue;
 183         //if(abs(Pdg)==211) N2++;
 184
 185         // Mark track as "done"
 186         done[label]=kTRUE; tracks++;
 187
 188         // create AliTPCtrack object
 189         tpctrack = BuildTrack(Alpha,xl,yl,zl,hPx,hPy,hPz,hPt,charge,label);
 190
 191         // put track in array
 192         tarray.AddLast(tpctrack);
 193
 194       }
 195
 196     } // loop over entries in TreeH
 197
 198     TObjArray newtarray(20000);
 199
 200     // assing covariance matrixes and smear track parameters
 201     CookTracks(tarray,newtarray);
 202
 203     // sort array with TPC tracks (decreasing pT)
 204     newtarray.Sort();
 205
 206
 207     Int_t arrentr = newtarray.GetEntriesFast();
 208     //printf("\n  %d  \n\n",arrentr);
 209     for(Int_t l=0; l<arrentr; l++) {
 210       tpctrack=(AliTPCtrack*)newtarray.UncheckedAt(l);
 211       tracktree->Fill();
 212     }
 213
 214     // write the tree with tracks in the output file
 215     out->cd();
 216     tracktree->Write();
 217
 218     delete tracktree;
 219
 220     printf("\n\n+++\n+++ Number of TPC tracks: %d\n+++\n",tracks);
 221     //printf("Average Eff: %f\n",(Float_t)N2/N1);
 222
 223   } // loop on events
 224
 225   return 0;
 226 }
 227
 228 //-----------------------------------------------------------------
 229 AliTPCtrack* AliTPCtrackerParam::BuildTrack(Double_t alpha,Double_t x,
 230                                             Double_t y,Double_t z,Double_t Px,
 231                                             Double_t Py,Double_t Pz,Double_t Pt,
 232                                             Int_t ch,Int_t lab)
 233 {
 234   Double_t xref = x;
 235   Double_t xx[5],cc[15];
 236   cc[0]=cc[2]=cc[5]=cc[9]=cc[14]=10.;
 237   cc[1]=cc[3]=cc[4]=cc[6]=cc[7]=cc[8]=cc[10]=cc[11]=cc[12]=cc[13]=0.;
 238
 239   // Magnetic field
 240   TVector3 Bfield(0.,0.,fBz);
 241
 242
 243   // radius [cm] of track projection in (x,y)
 244   Double_t rho = Pt*100/0.299792458/Bfield.Z();
 245   // center of track projection in local reference frame
 246   TVector3 MomH,PosH;
 247
 248
 249   // position (local) and momentum (local) at the hit
 250   // in the bending plane (z=0)
 251   PosH.SetXYZ(x,y,0.);
 252   MomH.SetXYZ(Px*TMath::Cos(alpha)+Py*TMath::Sin(alpha),-Px*TMath::Sin(alpha)+Py*TMath::Cos(alpha),0.);
 253   TVector3 Vrho = MomH.Cross(Bfield);
 254   Vrho *= ch;
 255   Vrho.SetMag(rho);
 256
 257   TVector3 Vcenter = PosH+Vrho;
 258
 259   Double_t x0 = Vcenter.X();
 260
 261   // fX     = xref         X-coordinate of this track (reference plane)
 262   // fAlpha = Alpha        Rotation angle the local (TPC sector)
 263   // fP0    = YL           Y-coordinate of a track
 264   // fP1    = ZG           Z-coordinate of a track
 265   // fP2    = C*x0         x0 is center x in rotated frame
 266   // fP3    = Tgl          tangent of the track momentum dip angle
 267   // fP4    = C            track curvature
 268   xx[0] = y;
 269   xx[1] = z;
 270   xx[3] = Pz/Pt;
 271   xx[4] = -ch/rho;
 272   xx[2] = xx[4]*x0;
 273
 274   // create the object AliTPCtrack
 275   AliTPCtrack* track = new AliTPCtrack(0,xx,cc,xref,alpha);
 276   // set the label
 277   track->SetLabel(lab);
 278
 279   return track;
 280 }
 281
 282 //-----------------------------------------------------------------
 283 Bool_t AliTPCtrackerParam::SelectedTrack(Int_t pdg,Double_t pt,Double_t eta)
 284 {
 285   Double_t eff=0.;
 286
 287   //eff computed with | zl+(244-xl)*pz/pt | < 252
 288   Double_t effPi[27] = {0.724587,0.743389,0.619273,0.798477,0.812036,0.823195,0.771437,0.775826,0.784136,0.809071,0.762001,0.774576,0.848834,0.787201,0.792548,0.942089,0.951631,0.951085,0.960885,0.971451,0.969103,0.983245,0.978939,0.988706,0.990852,0.985679,0.993606};
 289   Double_t effK[18]  = {0.377934,0.363962,0.321721,0.518784,0.547459,0.517878,0.612704,0.619101,0.620894,0.733411,0.732128,0.750373,0.790630,0.806565,0.791353,0.967486,0.970483,0.974527};
 290   Double_t effP[15]  = {0.131173,0.165114,0.229658,0.365357,0.412989,0.483297,0.454614,0.505173,0.658615,0.694753,0.730661,0.815680,0.873461,0.887227,0.899324};
 291   Double_t effEl[15] = {0.835549,0.853746,0.718207,0.835230,0.831489,0.862222,0.757783,0.747301,0.824096,0.867949,0.871891,0.808480,0.890625,0.911765,0.973684};
 292   Double_t effMu[15] = {0.553486,0.641392,0.609932,0.591126,0.706729,0.750755,0.747952,0.729051,0.760849,0.898810,0.737500,0.830357,0.735294,0.800000,0.882353};
 293
 294
 295   if(TMath::Abs(pdg)==211)  eff = LinearInterpolation(9,effPi,pt,eta);
 296   if(TMath::Abs(pdg)==321)  eff = LinearInterpolation(6,effK,pt,eta);
 297   if(TMath::Abs(pdg)==2212) eff = LinearInterpolation(5,effP,pt,eta);
 298   if(TMath::Abs(pdg)==11)   eff = LinearInterpolation(5,effEl,pt,eta);
 299   if(TMath::Abs(pdg)==13)   eff = LinearInterpolation(5,effMu,pt,eta);
 300
 301   if(gRandom->Rndm() < eff) return kTRUE;
 302
 303   return kFALSE;
 304 }
 305
 306 //-----------------------------------------------------------------
 307 Double_t AliTPCtrackerParam::LinearInterpolation(Int_t ptBins,Double_t *value,
 308                                                  Double_t pt,Double_t eta)
 309 {
 310   Double_t kValue=0,kValue1=0,kValue2=0;
 311   Int_t kEtaSide = (TMath::Abs(eta)<.45 ? 0 : 1);
 312   Double_t kEta[3]={0.15,0.45,0.75};
 313   Double_t kPt[9]={0.244,0.390,0.676,1.190,2.36,4.,6.,10.,20.};
 314   if(ptBins==6) kPt[5]=10.;
 315
 316   for(Int_t i=0; i<ptBins; i++) {
 317     if(pt<kPt[i]) {
 318       if(i==0) i=1;
 319       kValue1 = value[3*i-3+kEtaSide]+(value[3*i-3+kEtaSide]-value[3*i+kEtaSide])/(kPt[i-1]-kPt[i])*(pt-kPt[i-1]);
 320       kValue2 = value[3*i-3+kEtaSide+1]+(value[3*i-3+kEtaSide+1]-value[3*i+kEtaSide+1])/(kPt[i-1]-kPt[i])*(pt-kPt[i-1]);
 321
 322       kValue = kValue1+(kValue1-kValue2)/(kEta[kEtaSide]-kEta[kEtaSide+1])*(eta-kEta[kEtaSide]);
 323       break;
 324     }
 325     if(i==ptBins-1) {
 326       i=ptBins-2;
 327       kValue1 = value[3*i-3+kEtaSide]+(value[3*i-3+kEtaSide]-value[3*i+kEtaSide])/(kPt[i-1]-kPt[i])*(pt-kPt[i-1]);
 328       kValue2 = value[3*i-3+kEtaSide+1]+(value[3*i-3+kEtaSide+1]-value[3*i+kEtaSide+1])/(kPt[i-1]-kPt[i])*(pt-kPt[i-1]);
 329
 330       kValue = kValue1+(kValue1-kValue2)/(kEta[kEtaSide]-kEta[kEtaSide+1])*(eta-kEta[kEtaSide]);
 331       break;
 332     }
 333   }
 334
 335   return kValue;
 336 }
 337
 338 //-----------------------------------------------------------------
 339 Int_t AliTPCtrackerParam::GetBin(Double_t pt,Double_t eta) {
 340
 341   if(TMath::Abs(eta)<0.3) {
 342     if(pt<0.3)            return 0;
 343     if(pt>=0.3 && pt<0.5) return 3;
 344     if(pt>=0.5 && pt<1.)  return 6;
 345     if(pt>=1. && pt<1.5)  return 9;
 346     if(pt>=1.5 && pt<3.)  return 12;
 347     if(pt>=3. && pt<5.)   return 15;
 348     if(pt>=5. && pt<7.)   return 18;
 349     if(pt>=7. && pt<15.)  return 21;
 350     if(pt>=15.)           return 24;
 351   }
 352   if(TMath::Abs(eta)>=0.3 && TMath::Abs(eta)<0.6) {
 353     if(pt<0.3)            return 1;
 354     if(pt>=0.3 && pt<0.5) return 4;
 355     if(pt>=0.5 && pt<1.)  return 7;
 356     if(pt>=1. && pt<1.5)  return 10;
 357     if(pt>=1.5 && pt<3.)  return 13;
 358     if(pt>=3. && pt<5.)   return 16;
 359     if(pt>=5. && pt<7.)   return 19;
 360     if(pt>=7. && pt<15.)  return 22;
 361     if(pt>=15.)           return 25;
 362   }
 363   if(TMath::Abs(eta)>=0.6) {
 364     if(pt<0.3)            return 2;
 365     if(pt>=0.3 && pt<0.5) return 5;
 366     if(pt>=0.5 && pt<1.)  return 8;
 367     if(pt>=1. && pt<1.5)  return 11;
 368     if(pt>=1.5 && pt<3.)  return 14;
 369     if(pt>=3. && pt<5.)   return 17;
 370     if(pt>=5. && pt<7.)   return 20;
 371     if(pt>=7. && pt<15.)  return 23;
 372     if(pt>=15.)           return 26;
 373   }
 374
 375   return -1;
 376
 377 }
 378
 379 //-----------------------------------------------------------------
 380
 381 TMatrixD AliTPCtrackerParam::GetSmearingMatrix(Double_t* cc,Double_t pt,Double_t eta)
 382 {
 383   TMatrixD CovMat(5,5);
 384
 385   CovMat(0,0)=cc[0];
 386   CovMat(1,0)=cc[1];  CovMat(0,1)=CovMat(1,0);
 387   CovMat(1,1)=cc[2];
 388   CovMat(2,0)=cc[3];  CovMat(0,2)=CovMat(2,0);
 389   CovMat(2,1)=cc[4];  CovMat(1,2)=CovMat(2,1);
 390   CovMat(2,2)=cc[5];
 391   CovMat(3,0)=cc[6];  CovMat(0,3)=CovMat(3,0);
 392   CovMat(3,1)=cc[7];  CovMat(1,3)=CovMat(3,1);
 393   CovMat(3,2)=cc[8];  CovMat(2,3)=CovMat(3,2);
 394   CovMat(3,3)=cc[9];
 395   CovMat(4,0)=cc[10]; CovMat(0,4)=CovMat(4,0);
 396   CovMat(4,1)=cc[11]; CovMat(1,4)=CovMat(4,1);
 397   CovMat(4,2)=cc[12]; CovMat(2,4)=CovMat(4,2);
 398   CovMat(4,3)=cc[13]; CovMat(3,4)=CovMat(4,3);
 399   CovMat(4,4)=cc[14];
 400
 401   TMatrixD ScaleMat(5,5);
 402   for(Int_t k=0;k<5;k++) {
 403     for(Int_t l=0;l<5;l++) {
 404       ScaleMat(k,l)=0.;
 405     }
 406   }
 407
 408
 409   Double_t s00[27]={1.3553,1.2973,1.2446,1.3428,1.3031,1.2345,1.3244,1.2681,1.2046,1.3046,1.2430,1.1606,1.2462,1.2104,1.1082,1.2207,1.1189,1.0789,1.2079,1.1300,1.0426,1.1502,1.1122,1.0559,1.1419,1.1072,1.0208};
 410   Double_t s11[27]={1.0890,1.1463,1.2313,1.1149,1.1597,1.2280,1.1225,1.1584,1.2329,1.1149,1.1550,1.2369,1.1095,1.1353,1.2050,1.0649,1.0858,1.1546,1.0663,1.0672,1.1340,1.0416,1.0738,1.0945,1.0663,1.0654,1.0909};
 411   Double_t s22[27]={1.1709,1.1367,1.0932,1.2247,1.1832,1.1247,1.2470,1.2017,1.1441,1.2202,1.1653,1.1050,1.1819,1.1269,1.0583,1.1546,1.0621,0.9928,1.1305,1.0512,0.9576,1.0995,1.0445,0.9884,1.0968,1.0368,0.9574};
 412   Double_t s33[27]={0.9720,0.9869,1.0271,1.0030,1.0223,1.0479,1.0164,1.0305,1.0559,1.0339,1.0450,1.0686,1.0450,1.0507,1.0784,1.0334,1.0208,1.0863,1.0252,1.0114,1.0835,0.9854,1.0144,1.0507,1.0124,1.0159,1.0464};
 413   Double_t s44[27]={1.1104,1.0789,1.0479,1.1597,1.1234,1.0728,1.2087,1.1602,1.1041,1.1942,1.1428,1.0831,1.1572,1.1036,1.0431,1.1296,1.0498,0.9844,1.1145,1.0266,0.9489,1.0959,1.0450,0.9875,1.0775,1.0266,0.9406};
 414
 415
 416   ScaleMat(0,0) = LinearInterpolation(9,s00,pt,eta);
 417   ScaleMat(1,1) = LinearInterpolation(9,s11,pt,eta);
 418   ScaleMat(2,2) = LinearInterpolation(9,s22,pt,eta);
 419   ScaleMat(3,3) = LinearInterpolation(9,s33,pt,eta);
 420   ScaleMat(4,4) = LinearInterpolation(9,s44,pt,eta);
 421
 422   TMatrixD Mat(ScaleMat,TMatrixD::kMult,CovMat);
 423   TMatrixD CovMatSmear(Mat,TMatrixD::kMult,ScaleMat);
 424
 425
 426   return CovMatSmear;
 427 }
 428
 429 //-----------------------------------------------------------------
 430 void AliTPCtrackerParam::SmearTrack(Double_t* xx,Double_t* xxsm,TMatrixD cov) {
 431
 432   AliGausCorr *corgen = new AliGausCorr(cov,5);
 433   TArrayD corr(5);
 434   corgen->GetGaussN(corr);
 435   delete corgen;
 436   corgen = 0;
 437
 438   for(Int_t l=0;l<5;l++) {
 439     xxsm[l] = xx[l]+corr[l];
 440   }
 441
 442   return;
 443 }
 444
 445 //-----------------------------------------------------------------
 446 void AliTPCtrackerParam::CookTracks(TObjArray& tarray,TObjArray& newtarray)
 447 {
 448   TString* s = new TString("$ALICE_ROOT/TPC/CovMatrixDB_");
 449   if(fColl==0) s->Append("PbPb6000");
 450   if(fBz==0.4) s->Append("_B0.4T.root");
 451   // open file with matrixes DB
 452   TFile* DBfile = new TFile(s->Data());
 453
 454   AliTPCtrack* track = 0;
 455   Int_t entr = (Int_t)tarray.GetEntriesFast();
 456
 457   for(Int_t k=0; k<entr; k++) {
 458     track=(AliTPCtrack*)tarray.UncheckedAt(k);
 459
 460     Double_t pt = 1/TMath::Abs(track->Get1Pt());
 461     Double_t eta = -TMath::Log(TMath::Tan(0.25*TMath::Pi()-0.5*TMath::ATan(track->GetTgl())));
 462
 463     Int_t bin = GetBin(pt,eta);
 464
 465     // string with tree name
 466     TString str("Tree_bin");
 467     str+=bin;
 468
 469     // get the right tree
 470     TTree* CovTree = (TTree*)DBfile->Get(str.Data());
 471     TArrayF* matrix = new TArrayF;
 472     CovTree->SetBranchAddress("matrixes",&matrix);
 473
 474     // get random entry from the tree
 475     Int_t Entries = (Int_t)CovTree->GetEntries();
 476     CovTree->GetEvent(gRandom->Integer(Entries));
 477
 478     Double_t xref,alpha,xx[5],xxsm[5],cc[15];
 479     Int_t lab;
 480     // get P and Cosl from track
 481     Double_t Cosl = TMath::Cos(TMath::ATan(track->GetTgl()));
 482     Double_t P = 1/TMath::Abs(track->Get1Pt())/Cosl;
 483
 484     // get covariance matrix from regularized matrix
 485     cc[0]=matrix->At(0)*(1.588e-3+1.911e-4/TMath::Power(P,1.5));
 486     cc[1]=matrix->At(1);
 487     cc[2]=matrix->At(2)*(1.195e-3+0.8102e-3/P);
 488     cc[3]=matrix->At(3)*(7.275e-5+1.181e-5/TMath::Power(P,1.5));
 489     cc[4]=matrix->At(4);
 490     cc[5]=matrix->At(5)*(5.163e-6+1.138e-6/TMath::Power(P,2.)/Cosl);
 491     cc[6]=matrix->At(6);
 492     cc[7]=matrix->At(7)*(1.176e-5+1.175e-5/TMath::Power(P,1.5)/Cosl/Cosl/Cosl);
 493     cc[8]=matrix->At(8);
 494     cc[9]=matrix->At(9)*(1.289e-7+4.636e-7/TMath::Power(P,1.7)/Cosl/Cosl/Cosl/Cosl);
 495     cc[10]=matrix->At(10)*(4.056e-7+4.379e-8/TMath::Power(P,1.5));
 496     cc[11]=matrix->At(11);
 497     cc[12]=matrix->At(12)*(3.049e-8+8.244e-9/TMath::Power(P,2.)/Cosl);
 498     cc[13]=matrix->At(13);
 499     cc[14]=matrix->At(14)*(1.847e-10+5.822e-11/TMath::Power(P,2.)/Cosl/Cosl/Cosl);
 500
 501     TMatrixD CovMatSmear(5,5);
 502
 503     CovMatSmear = GetSmearingMatrix(cc,pt,eta);
 504
 505     // get track original parameters
 506     xref=track->GetX();
 507     alpha=track->GetAlpha();
 508     xx[0]=track->GetY();
 509     xx[1]=track->GetZ();
 510     xx[2]=track->GetX()*track->GetC()-track->GetSnp();
 511     xx[3]=track->GetTgl();
 512     xx[4]=track->GetC();
 513     lab=track->GetLabel();
 514
 515     // use smearing matrix to smear the original parameters
 516     SmearTrack(xx,xxsm,CovMatSmear);
 517
 518     AliTPCtrack* tpctrack = new AliTPCtrack(0,xxsm,cc,xref,alpha);
 519     tpctrack->SetLabel(lab);
 520
 521     // fill the array
 522     newtarray.AddLast(tpctrack);
 523
 524    delete matrix;
 525
 526   }
 527
 528   DBfile->Close();
 529
 530   delete s;
 531   delete DBfile;
 532
 533
 534   return;
 535 }
 536 //-----------------------------------------------------------------
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548