HMPID/AliHMPIDRecon.cxx

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  15
  16 //////////////////////////////////////////////////////////////////////////
  17 //                                                                      //
  18 // AliHMPIDRecon                                                         //
  19 //                                                                      //
  20 // HMPID class to perfom pattern recognition based on Hough transfrom    //
  21 // for single chamber                                                   //
  22 //////////////////////////////////////////////////////////////////////////
  23
  24 #include "AliHMPIDRecon.h"   //class header
  25 #include "AliHMPIDParam.h"   //CkovAngle()
  26 #include "AliHMPIDCluster.h" //CkovAngle()
  27 #include <TMinuit.h>         //FitEllipse()
  28 #include <TRotation.h>       //TracePhot()
  29 #include <TH1D.h>            //HoughResponse()
  30 #include <TClonesArray.h>    //CkovAngle()
  31 #include <AliESDtrack.h>     //CkovAngle()
  32
  33 const Double_t AliHMPIDRecon::fgkRadThick=1.5;
  34 const Double_t AliHMPIDRecon::fgkWinThick=0.5;
  35 const Double_t AliHMPIDRecon::fgkGapThick=8.0;
  36 const Double_t AliHMPIDRecon::fgkWinIdx  =1.5787;
  37 const Double_t AliHMPIDRecon::fgkGapIdx  =1.0005;
  38
  39 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  40 AliHMPIDRecon::AliHMPIDRecon():TTask("RichRec","RichPat"),
  41   fRadNmean(1.292),
  42   fPhotCnt(-1),
  43   fCkovSigma2(0),
  44   fIsWEIGHT(kFALSE),
  45   fDTheta(0.001),
  46   fWindowWidth(0.045),
  47   fTrkDir(TVector3(0,0,1)),fTrkPos(TVector2(30,40))
  48 {
  49 // main ctor
  50   for (Int_t i=0; i<3000; i++) {
  51     fPhotFlag[i] =  0;
  52     fPhotCkov[i] = -1;
  53     fPhotPhi [i] = -1;
  54     fPhotWei [i] =  0;
  55   }
  56 //hidden algorithm
  57   fMipX=fMipY=fThTrkFit=fPhTrkFit=fCkovFit=fMipQ=fRadX=fRadY=-999;
  58   fIdxMip=fNClu=0;
  59   fCkovSig2=0;
  60   for (Int_t i=0; i<100; i++) {
  61     fXClu[i] = fYClu[i] = 0;
  62     fClCk[i] = kTRUE;
  63   }
  64 }
  65 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  66 void AliHMPIDRecon::CkovAngle(AliESDtrack *pTrk,TClonesArray *pCluLst,Double_t nmean,Double_t qthre)
  67 {
  68 // Pattern recognition method based on Hough transform
  69 // Arguments:   pTrk     - track for which Ckov angle is to be found
  70 //              pCluLst  - list of clusters for this chamber
  71 //   Returns:            - track ckov angle, [rad],
  72
  73   AliHMPIDParam *pParam=AliHMPIDParam::Instance();
  74
  75   if(pCluLst->GetEntries()>pParam->MultCut()) fIsWEIGHT = kTRUE; // offset to take into account bkg in reconstruction
  76   else                                        fIsWEIGHT = kFALSE;
  77
  78   fIsWEIGHT = kTRUE;
  79
  80   Float_t xRa,yRa,th,ph;
  81   pTrk->GetHMPIDtrk(xRa,yRa,th,ph);        //initialize this track: th and ph angles at middle of RAD
  82   SetTrack(xRa,yRa,th,ph);
  83
  84   fRadNmean=nmean;
  85
  86   Float_t dMin=999,mipX=-1,mipY=-1;Int_t chId=-1,mipId=-1,mipQ=-1;
  87   fPhotCnt=0;
  88   for (Int_t iClu=0; iClu<pCluLst->GetEntriesFast();iClu++){//clusters loop
  89     AliHMPIDCluster *pClu=(AliHMPIDCluster*)pCluLst->UncheckedAt(iClu);                       //get pointer to current cluster
  90     chId=pClu->Ch();
  91     if(pClu->Q()>qthre){                                                                      //charge compartible with MIP clusters
  92       Float_t dX=fPc.X()-pClu->X(),dY=fPc.Y()-pClu->Y(),d =TMath::Sqrt(dX*dX+dY*dY);          //distance between current cluster and intersection point
  93       if( d < dMin) {mipId=iClu; dMin=d;mipX=pClu->X();mipY=pClu->Y();mipQ=(Int_t)pClu->Q();} //current cluster is closer, overwrite data for min cluster
  94     }else{                                                                                    //charge compatible with photon cluster
  95       Double_t thetaCer,phiCer;
  96       if(FindPhotCkov(pClu->X(),pClu->Y(),thetaCer,phiCer)){                                  //find ckov angle for this  photon candidate
  97         fPhotCkov[fPhotCnt]=thetaCer;                                                         //actual theta Cerenkov (in TRS)
  98         fPhotPhi [fPhotCnt]=phiCer;                                                           //actual phi   Cerenkov (in TRS): -pi to come back to "unusual" ref system (X,Y,-Z)
  99         //PH        Printf("photon n. %i reconstructed theta = %f",fPhotCnt,fPhotCkov[fPhotCnt]);
 100         fPhotCnt++;                                                                           //increment counter of photon candidates
 101       }
 102     }
 103   }//clusters loop
 104   fMipPos.Set(mipX,mipY);
 105   if(fPhotCnt<=3) pTrk->SetHMPIDsignal(kNoPhotAccept);                                        //no reconstruction with <=3 photon candidates
 106   Int_t iNacc=FlagPhot(HoughResponse());                                                      //flag photons according to individual theta ckov with respect to most probable
 107   pTrk->SetHMPIDmip(mipX,mipY,mipQ,iNacc);                                                    //store mip info
 108
 109   if(mipId==-1)              {pTrk->SetHMPIDsignal(kMipQdcCut);  return;}                     //no clusters with QDC more the threshold at all
 110   if(dMin>pParam->DistCut()) {pTrk->SetHMPIDsignal(kMipDistCut); return;}                     //closest cluster with enough charge is still too far from intersection
 111   pTrk->SetHMPIDcluIdx(chId,mipId);                                                           //set index of cluster
 112   if(iNacc<1){
 113     pTrk->SetHMPIDsignal(kNoPhotAccept);                                                      //no photon candidates is accepted
 114   }
 115   else {
 116     pTrk->SetHMPIDsignal(FindRingCkov(pCluLst->GetEntries()));                                //find best Theta ckov for ring i.e. track
 117     pTrk->SetHMPIDchi2(fCkovSigma2);                                                          //errors squared
 118   }
 119
 120 }//CkovAngle()
 121 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 122 Bool_t AliHMPIDRecon::FindPhotCkov(Double_t cluX,Double_t cluY,Double_t &thetaCer,Double_t &phiCer)
 123 {
 124 // Finds Cerenkov angle  for this photon candidate
 125 // Arguments: cluX,cluY - position of cadidate's cluster
 126 // Returns: Cerenkov angle
 127
 128   TVector3 dirCkov;
 129
 130   Double_t zRad= -0.5*fgkRadThick-0.5*fgkWinThick;                   //z position of middle of RAD
 131   TVector3 rad(fTrkPos.X(),fTrkPos.Y(),zRad);                        //impact point at middle of RAD
 132   TVector3  pc(cluX,cluY,0.5*fgkWinThick+fgkGapIdx);                 //mip at PC
 133   Double_t cluR = TMath::Sqrt((cluX-fTrkPos.X())*(cluX-fTrkPos.X())+
 134                               (cluY-fTrkPos.Y())*(cluY-fTrkPos.Y()));//ref. distance impact RAD-CLUSTER
 135   Double_t phi=(pc-rad).Phi();                                       //phi of photon
 136
 137   Double_t ckov1=0;
 138   Double_t ckov2=0.75+fTrkDir.Theta();                        //start to find theta cerenkov in DRS
 139   const Double_t kTol=0.01;
 140   Int_t iIterCnt = 0;
 141   while(1){
 142     if(iIterCnt>=50) return kFALSE;
 143     Double_t ckov=0.5*(ckov1+ckov2);
 144     dirCkov.SetMagThetaPhi(1,ckov,phi);
 145     TVector2 posC=TraceForward(dirCkov);                      //trace photon with actual angles
 146     Double_t dist=cluR-(posC-fTrkPos).Mod();                  //get distance between trial point and cluster position
 147     if(posC.X()==-999) dist = - 999;                          //total reflection problem
 148     iIterCnt++;                                               //counter step
 149     if     (dist> kTol) ckov1=ckov;                           //cluster @ larger ckov
 150     else if(dist<-kTol) ckov2=ckov;                           //cluster @ smaller ckov
 151     else{                                                     //precision achived: ckov in DRS found
 152       dirCkov.SetMagThetaPhi(1,ckov,phi);                     //
 153       RecPhot(dirCkov,thetaCer,phiCer);                       //find ckov (in TRS:the effective Cherenkov angle!)
 154       return kTRUE;
 155     }
 156   }
 157 }//FindPhotTheta()
 158 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 159 TVector2 AliHMPIDRecon::TraceForward(TVector3 dirCkov)const
 160 {
 161   //Trace forward a photon from (x,y) up to PC
 162   // Arguments: dirCkov photon vector in LORS
 163   //   Returns: pos of traced photon at PC
 164   TVector2 pos(-999,-999);
 165   Double_t thetaCer = dirCkov.Theta();
 166   if(thetaCer > TMath::ASin(1./fRadNmean))  return pos;         //total refraction on WIN-GAP boundary
 167   Double_t zRad= -0.5*fgkRadThick-0.5*fgkWinThick;              //z position of middle of RAD
 168   TVector3  posCkov(fTrkPos.X(),fTrkPos.Y(),zRad);              //RAD: photon position is track position @ middle of RAD
 169   Propagate(dirCkov,posCkov,           -0.5*fgkWinThick);       //go to RAD-WIN boundary
 170   Refract  (dirCkov,         fRadNmean,fgkWinIdx);              //RAD-WIN refraction
 171   Propagate(dirCkov,posCkov,            0.5*fgkWinThick);       //go to WIN-GAP boundary
 172   Refract  (dirCkov,         fgkWinIdx,fgkGapIdx);              //WIN-GAP refraction
 173   Propagate(dirCkov,posCkov,0.5*fgkWinThick+fgkGapThick);       //go to PC
 174   pos.Set(posCkov.X(),posCkov.Y());
 175   return pos;
 176 }//TraceForward()
 177 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 178 void AliHMPIDRecon::RecPhot(TVector3 dirCkov,Double_t &thetaCer,Double_t &phiCer)
 179 {
 180   //Theta Cerenkov reconstruction
 181   // Arguments: (x,y) of initial point in LORS, dirCkov photon vector in LORS
 182   //   Returns: thetaCer theta cerenkov reconstructed
 183 //  TVector3 dirTrk;
 184 //  dirTrk.SetMagThetaPhi(1,fTrkDir.Theta(),fTrkDir.Phi());
 185 //  Double_t thetaCer = TMath::ACos(dirCkov*dirTrk);
 186   TRotation mtheta;   mtheta.RotateY(- fTrkDir.Theta());
 187   TRotation mphi;       mphi.RotateZ(- fTrkDir.Phi());
 188   TRotation mrot=mtheta*mphi;
 189   TVector3 dirCkovTRS;
 190   dirCkovTRS=mrot*dirCkov;
 191   phiCer  = dirCkovTRS.Phi();                                          //actual value of the phi of the photon
 192   thetaCer= dirCkovTRS.Theta();                                        //actual value of thetaCerenkov of the photon
 193 }
 194 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 195 Double_t AliHMPIDRecon::FindRingArea(Double_t ckovAng)const
 196 {
 197 // Find area covered in the PC acceptance
 198 // Arguments: ckovAng - cerenkov angle
 199 //   Returns: area of the ring in cm^2 for given theta ckov
 200
 201   const Int_t kN=100;
 202   TVector2 pos1;
 203   Double_t area=0;
 204   Bool_t first=kFALSE;
 205   for(Int_t i=0;i<kN;i++){
 206    if(!first) {
 207      pos1=TracePhot(ckovAng,Double_t(TMath::TwoPi()*(i+1)/kN));                                     //find a good trace for the first photon
 208      if(pos1.X()==-999) continue;                                                                   //no area: open ring
 209      if(!AliHMPIDParam::IsInside(pos1.X(),pos1.Y(),0)) pos1 = IntWithEdge(fMipPos,pos1);            // ffind the very first intersection...
 210      first=kTRUE;
 211      continue;
 212    }
 213    TVector2 pos2=TracePhot(ckovAng,Double_t(TMath::TwoPi()*(i+1)/kN));                              //trace the next photon
 214    if(pos2.X()==-999) continue;                                                                     //no area: open ring
 215    if(!AliHMPIDParam::IsInside(pos2.X(),pos2.Y(),0)) {
 216      pos2 = IntWithEdge(fMipPos,pos2);
 217    }
 218    area+=TMath::Abs((pos1-fMipPos).X()*(pos2-fMipPos).Y()-(pos1-fMipPos).Y()*(pos2-fMipPos).X());   //add area of the triangle...
 219    pos1 = pos2;
 220   }
 221 //---  find points from ring
 222   area*=0.5;
 223   return area;
 224 }//FindRingArea()
 225 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 226 TVector2 AliHMPIDRecon::IntWithEdge(TVector2 p1,TVector2 p2)const
 227 {
 228 // It finds the intersection of the line for 2 points traced as photons
 229 // and the edge of a given PC
 230 // Arguments: 2 points obtained tracing the photons
 231 //   Returns: intersection point with detector (PC) edges
 232
 233   AliHMPIDParam *pParam = AliHMPIDParam::Instance();
 234
 235   Double_t xmin = (p1.X()<p2.X())? p1.X():p2.X();
 236   Double_t xmax = (p1.X()<p2.X())? p2.X():p1.X();
 237   Double_t ymin = (p1.Y()<p2.Y())? p1.Y():p2.Y();
 238   Double_t ymax = (p1.Y()<p2.Y())? p2.Y():p1.Y();
 239
 240   Double_t m = TMath::Tan((p2-p1).Phi());
 241   TVector2 pint;
 242   //intersection with low  X
 243   pint.Set((Double_t)(p1.X() + (0-p1.Y())/m),0.);
 244   if(pint.X()>=0 && pint.X()<=pParam->SizeAllX() &&
 245      pint.X()>=xmin && pint.X()<=xmax            &&
 246      pint.Y()>=ymin && pint.Y()<=ymax) return pint;
 247   //intersection with high X
 248   pint.Set((Double_t)(p1.X() + (pParam->SizeAllY()-p1.Y())/m),(Double_t)(pParam->SizeAllY()));
 249   if(pint.X()>=0 && pint.X()<=pParam->SizeAllX() &&
 250      pint.X()>=xmin && pint.X()<=xmax            &&
 251      pint.Y()>=ymin && pint.Y()<=ymax) return pint;
 252   //intersection with left Y
 253   pint.Set(0.,(Double_t)(p1.Y() + m*(0-p1.X())));
 254   if(pint.Y()>=0 && pint.Y()<=pParam->SizeAllY() &&
 255      pint.Y()>=ymin && pint.Y()<=ymax            &&
 256      pint.X()>=xmin && pint.X()<=xmax) return pint;
 257   //intersection with righ Y
 258   pint.Set((Double_t)(pParam->SizeAllX()),(Double_t)(p1.Y() + m*(pParam->SizeAllX()-p1.X())));
 259   if(pint.Y()>=0 && pint.Y()<=pParam->SizeAllY() &&
 260      pint.Y()>=ymin && pint.Y()<=ymax            &&
 261      pint.X()>=xmin && pint.X()<=xmax) return pint;
 262   return p1;
 263 }//IntWithEdge()
 264 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 265 Double_t AliHMPIDRecon::FindRingCkov(Int_t)
 266 {
 267 // Loops on all Ckov candidates and estimates the best Theta Ckov for a ring formed by those candidates. Also estimates an error for that Theat Ckov
 268 // collecting errors for all single Ckov candidates thetas. (Assuming they are independent)
 269 // Arguments: iNclus- total number of clusters in chamber for background estimation
 270 //    Return: best estimation of track Theta ckov
 271
 272   Double_t wei = 0.;
 273   Double_t weightThetaCerenkov = 0.;
 274
 275   Double_t ckovMin=9999.,ckovMax=0.;
 276   Double_t sigma2 = 0;   //to collect error squared for this ring
 277
 278   for(Int_t i=0;i<fPhotCnt;i++){//candidates loop
 279     if(fPhotFlag[i] == 2){
 280       if(fPhotCkov[i]<ckovMin) ckovMin=fPhotCkov[i];                         //find max and min Theta ckov from all candidates within probable window
 281       if(fPhotCkov[i]>ckovMax) ckovMax=fPhotCkov[i];
 282       weightThetaCerenkov += fPhotCkov[i]*fPhotWei[i];
 283       wei += fPhotWei[i];                                                    //collect weight as sum of all candidate weghts
 284
 285       sigma2 += 1./Sigma2(fPhotCkov[i],fPhotPhi[i]);
 286     }
 287   }//candidates loop
 288
 289   if(sigma2>0) fCkovSigma2=1./sigma2;
 290   else         fCkovSigma2=1e10;
 291
 292   if(wei != 0.) weightThetaCerenkov /= wei; else weightThetaCerenkov = 0.;
 293   return weightThetaCerenkov;
 294 }//FindCkovRing()
 295 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 296 Int_t AliHMPIDRecon::FlagPhot(Double_t ckov)
 297 {
 298 // Flag photon candidates if their individual ckov angle is inside the window around ckov angle returned by  HoughResponse()
 299 // Arguments: ckov- value of most probable ckov angle for track as returned by HoughResponse()
 300 //   Returns: number of photon candidates happened to be inside the window
 301
 302 // Photon Flag:  Flag = 0 initial set;
 303 //               Flag = 1 good candidate (charge compatible with photon);
 304 //               Flag = 2 photon used for the ring;
 305
 306   Int_t steps = (Int_t)((ckov )/ fDTheta); //how many times we need to have fDTheta to fill the distance between 0  and thetaCkovHough
 307
 308   Double_t tmin = (Double_t)(steps - 1)*fDTheta;
 309   Double_t tmax = (Double_t)(steps)*fDTheta;
 310   Double_t tavg = 0.5*(tmin+tmax);
 311
 312   tmin = tavg - 0.5*fWindowWidth;  tmax = tavg + 0.5*fWindowWidth;
 313
 314   Int_t iInsideCnt = 0; //count photons which Theta ckov inside the window
 315   for(Int_t i=0;i<fPhotCnt;i++){//photon candidates loop
 316     fPhotFlag[i] = 0;
 317     if(fPhotCkov[i] >= tmin && fPhotCkov[i] <= tmax)    {
 318       fPhotFlag[i]=2;
 319       iInsideCnt++;
 320     }
 321   }
 322   return iInsideCnt;
 323 }//FlagPhot()
 324 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 325 TVector2 AliHMPIDRecon::TracePhot(Double_t ckovThe,Double_t ckovPhi)const
 326 {
 327 // Trace a single Ckov photon from emission point somewhere in radiator up to photocathode taking into account ref indexes of materials it travereses
 328 // Arguments: ckovThe,ckovPhi- photon ckov angles in DRS, [rad]
 329 //   Returns: distance between photon point on PC and track projection
 330   TRotation mtheta;   mtheta.RotateY(fTrkDir.Theta());
 331   TRotation mphi;       mphi.RotateZ(fTrkDir.Phi());
 332   TRotation mrot=mphi*mtheta;
 333   TVector3  dirCkov,dirCkovTors;
 334
 335   dirCkovTors.SetMagThetaPhi(1,ckovThe,ckovPhi);                    //initially photon is directed according to requested ckov angle
 336   dirCkov=mrot*dirCkovTors;                                         //now we know photon direction in LORS
 337   return TraceForward(dirCkov);
 338 }//TracePhot()
 339 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 340 void AliHMPIDRecon::Propagate(const TVector3 dir,TVector3 &pos,Double_t z)const
 341 {
 342 // Finds an intersection point between a line and XY plane shifted along Z.
 343 // Arguments:  dir,pos   - vector along the line and any point of the line
 344 //             z         - z coordinate of plain
 345 //   Returns:  none
 346 //   On exit:  pos is the position if this intesection if any
 347   static TVector3 nrm(0,0,1);
 348          TVector3 pnt(0,0,z);
 349
 350   TVector3 diff=pnt-pos;
 351   Double_t sint=(nrm*diff)/(nrm*dir);
 352   pos+=sint*dir;
 353 }//Propagate()
 354 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 355 void AliHMPIDRecon::Refract(TVector3 &dir,Double_t n1,Double_t n2)const
 356 {
 357 // Refract direction vector according to Snell law
 358 // Arguments:
 359 //            n1 - ref idx of first substance
 360 //            n2 - ref idx of second substance
 361 //   Returns: none
 362 //   On exit: dir is new direction
 363   Double_t sinref=(n1/n2)*TMath::Sin(dir.Theta());
 364   if(TMath::Abs(sinref)>1.) dir.SetXYZ(-999,-999,-999);
 365   else             dir.SetTheta(TMath::ASin(sinref));
 366 }//Refract()
 367 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 368 Double_t AliHMPIDRecon::HoughResponse()
 369 {
 370 //
 371 //    fIdxMip = mipId;
 372
 373 //
 374   Double_t kThetaMax=0.75;
 375   Int_t nChannels = (Int_t)(kThetaMax/fDTheta+0.5);
 376   TH1D *phots   = new TH1D("Rphot"  ,"phots"         ,nChannels,0,kThetaMax);
 377   TH1D *photsw  = new TH1D("RphotWeighted" ,"photsw" ,nChannels,0,kThetaMax);
 378   TH1D *resultw = new TH1D("resultw","resultw"       ,nChannels,0,kThetaMax);
 379   Int_t nBin = (Int_t)(kThetaMax/fDTheta);
 380   Int_t nCorrBand = (Int_t)(fWindowWidth/(2*fDTheta));
 381
 382   for (Int_t i=0; i< fPhotCnt; i++){//photon cadidates loop
 383     Double_t angle = fPhotCkov[i];  if(angle<0||angle>kThetaMax) continue;
 384     phots->Fill(angle);
 385     Int_t bin = (Int_t)(0.5+angle/(fDTheta));
 386     Double_t weight=1.;
 387     if(fIsWEIGHT){
 388       Double_t lowerlimit = ((Double_t)bin)*fDTheta - 0.5*fDTheta;  Double_t upperlimit = ((Double_t)bin)*fDTheta + 0.5*fDTheta;
 389       Double_t diffArea = FindRingArea(upperlimit)-FindRingArea(lowerlimit);
 390       if(diffArea>0) weight = 1./diffArea;
 391     }
 392     photsw->Fill(angle,weight);
 393     fPhotWei[i]=weight;
 394   }//photon candidates loop
 395
 396   for (Int_t i=1; i<=nBin;i++){
 397     Int_t bin1= i-nCorrBand;
 398     Int_t bin2= i+nCorrBand;
 399     if(bin1<1) bin1=1;
 400     if(bin2>nBin)bin2=nBin;
 401     Double_t sumPhots=phots->Integral(bin1,bin2);
 402     if(sumPhots<3) continue;                            // if less then 3 photons don't trust to this ring
 403     Double_t sumPhotsw=photsw->Integral(bin1,bin2);
 404     resultw->Fill((Double_t)((i+0.5)*fDTheta),sumPhotsw);
 405   }
 406 // evaluate the "BEST" theta ckov as the maximum value of histogramm
 407   Double_t *pVec = resultw->GetArray();
 408   Int_t locMax = TMath::LocMax(nBin,pVec);
 409   delete phots;delete photsw;delete resultw; // Reset and delete objects
 410
 411   return (Double_t)(locMax*fDTheta+0.5*fDTheta); //final most probable track theta ckov
 412 }//HoughResponse()
 413 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 414 Double_t AliHMPIDRecon::Sigma2(Double_t ckovTh, Double_t ckovPh)const
 415 {
 416 // Analithical calculation of total error (as a sum of localization, geometrical and chromatic errors) on Cerenkov angle for a given Cerenkov photon
 417 // created by a given MIP. Fromulae according to CERN-EP-2000-058
 418 // Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
 419 //            dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
 420 //            MIP beta
 421 //   Returns: absolute error on Cerenkov angle, [radians]
 422
 423   TVector3 v(-999,-999,-999);
 424   Double_t trkBeta = 1./(TMath::Cos(ckovTh)*fRadNmean);
 425
 426   if(trkBeta > 1) trkBeta = 1;                 //protection against bad measured thetaCer
 427   if(trkBeta < 0) trkBeta = 0.0001;            //
 428
 429   v.SetX(SigLoc (ckovTh,ckovPh,trkBeta));
 430   v.SetY(SigGeom(ckovTh,ckovPh,trkBeta));
 431   v.SetZ(SigCrom(ckovTh,ckovPh,trkBeta));
 432
 433   return v.Mag2();
 434 }
 435 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 436 Double_t AliHMPIDRecon::SigLoc(Double_t thetaC, Double_t phiC,Double_t betaM)const
 437 {
 438 // Analithical calculation of localization error (due to finite segmentation of PC) on Cerenkov angle for a given Cerenkov photon
 439 // created by a given MIP. Fromulae according to CERN-EP-2000-058
 440 // Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
 441 //            dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
 442 //            MIP beta
 443 //   Returns: absolute error on Cerenkov angle, [radians]
 444
 445   Double_t phiDelta = phiC - fTrkDir.Phi();
 446
 447   Double_t sint     = TMath::Sin(fTrkDir.Theta());
 448   Double_t cost     = TMath::Cos(fTrkDir.Theta());
 449   Double_t sinf     = TMath::Sin(fTrkDir.Phi());
 450   Double_t cosf     = TMath::Cos(fTrkDir.Phi());
 451   Double_t sinfd    = TMath::Sin(phiDelta);
 452   Double_t cosfd    = TMath::Cos(phiDelta);
 453   Double_t tantheta = TMath::Tan(thetaC);
 454
 455   Double_t alpha =cost-tantheta*cosfd*sint;                                                 // formula (11)
 456   Double_t k = 1.-fRadNmean*fRadNmean+alpha*alpha/(betaM*betaM);                            // formula (after 8 in the text)
 457   if (k<0) return 1e10;
 458   Double_t mu =sint*sinf+tantheta*(cost*cosfd*sinf+sinfd*cosf);                             // formula (10)
 459   Double_t e  =sint*cosf+tantheta*(cost*cosfd*cosf-sinfd*sinf);                             // formula (9)
 460
 461   Double_t kk = betaM*TMath::Sqrt(k)/(fgkGapThick*alpha);                                   // formula (6) and (7)
 462   Double_t dtdxc = kk*(k*(cosfd*cosf-cost*sinfd*sinf)-(alpha*mu/(betaM*betaM))*sint*sinfd); // formula (6)
 463   Double_t dtdyc = kk*(k*(cosfd*sinf+cost*sinfd*cosf)+(alpha* e/(betaM*betaM))*sint*sinfd); // formula (7)            pag.4
 464
 465   Double_t errX = 0.2,errY=0.25;                                                            //end of page 7
 466   return  TMath::Sqrt(errX*errX*dtdxc*dtdxc + errY*errY*dtdyc*dtdyc);
 467 }
 468 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 469 Double_t AliHMPIDRecon::SigCrom(Double_t thetaC, Double_t phiC,Double_t betaM)const
 470 {
 471 // Analithical calculation of chromatic error (due to lack of knowledge of Cerenkov photon energy) on Cerenkov angle for a given Cerenkov photon
 472 // created by a given MIP. Fromulae according to CERN-EP-2000-058
 473 // Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
 474 //            dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
 475 //            MIP beta
 476 //   Returns: absolute error on Cerenkov angle, [radians]
 477
 478   Double_t phiDelta = phiC - fTrkDir.Phi();
 479
 480   Double_t sint     = TMath::Sin(fTrkDir.Theta());
 481   Double_t cost     = TMath::Cos(fTrkDir.Theta());
 482   Double_t cosfd    = TMath::Cos(phiDelta);
 483   Double_t tantheta = TMath::Tan(thetaC);
 484
 485   Double_t alpha =cost-tantheta*cosfd*sint;                                                 // formula (11)
 486   Double_t dtdn = cost*fRadNmean*betaM*betaM/(alpha*tantheta);                              // formula (12)
 487
 488 //  Double_t f = 0.00928*(7.75-5.635)/TMath::Sqrt(12.);
 489   Double_t f = 0.0172*(7.75-5.635)/TMath::Sqrt(24.);
 490
 491   return f*dtdn;
 492 }//SigCrom()
 493 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 494 Double_t AliHMPIDRecon::SigGeom(Double_t thetaC, Double_t phiC,Double_t betaM)const
 495 {
 496 // Analithical calculation of geometric error (due to lack of knowledge of creation point in radiator) on Cerenkov angle for a given Cerenkov photon
 497 // created by a given MIP. Formulae according to CERN-EP-2000-058
 498 // Arguments: Cerenkov and azimuthal angles for Cerenkov photon, [radians]
 499 //            dip and azimuthal angles for MIP taken at the entrance to radiator, [radians]
 500 //            MIP beta
 501 //   Returns: absolute error on Cerenkov angle, [radians]
 502
 503   Double_t phiDelta = phiC - fTrkDir.Phi();
 504
 505   Double_t sint     = TMath::Sin(fTrkDir.Theta());
 506   Double_t cost     = TMath::Cos(fTrkDir.Theta());
 507   Double_t sinf     = TMath::Sin(fTrkDir.Phi());
 508   Double_t cosfd    = TMath::Cos(phiDelta);
 509   Double_t costheta = TMath::Cos(thetaC);
 510   Double_t tantheta = TMath::Tan(thetaC);
 511
 512   Double_t alpha =cost-tantheta*cosfd*sint;                                                  // formula (11)
 513
 514   Double_t k = 1.-fRadNmean*fRadNmean+alpha*alpha/(betaM*betaM);                             // formula (after 8 in the text)
 515   if (k<0) return 1e10;
 516
 517   Double_t eTr = 0.5*fgkRadThick*betaM*TMath::Sqrt(k)/(fgkGapThick*alpha);                   // formula (14)
 518   Double_t lambda = 1.-sint*sint*sinf*sinf;                                                  // formula (15)
 519
 520   Double_t c1 = 1./(1.+ eTr*k/(alpha*alpha*costheta*costheta));                              // formula (13.a)
 521   Double_t c2 = betaM*TMath::Power(k,1.5)*tantheta*lambda/(fgkGapThick*alpha*alpha);         // formula (13.b)
 522   Double_t c3 = (1.+eTr*k*betaM*betaM)/((1+eTr)*alpha*alpha);                                // formula (13.c)
 523   Double_t c4 = TMath::Sqrt(k)*tantheta*(1-lambda)/(fgkGapThick*betaM);                      // formula (13.d)
 524   Double_t dtdT = c1 * (c2+c3*c4);
 525   Double_t trErr = fgkRadThick/(TMath::Sqrt(12.)*cost);
 526
 527   return trErr*dtdT;
 528 }//SigGeom()
 529 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 530 //
 531 // From here HTA....
 532 //
 533 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 534 Bool_t AliHMPIDRecon::CkovHiddenTrk(AliESDtrack *pTrk,TClonesArray *pCluLst,Double_t nmean, Double_t qthre)
 535 {
 536 // Pattern recognition method without any infos from tracking:HTA (Hidden Track Algorithm)...
 537 // The method finds in the chmber the cluster with the highest charge
 538 // compatibile with a MIP, then the strategy is applied
 539 // Arguments:  pTrk     - pointer to ESD track
 540 //             pCluLs   - list of clusters for a given chamber
 541 //             nmean    - mean freon ref. index
 542 //   Returns:           - 0=ok,1=not fitted
 543
 544   fRadNmean=nmean;
 545
 546   if(pCluLst->GetEntriesFast()>100) return kFALSE;                                            //boundary check for CluX,CluY...
 547   Float_t mipX=-1,mipY=-1;Int_t mipId=-1,mipQ=-1;
 548   Double_t qRef = 0;
 549   Int_t nCh=0;
 550   for (Int_t iClu=0;iClu<pCluLst->GetEntriesFast();iClu++){                                   //clusters loop
 551     AliHMPIDCluster *pClu=(AliHMPIDCluster*)pCluLst->UncheckedAt(iClu);                       //get pointer to current cluster
 552     nCh = pClu->Ch();
 553     fXClu[iClu] = pClu->X();fYClu[iClu] = pClu->Y();                                          //store x,y for fitting procedure
 554     fClCk[iClu] = kTRUE;                                                                      //all cluster are accepted at this stage to be reconstructed
 555     if(pClu->Q()>qRef){                                                                       //searching the highest charge to select a MIP
 556       qRef = pClu->Q();
 557       mipId=iClu; mipX=pClu->X();mipY=pClu->Y();mipQ=(Int_t)pClu->Q();
 558     }
 559   }//clusters loop
 560
 561   fNClu = pCluLst->GetEntriesFast();
 562   if(qRef>qthre){                                                                     //charge compartible with MIP clusters
 563     fIdxMip = mipId;
 564     fClCk[mipId] = kFALSE;
 565     fMipX = mipX; fMipY=mipY; fMipQ = qRef;
 566     if(!DoRecHiddenTrk(pCluLst)) {
 567       pTrk->SetHMPIDsignal(kNoPhotAccept);
 568       return kFALSE;
 569     }                                                                           //Do track and ring reconstruction,if problems returns 1
 570     pTrk->SetHMPIDtrk(fRadX,fRadY,fThTrkFit,fPhTrkFit);                                        //store track intersection info
 571     pTrk->SetHMPIDmip(fMipX,fMipY,(Int_t)fMipQ,fNClu);                                         //store mip info
 572     pTrk->SetHMPIDcluIdx(nCh,fIdxMip);                                                         //set cham number and index of cluster
 573     pTrk->SetHMPIDsignal(fCkovFit);                                                            //find best Theta ckov for ring i.e. track
 574     pTrk->SetHMPIDchi2(fCkovSig2);                                                             //errors squared
 575 //    Printf(" n clusters tot %i accepted %i",pCluLst->GetEntriesFast(),fNClu);
 576     return kTRUE;
 577   }
 578
 579   return kFALSE;
 580 }//CkovHiddenTrk()
 581 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 582 Bool_t AliHMPIDRecon::DoRecHiddenTrk(TClonesArray *pCluLst)
 583 {
 584 // Pattern recognition method without any infos from tracking...
 585 // First a preclustering filter to avoid part of the noise
 586 // Then only ellipsed-rings are fitted (no possibility,
 587 // for the moment, to reconstruct very inclined tracks)
 588 // Finally a fitting with (th,ph) free, starting by very close values
 589 // previously evaluated.
 590 // Arguments:   none
 591 //   Returns:   none
 592   Double_t phiRec;
 593   if(!CluPreFilter(pCluLst)) {return kFALSE;}
 594   if(!FitEllipse(phiRec)) {return kFALSE;}
 595   Int_t nClTmp1 = pCluLst->GetEntriesFast()-1;  //minus MIP...
 596   Int_t nClTmp2 = 0;
 597   while(nClTmp1 != nClTmp2){
 598     SetNClu(pCluLst->GetEntriesFast());
 599     if(!FitFree(phiRec)) {return kFALSE;}
 600     nClTmp2 = NClu();
 601     if(nClTmp2!=nClTmp1) {nClTmp1=nClTmp2;nClTmp2=0;}
 602   }
 603   fNClu = nClTmp2;
 604   return kTRUE;
 605 }//DoRecHiddenTrk()
 606 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 607 Bool_t AliHMPIDRecon::CluPreFilter(TClonesArray *pCluLst)
 608 {
 609 // Filter of bkg clusters
 610 // based on elliptical-shapes...
 611 //
 612   if(pCluLst->GetEntriesFast()>50||pCluLst->GetEntriesFast()<4) return kFALSE;
 613   else return kTRUE;
 614 }
 615 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 616 Bool_t AliHMPIDRecon::FitEllipse(Double_t &phiRec)
 617 {
 618 //Fit a set of clusters with an analitical conical section function:
 619   //
 620   // Ax^2 + B*y^2 + 2Hxy + 2Gx + 2Fy + 1 = 0   ---> conical section
 621   //
 622   //  H*H - A*B > 0 hyperbola
 623   //            < 0 ellipse
 624   //            = 0 parabola
 625   //
 626   // tan 2alfa = 2H/(A-B)  alfa=angle of rotation
 627   //
 628   // coordinate of the centre of the conical section:
 629   //   x = x' + a
 630   //   y = y' + b
 631   //
 632   //       HF - BG
 633   //  a = ---------
 634   //       AB - H^2
 635   //
 636   //       HG - AF
 637   //  b = --------
 638   //       AB - H^2
 639   Double_t cA,cB,cF,cG,cH;
 640   Double_t aArg=-1;      Int_t iErrFlg;                                                //tmp vars for TMinuit
 641
 642   if(!gMinuit) gMinuit = new TMinuit(5);                                               //init MINUIT with this number of parameters (5 params)
 643   gMinuit->mncler();                                                                   // reset Minuit list of paramters
 644   gMinuit->SetObjectFit((TObject*)this);  gMinuit->SetFCN(AliHMPIDRecon::FunMinEl);    //set fit function
 645   gMinuit->mnexcm("SET PRI",&aArg,1,iErrFlg);                                          //suspend all printout from TMinuit
 646   gMinuit->mnexcm("SET NOW",&aArg,0,iErrFlg);                                          //suspend all warning printout from TMinuit
 647
 648   Double_t d1,d2,d3;
 649   TString sName;
 650
 651   gMinuit->mnparm(0," A ",1,0.01,0,0,iErrFlg);
 652   gMinuit->mnparm(1," B ",1,0.01,0,0,iErrFlg);
 653   gMinuit->mnparm(2," H ",1,0.01,0,0,iErrFlg);
 654   gMinuit->mnparm(3," G ",1,0.01,0,0,iErrFlg);
 655   gMinuit->mnparm(4," F ",1,0.01,0,0,iErrFlg);
 656
 657   gMinuit->mnexcm("SIMPLEX",&aArg,0,iErrFlg);
 658   gMinuit->mnexcm("MIGRAD" ,&aArg,0,iErrFlg);
 659   gMinuit->mnpout(0,sName,cA,d1,d2,d3,iErrFlg);
 660   gMinuit->mnpout(1,sName,cB,d1,d2,d3,iErrFlg);
 661   gMinuit->mnpout(2,sName,cH,d1,d2,d3,iErrFlg);
 662   gMinuit->mnpout(3,sName,cG,d1,d2,d3,iErrFlg);
 663   gMinuit->mnpout(4,sName,cF,d1,d2,d3,iErrFlg);
 664   delete gMinuit;
 665
 666   Double_t i2 = cA*cB-cH*cH;                                       //quartic invariant : i2 > 0  ellipse, i2 < 0 hyperbola
 667   if(i2<=0) return kFALSE;
 668   Double_t aX = (cH*cF-cB*cG)/i2;                                  //x centre of the canonical section
 669   Double_t bY = (cH*cG-cA*cF)/i2;                                  //y centre of the canonical section
 670   Double_t alfa1 = TMath::ATan(2*cH/(cA-cB));                      //alpha = angle of rotation of the conical section
 671   if(alfa1<0) alfa1+=TMath::Pi();
 672   alfa1*=0.5;
 673 //  Double_t alfa2 = alfa1+TMath::Pi();
 674   Double_t phiref = TMath::ATan2(bY-fMipY,aX-fMipX);               //evaluate in a unique way the angle of rotation comparing it
 675   if(phiref<0) phiref+=TMath::TwoPi();                             //with the vector that points to the centre from the mip
 676   if(i2<0) phiref+=TMath::Pi();
 677   if(phiref>TMath::TwoPi()) phiref-=TMath::TwoPi();
 678
 679 //  Printf(" alfa1 %f",alfa1*TMath::RadToDeg());
 680 //  Printf(" alfa2 %f",alfa2*TMath::RadToDeg());
 681 //  Printf(" firef %f",phiref*TMath::RadToDeg());
 682 //  if(TMath::Abs(alfa1-phiref)<TMath::Abs(alfa2-phiref)) phiRec = alfa1; else phiRec = alfa2;
 683
 684 //  Printf("FitEllipse: phi reconstructed %f",phiRec*TMath::RadToDeg());
 685   phiRec=phiref;
 686   return kTRUE;
 687 //
 688 }
 689 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 690 Bool_t AliHMPIDRecon::FitFree(Double_t phiRec)
 691 {
 692 // Fit performed by minimizing RMS/sqrt(n) of the
 693 // photons reconstructed. First phi is fixed and theta
 694 // is fouond, then (th,ph) of the track
 695 // as free parameters
 696 // Arguments:    PhiRec phi of the track
 697 //   Returns:    none
 698   Double_t aArg=-1;  Int_t iErrFlg;                                                    //tmp vars for TMinuit
 699   if(!gMinuit) gMinuit = new TMinuit(2);                                               //init MINUIT with this number of parameters (5 params)
 700   gMinuit->mncler();                                                                   // reset Minuit list of paramters
 701   gMinuit->SetObjectFit((TObject*)this);  gMinuit->SetFCN(AliHMPIDRecon::FunMinPhot);  //set fit function
 702   gMinuit->mnexcm("SET PRI",&aArg,1,iErrFlg);                                          //suspend all printout from TMinuit
 703   gMinuit->mnexcm("SET NOW",&aArg,0,iErrFlg);                                          //suspend all warning printout from TMinuit
 704
 705   Double_t d1,d2,d3;
 706   TString sName;
 707   Double_t th,ph;
 708
 709   gMinuit->mnparm(0," theta ",  0.01,0.01,0,TMath::PiOver2(),iErrFlg);
 710   gMinuit->mnparm(1," phi   ",phiRec,0.01,0,TMath::TwoPi()  ,iErrFlg);
 711
 712   gMinuit->FixParameter(1);
 713   gMinuit->mnexcm("SIMPLEX" ,&aArg,0,iErrFlg);
 714   gMinuit->mnexcm("MIGRAD"  ,&aArg,0,iErrFlg);
 715   gMinuit->Release(1);
 716   gMinuit->mnexcm("MIGRAD"  ,&aArg,0,iErrFlg);
 717
 718   gMinuit->mnpout(0,sName,th,d1,d2,d3,iErrFlg);
 719   gMinuit->mnpout(1,sName,ph,d1,d2,d3,iErrFlg);
 720
 721   Double_t outPar[2] = {th,ph}; Double_t g; Double_t f;Int_t flag = 3;
 722   gMinuit->Eval(2, &g, f, outPar,flag);
 723
 724   SetTrkFit(th,ph);
 725
 726   return kTRUE;
 727 }
 728 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 729 Double_t AliHMPIDRecon::FunConSect(Double_t *c,Double_t x,Double_t y)
 730 {
 731   return c[0]*x*x+c[1]*y*y+2*c[2]*x*y+2*c[3]*x+2*c[4]*y+1;
 732 }
 733 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 734 void AliHMPIDRecon::FunMinEl(Int_t &/* */,Double_t* /* */,Double_t &f,Double_t *par,Int_t /* */)
 735 {
 736   AliHMPIDRecon *pRec=(AliHMPIDRecon*)gMinuit->GetObjectFit();
 737   Double_t minFun = 0;
 738   Int_t np = pRec->NClu();
 739   for(Int_t i=0;i<np;i++) {
 740     if(i==pRec->IdxMip()) continue;
 741     Double_t el = pRec->FunConSect(par,pRec->XClu(i),pRec->YClu(i));
 742     minFun +=el*el;
 743   }
 744   f = minFun;
 745 }
 746 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 747 void AliHMPIDRecon::FunMinPhot(Int_t &/* */,Double_t* /* */,Double_t &f,Double_t *par,Int_t iflag)
 748 {
 749   AliHMPIDRecon *pRec=(AliHMPIDRecon*)gMinuit->GetObjectFit();
 750   Double_t sizeCh = 0.5*fgkRadThick+fgkWinThick+fgkGapThick;
 751   Double_t thTrk = par[0];
 752   Double_t phTrk = par[1];
 753   Double_t xrad = pRec->MipX() - sizeCh*TMath::Tan(thTrk)*TMath::Cos(phTrk);
 754   Double_t yrad = pRec->MipY() - sizeCh*TMath::Tan(thTrk)*TMath::Sin(phTrk);
 755   pRec->SetRadXY(xrad,yrad);
 756   pRec->SetTrack(xrad,yrad,thTrk,phTrk);
 757
 758   Double_t meanCkov =0;
 759   Double_t meanCkov2=0;
 760   Double_t thetaCer,phiCer;
 761   Int_t nClAcc = 0;
 762   Int_t nClTot=pRec->NClu();
 763
 764   for(Int_t i=0;i<nClTot;i++) {
 765     if(!(pRec->ClCk(i))) continue;
 766     pRec->FindPhotCkov(pRec->XClu(i),pRec->YClu(i),thetaCer,phiCer);
 767     meanCkov  += thetaCer;
 768     meanCkov2 += thetaCer*thetaCer;
 769     nClAcc++;
 770   }
 771   if(nClAcc==0) {f=999;return;}
 772   meanCkov/=nClAcc;
 773   Double_t rms = (meanCkov2 - meanCkov*meanCkov*nClAcc)/nClAcc;
 774   if(rms<0) Printf(" rms2 = %f, strange!!!",rms);
 775   rms = TMath::Sqrt(rms);
 776   f = rms/TMath::Sqrt(nClAcc);
 777
 778
 779   if(iflag==3) {
 780     Printf("FunMinPhot before: photons candidates %i used %i",nClTot,nClAcc);
 781     nClAcc = 0;
 782     Double_t meanCkov1=0;
 783     Double_t meanCkov2=0;
 784     for(Int_t i=0;i<nClTot;i++) {
 785       if(!(pRec->ClCk(i))) continue;
 786       pRec->FindPhotCkov(pRec->XClu(i),pRec->YClu(i),thetaCer,phiCer);
 787       if(TMath::Abs(thetaCer-meanCkov)<2*rms) {
 788         meanCkov1 += thetaCer;
 789         meanCkov2 += thetaCer*thetaCer;
 790         nClAcc++;
 791       } else pRec->SetClCk(i,kFALSE);
 792     }
 793     meanCkov1/=nClAcc;
 794     Double_t rms2 = (meanCkov2 - meanCkov*meanCkov*nClAcc)/nClAcc;
 795     Printf("FunMinPhot after: photons candidates %i used %i thetaCer %f",nClTot,nClAcc,meanCkov1);
 796     pRec->SetCkovFit(meanCkov1);
 797     pRec->SetCkovSig2(rms2);
 798     pRec->SetNClu(nClAcc);
 799   }
 800 }//FunMinPhot()
 801 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 802 //
 803 // ended Hidden track algorithm....
 804 //
 805 //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++