]> git.uio.no Git - u/mrichter/AliRoot.git/blobdiff - TRD/AliTRDtrackerV1.cxx
changing the option for background cluster
[u/mrichter/AliRoot.git] / TRD / AliTRDtrackerV1.cxx
index 24b2699d233063419d8d45055cdfaed4ed49c60c..87fbcaa34cff3e39003b21383ccf6b9447cf220c 100644 (file)
@@ -1,18 +1,17 @@
-
 /**************************************************************************
- * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
- *                                                                        *
- * Author: The ALICE Off-line Project.                                    *
- * Contributors are mentioned in the code where appropriate.              *
- *                                                                        *
- * Permission to use, copy, modify and distribute this software and its   *
- * documentation strictly for non-commercial purposes is hereby granted   *
- * without fee, provided that the above copyright notice appears in all   *
- * copies and that both the copyright notice and this permission notice   *
- * appear in the supporting documentation. The authors make no claims     *
- * about the suitability of this software for any purpose. It is          *
- * provided "as is" without express or implied warranty.                  *
- **************************************************************************/
+* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
+*                                                                        *
+* Author: The ALICE Off-line Project.                                    *
+* Contributors are mentioned in the code where appropriate.              *
+*                                                                        *
+* Permission to use, copy, modify and distribute this software and its   *
+* documentation strictly for non-commercial purposes is hereby granted   *
+* without fee, provided that the above copyright notice appears in all   *
+* copies and that both the copyright notice and this permission notice   *
+* appear in the supporting documentation. The authors make no claims     *
+* about the suitability of this software for any purpose. It is          *
+* provided "as is" without express or implied warranty.                  *
+**************************************************************************/
 
 /* $Id$ */
 
 //                                                                           //
 ///////////////////////////////////////////////////////////////////////////////
 
-// #include <Riostream.h>
-// #include <stdio.h>
-// #include <string.h>
-
 #include <TBranch.h>
 #include <TDirectory.h>
 #include <TLinearFitter.h>
 #include <TTree.h>  
 #include <TClonesArray.h>
 #include <TTreeStream.h>
+#include <TGeoMatrix.h>
+#include <TGeoManager.h>
 
 #include "AliLog.h"
+#include "AliMathBase.h"
 #include "AliESDEvent.h"
 #include "AliGeomManager.h"
 #include "AliRieman.h"
@@ -51,6 +49,7 @@
 #include "AliTRDrecoParam.h"
 
 #include "AliTRDcluster.h" 
+#include "AliTRDdigitsParam.h"
 #include "AliTRDseedV1.h"
 #include "AliTRDtrackV1.h"
 #include "AliTRDtrackerV1.h"
 #include "AliTRDtrackingChamber.h"
 #include "AliTRDchamberTimeBin.h"
 
-
-
 ClassImp(AliTRDtrackerV1)
-
+ClassImp(AliTRDtrackerV1::AliTRDLeastSquare)
+ClassImp(AliTRDtrackerV1::AliTRDtrackFitterRieman)
 
 const  Float_t  AliTRDtrackerV1::fgkMinClustersInTrack =  0.5;  //
 const  Float_t  AliTRDtrackerV1::fgkLabelFraction      =  0.8;  //
@@ -69,40 +67,65 @@ const  Double_t AliTRDtrackerV1::fgkMaxChi2            = 12.0;  //
 const  Double_t AliTRDtrackerV1::fgkMaxSnp             =  0.95; // Maximum local sine of the azimuthal angle
 const  Double_t AliTRDtrackerV1::fgkMaxStep            =  2.0;  // Maximal step size in propagation 
 Double_t AliTRDtrackerV1::fgTopologicQA[kNConfigs] = {
-  0.1112, 0.1112, 0.1112, 0.0786, 0.0786,
+  0.5112, 0.5112, 0.5112, 0.0786, 0.0786,
   0.0786, 0.0786, 0.0579, 0.0579, 0.0474,
   0.0474, 0.0408, 0.0335, 0.0335, 0.0335
-};
+};  
+const Double_t AliTRDtrackerV1::fgkX0[kNPlanes]    = {
+  300.2, 312.8, 325.4, 338.0, 350.6, 363.2};
 Int_t AliTRDtrackerV1::fgNTimeBins = 0;
-TTreeSRedirector *AliTRDtrackerV1::fgDebugStreamer = 0x0;
-AliRieman* AliTRDtrackerV1::fgRieman = 0x0;
-TLinearFitter* AliTRDtrackerV1::fgTiltedRieman = 0x0;
-TLinearFitter* AliTRDtrackerV1::fgTiltedRiemanConstrained = 0x0;
+AliRieman* AliTRDtrackerV1::fgRieman = NULL;
+TLinearFitter* AliTRDtrackerV1::fgTiltedRieman = NULL;
+TLinearFitter* AliTRDtrackerV1::fgTiltedRiemanConstrained = NULL;
 
 //____________________________________________________________________
-AliTRDtrackerV1::AliTRDtrackerV1() 
+AliTRDtrackerV1::AliTRDtrackerV1(AliTRDReconstructor *rec
   :AliTracker()
-  ,fGeom(new AliTRDgeometry())
-  ,fClusters(0x0)
-  ,fTracklets(0x0)
-  ,fTracks(0x0)
+  ,fkReconstructor(NULL)
+  ,fkRecoParam(NULL)
+  ,fGeom(NULL)
+  ,fClusters(NULL)
+  ,fTracklets(NULL)
+  ,fTracks(NULL)
+  ,fTracksESD(NULL)
   ,fSieveSeeding(0)
 {
   //
   // Default constructor.
   // 
-  if (!AliTRDcalibDB::Instance()) {
-    AliFatal("Could not get calibration object");
+  
+  SetReconstructor(rec); // initialize reconstructor
+
+  // initialize geometry
+  if(!AliGeomManager::GetGeometry()){
+    AliFatal("Could not get geometry.");
+  }
+  fGeom = new AliTRDgeometry();
+  fGeom->CreateClusterMatrixArray();
+  TGeoHMatrix *matrix = NULL;
+  Double_t loc[] = {0., 0., 0.};
+  Double_t glb[] = {0., 0., 0.};
+  for(Int_t ily=kNPlanes; ily--;){
+    Int_t ism = 0;
+    while(!(matrix = fGeom->GetClusterMatrix(AliTRDgeometry::GetDetector(ily, 2, ism)))) ism++;
+    if(!matrix){
+      AliError(Form("Could not get transformation matrix for layer %d. Use default.", ily));
+      fR[ily] = fgkX0[ily];
+      continue;
+    }
+    matrix->LocalToMaster(loc, glb);
+    fR[ily] = glb[0]+ AliTRDgeometry::AnodePos()-.5*AliTRDgeometry::AmThick() - AliTRDgeometry::DrThick();
   }
-  fgNTimeBins = AliTRDcalibDB::Instance()->GetNumberOfTimeBins();
 
-  for (Int_t isector = 0; isector < AliTRDgeometry::kNsect; isector++) new(&fTrSec[isector]) AliTRDtrackingSector(fGeom, isector);
+  // initialize cluster containers
+  for (Int_t isector = 0; isector < AliTRDgeometry::kNsector; isector++) new(&fTrSec[isector]) AliTRDtrackingSector(fGeom, isector);
   
-  if(AliTRDReconstructor::StreamLevel() > 1){
-    TDirectory *savedir = gDirectory; 
-    fgDebugStreamer    = new TTreeSRedirector("TRD.TrackerDebug.root");
-    savedir->cd();
-  }
+  // initialize arrays
+  memset(fTrackQuality, 0, kMaxTracksStack*sizeof(Double_t));
+  memset(fSeedLayer, 0, kMaxTracksStack*sizeof(Int_t));
+  memset(fSeedTB, 0, kNSeedPlanes*sizeof(AliTRDchamberTimeBin*));
+  fTracksESD = new TClonesArray("AliESDtrack", 2*kMaxTracksStack);
+  fTracksESD->SetOwner();
 }
 
 //____________________________________________________________________
@@ -111,14 +134,17 @@ AliTRDtrackerV1::~AliTRDtrackerV1()
   //
   // Destructor
   //
-       
-  if(fgDebugStreamer) delete fgDebugStreamer;
-  if(fgRieman) delete fgRieman;
-  if(fgTiltedRieman) delete fgTiltedRieman;
-  if(fgTiltedRiemanConstrained) delete fgTiltedRiemanConstrained;
+  
+  if(fgRieman) delete fgRieman; fgRieman = NULL;
+  if(fgTiltedRieman) delete fgTiltedRieman; fgTiltedRieman = NULL;
+  if(fgTiltedRiemanConstrained) delete fgTiltedRiemanConstrained; fgTiltedRiemanConstrained = NULL;
+  for(Int_t isl =0; isl<kNSeedPlanes; isl++) if(fSeedTB[isl]) delete fSeedTB[isl];
+  if(fTracksESD){ fTracksESD->Delete(); delete fTracksESD; }
   if(fTracks) {fTracks->Delete(); delete fTracks;}
   if(fTracklets) {fTracklets->Delete(); delete fTracklets;}
-  if(fClusters) {fClusters->Delete(); delete fClusters;}
+  if(fClusters) {
+    fClusters->Delete(); delete fClusters;
+  }
   if(fGeom) delete fGeom;
 }
 
@@ -140,19 +166,19 @@ Int_t AliTRDtrackerV1::Clusters2Tracks(AliESDEvent *esd)
   //    See AliTRDtrackerV1::Clusters2TracksSM() for details.
   //
 
-  if(!AliTRDReconstructor::RecoParam()){
+  if(!fkRecoParam){
     AliError("Reconstruction configuration not initialized. Call first AliTRDReconstructor::SetRecoParam().");
     return 0;
   }
-       
+  
   //AliInfo("Start Track Finder ...");
   Int_t ntracks = 0;
-  for(int ism=0; ism<AliTRDgeometry::kNsect; ism++){
+  for(int ism=0; ism<AliTRDgeometry::kNsector; ism++){
     // for(int ism=1; ism<2; ism++){
     //AliInfo(Form("Processing supermodule %i ...", ism));
     ntracks += Clusters2TracksSM(ism, esd);
   }
-  AliInfo(Form("Number of found tracks : %d", ntracks));
+  AliInfo(Form("Number of tracks: !TRDin[%d]", ntracks));
   return ntracks;
 }
 
@@ -161,51 +187,42 @@ Int_t AliTRDtrackerV1::Clusters2Tracks(AliESDEvent *esd)
 Bool_t AliTRDtrackerV1::GetTrackPoint(Int_t index, AliTrackPoint &p) const
 {
   //AliInfo(Form("Asking for tracklet %d", index));
-       
-  if(index<0) return kFALSE;
-  AliTRDseedV1 *tracklet = 0x0; 
-  if(!(tracklet = (AliTRDseedV1*)fTracklets->UncheckedAt(index))) return kFALSE;
-       
+  
+  // reset position of the point before using it
+  p.SetXYZ(0., 0., 0.);
+  AliTRDseedV1 *tracklet = GetTracklet(index); 
+  if (!tracklet) return kFALSE;
+
   // get detector for this tracklet
-  AliTRDcluster *cl = 0x0;
-  Int_t ic = 0; do; while(!(cl = tracklet->GetClusters(ic++)));         
-  Int_t  idet     = cl->GetDetector();
-               
+  Int_t det = tracklet->GetDetector();
+  Int_t sec = fGeom->GetSector(det);
+  Double_t alpha = (sec+.5)*AliTRDgeometry::GetAlpha(),
+           sinA  = TMath::Sin(alpha),
+           cosA  = TMath::Cos(alpha);
   Double_t local[3];
-  local[0] = tracklet->GetX0(); 
-  local[1] = tracklet->GetYfit(0);
-  local[2] = tracklet->GetZfit(0);
+  local[0] = tracklet->GetX(); 
+  local[1] = tracklet->GetY();
+  local[2] = tracklet->GetZ();
   Double_t global[3];
-  fGeom->RotateBack(idet, local, global);
-  p.SetXYZ(global[0],global[1],global[2]);
-       
-       
+  fGeom->RotateBack(det, local, global);
+
+  Double_t cov2D[3]; Float_t cov[6];
+  tracklet->GetCovAt(local[0], cov2D);
+  cov[0] = cov2D[0]*sinA*sinA;
+  cov[1] =-cov2D[0]*sinA*cosA;
+  cov[2] =-cov2D[1]*sinA;
+  cov[3] = cov2D[0]*cosA*cosA;
+  cov[4] = cov2D[1]*cosA;
+  cov[5] = cov2D[2];
+  // store the global position of the tracklet and its covariance matrix in the track point 
+  p.SetXYZ(global[0],global[1],global[2], cov);
+  
   // setting volume id
-  AliGeomManager::ELayerID iLayer = AliGeomManager::kTRD1;
-  switch (fGeom->GetPlane(idet)) {
-  case 0:
-    iLayer = AliGeomManager::kTRD1;
-    break;
-  case 1:
-    iLayer = AliGeomManager::kTRD2;
-    break;
-  case 2:
-    iLayer = AliGeomManager::kTRD3;
-    break;
-  case 3:
-    iLayer = AliGeomManager::kTRD4;
-    break;
-  case 4:
-    iLayer = AliGeomManager::kTRD5;
-    break;
-  case 5:
-    iLayer = AliGeomManager::kTRD6;
-    break;
-  };
-  Int_t    modId = fGeom->GetSector(idet) * fGeom->Ncham() + fGeom->GetChamber(idet);
+  AliGeomManager::ELayerID iLayer = AliGeomManager::ELayerID(AliGeomManager::kTRD1+fGeom->GetLayer(det));
+  Int_t    modId = fGeom->GetSector(det) * AliTRDgeometry::kNstack + fGeom->GetStack(det);
   UShort_t volid = AliGeomManager::LayerToVolUID(iLayer, modId);
   p.SetVolumeID(volid);
-               
+    
   return kTRUE;
 }
 
@@ -222,197 +239,224 @@ TLinearFitter* AliTRDtrackerV1::GetTiltedRiemanFitterConstraint()
   if(!fgTiltedRiemanConstrained) fgTiltedRiemanConstrained = new TLinearFitter(2, "hyp2");
   return fgTiltedRiemanConstrained;
 }
-       
+  
 //____________________________________________________________________ 
 AliRieman* AliTRDtrackerV1::GetRiemanFitter()
 {
-  if(!fgRieman) fgRieman = new AliRieman(AliTRDtrackingChamber::kNTimeBins * AliTRDgeometry::kNplan);
+  if(!fgRieman) fgRieman = new AliRieman(AliTRDseedV1::kNtb * AliTRDgeometry::kNlayer);
   return fgRieman;
 }
-       
+  
 //_____________________________________________________________________________
 Int_t AliTRDtrackerV1::PropagateBack(AliESDEvent *event) 
 {
-  //
-  // Gets seeds from ESD event. The seeds are AliTPCtrack's found and
-  // backpropagated by the TPC tracker. Each seed is first propagated 
-  // to the TRD, and then its prolongation is searched in the TRD.
-  // If sufficiently long continuation of the track is found in the TRD
-  // the track is updated, otherwise it's stored as originaly defined 
-  // by the TPC tracker.   
-  //  
-
-  // Calibration monitor
-  AliTRDCalibraFillHisto *calibra = AliTRDCalibraFillHisto::Instance();
-  if (!calibra) AliInfo("Could not get Calibra instance\n");
-  
-  Int_t   found    = 0;     // number of tracks found
-  Float_t foundMin = 20.0;
-       
-  Int_t    nSeed   = event->GetNumberOfTracks();
-  if(!nSeed){
-    // run stand alone tracking
-    if (AliTRDReconstructor::SeedingOn()) Clusters2Tracks(event);
+// Propagation of ESD tracks from TPC to TOF detectors and building of the TRD track. For building
+// a TRD track an ESD track is used as seed. The informations obtained on the TRD track (measured points,
+// covariance, PID, etc.) are than used to update the corresponding ESD track.
+// Each track seed is first propagated to the geometrical limit of the TRD detector. 
+// Its prolongation is searched in the TRD and if corresponding clusters are found tracklets are 
+// constructed out of them (see AliTRDseedV1::AttachClusters()) and the track is updated. 
+// Otherwise the ESD track is left unchanged.
+// 
+// The following steps are performed:
+// 1. Selection of tracks based on the variance in the y-z plane.
+// 2. Propagation to the geometrical limit of the TRD volume. If track propagation fails the AliESDtrack::kTRDStop is set.
+// 3. Prolongation inside the fiducial volume (see AliTRDtrackerV1::FollowBackProlongation()) and marking
+// the following status bits:
+//   - AliESDtrack::kTRDin - if the tracks enters the TRD fiducial volume
+//   - AliESDtrack::kTRDStop - if the tracks fails propagation
+//   - AliESDtrack::kTRDbackup - if the tracks fulfills chi2 conditions and qualify for refitting
+// 4. Writting to friends, PID, MC label, quality etc. Setting status bit AliESDtrack::kTRDout.
+// 5. Propagation to TOF. If track propagation fails the AliESDtrack::kTRDStop is set.
+//  
+
+  if(!fClusters || !fClusters->GetEntriesFast()){ 
+    AliInfo("No TRD clusters");
     return 0;
   }
-       
-  Float_t *quality = new Float_t[nSeed];
-  Int_t   *index   = new Int_t[nSeed];
-  for (Int_t iSeed = 0; iSeed < nSeed; iSeed++) {
-    AliESDtrack *seed = event->GetTrack(iSeed);
-    Double_t covariance[15];
-    seed->GetExternalCovariance(covariance);
-    quality[iSeed] = covariance[0] + covariance[2];
-  }
-  // Sort tracks according to covariance of local Y and Z
-  TMath::Sort(nSeed,quality,index,kFALSE);
-       
-  // Backpropagate all seeds
+  AliTRDCalibraFillHisto *calibra = AliTRDCalibraFillHisto::Instance(); // Calibration monitor
+  if (!calibra) AliInfo("Could not get Calibra instance");
+  if (!fgNTimeBins) fgNTimeBins = fkReconstructor->GetNTimeBins(); 
+
+  // Define scalers
+  Int_t nFound   = 0, // number of tracks found
+        nBacked  = 0, // number of tracks backed up for refit
+        nSeeds   = 0, // total number of ESD seeds
+        nTRDseeds= 0, // number of seeds in the TRD acceptance
+        nTPCseeds= 0; // number of TPC seeds
+  Float_t foundMin = 20.0;
+  
+  Float_t *quality = NULL;
+  Int_t   *index   = NULL;
+  nSeeds   = event->GetNumberOfTracks();
+  // Sort tracks according to quality 
+  // (covariance in the yz plane)
+  if(nSeeds){  
+    quality = new Float_t[nSeeds];
+    index   = new Int_t[nSeeds];
+    for (Int_t iSeed = nSeeds; iSeed--;) {
+      AliESDtrack *seed = event->GetTrack(iSeed);
+      Double_t covariance[15];
+      seed->GetExternalCovariance(covariance);
+      quality[iSeed] = covariance[0] + covariance[2];
+    }
+    TMath::Sort(nSeeds, quality, index,kFALSE);
+  }
+  
+  // Propagate all seeds
   Int_t   expectedClr;
   AliTRDtrackV1 track;
-  for (Int_t iSeed = 0; iSeed < nSeed; iSeed++) {
-       
+  for (Int_t iSeed = 0; iSeed < nSeeds; iSeed++) {
+  
     // Get the seeds in sorted sequence
     AliESDtrack *seed = event->GetTrack(index[iSeed]);
-       
+    Float_t p4  = seed->GetC(seed->GetBz());
+  
     // Check the seed status
     ULong_t status = seed->GetStatus();
     if ((status & AliESDtrack::kTPCout) == 0) continue;
     if ((status & AliESDtrack::kTRDout) != 0) continue;
-       
-    // Do the back prolongation
-    Int_t   lbl         = seed->GetLabel();
+
+    // Propagate to the entrance in the TRD mother volume
     new(&track) AliTRDtrackV1(*seed);
-    //track->Print();
-    track.SetSeedLabel(lbl);
-    seed->UpdateTrackParams(&track, AliESDtrack::kTRDbackup); // Make backup
-    Float_t p4          = track.GetC();
-    if((expectedClr = FollowBackProlongation(track))){
+    if(AliTRDgeometry::GetXtrdBeg() > (fgkMaxStep + track.GetX()) && !PropagateToX(track, AliTRDgeometry::GetXtrdBeg(), fgkMaxStep)){ 
+      seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+      continue;
+    }    
+    if(!AdjustSector(&track)){
+      seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+      continue;
+    }
+    if(TMath::Abs(track.GetSnp()) > fgkMaxSnp) {
+      seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+      continue;
+    }
+
+    nTPCseeds++;
+
+    // store track status at TRD entrance
+    seed->UpdateTrackParams(&track, AliESDtrack::kTRDbackup);
+
+    // prepare track and do propagation in the TRD
+    track.SetReconstructor(fkReconstructor);
+    track.SetKink(Bool_t(seed->GetKinkIndex(0)));
+    track.SetPrimary(status & AliESDtrack::kTPCin);
+    expectedClr = FollowBackProlongation(track);
+    // check if track entered the TRD fiducial volume
+    if(track.GetTrackIn()){ 
+      seed->UpdateTrackParams(&track, AliESDtrack::kTRDin);
+      nTRDseeds++;
+    }
+    // check if track was stopped in the TRD
+    if (expectedClr<0){      
+      seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+      continue;
+    }
+
+    if(expectedClr){
+      nFound++;  
       // computes PID for track
       track.CookPID();
       // update calibration references using this track
       if(calibra->GetHisto2d()) calibra->UpdateHistogramsV1(&track);
+      // save calibration object
+      if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0) { 
+        AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(track);
+        calibTrack->SetOwner();
+        seed->AddCalibObject(calibTrack);
+      }
+      //update ESD track
+      seed->UpdateTrackParams(&track, AliESDtrack::kTRDout);
+      track.UpdateESDtrack(seed);
     }
 
-    if ((TMath::Abs(track.GetC() - p4) / TMath::Abs(p4) < 0.2) ||
-       (track.Pt() > 0.8)) {
-      //
+    if ((TMath::Abs(track.GetC(track.GetBz()) - p4) / TMath::Abs(p4) < 0.2) ||(track.Pt() > 0.8)) {
+
       // Make backup for back propagation
-      //
       Int_t foundClr = track.GetNumberOfClusters();
       if (foundClr >= foundMin) {
-       //AliInfo(Form("Making backup track ncls [%d]...", foundClr));
-       track.CookdEdx();
-       track.CookdEdxTimBin(seed->GetID());
-       track.CookLabel(1. - fgkLabelFraction);
-       if(track.GetBackupTrack()) UseClusters(track.GetBackupTrack());
-                               
-
-       // Sign only gold tracks
-       if (track.GetChi2() / track.GetNumberOfClusters() < 4) {
-         if ((seed->GetKinkIndex(0)      ==   0) &&
-             (track.Pt()                <  1.5)) UseClusters(&track);
-       }
-       Bool_t isGold = kFALSE;
-       
-       // Full gold track
-       if (track.GetChi2() / track.GetNumberOfClusters() < 5) {
-         if (track.GetBackupTrack()) seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
-
-         isGold = kTRUE;
-       }
-       
-       // Almost gold track
-       if ((!isGold)  && (track.GetNCross() == 0) &&
-           (track.GetChi2() / track.GetNumberOfClusters()  < 7)) {
-         //seed->UpdateTrackParams(track, AliESDtrack::kTRDbackup);
-         if (track.GetBackupTrack()) seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
-                                       
-         isGold = kTRUE;
-       }
-                               
-       if ((!isGold) && (track.GetBackupTrack())) {
-         if ((track.GetBackupTrack()->GetNumberOfClusters() > foundMin) && ((track.GetBackupTrack()->GetChi2()/(track.GetBackupTrack()->GetNumberOfClusters()+1)) < 7)) {
-           seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
-           isGold = kTRUE;
-         }
-       }
-       
-       //if ((track->StatusForTOF() > 0) && (track->GetNCross() == 0) && (Float_t(track->GetNumberOfClusters()) / Float_t(track->GetNExpected())  > 0.4)) {
-       //seed->UpdateTrackParams(track->GetBackupTrack(), AliESDtrack::kTRDbackup);
-       //}
+        track.CookLabel(1. - fgkLabelFraction);
+        //if(track.GetBackupTrack()) UseClusters(track.GetBackupTrack());
+
+        // Sign only gold tracks
+        if (track.GetChi2() / track.GetNumberOfClusters() < 4) {
+          //if ((seed->GetKinkIndex(0)      ==   0) && (track.Pt() <  1.5)) UseClusters(&track);
+        }
+        Bool_t isGold = kFALSE;
+  
+        // Full gold track
+        if (track.GetChi2() / track.GetNumberOfClusters() < 5) {
+          if (track.GetBackupTrack()) seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
+          nBacked++;
+          isGold = kTRUE;
+        }
+  
+        // Almost gold track
+        if ((!isGold)  && (track.GetNCross() == 0) &&  (track.GetChi2() / track.GetNumberOfClusters()  < 7)) {
+          //seed->UpdateTrackParams(track, AliESDtrack::kTRDbackup);
+          if (track.GetBackupTrack()) seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
+          nBacked++;
+          isGold = kTRUE;
+        }
+        
+        if ((!isGold) && (track.GetBackupTrack())) {
+          if ((track.GetBackupTrack()->GetNumberOfClusters() > foundMin) && ((track.GetBackupTrack()->GetChi2()/(track.GetBackupTrack()->GetNumberOfClusters()+1)) < 7)) {
+            seed->UpdateTrackParams(track.GetBackupTrack(),AliESDtrack::kTRDbackup);
+            nBacked++;
+            isGold = kTRUE;
+          }
+        }
       }
     }
-
-    // Propagation to the TOF (I.Belikov)
-    if (track.GetStop() == kFALSE) {
-      Double_t xtof  = 371.0;
-      Double_t xTOF0 = 370.0;
-               
-      Double_t c2    = track.GetSnp() + track.GetC() * (xtof - track.GetX());
-      if (TMath::Abs(c2) >= 0.99) continue;
-                       
-      PropagateToX(track, xTOF0, fgkMaxStep);
-       
-      // Energy losses taken to the account - check one more time
-      c2 = track.GetSnp() + track.GetC() * (xtof - track.GetX());
-      if (TMath::Abs(c2) >= 0.99) continue;
-                       
-      //if (!PropagateToX(*track,xTOF0,fgkMaxStep)) {
-      //       fHBackfit->Fill(7);
-      //delete track;
-      //       continue;
-      //}
-       
-      Double_t ymax = xtof * TMath::Tan(0.5 * AliTRDgeometry::GetAlpha());
-      Double_t y;
-      track.GetYAt(xtof,GetBz(),y);
-      if (y >  ymax) {
-       if (!track.Rotate( AliTRDgeometry::GetAlpha())) continue;
-      }else if (y < -ymax) {
-       if (!track.Rotate(-AliTRDgeometry::GetAlpha())) continue;
+    
+    // Propagation to the TOF
+    if(!(seed->GetStatus()&AliESDtrack::kTRDStop)) {
+      Int_t sm = track.GetSector();
+      // default value in case we have problems with the geometry.
+      Double_t xtof  = 371.; 
+      //Calculate radial position of the beginning of the TOF
+      //mother volume. In order to avoid mixing of the TRD 
+      //and TOF modules some hard values are needed. This are:
+      //1. The path to the TOF module.
+      //2. The width of the TOF (29.05 cm)
+      //(with the help of Annalisa de Caro Mar-17-2009)
+      if(gGeoManager){
+        gGeoManager->cd(Form("/ALIC_1/B077_1/BSEGMO%d_1/BTOF%d_1", sm, sm));
+        TGeoHMatrix *m = NULL;
+        Double_t loc[]={0., 0., -.5*29.05}, glob[3];
+        
+        if((m=gGeoManager->GetCurrentMatrix())){
+          m->LocalToMaster(loc, glob);
+          xtof = TMath::Sqrt(glob[0]*glob[0]+glob[1]*glob[1]);
+        }
       }
-                                       
-      if (track.PropagateTo(xtof)) {
-       seed->UpdateTrackParams(&track, AliESDtrack::kTRDout);
-       track.UpdateESDtrack(seed);
-                               
-       // Add TRD track to ESDfriendTrack
-       if (AliTRDReconstructor::StreamLevel() > 0 /*&& quality TODO*/){ 
-         AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(track);
-         calibTrack->SetOwner();
-         seed->AddCalibObject(calibTrack);
-       }
-       found++;
+      if(xtof > (fgkMaxStep + track.GetX()) && !PropagateToX(track, xtof, fgkMaxStep)){ 
+        seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+        continue;
       }
-    } else {                   
-      if ((track.GetNumberOfClusters() >              15) &&
-         (track.GetNumberOfClusters() > 0.5*expectedClr)) {
-       seed->UpdateTrackParams(&track, AliESDtrack::kTRDout);
-       
-       track.UpdateESDtrack(seed);
-                               
-       // Add TRD track to ESDfriendTrack
-       if (AliTRDReconstructor::StreamLevel() > 0 /*&& quality TODO*/){ 
-         AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(track);
-         calibTrack->SetOwner();
-         seed->AddCalibObject(calibTrack);
-       }
-       found++;
+      if(!AdjustSector(&track)){ 
+        seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+        continue;
+      }
+      if(TMath::Abs(track.GetSnp()) > fgkMaxSnp){ 
+        seed->UpdateTrackParams(&track, AliESDtrack::kTRDStop);
+        continue;
       }
+      //seed->UpdateTrackParams(&track, AliESDtrack::kTRDout);
+      // TODO obsolete - delete
+      seed->SetTRDQuality(track.StatusForTOF()); 
     }
-       
-    seed->SetTRDQuality(track.StatusForTOF());
     seed->SetTRDBudget(track.GetBudget(0));
   }
-       
+  if(index) delete [] index;
+  if(quality) delete [] quality;
 
-  AliInfo(Form("Number of seeds: %d", nSeed));
-  AliInfo(Form("Number of back propagated TRD tracks: %d", found));
-                       
-  delete [] index;
-  delete [] quality;
-       
+  AliInfo(Form("Number of seeds: TPCout[%d] TRDin[%d]", nTPCseeds, nTRDseeds));
+  AliInfo(Form("Number of tracks: TRDout[%d] TRDbackup[%d]", nFound, nBacked));
+
+  // run stand alone tracking
+  if (fkReconstructor->IsSeeding()) Clusters2Tracks(event);
+  
   return 0;
 }
 
@@ -432,19 +476,25 @@ Int_t AliTRDtrackerV1::RefitInward(AliESDEvent *event)
   Int_t   found    = 0; // contor for updated TRD tracks
   
   
+  if(!fClusters || !fClusters->GetEntriesFast()){ 
+    AliInfo("No TRD clusters");
+    return 0;
+  }
   AliTRDtrackV1 track;
   for (Int_t itrack = 0; itrack < event->GetNumberOfTracks(); itrack++) {
     AliESDtrack *seed = event->GetTrack(itrack);
-    new(&track) AliTRDtrackV1(*seed);
+    ULong_t status = seed->GetStatus();
 
+    new(&track) AliTRDtrackV1(*seed);
     if (track.GetX() < 270.0) {
       seed->UpdateTrackParams(&track, AliESDtrack::kTRDbackup);
       continue;
     }
 
-    ULong_t status = seed->GetStatus();
-    if((status & AliESDtrack::kTRDout) == 0) continue;
-    if((status & AliESDtrack::kTRDin)  != 0) continue;
+    // reject tracks which failed propagation in the TRD or
+    // are produced by the TRD stand alone tracker
+    if(!(status & AliESDtrack::kTRDout)) continue;
+    if(!(status & AliESDtrack::kTRDin)) continue;
     nseed++; 
 
     track.ResetCovariance(50.0);
@@ -453,27 +503,36 @@ Int_t AliTRDtrackerV1::RefitInward(AliESDEvent *event)
     Bool_t kUPDATE = kFALSE;
     Double_t xTPC = 250.0;
     if(FollowProlongation(track)){     
+      // Update the friend track
+      if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0){ 
+        TObject *o = NULL; Int_t ic = 0;
+        AliTRDtrackV1 *calibTrack = NULL; 
+        while((o = seed->GetCalibObject(ic++))){
+          if(!(calibTrack = dynamic_cast<AliTRDtrackV1*>(o))) continue;
+          calibTrack->SetTrackOut(&track);
+        }
+      }
+
       // Prolongate to TPC
       if (PropagateToX(track, xTPC, fgkMaxStep)) { //  -with update
-       seed->UpdateTrackParams(&track, AliESDtrack::kTRDrefit);
-       found++;
-       kUPDATE = kTRUE;
+        seed->UpdateTrackParams(&track, AliESDtrack::kTRDrefit);
+        found++;
+        kUPDATE = kTRUE;
       }
-    }   
-               
+    }
+    
     // Prolongate to TPC without update
     if(!kUPDATE) {
       AliTRDtrackV1 tt(*seed);
-      if (PropagateToX(tt, xTPC, fgkMaxStep)) seed->UpdateTrackParams(&tt, AliESDtrack::kTRDrefit);
+      if (PropagateToX(tt, xTPC, fgkMaxStep)) seed->UpdateTrackParams(&tt, AliESDtrack::kTRDbackup);
     }
   }
-  AliInfo(Form("Number of loaded seeds: %d",nseed));
-  AliInfo(Form("Number of found tracks from loaded seeds: %d",found));
+  AliInfo(Form("Number of seeds: TRDout[%d]", nseed));
+  AliInfo(Form("Number of tracks: TRDrefit[%d]", found));
   
   return 0;
 }
 
-
 //____________________________________________________________________
 Int_t AliTRDtrackerV1::FollowProlongation(AliTRDtrackV1 &t)
 {
@@ -502,23 +561,25 @@ Int_t AliTRDtrackerV1::FollowProlongation(AliTRDtrackV1 &t)
   //
   
   Int_t    nClustersExpected = 0;
-  Int_t lastplane = 5; //GetLastPlane(&t);
-  for (Int_t iplane = lastplane; iplane >= 0; iplane--) {
-    Int_t   index   = 0;
+  for (Int_t iplane = kNPlanes; iplane--;) {
+    Int_t   index(-1);
     AliTRDseedV1 *tracklet = GetTracklet(&t, iplane, index);
+    AliDebug(2, Form("Tracklet[%p] ly[%d] idx[%d]", (void*)tracklet, iplane, index));
     if(!tracklet) continue;
-    if(!tracklet->IsOK()) AliWarning("tracklet not OK");
-               
-    Double_t x  = tracklet->GetX0();
+    if(!tracklet->IsOK()){ 
+      AliDebug(1, Form("Tracklet Det[%d] !OK", tracklet->GetDetector()));
+      continue;
+    }
+    Double_t x  = tracklet->GetX();//GetX0();
     // reject tracklets which are not considered for inward refit
     if(x > t.GetX()+fgkMaxStep) continue;
 
     // append tracklet to track
-    t.SetTracklet(tracklet, iplane, index);
-               
+    t.SetTracklet(tracklet, index);
+    
     if (x < (t.GetX()-fgkMaxStep) && !PropagateToX(t, x+fgkMaxStep, fgkMaxStep)) break;
     if (!AdjustSector(&t)) break;
-     
+    
     // Start global position
     Double_t xyz0[3];
     t.GetXYZ(xyz0);
@@ -530,40 +591,55 @@ Int_t AliTRDtrackerV1::FollowProlongation(AliTRDtrackV1 &t)
     xyz1[0] =  x * TMath::Cos(alpha) - y * TMath::Sin(alpha);
     xyz1[1] =  x * TMath::Sin(alpha) + y * TMath::Cos(alpha);
     xyz1[2] =  z;
-                               
-    // Get material budget
-    Double_t param[7];
-    AliTracker::MeanMaterialBudget(xyz0, xyz1, param);
-    Double_t xrho= param[0]*param[4];
-    Double_t xx0 = param[1]; // Get mean propagation parameters
+        
+    Double_t length = TMath::Sqrt(
+      (xyz0[0]-xyz1[0])*(xyz0[0]-xyz1[0]) +
+      (xyz0[1]-xyz1[1])*(xyz0[1]-xyz1[1]) +
+      (xyz0[2]-xyz1[2])*(xyz0[2]-xyz1[2])
+    );
+    if(length>0.){
+      // Get material budget
+      Double_t param[7];
+      if(AliTracker::MeanMaterialBudget(xyz0, xyz1, param)<=0.) break;
+      Double_t xrho= param[0]*param[4];
+      Double_t xx0 = param[1]; // Get mean propagation parameters
+  
+      // Propagate and update          
+      t.PropagateTo(x, xx0, xrho);
+      if (!AdjustSector(&t)) break;
+    }
 
-    // Propagate and update            
-    t.PropagateTo(x, xx0, xrho);
-    if (!AdjustSector(&t)) break;
-         
-    Double_t maxChi2 = t.GetPredictedChi2(tracklet);
-    if (maxChi2 < 1e+10 && t.Update(tracklet, maxChi2)){ 
+    Double_t cov[3]; tracklet->GetCovAt(x, cov);
+    Double_t p[2] = { tracklet->GetY(), tracklet->GetZ()};
+    Double_t chi2 = ((AliExternalTrackParam)t).GetPredictedChi2(p, cov);
+    if (chi2 < 1e+10 && ((AliExternalTrackParam&)t).Update(p, cov)){ 
+      // Register info to track
+      t.SetNumberOfClusters();
+      t.UpdateChi2(chi2);
       nClustersExpected += tracklet->GetN();
     }
   }
 
-  if(AliTRDReconstructor::StreamLevel() > 1){
+  if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 1){
     Int_t index;
-    for(int iplane=0; iplane<6; iplane++){
+    for(int iplane=0; iplane<AliTRDgeometry::kNlayer; iplane++){
       AliTRDseedV1 *tracklet = GetTracklet(&t, iplane, index);
       if(!tracklet) continue;
-      t.SetTracklet(tracklet, iplane, index);
+      t.SetTracklet(tracklet, index);
     }
 
-    Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
-    TTreeSRedirector &cstreamer = *fgDebugStreamer;
-    cstreamer << "FollowProlongation"
-             << "EventNumber=" << eventNumber
-             << "ncl="                                 << nClustersExpected
-             << "track.="                      << &t
-             << "\n";
+    if(fkReconstructor->IsDebugStreaming()){
+      Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
+      TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
+      AliTRDtrackV1 track(t);
+      track.SetOwner();
+      cstreamer << "FollowProlongation"
+          << "EventNumber="    << eventNumber
+          << "ncl="                                    << nClustersExpected
+          << "track.="                 << &track
+          << "\n";
+    }
   }
-
   return nClustersExpected;
 
 }
@@ -571,159 +647,385 @@ Int_t AliTRDtrackerV1::FollowProlongation(AliTRDtrackV1 &t)
 //_____________________________________________________________________________
 Int_t AliTRDtrackerV1::FollowBackProlongation(AliTRDtrackV1 &t)
 {
-  // Extrapolates the TRD track in the TOF direction.
-  //
-  // Parameters
-  //   t : the TRD track which has to be extrapolated
-  // 
-  // Output
-  //   number of clusters attached to the track
-  //
-  // Detailed description
-  //
-  // Starting from current radial position of track <t> this function
-  // extrapolates the track through the 6 TRD layers. The following steps
-  // are being performed for each plane:
-  // 1. prepare track:
-  //   a. get plane limits in the local x direction
-  //   b. check crossing sectors 
-  //   c. check track inclination
-  // 2. build tracklet (see AliTRDseed::AttachClusters() for details)
-  // 3. evaluate material budget using the geo manager
-  // 4. propagate and update track using the tracklet information.
-  //
-  // Debug level 2
-  //
-
-  Int_t nClustersExpected = 0;
-  Double_t clength = AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick();
-  AliTRDtrackingChamber *chamber = 0x0;
+// Extrapolates/Build the TRD track in the TOF direction.
+//
+// Parameters
+//   t : the TRD track which has to be extrapolated
+// 
+// Output
+//   number of clusters attached to the track
+//
+// Starting from current radial position of track <t> this function
+// extrapolates the track through the 6 TRD layers. The following steps
+// are being performed for each plane:
+// 1. Propagate track to the entrance of the next chamber:
+//   - get chamber limits in the radial direction
+//   - check crossing sectors 
+//   - check track inclination
+//   - check track prolongation against boundary conditions (see exclusion boundaries on AliTRDgeometry::IsOnBoundary())
+// 2. Build tracklet (see AliTRDseed::AttachClusters() for details) for this layer if needed. If only 
+//    Kalman filter is needed and tracklets are already linked to the track this step is skipped.
+// 3. Fit tracklet using the information from the Kalman filter.
+// 4. Propagate and update track at reference radial position of the tracklet.
+// 5. Register tracklet with the tracker and track; update pulls monitoring.
+//
+// Observation
+//   1. During the propagation a bit map is filled detailing the status of the track in each TRD chamber. The following errors are being registered for each tracklet:
+// - AliTRDtrackV1::kProlongation : track prolongation failed
+// - AliTRDtrackV1::kPropagation : track prolongation failed
+// - AliTRDtrackV1::kAdjustSector : failed during sector crossing
+// - AliTRDtrackV1::kSnp : too large bending
+// - AliTRDtrackV1::kTrackletInit : fail to initialize tracklet
+// - AliTRDtrackV1::kUpdate : fail to attach clusters or fit the tracklet
+// - AliTRDtrackV1::kUnknown : anything which is not covered before
+//   2. By default the status of the track before first TRD update is saved. 
+// 
+// Debug level 2
+//
+// Author
+//   Alexandru Bercuci <A.Bercuci@gsi.de>
+//
+
+  Int_t n = 0;
+  Double_t driftLength = .5*AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick();
+  AliTRDtrackingChamber *chamber = NULL;
   
-  // Loop through the TRD planes
-  for (Int_t iplane = 0; iplane < AliTRDgeometry::Nplan(); iplane++) {
-    // BUILD TRACKLET IF NOT ALREADY BUILT
-    Double_t x = 0., y, z, alpha;
-    AliTRDseedV1 tracklet(*t.GetTracklet(iplane));
-    if(!tracklet.IsOK()){
-      alpha = t.GetAlpha();
-      Int_t sector = Int_t(alpha/AliTRDgeometry::GetAlpha() + (alpha>0. ? 0 : AliTRDgeometry::kNsect));
-
-      if(!fTrSec[sector].GetNChambers()) continue;
-               
-      if((x = fTrSec[sector].GetX(iplane)) < 1.) continue;
-               
-      if (!t.GetProlongation(x, y, z)) break;
-      Int_t stack = fGeom->GetChamber(z, iplane);
-      Int_t nCandidates = stack >= 0 ? 1 : 2;
-      z -= stack >= 0 ? 0. : 4.; 
-                       
-      for(int icham=0; icham<nCandidates; icham++, z+=8){
-                               if((stack = fGeom->GetChamber(z, iplane)) < 0) continue;
-                                               
-                               if(!(chamber = fTrSec[sector].GetChamber(stack, iplane))) continue;
-                                               
-                               if(chamber->GetNClusters() < fgNTimeBins*AliTRDReconstructor::RecoParam()->GetFindableClusters()) continue;
-                                               
-                               x = chamber->GetX();
-                                               
-                               AliTRDpadPlane *pp = fGeom->GetPadPlane(iplane, stack);
-                               tracklet.SetTilt(TMath::Tan(-TMath::DegToRad()*pp->GetTiltingAngle()));
-                               tracklet.SetPadLength(pp->GetLengthIPad());
-                               tracklet.SetPlane(iplane);
-                               tracklet.SetX0(x);
-                               if(!tracklet.Init(&t)) continue;
-                               if(!tracklet.AttachClustersIter(chamber, 1000.)) continue;
-                               tracklet.Init(&t);
-                                                       
-                               if(tracklet.GetN() < fgNTimeBins * AliTRDReconstructor::RecoParam()->GetFindableClusters()) continue;
-                                               
-                               break;
-                       }
-    }
-    if(!tracklet.IsOK()){
-      if(x < 1.) continue; //temporary
-      if(!PropagateToX(t, x-fgkMaxStep, fgkMaxStep)) break;
-      if(!AdjustSector(&t)) break;
-      if(TMath::Abs(t.GetSnp()) > fgkMaxSnp) break;
+  Int_t debugLevel = fkReconstructor->IsDebugStreaming() ? fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) : 0;
+  TTreeSRedirector *cstreamer = fkReconstructor->IsDebugStreaming() ? fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker) : 0x0;
+
+  Bool_t kStoreIn(kTRUE),     //
+         kPropagateIn(kTRUE), //
+         kStandAlone(kFALSE), // toggle tracker awarness of stand alone seeding 
+         kUseTRD(fkRecoParam->IsOverPtThreshold(t.Pt()));// use TRD measurment to update Kalman
+
+  Int_t startLayer(0);
+  AliTRDseedV1 tracklet, *ptrTracklet = NULL;
+  // Special case for stand alone tracking
+  // - store all tracklets found by seeding
+  // - start propagation from first tracklet found
+  AliTRDseedV1 *tracklets[kNPlanes];
+  memset(tracklets, 0, sizeof(AliTRDseedV1 *) * kNPlanes);
+  for(Int_t ip(kNPlanes); ip--;){
+    if(!(tracklets[ip] = t.GetTracklet(ip))) continue;
+    t.UnsetTracklet(ip);
+    if(tracklets[ip]->IsOK()) startLayer=ip;
+    kStandAlone = kTRUE;
+    kUseTRD = kTRUE;
+  } 
+  AliDebug(4, Form("SA[%c] Start[%d]\n"
+    "  [0]idx[%d] traklet[%p]\n"
+    "  [1]idx[%d] traklet[%p]\n"
+    "  [2]idx[%d] traklet[%p]\n"
+    "  [3]idx[%d] traklet[%p]\n"
+    "  [4]idx[%d] traklet[%p]\n"
+    "  [5]idx[%d] traklet[%p]"
+    , kStandAlone?'y':'n', startLayer
+    , t.GetTrackletIndex(0), (void*)tracklets[0]
+    , t.GetTrackletIndex(1), (void*)tracklets[1]
+    , t.GetTrackletIndex(2), (void*)tracklets[2]
+    , t.GetTrackletIndex(3), (void*)tracklets[3]
+    , t.GetTrackletIndex(4), (void*)tracklets[4]
+    , t.GetTrackletIndex(5), (void*)tracklets[5]));
+
+  // Loop through the TRD layers
+  TGeoHMatrix *matrix = NULL;
+  Double_t x, y, z;
+  for (Int_t ily=startLayer, sm=-1, stk=-1, det=-1; ily < AliTRDgeometry::kNlayer; ily++) {
+    AliDebug(2, Form("Propagate to x[%d] = %7.2f", ily, fR[ily]));
+
+    // rough estimate of the entry point
+    if (!t.GetProlongation(fR[ily], y, z)){
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kProlongation);
+      AliDebug(4, Form("Failed Rough Prolongation to ly[%d] x[%7.2f] y[%7.2f] z[%7.2f]", ily, fR[ily], y, z));
+      break;
+    }
+
+    // find sector / stack / detector
+    sm = t.GetSector();
+    // TODO cross check with y value !
+    stk = fGeom->GetStack(z, ily);
+    det = stk>=0 ? AliTRDgeometry::GetDetector(ily, stk, sm) : -1;
+    matrix = det>=0 ? fGeom->GetClusterMatrix(det) : NULL;
+    AliDebug(3, Form("Propagate to det[%3d]", det));
+
+    // check if supermodule/chamber is installed
+    if( !fGeom->GetSMstatus(sm) ||
+        stk<0. ||
+        fGeom->IsHole(ily, stk, sm) ||
+        !matrix ){ 
+      AliDebug(4, Form("Missing Geometry ly[%d]. Guess radial position", ily));
+      // propagate to the default radial position
+      if(fR[ily] > (fgkMaxStep + t.GetX()) && !PropagateToX(t, fR[ily], fgkMaxStep)){
+        n=-1; 
+        t.SetStatus(AliTRDtrackV1::kPropagation);
+        AliDebug(4, "Failed Propagation [Missing Geometry]");
+        break;
+      }
+      if(!AdjustSector(&t)){
+        n=-1; 
+        t.SetStatus(AliTRDtrackV1::kAdjustSector);
+        AliDebug(4, "Failed Adjust Sector [Missing Geometry]");
+        break;
+      }
+      if(TMath::Abs(t.GetSnp()) > fgkMaxSnp){
+        n=-1; 
+        t.SetStatus(AliTRDtrackV1::kSnp);
+        AliDebug(4, "Failed Max Snp [Missing Geometry]");
+        break;
+      }
+      t.SetStatus(AliTRDtrackV1::kGeometry, ily);
       continue;
     }
-    
-    // Propagate closer to the current chamber if neccessary 
-    x -= clength;
-    if (x > (fgkMaxStep + t.GetX()) && !PropagateToX(t, x-fgkMaxStep, fgkMaxStep)) break;
-    if (!AdjustSector(&t)) break;
-    if (TMath::Abs(t.GetSnp()) > fgkMaxSnp) break;
-               
-    // load tracklet to the tracker and the track
-    Int_t index = SetTracklet(&tracklet);
-    t.SetTracklet(&tracklet, iplane, index);
-   
-   
-    // Calculate the mean material budget along the path inside the chamber
-    //Calculate global entry and exit positions of the track in chamber (only track prolongation)
-    Double_t xyz0[3]; // entry point 
-    t.GetXYZ(xyz0);
-    alpha = t.GetAlpha();
-    x = tracklet.GetX0();
-    if (!t.GetProlongation(x, y, z)) break;
-    Double_t xyz1[3]; // exit point
-    xyz1[0] =  x * TMath::Cos(alpha) - y * TMath::Sin(alpha); 
-    xyz1[1] = +x * TMath::Sin(alpha) + y * TMath::Cos(alpha);
-    xyz1[2] =  z;
-    Double_t param[7];
-    AliTracker::MeanMaterialBudget(xyz0, xyz1, param); 
-    // The mean propagation parameters
-    Double_t xrho = param[0]*param[4]; // density*length
-    Double_t xx0  = param[1]; // radiation length
-               
-    // Propagate and update track
-    t.PropagateTo(x, xx0, xrho);
-    if (!AdjustSector(&t)) break;
-    Double_t maxChi2 = t.GetPredictedChi2(&tracklet);
-    if (maxChi2<1e+10 && t.Update(&tracklet, maxChi2)){ 
-      nClustersExpected += tracklet.GetN();
+
+    // retrieve rotation matrix for the current chamber
+    Double_t loc[] = {AliTRDgeometry::AnodePos()- driftLength, 0., 0.};
+    Double_t glb[] = {0., 0., 0.};
+    matrix->LocalToMaster(loc, glb);
+
+    // Propagate to the radial distance of the current layer
+    x = glb[0] - fgkMaxStep;
+    if(x > (fgkMaxStep + t.GetX()) && !PropagateToX(t, x, fgkMaxStep)){
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kPropagation);
+      AliDebug(4, Form("Failed Initial Propagation to x[%7.2f]", x));
+      break;
+    }
+    if(!AdjustSector(&t)){
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kAdjustSector);
+      AliDebug(4, "Failed Adjust Sector Start");
+      break;
+    }
+    if(TMath::Abs(t.GetSnp()) > fgkMaxSnp) {
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kSnp);
+      AliDebug(4, Form("Failed Max Snp[%f] MaxSnp[%f]", t.GetSnp(), fgkMaxSnp));
+      break;
+    }
+    Bool_t doRecalculate = kFALSE;
+    if(sm != t.GetSector()){
+      sm = t.GetSector(); 
+      doRecalculate = kTRUE;
+    }
+    if(stk != fGeom->GetStack(z, ily)){
+      stk = fGeom->GetStack(z, ily);
+      doRecalculate = kTRUE;
+    }
+    if(doRecalculate){
+      det = AliTRDgeometry::GetDetector(ily, stk, sm);
+      if(!(matrix = fGeom->GetClusterMatrix(det))){ 
+        t.SetStatus(AliTRDtrackV1::kGeometry, ily);
+        AliDebug(4, Form("Failed Geometry Matrix ly[%d]", ily));
+        continue;
+      }
+      matrix->LocalToMaster(loc, glb);
+      x = glb[0] - fgkMaxStep;
     }
+
+    // check if track is well inside fiducial volume 
+    if (!t.GetProlongation(x+fgkMaxStep, y, z)) {
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kProlongation);
+      AliDebug(4, Form("Failed Prolongation to x[%7.2f] y[%7.2f] z[%7.2f]", x+fgkMaxStep, y, z));
+      break;
+    }
+    if(fGeom->IsOnBoundary(det, y, z, .5)){ 
+      t.SetStatus(AliTRDtrackV1::kBoundary, ily);
+      AliDebug(4, "Failed Track on Boundary");
+      continue;
+    }
+    // mark track as entering the FIDUCIAL volume of TRD
+    if(kStoreIn){
+      t.SetTrackIn(); 
+      kStoreIn = kFALSE;
+    }
+
+    ptrTracklet  = tracklets[ily];
+    if(!ptrTracklet){ // BUILD TRACKLET
+      AliDebug(3, Form("Building tracklet det[%d]", det));
+      // check data in supermodule
+      if(!fTrSec[sm].GetNChambers()){ 
+        t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
+        AliDebug(4, "Failed NoClusters");
+        continue;
+      }
+      if(fTrSec[sm].GetX(ily) < 1.){ 
+        t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
+        AliDebug(4, "Failed NoX");
+        continue;
+      }
+      
+      // check data in chamber
+      if(!(chamber = fTrSec[sm].GetChamber(stk, ily))){ 
+        t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
+        AliDebug(4, "Failed No Detector");
+        continue;
+      }
+      if(chamber->GetNClusters() < fgNTimeBins*fkRecoParam ->GetFindableClusters()){ 
+        t.SetStatus(AliTRDtrackV1::kNoClusters, ily);
+        AliDebug(4, "Failed Not Enough Clusters in Detector");
+        continue;
+      }      
+      // build tracklet
+      ptrTracklet = new(&tracklet) AliTRDseedV1(det);
+      ptrTracklet->SetReconstructor(fkReconstructor);
+      ptrTracklet->SetKink(t.IsKink());
+      ptrTracklet->SetPrimary(t.IsPrimary());
+      ptrTracklet->SetPadPlane(fGeom->GetPadPlane(ily, stk));
+      ptrTracklet->SetX0(glb[0]+driftLength);
+      if(!tracklet.Init(&t)){
+        n=-1; 
+        t.SetStatus(AliTRDtrackV1::kTrackletInit);
+        AliDebug(4, "Failed Tracklet Init");
+        break;
+      }
+      if(!tracklet.AttachClusters(chamber, kTRUE)){   
+        t.SetStatus(AliTRDtrackV1::kNoAttach, ily);
+        if(debugLevel>3){
+          AliTRDseedV1 trackletCp(*ptrTracklet);
+          UChar_t status(t.GetStatusTRD(ily));
+          (*cstreamer)   << "FollowBackProlongation2"
+          <<"status="    << status
+          <<"tracklet.=" << &trackletCp
+          << "\n";
+        }
+        AliDebug(4, "Failed Attach Clusters");
+        continue;
+      }
+      AliDebug(3, Form("Number of Clusters in Tracklet: %d", tracklet.GetN()));
+      if(tracklet.GetN() < fgNTimeBins*fkRecoParam ->GetFindableClusters()){
+        t.SetStatus(AliTRDtrackV1::kNoClustersTracklet, ily);
+        if(debugLevel>3){
+          AliTRDseedV1 trackletCp(*ptrTracklet);
+          UChar_t status(t.GetStatusTRD(ily));
+          (*cstreamer)   << "FollowBackProlongation2"
+          <<"status="    << status
+          <<"tracklet.=" << &trackletCp
+          << "\n";
+        }
+        AliDebug(4, "Failed N Clusters Attached");
+        continue;
+      }
+      ptrTracklet->UpdateUsed();
+    } else AliDebug(2, Form("Use external tracklet ly[%d]", ily));
+    // propagate track to the radial position of the tracklet
+
+    // fit tracklet 
+    // tilt correction options
+    // 0 : no correction
+    // 2 : pseudo tilt correction
+    if(!ptrTracklet->Fit(2)){
+      t.SetStatus(AliTRDtrackV1::kNoFit, ily);
+      AliDebug(4, "Failed Tracklet Fit");
+      continue;
+    } 
+    x = ptrTracklet->GetX(); //GetX0();
+    if(x > (fgkMaxStep + t.GetX()) && !PropagateToX(t, x, fgkMaxStep)) {
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kPropagation);
+      AliDebug(4, Form("Failed Propagation to Tracklet x[%7.2f]", x));
+      break;
+    }
+    if(!AdjustSector(&t)) {
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kAdjustSector);
+      AliDebug(4, "Failed Adjust Sector");
+      break;
+    }
+    if(TMath::Abs(t.GetSnp()) > fgkMaxSnp) {
+      n=-1; 
+      t.SetStatus(AliTRDtrackV1::kSnp);
+      AliDebug(4, Form("Failed Max Snp[%f] MaxSnp[%f]", t.GetSnp(), fgkMaxSnp));
+      break;
+    }
+    if(kPropagateIn){
+      t.SetTrackIn(); 
+      kPropagateIn = kFALSE;
+    }
+    Double_t cov[3]; ptrTracklet->GetCovAt(x, cov);
+    Double_t p[2] = { ptrTracklet->GetY(), ptrTracklet->GetZ()};
+    Double_t chi2 = ((AliExternalTrackParam)t).GetPredictedChi2(p, cov);
+    // update Kalman with the TRD measurement
+    if(chi2>1e+10){ // TODO
+      t.SetStatus(AliTRDtrackV1::kChi2, ily);
+      if(debugLevel > 2){
+        UChar_t status(t.GetStatusTRD());
+        AliTRDseedV1  trackletCp(*ptrTracklet);
+        AliTRDtrackV1 trackCp(t);
+        trackCp.SetOwner();
+        (*cstreamer) << "FollowBackProlongation1"
+            << "status="      << status
+            << "tracklet.="   << &trackletCp
+            << "track.="      << &trackCp
+            << "\n";
+      }
+      AliDebug(4, Form("Failed Chi2[%f]", chi2));
+      continue; 
+    }
+    if(kUseTRD){
+      if(!((AliExternalTrackParam&)t).Update(p, cov)) {
+        n=-1; 
+        t.SetStatus(AliTRDtrackV1::kUpdate);
+        if(debugLevel > 2){
+          UChar_t status(t.GetStatusTRD());
+          AliTRDseedV1  trackletCp(*ptrTracklet);
+          AliTRDtrackV1 trackCp(t);
+          trackCp.SetOwner();
+          (*cstreamer) << "FollowBackProlongation1"
+              << "status="      << status
+              << "tracklet.="   << &trackletCp
+              << "track.="      << &trackCp
+              << "\n";
+        }
+        AliDebug(4, Form("Failed Track Update @ y[%7.2f] z[%7.2f] s2y[%f] s2z[%f] covyz[%f]", p[0], p[1], cov[0], cov[2], cov[1]));
+        break;
+      }
+    }
+    if(!kStandAlone) ptrTracklet->UseClusters();
+    // fill residuals ?!
+    AliTracker::FillResiduals(&t, p, cov, ptrTracklet->GetVolumeId());
+  
+
+    // load tracklet to the tracker
+    ptrTracklet->Update(&t);
+    ptrTracklet = SetTracklet(ptrTracklet);
+    Int_t index(fTracklets->GetEntriesFast()-1);
+    t.SetTracklet(ptrTracklet, index);
+    // Register info to track
+    t.SetNumberOfClusters();
+    t.UpdateChi2(chi2);
+
+    n += ptrTracklet->GetN();
+    AliDebug(2, Form("Setting Tracklet[%d] @ Idx[%d]", ily, index));
+
     // Reset material budget if 2 consecutive gold
-    if(iplane>0 && tracklet.GetN() + t.GetTracklet(iplane-1)->GetN() > 20) t.SetBudget(2, 0.);
+//     if(ilayer>0 && t.GetTracklet(ilayer-1) && ptrTracklet->GetN() + t.GetTracklet(ilayer-1)->GetN() > 20) t.SetBudget(2, 0.);
 
     // Make backup of the track until is gold
-    // TO DO update quality check of the track.
-    // consider comparison with fTimeBinsRange
-    Float_t ratio0 = tracklet.GetN() / Float_t(fgNTimeBins);
-    //Float_t ratio1 = Float_t(t.GetNumberOfClusters()+1) / Float_t(t.GetNExpected()+1);       
-    //printf("tracklet.GetChi2() %f     [< 18.0]\n", tracklet.GetChi2()); 
-    //printf("ratio0    %f              [>   0.8]\n", ratio0);
-    //printf("ratio1     %f             [>   0.6]\n", ratio1); 
-    //printf("ratio0+ratio1 %f          [>   1.5]\n", ratio0+ratio1); 
-    //printf("t.GetNCross()  %d         [==    0]\n", t.GetNCross()); 
-    //printf("TMath::Abs(t.GetSnp()) %f [<  0.85]\n", TMath::Abs(t.GetSnp()));
-    //printf("t.GetNumberOfClusters() %d [>    20]\n", t.GetNumberOfClusters());
-    
-    if (//(tracklet.GetChi2()      <  18.0) && TO DO check with FindClusters and move it to AliTRDseed::Update 
-        (ratio0                  >   0.8) && 
-        //(ratio1                  >   0.6) && 
-        //(ratio0+ratio1           >   1.5) && 
-        (t.GetNCross()           ==    0) && 
-        (TMath::Abs(t.GetSnp())  <  0.85) &&
-        (t.GetNumberOfClusters() >    20)) t.MakeBackupTrack();
-               
-  } // end planes loop
-
-  if(AliTRDReconstructor::StreamLevel() > 1){
-    TTreeSRedirector &cstreamer = *fgDebugStreamer;
+    Int_t failed(0);
+    if(!kStandAlone && (failed = t.MakeBackupTrack())) AliDebug(2, Form("Failed backup on cut[%d]", failed));
+
+  } // end layers loop
+  //printf("clusters[%d] chi2[%f] x[%f] status[%d ", n, t.GetChi2(), t.GetX(), t.GetStatusTRD());
+  //for(int i=0; i<6; i++) printf("%d ", t.GetStatusTRD(i)); printf("]\n");
+
+  if(debugLevel > 1){
     Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
-    cstreamer << "FollowBackProlongation"
-             << "EventNumber="                 << eventNumber
-             << "ncl="                                                 << nClustersExpected
-             << "track.="                                      << &t
-             << "\n";
+    AliTRDtrackV1 track(t);
+    track.SetOwner();
+    (*cstreamer) << "FollowBackProlongation0"
+        << "EventNumber=" << eventNumber
+        << "ncl="         << n
+        << "track.="      << &track
+        << "\n";
   }
-       
-  return nClustersExpected;
+  
+  return n;
 }
 
 //_________________________________________________________________________
-Float_t AliTRDtrackerV1::FitRieman(AliTRDseedV1 *tracklets, Double_t *chi2, Int_t *planes){
+Float_t AliTRDtrackerV1::FitRieman(AliTRDseedV1 *tracklets, Double_t *chi2, Int_t *const planes){
   //
   // Fits a Riemann-circle to the given points without tilting pad correction.
   // The fit is performed using an instance of the class AliRieman (equations 
@@ -746,7 +1048,7 @@ Float_t AliTRDtrackerV1::FitRieman(AliTRDseedV1 *tracklets, Double_t *chi2, Int_
   }
   for(Int_t il = 0; il < maxLayers; il++){
     if(!tracklets[ppl[il]].IsOK()) continue;
-    fitter->AddPoint(tracklets[ppl[il]].GetX0(), tracklets[ppl[il]].GetYfitR(0), tracklets[ppl[il]].GetZProb(),1,10);
+    fitter->AddPoint(tracklets[ppl[il]].GetX0(), tracklets[ppl[il]].GetYfit(0), tracklets[ppl[il]].GetZfit(0),1,10);
   }
   fitter->Update();
   // Set the reference position of the fit and calculate the chi2 values
@@ -754,7 +1056,7 @@ Float_t AliTRDtrackerV1::FitRieman(AliTRDseedV1 *tracklets, Double_t *chi2, Int_
   for(Int_t il = 0; il < maxLayers; il++){
     // Reference positions
     tracklets[ppl[il]].Init(fitter);
-               
+    
     // chi2
     if((!tracklets[ppl[il]].IsOK()) && (!planes)) continue;
     chi2[0] += tracklets[ppl[il]].GetChi2Y();
@@ -779,11 +1081,12 @@ void AliTRDtrackerV1::FitRieman(AliTRDcluster **seedcl, Double_t chi2[2])
   //
   AliRieman *fitter = AliTRDtrackerV1::GetRiemanFitter();
   fitter->Reset();
-  for(Int_t i = 0; i < 4; i++)
-    fitter->AddPoint(seedcl[i]->GetX(), seedcl[i]->GetY(), seedcl[i]->GetZ(), 1, 10);
+  for(Int_t i = 0; i < 4; i++){
+    fitter->AddPoint(seedcl[i]->GetX(), seedcl[i]->GetY(), seedcl[i]->GetZ(), 1., 10.);
+  }
   fitter->Update();
-       
-       
+  
+  
   // Update the seed and calculated the chi2 value
   chi2[0] = 0; chi2[1] = 0;
   for(Int_t ipl = 0; ipl < kNSeedPlanes; ipl++){
@@ -826,26 +1129,27 @@ Float_t AliTRDtrackerV1::FitTiltedRiemanConstraint(AliTRDseedV1 *tracklets, Doub
   TLinearFitter *fitter = GetTiltedRiemanFitterConstraint();
   fitter->StoreData(kTRUE);
   fitter->ClearPoints();
-  AliTRDcluster *cl = 0x0;
-       
+  AliTRDcluster *cl = NULL;
+  
   Float_t x, y, z, w, t, error, tilt;
   Double_t uvt[2];
   Int_t nPoints = 0;
-  for(Int_t ipl = 0; ipl < AliTRDgeometry::kNplan; ipl++){
-    if(!tracklets[ipl].IsOK()) continue;
-    for(Int_t itb = 0; itb < fgNTimeBins; itb++){
-      if(!tracklets[ipl].IsUsable(itb)) continue;
-      cl = tracklets[ipl].GetClusters(itb);
+  for(Int_t ilr = 0; ilr < AliTRDgeometry::kNlayer; ilr++){
+    if(!tracklets[ilr].IsOK()) continue;
+    for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
+      if(!tracklets[ilr].IsUsable(itb)) continue;
+      cl = tracklets[ilr].GetClusters(itb);
+      if(!cl->IsInChamber()) continue;
       x = cl->GetX();
       y = cl->GetY();
       z = cl->GetZ();
-      tilt = tracklets[ipl].GetTilt();
+      tilt = tracklets[ilr].GetTilt();
       // Transformation
       t = 1./(x * x + y * y);
       uvt[0] = 2. * x * t;
       uvt[1] = 2. * x * t * tilt ;
       w = 2. * (y + tilt * (z - zVertex)) * t;
-      error = 2. * 0.2 * t;
+      error = 2. * TMath::Sqrt(cl->GetSigmaY2()+tilt*tilt*cl->GetSigmaZ2()) * t;
       fitter->AddPoint(uvt, w, error);
       nPoints++;
     }
@@ -859,9 +1163,11 @@ Float_t AliTRDtrackerV1::FitTiltedRiemanConstraint(AliTRDseedV1 *tracklets, Doub
 
   Float_t chi2track = fitter->GetChisquare()/Double_t(nPoints);
   for(Int_t ip = 0; ip < AliTRDtrackerV1::kNPlanes; ip++)
-    tracklets[ip].SetCC(curvature);
+    tracklets[ip].SetC(curvature, 1);
 
-  if(AliTRDReconstructor::StreamLevel() >= 5){
+  if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitTiltedRiemanConstraint: Chi2[%f] C[%5.2e] pt[%8.3f]\n", chi2track, curvature, GetBz()*kB2C/curvature);
+
+/*  if(fkReconstructor->GetRecoParam()->GetStreamLevel(AliTRDrecoParam::kTracker()) >= 5){
     //Linear Model on z-direction
     Double_t xref = CalculateReferenceX(tracklets);            // Relative to the middle of the stack
     Double_t slope = fitter->GetParameter(2);
@@ -869,16 +1175,16 @@ Float_t AliTRDtrackerV1::FitTiltedRiemanConstraint(AliTRDseedV1 *tracklets, Doub
     Float_t chi2Z = CalculateChi2Z(tracklets, zref, slope, xref);
     Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
     Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
-    TTreeSRedirector &treeStreamer = *fgDebugStreamer;
+    TTreeSRedirector &treeStreamer = *fkReconstructor->GetDebugStream(AliTRDReconstructor::kTracker);
     treeStreamer << "FitTiltedRiemanConstraint"
-                << "EventNumber="              << eventNumber
-                << "CandidateNumber="  << candidateNumber
-                << "Curvature="                                << curvature
-                << "Chi2Track="                                << chi2track
-                << "Chi2Z="                                            << chi2Z
-                << "zref="                                             << zref
-                << "\n";
-  }
+    << "EventNumber="          << eventNumber
+    << "CandidateNumber="      << candidateNumber
+    << "Curvature="                            << curvature
+    << "Chi2Track="                            << chi2track
+    << "Chi2Z="                                                << chi2Z
+    << "zref="                                         << zref
+    << "\n";
+  }*/
   return chi2track;
 }
 
@@ -918,22 +1224,25 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
   fitter->StoreData(kTRUE);
   fitter->ClearPoints();
   AliTRDLeastSquare zfitter;
-  AliTRDcluster *cl = 0x0;
+  AliTRDcluster *cl = NULL;
 
   Double_t xref = CalculateReferenceX(tracklets);
-  Double_t x, y, z, t, tilt, dx, w, we;
-  Double_t uvt[4];
+  Double_t x, y, z, t, tilt, dx, w, we, erry, errz;
+  Double_t uvt[4], sumPolY[5], sumPolZ[3];
+  memset(sumPolY, 0, sizeof(Double_t) * 5);
+  memset(sumPolZ, 0, sizeof(Double_t) * 3);
   Int_t nPoints = 0;
   // Containers for Least-square fitter
   for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
     if(!tracklets[ipl].IsOK()) continue;
-    for(Int_t itb = 0; itb < fgNTimeBins; itb++){
+    tilt = tracklets[ipl].GetTilt();
+    for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
       if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
+      if(!cl->IsInChamber()) continue;
       if (!tracklets[ipl].IsUsable(itb)) continue;
       x = cl->GetX();
       y = cl->GetY();
       z = cl->GetZ();
-      tilt = tracklets[ipl].GetTilt();
       dx = x - xref;
       // Transformation
       t = 1./(x*x + y*y);
@@ -944,13 +1253,25 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
       w = 2. * (y + tilt*z) * t;
       // error definition changes for the different calls
       we = 2. * t;
-      we *= sigError ? tracklets[ipl].GetSigmaY() : 0.2;
+      we *= sigError ? TMath::Sqrt(cl->GetSigmaY2()+tilt*tilt*cl->GetSigmaZ2()) : 0.2;
       fitter->AddPoint(uvt, w, we);
       zfitter.AddPoint(&x, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
+      // adding points for covariance matrix estimation
+      erry = 1./(TMath::Sqrt(cl->GetSigmaY2()) + 0.1);  // 0.1 is a systematic error (due to misalignment and miscalibration)
+      erry *= erry;
+      errz = 1./cl->GetSigmaZ2();
+      for(Int_t ipol = 0; ipol < 5; ipol++){
+        sumPolY[ipol] += erry;
+        erry *= x;
+        if(ipol < 3){
+          sumPolZ[ipol] += errz;
+          errz *= x;
+        }
+      }
       nPoints++;
     }
   }
-  fitter->Eval();
+  if (fitter->Eval()) return 1.e10;
   zfitter.Eval();
 
   Double_t offset = fitter->GetParameter(3);
@@ -963,7 +1284,7 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
   for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
     if(!tracklets[iLayer].IsOK()) continue;
     zref = offset + slope * (tracklets[iLayer].GetX0() - xref);
-    if (TMath::Abs(tracklets[iLayer].GetZProb() - zref) > tracklets[iLayer].GetPadLength() * 0.5 + 1.0) 
+    if (TMath::Abs(tracklets[iLayer].GetZfit(0) - zref) > tracklets[iLayer].GetPadLength() * 0.5 + 1.0) 
       acceptablez = kFALSE;
   }
   if (!acceptablez) {
@@ -983,21 +1304,49 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
   Double_t b     =  fitter->GetParameter(1);
   Double_t c     =  fitter->GetParameter(2);
   Double_t curvature =  1.0 + b*b - c*a;
-  if (curvature > 0.0) 
-    curvature  =  a / TMath::Sqrt(curvature);
+  if (curvature > 0.0) curvature  =  a / TMath::Sqrt(curvature);
 
   Double_t chi2track = fitter->GetChisquare()/Double_t(nPoints);
 
+  // Prepare error calculation
+  TMatrixD covarPolY(3,3);
+  covarPolY(0,0) = sumPolY[0]; covarPolY(1,1) = sumPolY[2]; covarPolY(2,2) = sumPolY[4];
+  covarPolY(0,1) = covarPolY(1,0) = sumPolY[1];
+  covarPolY(0,2) = covarPolY(2,0) = sumPolY[2];
+  covarPolY(2,1) = covarPolY(1,2) = sumPolY[3];
+  covarPolY.Invert();
+  TMatrixD covarPolZ(2,2);
+  covarPolZ(0,0) = sumPolZ[0]; covarPolZ(1,1) = sumPolZ[2];
+  covarPolZ(1,0) = covarPolZ(0,1) = sumPolZ[1];
+  covarPolZ.Invert();
+
   // Update the tracklets
-  Double_t dy, dz;
+  Double_t x1, dy, dz;
+  Double_t cov[15];
+  memset(cov, 0, sizeof(Double_t) * 15);
   for(Int_t iLayer = 0; iLayer < AliTRDtrackerV1::kNPlanes; iLayer++) {
 
     x  = tracklets[iLayer].GetX0();
+    x1 = x - xref;
     y  = 0;
     z  = 0;
     dy = 0;
     dz = 0;
-
+    memset(cov, 0, sizeof(Double_t) * 3);
+    TMatrixD transform(3,3);
+    transform(0,0) = 1;
+    transform(0,1) = x;
+    transform(0,2) = x*x;
+    transform(1,1) = 1;
+    transform(1,2) = x;
+    transform(2,2) = 1;
+    TMatrixD covariance(transform, TMatrixD::kMult, covarPolY);
+    covariance *= transform.T();
+    TMatrixD transformZ(2,2);
+    transformZ(0,0) = transformZ(1,1) = 1;
+    transformZ(0,1) = x;
+    TMatrixD covarZ(transformZ, TMatrixD::kMult, covarPolZ);
+    covarZ *= transformZ.T();
     // y:     R^2 = (x - x0)^2 + (y - y0)^2
     //     =>   y = y0 +/- Sqrt(R^2 - (x - x0)^2)
     //          R = Sqrt() = 1/Curvature
@@ -1009,6 +1358,9 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
       res = TMath::Sqrt(res);
       y    = (1.0 - res) / a;
     }
+    cov[0] = covariance(0,0);
+    cov[2] = covarZ(0,0);
+    cov[1] = 0.;
 
     // dy:      R^2 = (x - x0)^2 + (y - y0)^2
     //     =>     y = +/- Sqrt(R^2 - (x - x0)^2) + y0
@@ -1018,9 +1370,9 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
     Double_t x0 = -b / a;
     if (-c * a + b * b + 1 > 0) {
       if (1.0/(curvature * curvature) - (x - x0) * (x - x0) > 0.0) {
-       Double_t yderiv = (x - x0) / TMath::Sqrt(1.0/(curvature * curvature) - (x - x0) * (x - x0));
-       if (a < 0) yderiv *= -1.0;
-       dy = yderiv;
+       Double_t yderiv = (x - x0) / TMath::Sqrt(1.0/(curvature * curvature) - (x - x0) * (x - x0));
+        if (a < 0) yderiv *= -1.0;
+        dy = yderiv;
       }
     }
     z  = offset + slope * (x - xref);
@@ -1030,68 +1382,442 @@ Float_t AliTRDtrackerV1::FitTiltedRieman(AliTRDseedV1 *tracklets, Bool_t sigErro
     tracklets[iLayer].SetZref(0, z);
     tracklets[iLayer].SetZref(1, dz);
     tracklets[iLayer].SetC(curvature);
+    tracklets[iLayer].SetCovRef(cov);
     tracklets[iLayer].SetChi2(chi2track);
   }
-       
-  if(AliTRDReconstructor::StreamLevel() >=5){
-    TTreeSRedirector &cstreamer = *fgDebugStreamer;
+  if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitTiltedRieman: Chi2[%f] C[%5.2e] pt[%8.3f]\n", chi2track, curvature, GetBz()*kB2C/curvature);
+  
+/*  if(fkReconstructor->GetRecoParam()->GetStreamLevel(AliTRDrecoParam::kTracker) >=5){
+    TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
     Int_t eventNumber                  = AliTRDtrackerDebug::GetEventNumber();
     Int_t candidateNumber      = AliTRDtrackerDebug::GetCandidateNumber();
     Double_t chi2z = CalculateChi2Z(tracklets, offset, slope, xref);
     cstreamer << "FitTiltedRieman0"
-             << "EventNumber="                 << eventNumber
-             << "CandidateNumber="     << candidateNumber
-             << "xref="                                                << xref
-             << "Chi2Z="                                               << chi2z
-             << "\n";
-  }
+        << "EventNumber="                      << eventNumber
+        << "CandidateNumber="  << candidateNumber
+        << "xref="                                             << xref
+        << "Chi2Z="                                            << chi2z
+        << "\n";
+  }*/
   return chi2track;
 }
 
-//_________________________________________________________________________
-Float_t AliTRDtrackerV1::CalculateChi2Z(AliTRDseedV1 *tracklets, Double_t offset, Double_t slope, Double_t xref)
-{
-  //
-  // Calculates the chi2-value of the track in z-Direction including tilting pad correction.
-  // A linear dependence on the x-value serves as a model.
-  // The parameters are related to the tilted Riemann fit.
-  // Parameters: - Array of tracklets (AliTRDseedV1) related to the track candidate
-  //             - the offset for the reference x
-  //             - the slope
-  //             - the reference x position
-  // Output:     - The Chi2 value of the track in z-Direction
-  //
-  Float_t chi2Z = 0, nLayers = 0;
-  for (Int_t iLayer = 0; iLayer < AliTRDgeometry::kNplan; iLayer++) {
-    if(!tracklets[iLayer].IsOK()) continue;
-    Double_t z = offset + slope * (tracklets[iLayer].GetX0() - xref);
-    chi2Z += TMath::Abs(tracklets[iLayer].GetMeanz() - z);
-    nLayers++;
-  }
-  chi2Z /= TMath::Max((nLayers - 3.0),1.0);
-  return chi2Z;
-}
 
-//_____________________________________________________________________________
-Int_t AliTRDtrackerV1::PropagateToX(AliTRDtrackV1 &t, Double_t xToGo, Double_t maxStep)
+//____________________________________________________________________
+Double_t AliTRDtrackerV1::FitLine(const AliTRDtrackV1 *track, AliTRDseedV1 *tracklets, Bool_t err, Int_t np, AliTrackPoint *points)
 {
   //
-  // Starting from current X-position of track <t> this function
-  // extrapolates the track up to radial position <xToGo>. 
-  // Returns 1 if track reaches the plane, and 0 otherwise 
+  // Fit track with a staight line
+  // Fills an AliTrackPoint array with np points
+  // Function should be used to refit tracks when no magnetic field was on
   //
+  AliTRDLeastSquare yfitter, zfitter;
+  AliTRDcluster *cl = NULL;
+
+  AliTRDseedV1 work[kNPlanes], *tracklet = NULL;
+  if(!tracklets){
+    for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
+      if(!(tracklet = track->GetTracklet(ipl))) continue;
+      if(!tracklet->IsOK()) continue;
+      new(&work[ipl]) AliTRDseedV1(*tracklet);
+    }
+    tracklets = &work[0];
+  }
 
-  const Double_t kEpsilon = 0.00001;
-
-  // Current track X-position
-  Double_t xpos = t.GetX();
-
-  // Direction: inward or outward
-  Double_t dir  = (xpos < xToGo) ? 1.0 : -1.0;
-
-  while (((xToGo - xpos) * dir) > kEpsilon) {
-
-    Double_t xyz0[3];
+  Double_t xref = CalculateReferenceX(tracklets);
+  Double_t x, y, z, dx, ye, yr, tilt;
+  for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
+    if(!tracklets[ipl].IsOK()) continue;
+    for(Int_t itb = 0; itb < fgNTimeBins; itb++){
+      if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
+      if (!tracklets[ipl].IsUsable(itb)) continue;
+      x = cl->GetX();
+      z = cl->GetZ();
+      dx = x - xref;
+      zfitter.AddPoint(&dx, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
+    }
+  }
+  zfitter.Eval();
+  Double_t z0    = zfitter.GetFunctionParameter(0);
+  Double_t dzdx  = zfitter.GetFunctionParameter(1);
+  for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
+    if(!tracklets[ipl].IsOK()) continue;
+    for(Int_t itb = 0; itb < fgNTimeBins; itb++){
+      if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
+      if (!tracklets[ipl].IsUsable(itb)) continue;
+      x = cl->GetX();
+      y = cl->GetY();
+      z = cl->GetZ();
+      tilt = tracklets[ipl].GetTilt();
+      dx = x - xref;
+      yr = y + tilt*(z - z0 - dzdx*dx); 
+      // error definition changes for the different calls
+      ye = tilt*TMath::Sqrt(cl->GetSigmaZ2());
+      ye += err ? tracklets[ipl].GetSigmaY() : 0.2;
+      yfitter.AddPoint(&dx, yr, ye);
+    }
+  }
+  yfitter.Eval();
+  Double_t y0   = yfitter.GetFunctionParameter(0);
+  Double_t dydx = yfitter.GetFunctionParameter(1);
+  Double_t chi2 = 0.;//yfitter.GetChisquare()/Double_t(nPoints);
+
+  //update track points array
+  if(np && points){
+    Float_t xyz[3];
+    for(int ip=0; ip<np; ip++){
+      points[ip].GetXYZ(xyz);
+      xyz[1] = y0 + dydx * (xyz[0] - xref);
+      xyz[2] = z0 + dzdx * (xyz[0] - xref);
+      points[ip].SetXYZ(xyz);
+    }
+  }
+  return chi2;
+}
+
+
+//_________________________________________________________________________
+Double_t AliTRDtrackerV1::FitRiemanTilt(const AliTRDtrackV1 *track, AliTRDseedV1 *tracklets, Bool_t sigError, Int_t np, AliTrackPoint *points)
+{
+//
+// Performs a Riemann fit taking tilting pad correction into account
+//
+// Paramters:   - Array of tracklets (connected to the track candidate)
+//              - Flag selecting the error definition
+// Output:      - Chi2 values of the track (in Parameter list)
+//
+// The equations which has to be solved simultaneously are:
+// BEGIN_LATEX
+// R^{2} = (x-x_{0})^{2} + (y^{*}-y_{0})^{2}
+// y^{*} = y - tg(h)(z - z_{t})
+// z_{t} = z_{0}+dzdx*(x-x_{r})
+// END_LATEX
+// with (x, y, z) the coordinate of the cluster, (x_0, y_0, z_0) the coordinate of the center of the Riemann circle,
+// R its radius, x_r a constant refrence radial position in the middle of the TRD stack  and dzdx the slope of the 
+// track in the x-z plane. Using the following transformations
+// BEGIN_LATEX
+// t = 1 / (x^{2} + y^{2})
+// u = 2 * x * t
+// v = 2 * tan(h) * t
+// w = 2 * tan(h) * (x - x_{r}) * t
+// END_LATEX
+// One gets the following linear equation
+// BEGIN_LATEX
+// a + b * u + c * t + d * v  + e * w = 2 * (y + tg(h) * z) * t
+// END_LATEX
+// where the coefficients have the following meaning 
+// BEGIN_LATEX
+// a = -1/y_{0}
+// b = x_{0}/y_{0}
+// c = (R^{2} -x_{0}^{2} - y_{0}^{2})/y_{0}
+// d = z_{0}
+// e = dz/dx
+// END_LATEX
+// The error calculation for the free term is thus
+// BEGIN_LATEX
+// #sigma = 2 * #sqrt{#sigma^{2}_{y} + (tilt corr ...) + tg^{2}(h) * #sigma^{2}_{z}} * t
+// END_LATEX
+//
+// From this simple model one can compute chi^2 estimates and a rough approximation of pt from the curvature according 
+// to the formula:
+// BEGIN_LATEX
+// C = 1/R = a/(1 + b^{2} + c*a)
+// END_LATEX
+//
+// Authors
+//   M.Ivanov <M.Ivanov@gsi.de>
+//   A.Bercuci <A.Bercuci@gsi.de>
+//   M.Fasel <M.Fasel@gsi.de>
+
+  TLinearFitter *fitter = GetTiltedRiemanFitter();
+  fitter->StoreData(kTRUE);
+  fitter->ClearPoints();
+  AliTRDLeastSquare zfitter;
+  AliTRDcluster *cl = NULL;
+
+  AliTRDseedV1 work[kNPlanes], *tracklet = NULL;
+  if(!tracklets){
+    for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
+      if(!(tracklet = track->GetTracklet(ipl))) continue;
+      if(!tracklet->IsOK()) continue;
+      new(&work[ipl]) AliTRDseedV1(*tracklet);
+    }
+    tracklets = &work[0];
+  }
+
+  Double_t xref = CalculateReferenceX(tracklets);
+  if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitRiemanTilt:\nx0[(0)%6.2f (1)%6.2f (2)%6.2f (3)%6.2f (4)%6.2f (5)%6.2f] xref[%6.2f]", tracklets[0].GetX0(), tracklets[1].GetX0(), tracklets[2].GetX0(), tracklets[3].GetX0(), tracklets[4].GetX0(), tracklets[5].GetX0(), xref);
+  Double_t x, y, z, t, tilt, dx, w, we;
+  Double_t uvt[4];
+  Int_t nPoints = 0;
+  // Containers for Least-square fitter
+  for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
+    if(!tracklets[ipl].IsOK()) continue;
+    for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
+      if(!(cl = tracklets[ipl].GetClusters(itb))) continue;
+      //if (!tracklets[ipl].IsUsable(itb)) continue;
+      x = cl->GetX();
+      y = cl->GetY();
+      z = cl->GetZ();
+      tilt = tracklets[ipl].GetTilt();
+      dx = x - xref;
+      // Transformation
+      t = 1./(x*x + y*y);
+      uvt[0] = 2. * x * t;
+      uvt[1] = t;
+      uvt[2] = 2. * tilt * t;
+      uvt[3] = 2. * tilt * dx * t;
+      w = 2. * (y + tilt*z) * t;
+      // error definition changes for the different calls
+      we = 2. * t;
+      we *= sigError ? TMath::Sqrt(cl->GetSigmaY2()) : 0.2;
+      fitter->AddPoint(uvt, w, we);
+      zfitter.AddPoint(&x, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
+      nPoints++;
+    }
+  }
+  if(fitter->Eval()) return 1.E10;
+
+  Double_t z0    = fitter->GetParameter(3);
+  Double_t dzdx  = fitter->GetParameter(4);
+
+
+  // Linear fitter  - not possible to make boundaries
+  // Do not accept non possible z and dzdx combinations
+  Bool_t accept = kTRUE;
+  Double_t zref = 0.0;
+  for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
+    if(!tracklets[iLayer].IsOK()) continue;
+    zref = z0 + dzdx * (tracklets[iLayer].GetX0() - xref);
+    if (TMath::Abs(tracklets[iLayer].GetZfit(0) - zref) > tracklets[iLayer].GetPadLength() * 0.5 + 1.0) 
+      accept = kFALSE;
+  }
+  if (!accept) {
+    zfitter.Eval();
+    Double_t dzmf      = zfitter.GetFunctionParameter(1);
+    Double_t zmf       = zfitter.GetFunctionValue(&xref);
+    fitter->FixParameter(3, zmf);
+    fitter->FixParameter(4, dzmf);
+    fitter->Eval();
+    fitter->ReleaseParameter(3);
+    fitter->ReleaseParameter(4);
+    z0   = fitter->GetParameter(3); // = zmf ?
+    dzdx = fitter->GetParameter(4); // = dzmf ?
+  }
+
+  // Calculate Curvature
+  Double_t a    =  fitter->GetParameter(0);
+  Double_t b    =  fitter->GetParameter(1);
+  Double_t c    =  fitter->GetParameter(2);
+  Double_t y0   = 1. / a;
+  Double_t x0   = -b * y0;
+  Double_t tmp  = y0*y0 + x0*x0 - c*y0;
+  if(tmp<=0.) return 1.E10;
+  Double_t radius    = TMath::Sqrt(tmp);
+  Double_t curvature    =  1.0 + b*b - c*a;
+  if (curvature > 0.0)  curvature  =  a / TMath::Sqrt(curvature);
+
+  // Calculate chi2 of the fit 
+  Double_t chi2 = fitter->GetChisquare()/Double_t(nPoints);
+  if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")>3) printf("D-AliTRDtrackerV1::FitRiemanTilt:x0[%6.2f] y0[%6.2f] R[%6.2f] chi2[%f]\n", x0, y0, radius, chi2);
+
+  // Update the tracklets
+  if(!track){
+    for(Int_t ip = 0; ip < kNPlanes; ip++) {
+      x = tracklets[ip].GetX0();
+      tmp = radius*radius-(x-x0)*(x-x0);  
+      if(tmp <= 0.) continue;
+      tmp = TMath::Sqrt(tmp);  
+
+      // y:     R^2 = (x - x0)^2 + (y - y0)^2
+      //     =>   y = y0 +/- Sqrt(R^2 - (x - x0)^2)
+      tracklets[ip].SetYref(0, y0 - (y0>0.?1.:-1)*tmp);
+      //     => dy/dx = (x - x0)/Sqrt(R^2 - (x - x0)^2) 
+      tracklets[ip].SetYref(1, (x - x0) / tmp);
+      tracklets[ip].SetZref(0, z0 + dzdx * (x - xref));
+      tracklets[ip].SetZref(1, dzdx);
+      tracklets[ip].SetC(curvature);
+      tracklets[ip].SetChi2(chi2);
+    }
+  }
+  //update track points array
+  if(np && points){
+    Float_t xyz[3];
+    for(int ip=0; ip<np; ip++){
+      points[ip].GetXYZ(xyz);
+      xyz[1] = TMath::Abs(xyz[0] - x0) > radius ? 100. : y0 - (y0>0.?1.:-1.)*TMath::Sqrt((radius-(xyz[0]-x0))*(radius+(xyz[0]-x0)));
+      xyz[2] = z0 + dzdx * (xyz[0] - xref);
+      points[ip].SetXYZ(xyz);
+    }
+  }
+  
+  return chi2;
+}
+
+
+//____________________________________________________________________
+Double_t AliTRDtrackerV1::FitKalman(AliTRDtrackV1 *track, AliTRDseedV1 * const tracklets, Bool_t up, Int_t np, AliTrackPoint *points)
+{
+//   Kalman filter implementation for the TRD.
+//   It returns the positions of the fit in the array "points"
+// 
+//   Author : A.Bercuci@gsi.de
+
+  // printf("Start track @ x[%f]\n", track->GetX());
+       
+  //prepare marker points along the track
+  Int_t ip = np ? 0 : 1;
+  while(ip<np){
+    if((up?-1:1) * (track->GetX() - points[ip].GetX()) > 0.) break;
+    //printf("AliTRDtrackerV1::FitKalman() : Skip track marker x[%d] = %7.3f. Before track start ( %7.3f ).\n", ip, points[ip].GetX(), track->GetX());
+    ip++;
+  }
+  //if(points) printf("First marker point @ x[%d] = %f\n", ip, points[ip].GetX());
+
+
+  AliTRDseedV1 tracklet, *ptrTracklet = NULL;
+
+  //Loop through the TRD planes
+  for (Int_t jplane = 0; jplane < kNPlanes; jplane++) {
+    // GET TRACKLET OR BUILT IT                
+    Int_t iplane = up ? jplane : kNPlanes - 1 - jplane;
+    if(tracklets){ 
+      if(!(ptrTracklet = &tracklets[iplane])) continue;
+    }else{
+      if(!(ptrTracklet  = track->GetTracklet(iplane))){ 
+      /*AliTRDtrackerV1 *tracker = NULL;
+        if(!(tracker = dynamic_cast<AliTRDtrackerV1*>( AliTRDrecoParam:Tracker()))) continue;
+        ptrTracklet = new(&tracklet) AliTRDseedV1(iplane);
+        if(!tracker->MakeTracklet(ptrTracklet, track)) */
+        continue;
+      }
+    }
+    if(!ptrTracklet->IsOK()) continue;
+
+    Double_t x = ptrTracklet->GetX0();
+
+    while(ip < np){
+      //don't do anything if next marker is after next update point.
+      if((up?-1:1) * (points[ip].GetX() - x) - fgkMaxStep < 0) break;
+      if(((up?-1:1) * (points[ip].GetX() - track->GetX()) < 0) && !PropagateToX(*track, points[ip].GetX(), fgkMaxStep)) return -1.;
+      
+      Double_t xyz[3]; // should also get the covariance
+      track->GetXYZ(xyz);
+      track->Global2LocalPosition(xyz, track->GetAlpha());
+      points[ip].SetXYZ(xyz[0], xyz[1], xyz[2]);
+      ip++;
+    }
+    // printf("plane[%d] tracklet[%p] x[%f]\n", iplane, ptrTracklet, x);
+
+    // Propagate closer to the next update point 
+    if(((up?-1:1) * (x - track->GetX()) + fgkMaxStep < 0) && !PropagateToX(*track, x + (up?-1:1)*fgkMaxStep, fgkMaxStep)) return -1.;
+
+    if(!AdjustSector(track)) return -1;
+    if(TMath::Abs(track->GetSnp()) > fgkMaxSnp) return -1;
+    
+    //load tracklet to the tracker and the track
+/*    Int_t index;
+    if((index = FindTracklet(ptrTracklet)) < 0){
+      ptrTracklet = SetTracklet(&tracklet);
+      index = fTracklets->GetEntriesFast()-1;
+    }
+    track->SetTracklet(ptrTracklet, index);*/
+
+
+    // register tracklet to track with tracklet creation !!
+    // PropagateBack : loaded tracklet to the tracker and update index 
+    // RefitInward : update index 
+    // MakeTrack   : loaded tracklet to the tracker and update index 
+    if(!tracklets) track->SetTracklet(ptrTracklet, -1);
+    
+  
+    //Calculate the mean material budget along the path inside the chamber
+    Double_t xyz0[3]; track->GetXYZ(xyz0);
+    Double_t alpha = track->GetAlpha();
+    Double_t xyz1[3], y, z;
+    if(!track->GetProlongation(x, y, z)) return -1;
+    xyz1[0] =  x * TMath::Cos(alpha) - y * TMath::Sin(alpha); 
+    xyz1[1] = +x * TMath::Sin(alpha) + y * TMath::Cos(alpha);
+    xyz1[2] =  z;
+    if(TMath::Abs(xyz0[0] - xyz1[0]) < 1e-3 && TMath::Abs(xyz0[1] - xyz1[1]) < 1e-3) continue; // check wheter we are at the same global x position
+    Double_t param[7];
+    if(AliTracker::MeanMaterialBudget(xyz0, xyz1, param) <=0.) break;  
+    Double_t xrho = param[0]*param[4]; // density*length
+    Double_t xx0  = param[1]; // radiation length
+    
+    //Propagate the track
+    track->PropagateTo(x, xx0, xrho);
+    if (!AdjustSector(track)) break;
+  
+    //Update track
+    Double_t cov[3]; ptrTracklet->GetCovAt(x, cov);
+    Double_t p[2] = { ptrTracklet->GetY(), ptrTracklet->GetZ()};
+    Double_t chi2 = ((AliExternalTrackParam*)track)->GetPredictedChi2(p, cov);
+    if(chi2<1e+10) ((AliExternalTrackParam*)track)->Update(p, cov);
+    if(!up) continue;
+
+               //Reset material budget if 2 consecutive gold
+               if(iplane>0 && track->GetTracklet(iplane-1) && ptrTracklet->GetN() + track->GetTracklet(iplane-1)->GetN() > 20) track->SetBudget(2, 0.);
+       } // end planes loop
+
+  // extrapolation
+  while(ip < np){
+    if(((up?-1:1) * (points[ip].GetX() - track->GetX()) < 0) && !PropagateToX(*track, points[ip].GetX(), fgkMaxStep)) return -1.;
+    
+    Double_t xyz[3]; // should also get the covariance
+    track->GetXYZ(xyz); 
+    track->Global2LocalPosition(xyz, track->GetAlpha());
+    points[ip].SetXYZ(xyz[0], xyz[1], xyz[2]);
+    ip++;
+  }
+
+       return track->GetChi2();
+}
+
+//_________________________________________________________________________
+Float_t AliTRDtrackerV1::CalculateChi2Z(AliTRDseedV1 *tracklets, Double_t offset, Double_t slope, Double_t xref)
+{
+  //
+  // Calculates the chi2-value of the track in z-Direction including tilting pad correction.
+  // A linear dependence on the x-value serves as a model.
+  // The parameters are related to the tilted Riemann fit.
+  // Parameters: - Array of tracklets (AliTRDseedV1) related to the track candidate
+  //             - the offset for the reference x
+  //             - the slope
+  //             - the reference x position
+  // Output:     - The Chi2 value of the track in z-Direction
+  //
+  Float_t chi2Z = 0, nLayers = 0;
+  for (Int_t iLayer = 0; iLayer < AliTRDgeometry::kNlayer; iLayer++) {
+    if(!tracklets[iLayer].IsOK()) continue;
+    Double_t z = offset + slope * (tracklets[iLayer].GetX0() - xref);
+    chi2Z += TMath::Abs(tracklets[iLayer].GetZfit(0) - z);
+    nLayers++;
+  }
+  chi2Z /= TMath::Max((nLayers - 3.0),1.0);
+  return chi2Z;
+}
+
+//_____________________________________________________________________________
+Int_t AliTRDtrackerV1::PropagateToX(AliTRDtrackV1 &t, Double_t xToGo, Double_t maxStep)
+{
+  //
+  // Starting from current X-position of track <t> this function
+  // extrapolates the track up to radial position <xToGo>. 
+  // Returns 1 if track reaches the plane, and 0 otherwise 
+  //
+
+  const Double_t kEpsilon = 0.00001;
+
+  // Current track X-position
+  Double_t xpos = t.GetX();
+
+  // Direction: inward or outward
+  Double_t dir  = (xpos < xToGo) ? 1.0 : -1.0;
+
+  while (((xToGo - xpos) * dir) > kEpsilon) {
+
+    Double_t xyz0[3];
     Double_t xyz1[3];
     Double_t param[7];
     Double_t x;
@@ -1108,9 +1834,7 @@ Int_t AliTRDtrackerV1::PropagateToX(AliTRDtrackV1 &t, Double_t xToGo, Double_t m
     x = xpos + step;
 
     // Get local Y and Z at the X-position of the next step
-    if (!t.GetProlongation(x,y,z)) {
-      return 0; // No prolongation possible
-    }
+    if(t.GetProlongation(x,y,z)<0) return 0; // No prolongation possible
 
     // The global position of the end point of this prolongation step
     xyz1[0] =  x * TMath::Cos(t.GetAlpha()) - y * TMath::Sin(t.GetAlpha()); 
@@ -1119,12 +1843,10 @@ Int_t AliTRDtrackerV1::PropagateToX(AliTRDtrackV1 &t, Double_t xToGo, Double_t m
 
     // Calculate the mean material budget between start and
     // end point of this prolongation step
-    AliTracker::MeanMaterialBudget(xyz0, xyz1, param);
+    if(AliTracker::MeanMaterialBudget(xyz0, xyz1, param)<=0.) return 0;
 
     // Propagate the track to the X-position after the next step
-    if (!t.PropagateTo(x,param[1],param[0]*param[4])) {
-      return 0;
-    }
+    if (!t.PropagateTo(x, param[1], param[0]*param[4])) return 0;
 
     // Rotate the track if necessary
     AdjustSector(&t);
@@ -1159,7 +1881,9 @@ Int_t AliTRDtrackerV1::ReadClusters(TClonesArray* &array, TTree *clusterTree) co
   branch->SetAddress(&clusterArray); 
   
   if(!fClusters){ 
-    array = new TClonesArray("AliTRDcluster", nsize);
+    Float_t nclusters =  fkRecoParam->GetNClusters();
+    if(fkReconstructor->IsHLT()) nclusters /= AliTRDgeometry::kNsector;
+    array = new TClonesArray("AliTRDcluster", Int_t(nclusters));
     array->SetOwner(kTRUE);
   }
   
@@ -1167,7 +1891,7 @@ Int_t AliTRDtrackerV1::ReadClusters(TClonesArray* &array, TTree *clusterTree) co
   Int_t nEntries   = (Int_t) clusterTree->GetEntries();
   Int_t nbytes     = 0;
   Int_t ncl        = 0;
-  AliTRDcluster *c = 0x0;
+  AliTRDcluster *c = NULL;
   for (Int_t iEntry = 0; iEntry < nEntries; iEntry++) {
     // Import the tree
     nbytes += clusterTree->GetEvent(iEntry);  
@@ -1176,9 +1900,8 @@ Int_t AliTRDtrackerV1::ReadClusters(TClonesArray* &array, TTree *clusterTree) co
     Int_t nCluster = clusterArray->GetEntriesFast();  
     for (Int_t iCluster = 0; iCluster < nCluster; iCluster++) { 
       if(!(c = (AliTRDcluster *) clusterArray->UncheckedAt(iCluster))) continue;
-      c->SetInChamber();
       new((*fClusters)[ncl++]) AliTRDcluster(*c);
-      clusterArray->RemoveAt(iCluster); 
+      delete (clusterArray->RemoveAt(iCluster)); 
     }
 
   }
@@ -1191,63 +1914,140 @@ Int_t AliTRDtrackerV1::ReadClusters(TClonesArray* &array, TTree *clusterTree) co
 Int_t AliTRDtrackerV1::LoadClusters(TTree *cTree)
 {
   //
-  // Fills clusters into TRD tracking_sectors 
-  // Note that the numbering scheme for the TRD tracking_sectors 
-  // differs from that of TRD sectors
+  // Fills clusters into TRD tracking sectors
   //
+  
+  fkRecoParam = fkReconstructor->GetRecoParam(); // load reco param for this event
 
-       
-  if (ReadClusters(fClusters, cTree)) {
-    AliError("Problem with reading the clusters !");
+  if(!fkReconstructor->IsWritingClusters()){ 
+    fClusters = AliTRDReconstructor::GetClusters();
+  } else {
+    if (ReadClusters(fClusters, cTree)) {
+      AliError("Problem with reading the clusters !");
+      return 1;
+    }
+  }
+  SetClustersOwner();
+
+  if(!fClusters || !fClusters->GetEntriesFast()){ 
+    AliInfo("No TRD clusters");
     return 1;
   }
-  Int_t ncl  = fClusters->GetEntriesFast(), nin = 0;
-  if(!ncl){ 
-    AliInfo("Clusters 0");
+
+  //Int_t nin = 
+  BuildTrackingContainers();  
+
+  //Int_t ncl  = fClusters->GetEntriesFast();
+  //AliInfo(Form("Clusters %d [%6.2f %% in the active volume]", ncl, 100.*float(nin)/ncl));
+
+  return 0;
+}
+
+//_____________________________________________________________________________
+Int_t AliTRDtrackerV1::LoadClusters(TClonesArray * const clusters)
+{
+  //
+  // Fills clusters into TRD tracking sectors
+  // Function for use in the HLT
+  
+  if(!clusters || !clusters->GetEntriesFast()){ 
+    AliInfo("No TRD clusters");
     return 1;
   }
 
-  Int_t icl = ncl;
-  while (icl--) {
-    AliTRDcluster *c = (AliTRDcluster *) fClusters->UncheckedAt(icl);
+  fClusters = clusters;
+  SetClustersOwner();
+
+  fkRecoParam = fkReconstructor->GetRecoParam(); // load reco param for this event
+  BuildTrackingContainers();  
+
+  //Int_t ncl  = fClusters->GetEntriesFast();
+  //AliInfo(Form("Clusters %d [%6.2f %% in the active volume]", ncl, 100.*float(nin)/ncl));
+
+  return 0;
+}
+
+
+//____________________________________________________________________
+Int_t AliTRDtrackerV1::BuildTrackingContainers()
+{
+// Building tracking containers for clusters
+
+  Int_t nin(0), ncl(fClusters->GetEntriesFast());
+  while (ncl--) {
+    AliTRDcluster *c = (AliTRDcluster *) fClusters->UncheckedAt(ncl);
     if(c->IsInChamber()) nin++;
+    if(fkReconstructor->IsHLT()) c->SetRPhiMethod(AliTRDcluster::kCOG);
     Int_t detector       = c->GetDetector();
     Int_t sector         = fGeom->GetSector(detector);
-    Int_t stack          = fGeom->GetChamber(detector);
-    Int_t plane          = fGeom->GetPlane(detector);
-               
-    fTrSec[sector].GetChamber(stack, plane, kTRUE)->InsertCluster(c, icl);
+    Int_t stack          = fGeom->GetStack(detector);
+    Int_t layer          = fGeom->GetLayer(detector);
+    
+    fTrSec[sector].GetChamber(stack, layer, kTRUE)->InsertCluster(c, ncl);
   }
-  AliInfo(Form("Clusters %d in %6.2f %%", ncl, 100.*float(nin)/ncl));
-       
-  for(int isector =0; isector<AliTRDgeometry::kNsect; isector++){ 
+
+  for(int isector =0; isector<AliTRDgeometry::kNsector; isector++){ 
     if(!fTrSec[isector].GetNChambers()) continue;
-    fTrSec[isector].Init();
+    fTrSec[isector].Init(fkReconstructor);
   }
-  
-  return 0;
+
+  return nin;
 }
 
 
+
 //____________________________________________________________________
 void AliTRDtrackerV1::UnloadClusters() 
 { 
-  //
-  // Clears the arrays of clusters and tracks. Resets sectors and timebins 
-  //
-
-  if(fTracks) fTracks->Delete(); 
-  if(fTracklets) fTracklets->Delete();
-  if(fClusters) fClusters->Delete();
+//
+// Clears the arrays of clusters and tracks. Resets sectors and timebins 
+// If option "force" is also set the containers are also deleted. This is useful 
+// in case of HLT
+
+  if(fTracks){ 
+    fTracks->Delete(); 
+    if(HasRemoveContainers()){delete fTracks; fTracks = NULL;}
+  }
+  if(fTracklets){ 
+    fTracklets->Delete();
+    if(HasRemoveContainers()){delete fTracklets; fTracklets = NULL;}
+  }
+  if(fClusters){ 
+    if(IsClustersOwner()) fClusters->Delete();
+    
+    // save clusters array in the reconstructor for further use.
+    if(!fkReconstructor->IsWritingClusters()){
+      AliTRDReconstructor::SetClusters(fClusters);
+      SetClustersOwner(kFALSE);
+    } else AliTRDReconstructor::SetClusters(NULL);
+  }
 
-  for (int i = 0; i < AliTRDgeometry::kNsect; i++) fTrSec[i].Clear();
+  for (int i = 0; i < AliTRDgeometry::kNsector; i++) fTrSec[i].Clear();
 
   // Increment the Event Number
   AliTRDtrackerDebug::SetEventNumber(AliTRDtrackerDebug::GetEventNumber()  + 1);
 }
 
+// //____________________________________________________________________
+// void AliTRDtrackerV1::UseClusters(const AliKalmanTrack *t, Int_t) const
+// {
+//   const AliTRDtrackV1 *track = dynamic_cast<const AliTRDtrackV1*>(t);
+//   if(!track) return;
+// 
+//   AliTRDseedV1 *tracklet = NULL;
+//   for(Int_t ily=AliTRDgeometry::kNlayer; ily--;){
+//     if(!(tracklet = track->GetTracklet(ily))) continue;
+//     AliTRDcluster *c = NULL;
+//     for(Int_t ic=AliTRDseed::kNclusters; ic--;){
+//       if(!(c=tracklet->GetClusters(ic))) continue;
+//       c->Use();
+//     }
+//   }
+// }
+// 
+
 //_____________________________________________________________________________
-Bool_t AliTRDtrackerV1::AdjustSector(AliTRDtrackV1 *track) 
+Bool_t AliTRDtrackerV1::AdjustSector(AliTRDtrackV1 *const track) 
 {
   //
   // Rotates the track when necessary
@@ -1256,7 +2056,7 @@ Bool_t AliTRDtrackerV1::AdjustSector(AliTRDtrackV1 *track)
   Double_t alpha = AliTRDgeometry::GetAlpha(); 
   Double_t y     = track->GetY();
   Double_t ymax  = track->GetX()*TMath::Tan(0.5*alpha);
-
+  
   if      (y >  ymax) {
     if (!track->Rotate( alpha)) {
       return kFALSE;
@@ -1274,7 +2074,7 @@ Bool_t AliTRDtrackerV1::AdjustSector(AliTRDtrackV1 *track)
 
 
 //____________________________________________________________________
-AliTRDseedV1* AliTRDtrackerV1::GetTracklet(AliTRDtrackV1 *track, Int_t p, Int_t &idx)
+AliTRDseedV1* AliTRDtrackerV1::GetTracklet(AliTRDtrackV1 *const track, Int_t p, Int_t &idx)
 {
   // Find tracklet for TRD track <track>
   // Parameters
@@ -1288,13 +2088,13 @@ AliTRDseedV1* AliTRDtrackerV1::GetTracklet(AliTRDtrackV1 *track, Int_t p, Int_t
   // Detailed description
   //
   idx = track->GetTrackletIndex(p);
-  AliTRDseedV1 *tracklet = idx<0 ? 0x0 : (AliTRDseedV1*)fTracklets->UncheckedAt(idx);
+  AliTRDseedV1 *tracklet = (idx<0) ? NULL : (AliTRDseedV1*)fTracklets->UncheckedAt(idx);
 
   return tracklet;
 }
 
 //____________________________________________________________________
-Int_t AliTRDtrackerV1::SetTracklet(AliTRDseedV1 *tracklet)
+AliTRDseedV1* AliTRDtrackerV1::SetTracklet(const AliTRDseedV1 * const tracklet)
 {
   // Add this tracklet to the list of tracklets stored in the tracker
   //
@@ -1309,14 +2109,38 @@ Int_t AliTRDtrackerV1::SetTracklet(AliTRDseedV1 *tracklet)
   // and adds the new tracklet to the list.
   //
   if(!fTracklets){
-    fTracklets = new TClonesArray("AliTRDseedV1", AliTRDgeometry::Nsect()*kMaxTracksStack);
+    fTracklets = new TClonesArray("AliTRDseedV1", AliTRDgeometry::Nsector()*kMaxTracksStack);
     fTracklets->SetOwner(kTRUE);
   }
   Int_t nentries = fTracklets->GetEntriesFast();
-  new ((*fTracklets)[nentries]) AliTRDseedV1(*tracklet);
-  return nentries;
+  return new ((*fTracklets)[nentries]) AliTRDseedV1(*tracklet);
+}
+
+//____________________________________________________________________
+AliTRDtrackV1* AliTRDtrackerV1::SetTrack(const AliTRDtrackV1 * const track)
+{
+  // Add this track to the list of tracks stored in the tracker
+  //
+  // Parameters
+  //   - track : pointer to the track to be added to the list
+  //
+  // Output
+  //   - the pointer added
+  //
+  // Detailed description
+  // Build the tracks list if it is not yet created (late initialization)
+  // and adds the new track to the list.
+  //
+  if(!fTracks){
+    fTracks = new TClonesArray("AliTRDtrackV1", AliTRDgeometry::Nsector()*kMaxTracksStack);
+    fTracks->SetOwner(kTRUE);
+  }
+  Int_t nentries = fTracks->GetEntriesFast();
+  return new ((*fTracks)[nentries]) AliTRDtrackV1(*track);
 }
 
+
+
 //____________________________________________________________________
 Int_t AliTRDtrackerV1::Clusters2TracksSM(Int_t sector, AliESDEvent *esd)
 {
@@ -1338,40 +2162,53 @@ Int_t AliTRDtrackerV1::Clusters2TracksSM(Int_t sector, AliESDEvent *esd)
   //    See AliTRDtrackerV1::Clusters2TracksStack() for details.
   // 3. Pack results in the ESD event.
   //
-       
-  // allocate space for esd tracks in this SM
-  TClonesArray esdTrackList("AliESDtrack", 2*kMaxTracksStack);
-  esdTrackList.SetOwner();
-       
+  
   Int_t nTracks   = 0;
   Int_t nChambers = 0;
-  AliTRDtrackingChamber **stack = 0x0, *chamber = 0x0;
-  for(int istack = 0; istack<AliTRDgeometry::kNcham; istack++){
+  AliTRDtrackingChamber **stack = NULL, *chamber = NULL;
+  for(int istack = 0; istack<AliTRDgeometry::kNstack; istack++){
     if(!(stack = fTrSec[sector].GetStack(istack))) continue;
     nChambers = 0;
-    for(int iplane=0; iplane<AliTRDgeometry::kNplan; iplane++){
-      if(!(chamber = stack[iplane])) continue;
-      if(chamber->GetNClusters() < fgNTimeBins * AliTRDReconstructor::RecoParam()->GetFindableClusters()) continue;
+    for(int ilayer=0; ilayer<AliTRDgeometry::kNlayer; ilayer++){
+      if(!(chamber = stack[ilayer])) continue;
+      if(chamber->GetNClusters() < fgNTimeBins * fkRecoParam->GetFindableClusters()) continue;
       nChambers++;
-      //AliInfo(Form("sector %d stack %d plane %d clusters %d", sector, istack, iplane, chamber->GetNClusters()));
+      //AliInfo(Form("sector %d stack %d layer %d clusters %d", sector, istack, ilayer, chamber->GetNClusters()));
     }
     if(nChambers < 4) continue;
     //AliInfo(Form("Doing stack %d", istack));
-    nTracks += Clusters2TracksStack(stack, &esdTrackList);
+    nTracks += Clusters2TracksStack(stack, fTracksESD);
+  }
+  if(nTracks) AliDebug(2, Form("Number of tracks: SM_%02d[%d]", sector, nTracks));
+
+  for(int itrack=0; itrack<nTracks; itrack++){
+    AliESDtrack *esdTrack((AliESDtrack*)(fTracksESD->operator[](itrack)));
+    Int_t id = esd->AddTrack(esdTrack);
+
+    // set ESD id to stand alone TRD tracks
+    if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0){ 
+      esdTrack=esd->GetTrack(id);
+      TObject *o(NULL); Int_t ic(0);
+      AliTRDtrackV1 *calibTrack(NULL); 
+      while((o = esdTrack->GetCalibObject(ic++))){
+        if(!(calibTrack = dynamic_cast<AliTRDtrackV1*>(o))) continue;
+        calibTrack->SetESDid(esdTrack->GetID());
+        break;
+      }
+    }
   }
-  //AliInfo(Form("Found %d tracks in SM %d [%d]\n", nTracks, sector, esd->GetNumberOfTracks()));
-       
-  for(int itrack=0; itrack<nTracks; itrack++)
-    esd->AddTrack((AliESDtrack*)esdTrackList[itrack]);
 
   // Reset Track and Candidate Number
   AliTRDtrackerDebug::SetCandidateNumber(0);
   AliTRDtrackerDebug::SetTrackNumber(0);
+
+  // delete ESD tracks in the array
+  fTracksESD->Delete();
   return nTracks;
 }
 
 //____________________________________________________________________
-Int_t AliTRDtrackerV1::Clusters2TracksStack(AliTRDtrackingChamber **stack, TClonesArray *esdTrackList)
+Int_t AliTRDtrackerV1::Clusters2TracksStack(AliTRDtrackingChamber **stack, TClonesArray * const esdTrackList)
 {
   //
   // Make tracks in one TRD stack.
@@ -1399,46 +2236,67 @@ Int_t AliTRDtrackerV1::Clusters2TracksStack(AliTRDtrackingChamber **stack, TClon
   // 8. Build ESD track and register it to the output list
   //
 
-  AliTRDCalibraFillHisto *calibra = AliTRDCalibraFillHisto::Instance();
-  if (!calibra) AliInfo("Could not get Calibra instance\n");
-
-  AliTRDtrackingChamber *chamber = 0x0;
+  AliTRDtrackingChamber *chamber = NULL;
+  AliTRDtrackingChamber **ci = NULL;
   AliTRDseedV1 sseed[kMaxTracksStack*6]; // to be initialized
   Int_t pars[4]; // MakeSeeds parameters
 
   //Double_t alpha = AliTRDgeometry::GetAlpha();
   //Double_t shift = .5 * alpha;
   Int_t configs[kNConfigs];
-       
+  
+  // Purge used clusters from the containers
+  ci = &stack[0];
+  for(Int_t ic = kNPlanes; ic--; ci++){
+    if(!(*ci)) continue;
+    (*ci)->Update();
+  }
+
   // Build initial seeding configurations
   Double_t quality = BuildSeedingConfigs(stack, configs);
-  if(AliTRDReconstructor::StreamLevel() > 1){
+  if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 10){
     AliInfo(Form("Plane config %d %d %d Quality %f"
-                , configs[0], configs[1], configs[2], quality));
+    , configs[0], configs[1], configs[2], quality));
   }
-       
+
+  
   // Initialize contors
   Int_t ntracks,      // number of TRD track candidates
     ntracks1,     // number of registered TRD tracks/iter
     ntracks2 = 0; // number of all registered TRD tracks in stack
   fSieveSeeding = 0;
+
+  // Get stack index
+  Int_t ic = 0; ci = &stack[0];
+  while(ic<kNPlanes && !(*ci)){ic++; ci++;}
+  if(!(*ci)) return ntracks2;
+  Int_t istack = fGeom->GetStack((*ci)->GetDetector());
+
   do{
     // Loop over seeding configurations
     ntracks = 0; ntracks1 = 0;
-    for (Int_t iconf = 0; iconf<3; iconf++) {
+    for (Int_t iconf = 0; iconf<fkRecoParam->GetNumberOfSeedConfigs(); iconf++) {
       pars[0] = configs[iconf];
       pars[1] = ntracks;
+      pars[2] = istack;
       ntracks = MakeSeeds(stack, &sseed[6*ntracks], pars);
+      //AliInfo(Form("Number of Tracks after iteration step %d: %d\n", iconf, ntracks));
       if(ntracks == kMaxTracksStack) break;
     }
-    if(AliTRDReconstructor::StreamLevel() > 1) AliInfo(Form("Candidate TRD tracks %d in iteration %d.", ntracks, fSieveSeeding));
-               
+    AliDebug(2, Form("Candidate TRD tracks %d in iteration %d.", ntracks, fSieveSeeding));
     if(!ntracks) break;
-               
+    
     // Sort the seeds according to their quality
     Int_t sort[kMaxTracksStack];
     TMath::Sort(ntracks, fTrackQuality, sort, kTRUE);
-       
+    if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1") > 2){
+      AliDebug(3, "Track candidates classification:");
+      for (Int_t it(0); it < ntracks; it++) {
+        Int_t jt(sort[it]);
+        printf("   %2d idx[%d] Quality[%e]\n", it, jt, fTrackQuality[jt]);
+      }
+    }
+  
     // Initialize number of tracks so far and logic switches
     Int_t ntracks0 = esdTrackList->GetEntriesFast();
     Bool_t signedTrack[kMaxTracksStack];
@@ -1448,248 +2306,164 @@ Int_t AliTRDtrackerV1::Clusters2TracksStack(AliTRDtrackingChamber **stack, TClon
       fakeTrack[i] = kFALSE;
     }
     //AliInfo("Selecting track candidates ...");
-               
+    
     // Sieve clusters in decreasing order of track quality
-    Double_t trackParams[7];
-    //                 AliTRDseedV1 *lseed = 0x0;
-    Int_t jSieve = 0, candidates;
+    Int_t jSieve(0), rejectedCandidates(0);
     do{
-      //AliInfo(Form("\t\tITER = %i ", jSieve));
-
       // Check track candidates
-      candidates = 0;
+      rejectedCandidates=0;
       for (Int_t itrack = 0; itrack < ntracks; itrack++) {
-       Int_t trackIndex = sort[itrack];
-       if (signedTrack[trackIndex] || fakeTrack[trackIndex]) continue;
-       
-                               
-       // Calculate track parameters from tracklets seeds
-       Int_t labelsall[1000];
-       Int_t nlabelsall = 0;
-       Int_t naccepted  = 0;
-       Int_t ncl        = 0;
-       Int_t nused      = 0;
-       Int_t nlayers    = 0;
-       Int_t findable   = 0;
-       for (Int_t jLayer = 0; jLayer < kNPlanes; jLayer++) {
-         Int_t jseed = kNPlanes*trackIndex+jLayer;
-         if(!sseed[jseed].IsOK()) continue;
-         if (TMath::Abs(sseed[jseed].GetYref(0) / sseed[jseed].GetX0()) < 0.15) findable++;
-       
-         sseed[jseed].UpdateUsed();
-         ncl   += sseed[jseed].GetN2();
-         nused += sseed[jseed].GetNUsed();
-         nlayers++;
-       
-         // Cooking label
-         for (Int_t itime = 0; itime < fgNTimeBins; itime++) {
-           if(!sseed[jseed].IsUsable(itime)) continue;
-           naccepted++;
-           Int_t tindex = 0, ilab = 0;
-           while(ilab<3 && (tindex = sseed[jseed].GetClusters(itime)->GetLabel(ilab)) >= 0){
-             labelsall[nlabelsall++] = tindex;
-             ilab++;
-           }
-         }
-       }
-       // Filter duplicated tracks
-       if (nused > 30){
-         //printf("Skip %d nused %d\n", trackIndex, nused);
-         fakeTrack[trackIndex] = kTRUE;
-         continue;
-       }
-       if (Float_t(nused)/ncl >= .25){
-         //printf("Skip %d nused/ncl >= .25\n", trackIndex);
-         fakeTrack[trackIndex] = kTRUE;
-         continue;
-       }
-                               
-       // Classify tracks
-       Bool_t skip = kFALSE;
-       switch(jSieve){
-       case 0:
-         if(nlayers < 6) {skip = kTRUE; break;}
-         if(TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -5.){skip = kTRUE; break;}
-         break;
-       
-       case 1:
-         if(nlayers < findable){skip = kTRUE; break;}
-         if(TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -4.){skip = kTRUE; break;}
-         break;
-       
-       case 2:
-         if ((nlayers == findable) || (nlayers == 6)) { skip = kTRUE; break;}
-         if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -6.0){skip = kTRUE; break;}
-         break;
-       
-       case 3:
-         if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -5.){skip = kTRUE; break;}
-         break;
-       
-       case 4:
-         if (nlayers == 3){skip = kTRUE; break;}
-         //if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) - nused/(nlayers-3.0) < -15.0){skip = kTRUE; break;}
-         break;
-       }
-       if(skip){
-         candidates++;
-         //printf("REJECTED : %d [%d] nlayers %d trackQuality = %e nused %d\n", itrack, trackIndex, nlayers, fTrackQuality[trackIndex], nused);
-         continue;
-       }
-       signedTrack[trackIndex] = kTRUE;
-                                               
-
-       // Build track label - what happens if measured data ???
-       Int_t labels[1000];
-       Int_t outlab[1000];
-       Int_t nlab = 0;
-       for (Int_t iLayer = 0; iLayer < 6; iLayer++) {
-         Int_t jseed = kNPlanes*trackIndex+iLayer;
-         if(!sseed[jseed].IsOK()) continue;
-         for(int ilab=0; ilab<2; ilab++){
-           if(sseed[jseed].GetLabels(ilab) < 0) continue;
-           labels[nlab] = sseed[jseed].GetLabels(ilab);
-           nlab++;
-         }
-       }
-       Freq(nlab,labels,outlab,kFALSE);
-       Int_t   label     = outlab[0];
-       Int_t   frequency = outlab[1];
-       Freq(nlabelsall,labelsall,outlab,kFALSE);
-       Int_t   label1    = outlab[0];
-       Int_t   label2    = outlab[2];
-       Float_t fakeratio = (naccepted - outlab[1]) / Float_t(naccepted);
-       
-                               
-       // Sign clusters
-       AliTRDcluster *cl = 0x0; Int_t clusterIndex = -1;
-       for (Int_t jLayer = 0; jLayer < 6; jLayer++) {
-         Int_t jseed = kNPlanes*trackIndex+jLayer;
-         if(!sseed[jseed].IsOK()) continue;
-         if(TMath::Abs(sseed[jseed].GetYfit(1) - sseed[jseed].GetYfit(1)) >= .2) continue; // check this condition with Marian
-         sseed[jseed].UseClusters();
-         if(!cl){
-           Int_t ic = 0;
-           while(!(cl = sseed[jseed].GetClusters(ic))) ic++;
-           clusterIndex =  sseed[jseed].GetIndexes(ic);
-         }
-       }
-       if(!cl) continue;
-
-                               
-       // Build track parameters
-       AliTRDseedV1 *lseed =&sseed[trackIndex*6];
-       Int_t idx = 0;
-       while(idx<3 && !lseed->IsOK()) {
-         idx++;
-         lseed++;
-       }
-       Double_t cR = lseed->GetC();
-       trackParams[1] = lseed->GetYref(0);
-       trackParams[2] = lseed->GetZref(0);
-       trackParams[3] = lseed->GetX0() * cR - TMath::Sin(TMath::ATan(lseed->GetYref(1)));
-       trackParams[4] = lseed->GetZref(1) / TMath::Sqrt(1. + lseed->GetYref(1) * lseed->GetYref(1));
-       trackParams[5] = cR;
-       trackParams[0] = lseed->GetX0();
-       Int_t ich = 0; while(!(chamber = stack[ich])) ich++;
-       trackParams[6] = fGeom->GetSector(chamber->GetDetector());/* *alpha+shift;      // Supermodule*/
-
-       if(AliTRDReconstructor::StreamLevel() > 1){
-         AliInfo(Form("Track %d [%d] nlayers %d trackQuality = %e nused %d, yref = %3.3f", itrack, trackIndex, nlayers, fTrackQuality[trackIndex], nused, trackParams[1]));
-                                       
-         Int_t nclusters = 0;
-         AliTRDseedV1 *dseed[6];
-         for(int is=0; is<6; is++){
-           dseed[is] = new AliTRDseedV1(sseed[trackIndex*6+is]);
-           dseed[is]->SetOwner();
-           nclusters += sseed[is].GetN2();
-         }
-         //Int_t eventNrInFile = esd->GetEventNumberInFile();
-         //AliInfo(Form("Number of clusters %d.", nclusters));
-         Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
-         Int_t trackNumber = AliTRDtrackerDebug::GetTrackNumber();
-         Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
-         TTreeSRedirector &cstreamer = *fgDebugStreamer;
-         cstreamer << "Clusters2TracksStack"
-                   << "EventNumber="           << eventNumber
-                   << "TrackNumber="           << trackNumber
-                   << "CandidateNumber="       << candidateNumber
-                   << "Iter="                          << fSieveSeeding
-                   << "Like="                          << fTrackQuality[trackIndex]
-                   << "S0.="                           << dseed[0]
-                   << "S1.="                           << dseed[1]
-                   << "S2.="                           << dseed[2]
-                   << "S3.="                           << dseed[3]
-                   << "S4.="                           << dseed[4]
-                   << "S5.="                           << dseed[5]
-                   << "p0="                            << trackParams[0]
-                   << "p1="                            << trackParams[1]
-                   << "p2="                            << trackParams[2]
-                   << "p3="                            << trackParams[3]
-                   << "p4="                            << trackParams[4]
-                   << "p5="                            << trackParams[5]
-                   << "p6="                            << trackParams[6]
-                   << "Label="                         << label
-                   << "Label1="                        << label1
-                   << "Label2="                        << label2
-                   << "FakeRatio="                     << fakeratio
-                   << "Freq="                          << frequency
-                   << "Ncl="                           << ncl
-                   << "NLayers="                       << nlayers
-                   << "Findable="                      << findable
-
-                   << "NUsed="                         << nused
-                   << "\n";
-       }
-                       
-       AliTRDtrackV1 *track = MakeTrack(&sseed[trackIndex*kNPlanes], trackParams);
-       if(!track){
-         //AliWarning("Fail to build a TRD Track.");
-         continue;
-       }
-       //AliInfo("End of MakeTrack()");
-       // computes PID for track
-       track->CookPID();
-       // update calibration references using this track
-       if(calibra->GetHisto2d()) calibra->UpdateHistogramsV1(track);
-       AliESDtrack esdTrack;
-       esdTrack.UpdateTrackParams(track, AliESDtrack::kTRDout);
-       esdTrack.SetLabel(track->GetLabel());
-       track->UpdateESDtrack(&esdTrack);
-       // write ESD-friends if neccessary
-       if (AliTRDReconstructor::StreamLevel() > 0){
-         //printf("Creating Calibrations Object\n");
-         AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(*track);
-         calibTrack->SetOwner();
-         esdTrack.AddCalibObject(calibTrack);
-       }
-       new ((*esdTrackList)[ntracks0++]) AliESDtrack(esdTrack);
-       ntracks1++;
-       AliTRDtrackerDebug::SetTrackNumber(AliTRDtrackerDebug::GetTrackNumber() + 1);
+        Int_t trackIndex = sort[itrack];
+        if (signedTrack[trackIndex] || fakeTrack[trackIndex]) continue;
+        
+        // Calculate track parameters from tracklets seeds
+        Int_t ncl        = 0;
+        Int_t nused      = 0;
+        Int_t nlayers    = 0;
+        Int_t findable   = 0;
+        for (Int_t jLayer = 0; jLayer < kNPlanes; jLayer++) {
+          Int_t jseed = kNPlanes*trackIndex+jLayer;
+          sseed[jseed].UpdateUsed();
+          if(!sseed[jseed].IsOK()) continue;
+          // check if primary candidate
+          if (TMath::Abs(sseed[jseed].GetYref(0) / sseed[jseed].GetX0()) < 0.158) findable++;
+          ncl   += sseed[jseed].GetN();
+          nused += sseed[jseed].GetNUsed();
+          nlayers++;
+        }
+
+        // Filter duplicated tracks
+        if (nused > 30){
+          AliDebug(4, Form("REJECTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused));
+          fakeTrack[trackIndex] = kTRUE;
+          continue;
+        }
+        if (ncl>0 && Float_t(nused)/ncl >= .25){
+          AliDebug(4, Form("REJECTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d] used/ncl[%f]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused, Float_t(nused)/ncl));
+          fakeTrack[trackIndex] = kTRUE;
+          continue;
+        }
+
+        AliDebug(4, Form("Candidate[%d] Quality[%e] Tracklets[%d] Findable[%d] Ncl[%d] Nused[%d]", trackIndex, fTrackQuality[trackIndex], nlayers, findable, ncl, nused));
+
+        // Classify tracks
+        Bool_t skip = kFALSE;
+        switch(jSieve){
+          case 0: // select 6 tracklets primary tracks, good quality
+            if(nlayers > findable || nlayers < kNPlanes) {skip = kTRUE; break;}
+            if(TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -5.){skip = kTRUE; break;}
+            break;
+
+          case 1: // select shorter primary tracks, good quality
+            if(findable<4){skip = kTRUE; break;}
+            if(nlayers < findable){skip = kTRUE; break;}
+            if(TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -4.){skip = kTRUE; break;}
+            break;
+
+          case 2: // select 6 tracklets secondary tracks
+            if(nlayers < kNPlanes) { skip = kTRUE; break;}
+            if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -6.0){skip = kTRUE; break;}
+            break;
+
+          case 3: // select shorter tracks, good quality
+            if (nlayers<4){skip = kTRUE; break;}
+            if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) < -5.){skip = kTRUE; break;}
+            break;
+
+          case 4: // select anything with at least 4 tracklets
+            if (nlayers<4){skip = kTRUE; break;}
+            //if (TMath::Log(1.E-9+fTrackQuality[trackIndex]) - nused/(nlayers-3.0) < -15.0){skip = kTRUE; break;}
+            break;
+        }
+        if(skip){
+          rejectedCandidates++;
+          AliDebug(4, Form("REJECTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused));
+          continue;
+        } else AliDebug(4, Form("ACCEPTED : %d idx[%d] quality[%e] tracklets[%d] usedClusters[%d]", itrack, trackIndex, fTrackQuality[trackIndex], nlayers, nused));
+
+        signedTrack[trackIndex] = kTRUE;
+
+        AliTRDseedV1 *lseed =&sseed[trackIndex*kNPlanes];
+        AliTRDtrackV1 *track = MakeTrack(lseed);
+        if(!track){
+          AliDebug(1, "Track building failed.");
+          continue;
+        } else { 
+          if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1") > 1){
+            Int_t ich = 0; while(!(chamber = stack[ich])) ich++;
+            AliDebug(2, Form("Track pt=%7.2fGeV/c SM[%2d] Done.", track->Pt(), fGeom->GetSector(chamber->GetDetector())));
+          }
+        }
+
+        if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 1 && fkReconstructor->IsDebugStreaming()){
+          //AliInfo(Form("Track %d [%d] nlayers %d trackQuality = %e nused %d, yref = %3.3f", itrack, trackIndex, nlayers, fTrackQuality[trackIndex], nused, trackParams[1]));
+
+          AliTRDseedV1 *dseed[6];
+          for(Int_t iseed = AliTRDgeometry::kNlayer; iseed--;) dseed[iseed] = new AliTRDseedV1(lseed[iseed]);
+
+          //Int_t eventNrInFile = esd->GetEventNumberInFile();
+          Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
+          Int_t trackNumber = AliTRDtrackerDebug::GetTrackNumber();
+          Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
+          TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
+          cstreamer << "Clusters2TracksStack"
+              << "EventNumber="   << eventNumber
+              << "TrackNumber="   << trackNumber
+              << "CandidateNumber=" << candidateNumber
+              << "Iter="        << fSieveSeeding
+              << "Like="        << fTrackQuality[trackIndex]
+              << "S0.="       << dseed[0]
+              << "S1.="       << dseed[1]
+              << "S2.="       << dseed[2]
+              << "S3.="       << dseed[3]
+              << "S4.="       << dseed[4]
+              << "S5.="       << dseed[5]
+              << "Ncl="       << ncl
+              << "NLayers="   << nlayers
+              << "Findable="  << findable
+              << "NUsed="     << nused
+              << "\n";
+        }
+
+
+        AliESDtrack *esdTrack = new ((*esdTrackList)[ntracks0++]) AliESDtrack();
+        esdTrack->UpdateTrackParams(track, AliESDtrack::kTRDout);
+        esdTrack->SetLabel(track->GetLabel());
+        track->UpdateESDtrack(esdTrack);
+        // write ESD-friends if neccessary
+        if (fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 0){
+          AliTRDtrackV1 *calibTrack = new AliTRDtrackV1(*track);
+          calibTrack->SetOwner();
+          esdTrack->AddCalibObject(calibTrack);
+        }
+        ntracks1++;
+        AliTRDtrackerDebug::SetTrackNumber(AliTRDtrackerDebug::GetTrackNumber() + 1);
       }
 
       jSieve++;
-    } while(jSieve<5 && candidates); // end track candidates sieve
+    } while(jSieve<5 && rejectedCandidates); // end track candidates sieve
     if(!ntracks1) break;
 
     // increment counters
     ntracks2 += ntracks1;
+
+    if(fkReconstructor->IsHLT()) break;
     fSieveSeeding++;
 
     // Rebuild plane configurations and indices taking only unused clusters into account
     quality = BuildSeedingConfigs(stack, configs);
-    if(quality < 1.E-7) break; //AliTRDReconstructor::RecoParam()->GetPlaneQualityThreshold()) break;
-               
+    if(quality < 1.E-7) break; //fkReconstructor->GetRecoParam() ->GetPlaneQualityThreshold()) break;
+    
     for(Int_t ip = 0; ip < kNPlanes; ip++){ 
       if(!(chamber = stack[ip])) continue;
       chamber->Build(fGeom);//Indices(fSieveSeeding);
     }
 
-    if(AliTRDReconstructor::StreamLevel() > 1){ 
+    if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 10){ 
       AliInfo(Form("Sieve level %d Plane config %d %d %d Quality %f", fSieveSeeding, configs[0], configs[1], configs[2], quality));
     }
   } while(fSieveSeeding<10); // end stack clusters sieve
-       
+  
 
 
   //AliInfo(Form("Registered TRD tracks %d in stack %d.", ntracks2, pars[1]));
@@ -1724,83 +2498,94 @@ Double_t AliTRDtrackerV1::BuildSeedingConfigs(AliTRDtrackingChamber **stack, Int
   // The overall chamber quality is given by the product of this 2 contributions.
   // 
 
-  Double_t chamberQ[kNPlanes];
-  AliTRDtrackingChamber *chamber = 0x0;
+  Double_t chamberQ[kNPlanes];memset(chamberQ, 0, kNPlanes*sizeof(Double_t));
+  AliTRDtrackingChamber *chamber = NULL;
   for(int iplane=0; iplane<kNPlanes; iplane++){
     if(!(chamber = stack[iplane])) continue;
     chamberQ[iplane] = (chamber = stack[iplane]) ?  chamber->GetQuality() : 0.;
   }
 
-  Double_t tconfig[kNConfigs];
-  Int_t planes[4];
+  Double_t tconfig[kNConfigs];memset(tconfig, 0, kNConfigs*sizeof(Double_t));
+  Int_t planes[] = {0, 0, 0, 0};
   for(int iconf=0; iconf<kNConfigs; iconf++){
     GetSeedingConfig(iconf, planes);
     tconfig[iconf] = fgTopologicQA[iconf];
     for(int iplane=0; iplane<4; iplane++) tconfig[iconf] *= chamberQ[planes[iplane]]; 
   }
-       
+  
   TMath::Sort((Int_t)kNConfigs, tconfig, configs, kTRUE);
-  //   AliInfo(Form("q[%d] = %f", configs[0], tconfig[configs[0]]));
+  //   AliInfo(Form("q[%d] = %f", configs[0], tconfig[configs[0]]));
   //   AliInfo(Form("q[%d] = %f", configs[1], tconfig[configs[1]]));
   //   AliInfo(Form("q[%d] = %f", configs[2], tconfig[configs[2]]));
-       
+  
   return tconfig[configs[0]];
 }
 
 //____________________________________________________________________
-Int_t AliTRDtrackerV1::MakeSeeds(AliTRDtrackingChamber **stack, AliTRDseedV1 *sseed, Int_t *ipar)
+Int_t AliTRDtrackerV1::MakeSeeds(AliTRDtrackingChamber **stack, AliTRDseedV1 * const sseed, const Int_t * const ipar)
 {
-  //
-  // Make tracklet seeds in the TRD stack.
-  //
-  // Parameters :
-  //   layers : Array of stack propagation layers containing clusters
-  //   sseed  : Array of empty tracklet seeds. On exit they are filled.
-  //   ipar   : Control parameters:
-  //       ipar[0] -> seeding chambers configuration
-  //       ipar[1] -> stack index
-  //       ipar[2] -> number of track candidates found so far
-  //
-  // Output :
-  //   Number of tracks candidates found.
-  // 
-  // Detailed description
-  //
-  // The following steps are performed:
-  // 1. Select seeding layers from seeding chambers
-  // 2. Select seeding clusters from the seeding AliTRDpropagationLayerStack.
-  //   The clusters are taken from layer 3, layer 0, layer 1 and layer 2, in
-  //   this order. The parameters controling the range of accepted clusters in
-  //   layer 0, 1, and 2 are defined in AliTRDchamberTimeBin::BuildCond().
-  // 3. Helix fit of the cluster set. (see AliTRDtrackerFitter::FitRieman(AliTRDcluster**))
-  // 4. Initialize seeding tracklets in the seeding chambers.
-  // 5. Filter 0.
-  //   Chi2 in the Y direction less than threshold ... (1./(3. - sLayer))
-  //   Chi2 in the Z direction less than threshold ... (1./(3. - sLayer))
-  // 6. Attach clusters to seeding tracklets and find linear approximation of
-  //   the tracklet (see AliTRDseedV1::AttachClustersIter()). The number of used
-  //   clusters used by current seeds should not exceed ... (25).
-  // 7. Filter 1.
-  //   All 4 seeding tracklets should be correctly constructed (see
-  //   AliTRDseedV1::AttachClustersIter())
-  // 8. Helix fit of the seeding tracklets
-  // 9. Filter 2.
-  //   Likelihood calculation of the fit. (See AliTRDtrackerV1::CookLikelihood() for details)
-  // 10. Extrapolation of the helix fit to the other 2 chambers:
-  //    a) Initialization of extrapolation tracklet with fit parameters
-  //    b) Helix fit of tracklets
-  //    c) Attach clusters and linear interpolation to extrapolated tracklets
-  //    d) Helix fit of tracklets
-  // 11. Improve seeding tracklets quality by reassigning clusters.
-  //      See AliTRDtrackerV1::ImproveSeedQuality() for details.
-  // 12. Helix fit of all 6 seeding tracklets and chi2 calculation
-  // 13. Hyperplane fit and track quality calculation. See AliTRDtrackerFitter::FitHyperplane() for details.
-  // 14. Cooking labels for tracklets. Should be done only for MC
-  // 15. Register seeds.
-  //
-
-  AliTRDtrackingChamber *chamber = 0x0;
-  AliTRDcluster *c[4] = {0x0, 0x0, 0x0, 0x0}; // initilize seeding clusters
+//
+// Seed tracklets and build candidate TRD tracks. The procedure is used during barrel tracking to account for tracks which are 
+// either missed by TPC prolongation or conversions inside the TRD volume. 
+// For stand alone tracking the procedure is used to estimate all tracks measured by TRD. 
+//
+// Parameters :
+//   layers : Array of stack propagation layers containing clusters
+//   sseed  : Array of empty tracklet seeds. On exit they are filled.
+//   ipar   : Control parameters:
+//       ipar[0] -> seeding chambers configuration
+//       ipar[1] -> stack index
+//       ipar[2] -> number of track candidates found so far
+//
+// Output :
+//   Number of tracks candidates found.
+// 
+// The following steps are performed:
+// 1. Build seeding layers by collapsing all time bins from each of the four seeding chambers along the 
+// radial coordinate. See AliTRDtrackingChamber::GetSeedingLayer() for details. The chambers selection for seeding
+// is described in AliTRDtrackerV1::Clusters2TracksStack().
+// 2. Using the seeding clusters from the seeding layer (step 1) build combinatorics using the following algorithm:
+// - for each seeding cluster in the lower seeding layer find
+// - all seeding clusters in the upper seeding layer inside a road defined by a given phi angle. The angle 
+//   is calculated on the minimum pt of tracks from vertex accesible to the stand alone tracker.
+// - for each pair of two extreme seeding clusters select middle upper cluster using roads defined externally by the 
+//   reco params
+// - select last seeding cluster as the nearest to the linear approximation of the track described by the first three
+//   seeding clusters.
+//   The implementation of road calculation and cluster selection can be found in the functions AliTRDchamberTimeBin::BuildCond()
+//   and AliTRDchamberTimeBin::GetClusters().   
+// 3. Helix fit of the seeding clusters set. (see AliTRDtrackerFitter::FitRieman(AliTRDcluster**)). No tilt correction is 
+//    performed at this level 
+// 4. Initialize seeding tracklets in the seeding chambers.
+// 5. *Filter 0* Chi2 cut on the Y and Z directions. The threshold is set externally by the reco params.
+// 6. Attach (true) clusters to seeding tracklets (see AliTRDseedV1::AttachClusters()) and fit tracklet (see 
+//    AliTRDseedV1::Fit()). The number of used clusters used by current seeds should not exceed ... (25).
+// 7. *Filter 1* Check if all 4 seeding tracklets are correctly constructed.
+// 8. Helix fit of the clusters from the seeding tracklets with tilt correction. Refit tracklets using the new 
+//    approximation of the track.
+// 9. *Filter 2* Calculate likelihood of the track. (See AliTRDtrackerV1::CookLikelihood()). The following quantities are
+//    checked against the Riemann fit:
+//      - position resolution in y
+//      - angular resolution in the bending plane
+//      - likelihood of the number of clusters attached to the tracklet
+// 10. Extrapolation of the helix fit to the other 2 chambers *non seeding* chambers:
+//      - Initialization of extrapolation tracklets with the fit parameters
+//      - Attach clusters to extrapolated tracklets
+//      - Helix fit of tracklets
+// 11. Improve seeding tracklets quality by reassigning clusters based on the last parameters of the track
+//      See AliTRDtrackerV1::ImproveSeedQuality() for details.
+// 12. Helix fit of all 6 seeding tracklets and chi2 calculation
+// 13. Hyperplane fit and track quality calculation. See AliTRDtrackerFitter::FitHyperplane() for details.
+// 14. Cooking labels for tracklets. Should be done only for MC
+// 15. Register seeds.
+//
+// Authors:
+//   Marian Ivanov <M.Ivanov@gsi.de>
+//   Alexandru Bercuci <A.Bercuci@gsi.de>
+//   Markus Fasel <M.Fasel@gsi.de>
+
+  AliTRDtrackingChamber *chamber = NULL;
+  AliTRDcluster *c[kNSeedPlanes] = {NULL, NULL, NULL, NULL}; // initilize seeding clusters
   AliTRDseedV1 *cseed = &sseed[0]; // initialize tracklets for first track
   Int_t ncl, mcl; // working variable for looping over clusters
   Int_t index[AliTRDchamberTimeBin::kMaxClustersLayer], jndex[AliTRDchamberTimeBin::kMaxClustersLayer];
@@ -1809,363 +2594,500 @@ Int_t AliTRDtrackerV1::MakeSeeds(AliTRDtrackingChamber **stack, AliTRDseedV1 *ss
   // chi2[1] = tracklet chi2 on the R direction
   Double_t chi2[4];
 
-
-  // this should be data member of AliTRDtrack
+  // this should be data member of AliTRDtrack TODO
   Double_t seedQuality[kMaxTracksStack];
-       
+  
   // unpack control parameters
   Int_t config  = ipar[0];
   Int_t ntracks = ipar[1];
+  Int_t istack  = ipar[2];
   Int_t planes[kNSeedPlanes]; GetSeedingConfig(config, planes);        
-       
+  Int_t planesExt[kNPlanes-kNSeedPlanes]; GetExtrapolationConfig(config, planesExt);
+
+
   // Init chambers geometry
-  Int_t ic = 0; while(!(chamber = stack[ic])) ic++;
-  Int_t istack = fGeom->GetChamber(chamber->GetDetector());
   Double_t hL[kNPlanes];       // Tilting angle
   Float_t padlength[kNPlanes]; // pad lenghts
-  AliTRDpadPlane *pp = 0x0;
+  Float_t padwidth[kNPlanes];  // pad widths
+  AliTRDpadPlane *pp = NULL;
   for(int iplane=0; iplane<kNPlanes; iplane++){
     pp                = fGeom->GetPadPlane(iplane, istack);
-    hL[iplane]        = TMath::Tan(-TMath::DegToRad()*pp->GetTiltingAngle());
+    hL[iplane]        = TMath::Tan(TMath::DegToRad()*pp->GetTiltingAngle());
     padlength[iplane] = pp->GetLengthIPad();
+    padwidth[iplane] = pp->GetWidthIPad();
   }
-       
-  if(AliTRDReconstructor::StreamLevel() > 1){
-    AliInfo(Form("Making seeds Stack[%d] Config[%d] Tracks[%d]...", istack, config, ntracks));
+  
+  // Init anode wire position for chambers
+  Double_t x0[kNPlanes],       // anode wire position
+           driftLength = .5*AliTRDgeometry::AmThick() - AliTRDgeometry::DrThick(); // drift length
+  TGeoHMatrix *matrix = NULL;
+  Double_t loc[] = {AliTRDgeometry::AnodePos(), 0., 0.};
+  Double_t glb[] = {0., 0., 0.};
+  AliTRDtrackingChamber **cIter = &stack[0];
+  for(int iLayer=0; iLayer<kNPlanes; iLayer++,cIter++){
+    if(!(*cIter)) continue;
+    if(!(matrix = fGeom->GetClusterMatrix((*cIter)->GetDetector()))){ 
+      continue;
+      x0[iLayer] = fgkX0[iLayer];
+    }
+    matrix->LocalToMaster(loc, glb);
+    x0[iLayer] = glb[0];
   }
 
+  AliDebug(2, Form("Making seeds Stack[%d] Config[%d] Tracks[%d]...", istack, config, ntracks));
+
+  // Build seeding layers
+  ResetSeedTB();
   Int_t nlayers = 0;
-  AliTRDchamberTimeBin *layer[] = {0x0, 0x0, 0x0, 0x0};
   for(int isl=0; isl<kNSeedPlanes; isl++){ 
     if(!(chamber = stack[planes[isl]])) continue;
-    if(!(layer[isl] = chamber->GetSeedingLayer(fGeom))) continue;
+    if(!chamber->GetSeedingLayer(fSeedTB[isl], fGeom, fkReconstructor)) continue;
     nlayers++;
-    //AliInfo(Form("seeding plane %d clusters %d", planes[isl], Int_t(*layer[isl])));
   }
-  if(nlayers < 4) return 0;
-       
-       
+  if(nlayers < kNSeedPlanes) return ntracks;
+  
+  
   // Start finding seeds
   Double_t cond0[4], cond1[4], cond2[4];
   Int_t icl = 0;
-  while((c[3] = (*layer[3])[icl++])){
+  while((c[3] = (*fSeedTB[3])[icl++])){
     if(!c[3]) continue;
-    layer[0]->BuildCond(c[3], cond0, 0);
-    layer[0]->GetClusters(cond0, index, ncl);
+    fSeedTB[0]->BuildCond(c[3], cond0, 0);
+    fSeedTB[0]->GetClusters(cond0, index, ncl);
     //printf("Found c[3] candidates 0 %d\n", ncl);
     Int_t jcl = 0;
     while(jcl<ncl) {
-      c[0] = (*layer[0])[index[jcl++]];
+      c[0] = (*fSeedTB[0])[index[jcl++]];
       if(!c[0]) continue;
       Double_t dx    = c[3]->GetX() - c[0]->GetX();
-      Double_t theta = (c[3]->GetZ() - c[0]->GetZ())/dx;
-      Double_t phi   = (c[3]->GetY() - c[0]->GetY())/dx;
-      layer[1]->BuildCond(c[0], cond1, 1, theta, phi);
-      layer[1]->GetClusters(cond1, jndex, mcl);
+      Double_t dzdx = (c[3]->GetZ() - c[0]->GetZ())/dx;
+      Double_t dydx   = (c[3]->GetY() - c[0]->GetY())/dx;
+      fSeedTB[1]->BuildCond(c[0], cond1, 1, dzdx, dydx);
+      fSeedTB[1]->GetClusters(cond1, jndex, mcl);
       //printf("Found c[0] candidates 1 %d\n", mcl);
 
       Int_t kcl = 0;
       while(kcl<mcl) {
-       c[1] = (*layer[1])[jndex[kcl++]];
-       if(!c[1]) continue;
-       layer[2]->BuildCond(c[1], cond2, 2, theta, phi);
-       c[2] = layer[2]->GetNearestCluster(cond2);
-       //printf("Found c[1] candidate 2 %p\n", c[2]);
-       if(!c[2]) continue;
-                               
-       //                              AliInfo("Seeding clusters found. Building seeds ...");
-       //                              for(Int_t i = 0; i < kNSeedPlanes; i++) printf("%i. coordinates: x = %6.3f, y = %6.3f, z = %6.3f\n", i, c[i]->GetX(), c[i]->GetY(), c[i]->GetZ());
-                               
-       for (Int_t il = 0; il < 6; il++) cseed[il].Reset();
-
-       FitRieman(c, chi2);
-
-       AliTRDseedV1 *tseed = 0x0;
-       for(int iLayer=0; iLayer<kNSeedPlanes; iLayer++){
-         Int_t jLayer = planes[iLayer];
-         tseed = &cseed[jLayer];
-         tseed->SetPlane(jLayer);
-         tseed->SetTilt(hL[jLayer]);
-         tseed->SetPadLength(padlength[jLayer]);
-         tseed->SetX0(stack[jLayer]->GetX());
-         tseed->Init(GetRiemanFitter());
-       }
-
-       Bool_t isFake = kFALSE;
-       if(AliTRDReconstructor::StreamLevel() >= 2){
-         if (c[0]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
-         if (c[1]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
-         if (c[2]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
-
-         Double_t xpos[4];
-         for(Int_t l = 0; l < kNSeedPlanes; l++) xpos[l] = layer[l]->GetX();
-         Float_t yref[4];
-         for(int il=0; il<4; il++) yref[il] = cseed[planes[il]].GetYref(0);
-         Int_t ll = c[3]->GetLabel(0);
-         Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
-         Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
-         AliRieman *rim = GetRiemanFitter();
-         TTreeSRedirector &cs0 = *fgDebugStreamer;
-         cs0 << "MakeSeeds0"
-             <<"EventNumber="          << eventNumber
-             <<"CandidateNumber="      << candidateNumber
-             <<"isFake="                               << isFake
-             <<"config="                               << config
-             <<"label="                                << ll
-             <<"chi2z="                                << chi2[0]
-             <<"chi2y="                                << chi2[1]
-             <<"Y2exp="                                << cond2[0]     
-             <<"Z2exp="                                << cond2[1]
-             <<"X0="                                   << xpos[0] //layer[sLayer]->GetX()
-             <<"X1="                                   << xpos[1] //layer[sLayer + 1]->GetX()
-             <<"X2="                                   << xpos[2] //layer[sLayer + 2]->GetX()
-             <<"X3="                                   << xpos[3] //layer[sLayer + 3]->GetX()
-             <<"yref0="                                << yref[0]
-             <<"yref1="                                << yref[1]
-             <<"yref2="                                << yref[2]
-             <<"yref3="                                << yref[3]
-             <<"c0.="                          << c[0]
-             <<"c1.="                          << c[1]
-             <<"c2.="                          << c[2]
-             <<"c3.="                          << c[3]
-             <<"Seed0.="                               << &cseed[planes[0]]
-             <<"Seed1.="                               << &cseed[planes[1]]
-             <<"Seed2.="                               << &cseed[planes[2]]
-             <<"Seed3.="                               << &cseed[planes[3]]
-             <<"RiemanFitter.="                << rim
-             <<"\n";
-       }
-
-       if(chi2[0] > AliTRDReconstructor::RecoParam()->GetChi2Z()/*7./(3. - sLayer)*//*iter*/){
-         //AliInfo(Form("Failed chi2 filter on chi2Z [%f].", chi2[0]));
-         AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
-         continue;
-       }
-       if(chi2[1] > AliTRDReconstructor::RecoParam()->GetChi2Y()/*1./(3. - sLayer)*//*iter*/){
-         //AliInfo(Form("Failed chi2 filter on chi2Y [%f].", chi2[1]));
-         AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
-         continue;
-       }
-       //AliInfo("Passed chi2 filter.");
-
-       // try attaching clusters to tracklets
-       Int_t nUsedCl = 0;
-       Int_t nlayers = 0;
-       for(int iLayer=0; iLayer<kNSeedPlanes; iLayer++){
-         Int_t jLayer = planes[iLayer];
-         if(!cseed[jLayer].AttachClustersIter(stack[jLayer], 5., kFALSE, c[iLayer])) continue;
-         nUsedCl += cseed[jLayer].GetNUsed();
-         if(nUsedCl > 25) break;
-         nlayers++;
-       }
-       if(nlayers < kNSeedPlanes){ 
-         //AliInfo(Form("Failed updating all seeds %d [%d].", nlayers, kNSeedPlanes));
-         AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
-         continue;
-       }
-       // fit tracklets and cook likelihood
-       FitTiltedRieman(&cseed[0], kTRUE);// Update Seeds and calculate Likelihood
-       chi2[0] = GetChi2Y(&cseed[0]);
-       chi2[1] = GetChi2Z(&cseed[0]);
-       //Chi2 definitions in testing stage
-       //chi2[0] = GetChi2YTest(&cseed[0]);
-       //chi2[1] = GetChi2ZTest(&cseed[0]);
-       Double_t like = CookLikelihood(&cseed[0], planes, chi2); // to be checked
-
-       if (TMath::Log(1.E-9 + like) < AliTRDReconstructor::RecoParam()->GetTrackLikelihood()){
-         //AliInfo(Form("Failed likelihood %f[%e].", TMath::Log(1.E-9 + like), like));
-         AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
-         continue;
-       }
-       //AliInfo(Form("Passed likelihood %f[%e].", TMath::Log(1.E-9 + like), like));
-
-       // book preliminary results
-       seedQuality[ntracks] = like;
-       fSeedLayer[ntracks]  = config;/*sLayer;*/
-
-       // attach clusters to the extrapolation seeds
-       Int_t lextrap[2];
-       GetExtrapolationConfig(config, lextrap);
-       Int_t nusedf   = 0; // debug value
-       for(int iLayer=0; iLayer<2; iLayer++){
-         Int_t jLayer = lextrap[iLayer];
-         if(!(chamber = stack[jLayer])) continue;
-                                               
-         // prepare extrapolated seed
-         cseed[jLayer].Reset();
-         cseed[jLayer].SetPlane(jLayer);
-         cseed[jLayer].SetTilt(hL[jLayer]);
-         cseed[jLayer].SetX0(chamber->GetX());
-         cseed[jLayer].SetPadLength(padlength[jLayer]);
-
-         // fit extrapolated seed
-         if ((jLayer == 0) && !(cseed[1].IsOK())) continue;
-         if ((jLayer == 5) && !(cseed[4].IsOK())) continue;
-         AliTRDseedV1 tseed = cseed[jLayer];
-         if(!tseed.AttachClustersIter(chamber, 1000.)) continue;
-         cseed[jLayer] = tseed;
-         nusedf += cseed[jLayer].GetNUsed(); // debug value
-         FitTiltedRieman(cseed,  kTRUE);
-       }
-
-       // AliInfo("Extrapolation done.");
-       // Debug Stream containing all the 6 tracklets
-       if(AliTRDReconstructor::StreamLevel() >= 2){
-         TTreeSRedirector &cstreamer = *fgDebugStreamer;
-         TLinearFitter *tiltedRieman = GetTiltedRiemanFitter();
-         Int_t eventNumber             = AliTRDtrackerDebug::GetEventNumber();
-         Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
-         cstreamer << "MakeSeeds1"
-                   << "EventNumber="           << eventNumber
-                   << "CandidateNumber="       << candidateNumber
-                   << "S0.="                           << &cseed[0]
-                   << "S1.="                           << &cseed[1]
-                   << "S2.="                           << &cseed[2]
-                   << "S3.="                           << &cseed[3]
-                   << "S4.="                           << &cseed[4]
-                   << "S5.="                           << &cseed[5]
-                   << "FitterT.="                      << tiltedRieman
-                   << "\n";
-       }
-                               
-       if(ImproveSeedQuality(stack, cseed) < 4){
-         AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
-         continue;
-       }
-       //AliInfo("Improve seed quality done.");
-
-       // fit full track and cook likelihoods
-       //                              Double_t curv = FitRieman(&cseed[0], chi2);
-       //                              Double_t chi2ZF = chi2[0] / TMath::Max((nlayers - 3.), 1.);
-       //                              Double_t chi2RF = chi2[1] / TMath::Max((nlayers - 3.), 1.);
-
-       // do the final track fitting (Once with vertex constraint and once without vertex constraint)
-       Double_t chi2Vals[3];
-       chi2Vals[0] = FitTiltedRieman(&cseed[0], kFALSE);
-       chi2Vals[1] = FitTiltedRiemanConstraint(&cseed[0], GetZ());
-       chi2Vals[2] = GetChi2Z(&cseed[0]) / TMath::Max((nlayers - 3.), 1.);
-       // Chi2 definitions in testing stage
-       //chi2Vals[2] = GetChi2ZTest(&cseed[0]);
-       fTrackQuality[ntracks] = CalculateTrackLikelihood(&cseed[0], &chi2Vals[0]);
-       //AliInfo("Hyperplane fit done\n");
-
-       // finalize tracklets
-       Int_t labels[12];
-       Int_t outlab[24];
-       Int_t nlab = 0;
-       for (Int_t iLayer = 0; iLayer < 6; iLayer++) {
-         if (!cseed[iLayer].IsOK()) continue;
-
-         if (cseed[iLayer].GetLabels(0) >= 0) {
-           labels[nlab] = cseed[iLayer].GetLabels(0);
-           nlab++;
-         }
-
-         if (cseed[iLayer].GetLabels(1) >= 0) {
-           labels[nlab] = cseed[iLayer].GetLabels(1);
-           nlab++;
-         }
-       }
-       Freq(nlab,labels,outlab,kFALSE);
-       Int_t label     = outlab[0];
-       Int_t frequency = outlab[1];
-       for (Int_t iLayer = 0; iLayer < 6; iLayer++) {
-         cseed[iLayer].SetFreq(frequency);
-         cseed[iLayer].SetChi2Z(chi2[1]);
-       }
-           
-       if(AliTRDReconstructor::StreamLevel() >= 2){
-         TTreeSRedirector &cstreamer = *fgDebugStreamer;
-         Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
-         Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
-         TLinearFitter *fitterTC = GetTiltedRiemanFitterConstraint();
-         TLinearFitter *fitterT = GetTiltedRiemanFitter();
-         cstreamer << "MakeSeeds2"
-                   << "EventNumber="           << eventNumber
-                   << "CandidateNumber="       << candidateNumber
-                   << "Chi2TR="                        << chi2Vals[0]
-                   << "Chi2TC="                        << chi2Vals[1]
-                   << "Nlayers="                       << nlayers
-                   << "NUsedS="                        << nUsedCl
-                   << "NUsed="                         << nusedf
-                   << "Like="                          << like
-                   << "S0.="                           << &cseed[0]
-                   << "S1.="                           << &cseed[1]
-                   << "S2.="                           << &cseed[2]
-                   << "S3.="                           << &cseed[3]
-                   << "S4.="                           << &cseed[4]
-                   << "S5.="                           << &cseed[5]
-                   << "Label="                         << label
-                   << "Freq="                          << frequency
-                   << "FitterT.="                      << fitterT
-                   << "FitterTC.="                     << fitterTC
-                   << "\n";
-       }
-                               
-       ntracks++;
-       AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
-       if(ntracks == kMaxTracksStack){
-         AliWarning(Form("Number of seeds reached maximum allowed (%d) in stack.", kMaxTracksStack));
-         for(int isl=0; isl<4; isl++) delete layer[isl];
-         return ntracks;
-       }
-       cseed += 6;
+        c[1] = (*fSeedTB[1])[jndex[kcl++]];
+        if(!c[1]) continue;
+        fSeedTB[2]->BuildCond(c[1], cond2, 2, dzdx, dydx);
+        c[2] = fSeedTB[2]->GetNearestCluster(cond2);
+        //printf("Found c[1] candidate 2 %p\n", c[2]);
+        if(!c[2]) continue;
+
+               AliDebug(3, Form("Seeding clusters\n 0[%6.3f %6.3f %6.3f]\n 1[%6.3f %6.3f %6.3f]\n 2[%6.3f %6.3f %6.3f]\n 3[%6.3f %6.3f %6.3f].",
+          c[0]->GetX(), c[0]->GetY(), c[0]->GetZ(),
+          c[1]->GetX(), c[1]->GetY(), c[1]->GetZ(),
+          c[2]->GetX(), c[2]->GetY(), c[2]->GetZ(),
+          c[3]->GetX(), c[3]->GetY(), c[3]->GetZ()));
+              
+        for (Int_t il = 0; il < kNPlanes; il++) cseed[il].Reset();
+      
+        FitRieman(c, chi2);
+      
+        AliTRDseedV1 *tseed = &cseed[0];
+        cIter = &stack[0];
+        for(int iLayer=0; iLayer<kNPlanes; iLayer++, tseed++, cIter++){
+          Int_t det = (*cIter) ? (*cIter)->GetDetector() : -1;
+          tseed->SetDetector(det);
+          tseed->SetTilt(hL[iLayer]);
+          tseed->SetPadLength(padlength[iLayer]);
+          tseed->SetPadWidth(padwidth[iLayer]);
+          tseed->SetReconstructor(fkReconstructor);
+          tseed->SetX0(det<0 ? fR[iLayer]+driftLength : x0[iLayer]);
+          tseed->Init(GetRiemanFitter());
+          tseed->SetStandAlone(kTRUE);
+        }
+      
+        Bool_t isFake = kFALSE;
+        if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
+          if (c[0]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
+          if (c[1]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
+          if (c[2]->GetLabel(0) != c[3]->GetLabel(0)) isFake = kTRUE;
+      
+          Double_t xpos[4];
+          for(Int_t l = 0; l < kNSeedPlanes; l++) xpos[l] = fSeedTB[l]->GetX();
+          Float_t yref[4];
+          for(int il=0; il<4; il++) yref[il] = cseed[planes[il]].GetYref(0);
+          Int_t ll = c[3]->GetLabel(0);
+          Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
+          Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
+          AliRieman *rim = GetRiemanFitter();
+          TTreeSRedirector &cs0 = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
+          cs0 << "MakeSeeds0"
+              <<"EventNumber="         << eventNumber
+              <<"CandidateNumber="     << candidateNumber
+              <<"isFake="                              << isFake
+              <<"config="                              << config
+              <<"label="                               << ll
+              <<"chi2z="                               << chi2[0]
+              <<"chi2y="                               << chi2[1]
+              <<"Y2exp="                               << cond2[0]     
+              <<"Z2exp="                               << cond2[1]
+              <<"X0="                                  << xpos[0] //layer[sLayer]->GetX()
+              <<"X1="                                  << xpos[1] //layer[sLayer + 1]->GetX()
+              <<"X2="                                  << xpos[2] //layer[sLayer + 2]->GetX()
+              <<"X3="                                  << xpos[3] //layer[sLayer + 3]->GetX()
+              <<"yref0="                               << yref[0]
+              <<"yref1="                               << yref[1]
+              <<"yref2="                               << yref[2]
+              <<"yref3="                               << yref[3]
+              <<"c0.="                         << c[0]
+              <<"c1.="                         << c[1]
+              <<"c2.="                         << c[2]
+              <<"c3.="                         << c[3]
+              <<"Seed0.="                              << &cseed[planes[0]]
+              <<"Seed1.="                              << &cseed[planes[1]]
+              <<"Seed2.="                              << &cseed[planes[2]]
+              <<"Seed3.="                              << &cseed[planes[3]]
+              <<"RiemanFitter.="               << rim
+              <<"\n";
+        }
+        if(chi2[0] > fkRecoParam->GetChi2Z()/*7./(3. - sLayer)*//*iter*/){
+          AliDebug(3, Form("Filter on chi2Z [%f].", chi2[0]));
+          AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
+          continue;
+        }
+        if(chi2[1] > fkRecoParam->GetChi2Y()/*1./(3. - sLayer)*//*iter*/){
+          AliDebug(3, Form("Filter on chi2Y [%f].", chi2[1]));
+          AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
+          continue;
+        }
+        //AliInfo("Passed chi2 filter.");
+      
+        // try attaching clusters to tracklets
+        Int_t mlayers = 0; 
+        AliTRDcluster *cl = NULL;
+        for(int iLayer=0; iLayer<kNSeedPlanes; iLayer++){
+          Int_t jLayer = planes[iLayer];
+          Int_t nNotInChamber = 0;
+          if(!cseed[jLayer].AttachClusters(stack[jLayer], kTRUE)) continue;
+          if(/*fkReconstructor->IsHLT()*/kFALSE){ 
+            cseed[jLayer].UpdateUsed();
+            if(!cseed[jLayer].IsOK()) continue;
+          }else{
+            cseed[jLayer].Fit();
+            cseed[jLayer].UpdateUsed();
+            cseed[jLayer].ResetClusterIter();
+            while((cl = cseed[jLayer].NextCluster())){
+              if(!cl->IsInChamber()) nNotInChamber++;
+            }
+            //printf("clusters[%d], used[%d], not in chamber[%d]\n", cseed[jLayer].GetN(), cseed[jLayer].GetNUsed(), nNotInChamber);
+            if(cseed[jLayer].GetN() - (cseed[jLayer].GetNUsed() + nNotInChamber) < 5) continue; // checking for Cluster which are not in chamber is a much stronger restriction on real data
+          }
+          mlayers++;
+        }
+
+        if(mlayers < kNSeedPlanes){ 
+          AliDebug(2, Form("Found only %d tracklets out of %d. Skip.", mlayers, kNSeedPlanes));
+          AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
+          continue;
+        }
+
+        // temporary exit door for the HLT
+        if(fkReconstructor->IsHLT()){ 
+          // attach clusters to extrapolation chambers
+          for(int iLayer=0; iLayer<kNPlanes-kNSeedPlanes; iLayer++){
+            Int_t jLayer = planesExt[iLayer];
+            if(!(chamber = stack[jLayer])) continue;
+            if(!cseed[jLayer].AttachClusters(chamber, kTRUE)) continue;
+            cseed[jLayer].Fit();
+          }
+          //FitTiltedRiemanConstraint(&cseed[0], GetZ());
+          fTrackQuality[ntracks] = 1.; // dummy value
+          ntracks++;
+          if(ntracks == kMaxTracksStack) return ntracks;
+          cseed += 6; 
+          continue;
+        }
+
+
+        // Update Seeds and calculate Likelihood
+        // fit tracklets and cook likelihood
+        Double_t chi2Vals[4];
+        chi2Vals[0] = FitTiltedRieman(&cseed[0], kTRUE);
+        for(int iLayer=0; iLayer<kNSeedPlanes; iLayer++){
+          Int_t jLayer = planes[iLayer];
+          cseed[jLayer].Fit(1);
+        }
+        Double_t like = CookLikelihood(&cseed[0], planes); // to be checked
+      
+        if (TMath::Log(1.E-9 + like) < fkRecoParam->GetTrackLikelihood()){
+          AliDebug(3, Form("Filter on likelihood %f[%e].", TMath::Log(1.E-9 + like), like));
+          AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
+          continue;
+        }
+        //AliInfo(Form("Passed likelihood %f[%e].", TMath::Log(1.E-9 + like), like));
+      
+        // book preliminary results
+        seedQuality[ntracks] = like;
+        fSeedLayer[ntracks]  = config;/*sLayer;*/
+      
+        // attach clusters to the extrapolation seeds
+        Int_t elayers(0);
+        for(int iLayer=0; iLayer<kNPlanes-kNSeedPlanes; iLayer++){
+          Int_t jLayer = planesExt[iLayer];
+          if(!(chamber = stack[jLayer])) continue;
+      
+          // fit extrapolated seed
+          if ((jLayer == 0) && !(cseed[1].IsOK())) continue;
+          if ((jLayer == 5) && !(cseed[4].IsOK())) continue;
+          AliTRDseedV1 pseed = cseed[jLayer];
+          if(!pseed.AttachClusters(chamber, kTRUE)) continue;
+          pseed.Fit(1);
+          cseed[jLayer] = pseed;
+          chi2Vals[0] = FitTiltedRieman(cseed,  kTRUE);
+          cseed[jLayer].Fit(1);
+          elayers++;
+        }
+      
+        // AliInfo("Extrapolation done.");
+        // Debug Stream containing all the 6 tracklets
+        if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
+          TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
+          TLinearFitter *tiltedRieman = GetTiltedRiemanFitter();
+          Int_t eventNumber            = AliTRDtrackerDebug::GetEventNumber();
+          Int_t candidateNumber        = AliTRDtrackerDebug::GetCandidateNumber();
+          cstreamer << "MakeSeeds1"
+              << "EventNumber="                << eventNumber
+              << "CandidateNumber="    << candidateNumber
+              << "S0.="                                << &cseed[0]
+              << "S1.="                                << &cseed[1]
+              << "S2.="                                << &cseed[2]
+              << "S3.="                                << &cseed[3]
+              << "S4.="                                << &cseed[4]
+              << "S5.="                                << &cseed[5]
+              << "FitterT.="                   << tiltedRieman
+              << "\n";
+        }
+              
+        if(fkRecoParam->HasImproveTracklets()){ 
+          if(!ImproveSeedQuality(stack, cseed, chi2Vals[0])){
+            AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
+            AliDebug(3, "ImproveSeedQuality() failed.");
+          }
+        }
+      
+        // do track fitting with vertex constraint
+        if(fkRecoParam->IsVertexConstrained()) chi2Vals[1] = FitTiltedRiemanConstraint(&cseed[0], GetZ());
+        else chi2Vals[1] = -1.;
+        chi2Vals[2] = GetChi2Z(&cseed[0]);
+        chi2Vals[3] = GetChi2Phi(&cseed[0]);
+
+        // calculate track quality
+        fTrackQuality[ntracks] = CalculateTrackLikelihood(&chi2Vals[0]);
+                  
+        if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
+          TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
+          Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
+          Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
+          TLinearFitter *fitterTC = GetTiltedRiemanFitterConstraint();
+          TLinearFitter *fitterT = GetTiltedRiemanFitter();
+          Int_t ncls = 0; 
+          for(Int_t iseed = 0; iseed < kNPlanes; iseed++){
+               ncls += cseed[iseed].IsOK() ? cseed[iseed].GetN2() : 0;
+          }
+          cstreamer << "MakeSeeds2"
+              << "EventNumber="                << eventNumber
+              << "CandidateNumber="    << candidateNumber
+              << "Chi2TR="                     << chi2Vals[0]
+              << "Chi2TC="                     << chi2Vals[1]
+              << "Nlayers="                    << mlayers
+              << "NClusters="   << ncls
+              << "Like="                               << like
+              << "S0.="                                << &cseed[0]
+              << "S1.="                                << &cseed[1]
+              << "S2.="                                << &cseed[2]
+              << "S3.="                                << &cseed[3]
+              << "S4.="                                << &cseed[4]
+              << "S5.="                                << &cseed[5]
+              << "FitterT.="                   << fitterT
+              << "FitterTC.="                  << fitterTC
+              << "\n";
+        }
+        if(AliLog::GetDebugLevel("TRD", "AliTRDtrackerV1")){  
+          Double_t pt[]={0., 0.};
+          for(Int_t il(0); il<kNPlanes; il++){
+            if(!cseed[il].IsOK()) continue;
+            pt[0] = GetBz()*kB2C/cseed[il].GetC();
+            pt[1] = GetBz()*kB2C/cseed[il].GetC(1);
+            break;
+          }
+          AliDebug(2, Form("Candidate[%2d] pt[%7.3f %7.3f] Q[%e]\n"
+            "  [0] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
+            "  [1] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
+            "  [2] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
+            "  [3] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
+            "  [4] x[%6.2f] n[%2d] nu[%d] OK[%c]\n"
+            "  [5] x[%6.2f] n[%2d] nu[%d] OK[%c]"
+            , ntracks, pt[0], pt[1], fTrackQuality[ntracks]
+            ,cseed[0].GetX(), cseed[0].GetN(), cseed[0].GetNUsed(), cseed[0].IsOK()?'y':'n'
+            ,cseed[1].GetX(), cseed[1].GetN(), cseed[1].GetNUsed(), cseed[1].IsOK()?'y':'n'
+            ,cseed[2].GetX(), cseed[2].GetN(), cseed[2].GetNUsed(), cseed[2].IsOK()?'y':'n'
+            ,cseed[3].GetX(), cseed[3].GetN(), cseed[3].GetNUsed(), cseed[3].IsOK()?'y':'n'
+            ,cseed[4].GetX(), cseed[4].GetN(), cseed[4].GetNUsed(), cseed[4].IsOK()?'y':'n'
+            ,cseed[5].GetX(), cseed[5].GetN(), cseed[5].GetNUsed(), cseed[5].IsOK()?'y':'n'));
+        }
+        ntracks++;
+        AliTRDtrackerDebug::SetCandidateNumber(AliTRDtrackerDebug::GetCandidateNumber() + 1);
+        if(ntracks == kMaxTracksStack){
+          AliWarning(Form("Number of seeds reached maximum allowed (%d) in stack.", kMaxTracksStack));
+          return ntracks;
+        }
+        cseed += 6;
       }
     }
   }
-  for(int isl=0; isl<4; isl++) delete layer[isl];
-       
+  
   return ntracks;
 }
 
 //_____________________________________________________________________________
-AliTRDtrackV1* AliTRDtrackerV1::MakeTrack(AliTRDseedV1 *seeds, Double_t *params)
+AliTRDtrackV1* AliTRDtrackerV1::MakeTrack(AliTRDseedV1 * const tracklet)
 {
-  //
-  // Build a TRD track out of tracklet candidates
-  //
-  // Parameters :
-  //   seeds  : array of tracklets
-  //   params : track parameters (see MakeSeeds() function body for a detailed description)
-  //
-  // Output :
-  //   The TRD track.
-  //
-  // Detailed description
-  //
-  // To be discussed with Marian !!
-  //
-
+//
+// Build a TRD track out of tracklet candidates
+//
+// Parameters :
+//   seeds  : array of tracklets
+//   params : array of track parameters as they are estimated by stand alone tracker. 7 elements.
+//     [0] - radial position of the track at reference point
+//     [1] - y position of the fit at [0]
+//     [2] - z position of the fit at [0]
+//     [3] - snp of the first tracklet
+//     [4] - tgl of the first tracklet
+//     [5] - curvature of the Riemann fit - 1/pt
+//     [6] - sector rotation angle
+//
+// Output :
+//   The TRD track.
+//
+// Initialize the TRD track based on the parameters of the fit and a parametric covariance matrix 
+// (diagonal with constant variance terms TODO - correct parameterization) 
+// 
+// In case of HLT just register the tracklets in the tracker and return values of the Riemann fit. For the
+// offline case perform a full Kalman filter on the already found tracklets (see AliTRDtrackerV1::FollowBackProlongation() 
+// for details). Do also MC label calculation and PID if propagation successfully.
+
+  if(fkReconstructor->IsHLT()) FitTiltedRiemanConstraint(tracklet, 0);
   Double_t alpha = AliTRDgeometry::GetAlpha();
   Double_t shift = AliTRDgeometry::GetAlpha()/2.0;
+
+  // find first good tracklet
+  Int_t idx(0); while(idx<kNPlanes && !tracklet[idx].IsOK()) idx++;
+  if(idx>2){ AliDebug(1, Form("Found suspect track start @ layer idx[%d]\n"
+    "  %c[0] x0[%f] n[%d] nu[%d] OK[%c]\n"
+    "  %c[1] x0[%f] n[%d] nu[%d] OK[%c]\n"
+    "  %c[2] x0[%f] n[%d] nu[%d] OK[%c]\n"
+    "  %c[3] x0[%f] n[%d] nu[%d] OK[%c]\n"
+    "  %c[4] x0[%f] n[%d] nu[%d] OK[%c]\n"
+    "  %c[5] x0[%f] n[%d] nu[%d] OK[%c]"
+    ,idx
+    ,idx==0?'*':' ', tracklet[0].GetX0(), tracklet[0].GetN(), tracklet[0].GetNUsed(), tracklet[0].IsOK()?'y':'n'
+    ,idx==1?'*':' ', tracklet[1].GetX0(), tracklet[1].GetN(), tracklet[1].GetNUsed(), tracklet[1].IsOK()?'y':'n'
+    ,idx==2?'*':' ', tracklet[2].GetX0(), tracklet[2].GetN(), tracklet[2].GetNUsed(), tracklet[2].IsOK()?'y':'n'
+    ,idx==3?'*':' ', tracklet[3].GetX0(), tracklet[3].GetN(), tracklet[3].GetNUsed(), tracklet[3].IsOK()?'y':'n'
+    ,idx==4?'*':' ', tracklet[4].GetX0(), tracklet[4].GetN(), tracklet[4].GetNUsed(), tracklet[4].IsOK()?'y':'n'
+    ,idx==5?'*':' ', tracklet[5].GetX0(), tracklet[5].GetN(), tracklet[5].GetNUsed(), tracklet[5].IsOK()?'y':'n'));
+    return NULL;
+  }
+
+  Double_t dx(5.);
+  Double_t x(tracklet[idx].GetX0() - dx);
+  // Build track parameters
+  Double_t params[] = {
+    tracklet[idx].GetYref(0) - dx*tracklet[idx].GetYref(1) // y
+   ,tracklet[idx].GetZref(0) - dx*tracklet[idx].GetZref(1) // z
+   ,TMath::Sin(TMath::ATan(tracklet[idx].GetYref(1)))      // snp
+   ,tracklet[idx].GetZref(1) / TMath::Sqrt(1. + tracklet[idx].GetYref(1) * tracklet[idx].GetYref(1))   // tgl
+   ,tracklet[idx].GetC(fkReconstructor->IsHLT()?1:0)                                   // curvature -> 1/pt
+  };
+  Int_t sector(fGeom->GetSector(tracklet[idx].GetDetector()));
+
   Double_t c[15];
+  c[ 0] = 0.2; // s^2_y
+  c[ 1] = 0.0; c[ 2] = 2.0; // s^2_z
+  c[ 3] = 0.0; c[ 4] = 0.0; c[ 5] = 0.02; // s^2_snp
+  c[ 6] = 0.0; c[ 7] = 0.0; c[ 8] = 0.0;  c[ 9] = 0.1; // s^2_tgl
+  c[10] = 0.0; c[11] = 0.0; c[12] = 0.0;  c[13] = 0.0; c[14] = params[4]*params[4]*0.01; // s^2_1/pt
+
+  AliTRDtrackV1 track(tracklet, params, c, x, sector*alpha+shift);
+
+  AliTRDseedV1 *ptrTracklet = NULL;
+
+  // skip Kalman filter for HLT
+  if(/*fkReconstructor->IsHLT()*/kFALSE){ 
+    for (Int_t jLayer = 0; jLayer < AliTRDgeometry::kNlayer; jLayer++) {
+      track.UnsetTracklet(jLayer);
+      ptrTracklet = &tracklet[jLayer];
+      if(!ptrTracklet->IsOK()) continue;
+      if(TMath::Abs(ptrTracklet->GetYref(1) - ptrTracklet->GetYfit(1)) >= .2) continue; // check this condition with Marian
+      ptrTracklet = SetTracklet(ptrTracklet);
+      ptrTracklet->UseClusters();
+      track.SetTracklet(ptrTracklet, fTracklets->GetEntriesFast()-1);
+    }
+    AliTRDtrackV1 *ptrTrack = SetTrack(&track);
+    ptrTrack->CookPID();
+    ptrTrack->CookLabel(.9);
+    ptrTrack->SetReconstructor(fkReconstructor);
+    return ptrTrack;
+  }
 
-  c[ 0] = 0.2;
-  c[ 1] = 0.0; c[ 2] = 2.0;
-  c[ 3] = 0.0; c[ 4] = 0.0; c[ 5] = 0.02;
-  c[ 6] = 0.0; c[ 7] = 0.0; c[ 8] = 0.0;  c[ 9] = 0.1;
-  c[10] = 0.0; c[11] = 0.0; c[12] = 0.0;  c[13] = 0.0; c[14] = params[5]*params[5]*0.01;
-
-  AliTRDtrackV1 *track = new AliTRDtrackV1(seeds, &params[1], c, params[0], params[6]*alpha+shift);
-  track->PropagateTo(params[0]-5.0);
-  track->ResetCovariance(1);
-  Int_t nc = FollowBackProlongation(*track);
-  //AliInfo(Form("N clusters for track %d", nc));
-  if (nc < 30) {
-    delete track;
-    track = 0x0;
-  } else {
-    track->CookdEdx();
-    track->CookdEdxTimBin(-1);
-    track->CookLabel(.9);
+  // prevent the error message in AliTracker::MeanMaterialBudget: "start point out of geometry"
+  if(TMath::Abs(track.GetX()) + TMath::Abs(track.GetY()) + TMath::Abs(track.GetZ()) > 10000) return NULL;
+
+  track.ResetCovariance(1);
+  Int_t nc = TMath::Abs(FollowBackProlongation(track));
+  if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) > 5 && fkReconstructor->IsDebugStreaming()){
+    Int_t eventNumber          = AliTRDtrackerDebug::GetEventNumber();
+    Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
+    Double_t p[5]; // Track Params for the Debug Stream
+    track.GetExternalParameters(x, p);
+    TTreeSRedirector &cs = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
+    cs << "MakeTrack"
+    << "EventNumber="     << eventNumber
+    << "CandidateNumber=" << candidateNumber
+    << "nc="     << nc
+    << "X="      << x
+    << "Y="      << p[0]
+    << "Z="      << p[1]
+    << "snp="    << p[2]
+    << "tnd="    << p[3]
+    << "crv="    << p[4]
+    << "Yin="    << params[0]
+    << "Zin="    << params[1]
+    << "snpin="  << params[2]
+    << "tndin="  << params[3]
+    << "crvin="  << params[4]
+    << "track.=" << &track
+    << "\n";
+  }
+  if (nc < 30){ 
+    UnsetTrackletsTrack(&track);
+    return NULL;
+  }
+  AliTRDtrackV1 *ptrTrack = SetTrack(&track);
+  ptrTrack->SetReconstructor(fkReconstructor);
+  ptrTrack->CookLabel(.9);
+  for(Int_t il(kNPlanes); il--;){
+    if(!(ptrTracklet = ptrTrack->GetTracklet(il))) continue;
+    ptrTracklet->UseClusters();
   }
 
-  return track;
+  // computes PID for track
+  ptrTrack->CookPID();
+  // update calibration references using this track
+  AliTRDCalibraFillHisto *calibra = AliTRDCalibraFillHisto::Instance();
+  if (!calibra){ 
+    AliInfo("Could not get Calibra instance\n");
+    if(calibra->GetHisto2d()) calibra->UpdateHistogramsV1(ptrTrack);
+  }
+  return ptrTrack;
 }
 
 
 //____________________________________________________________________
-Int_t AliTRDtrackerV1::ImproveSeedQuality(AliTRDtrackingChamber **stack, AliTRDseedV1 *cseed)
+Bool_t AliTRDtrackerV1::ImproveSeedQuality(AliTRDtrackingChamber **stack, AliTRDseedV1 *cseed, Double_t &chi2)
 {
   //
   // Sort tracklets according to "quality" and try to "improve" the first 4 worst
@@ -2174,7 +3096,7 @@ Int_t AliTRDtrackerV1::ImproveSeedQuality(AliTRDtrackingChamber **stack, AliTRDs
   //  layers : Array of propagation layers for a stack/supermodule
   //  cseed  : Array of 6 seeding tracklets which has to be improved
   // 
-  // Output :
+  // Output : 
   //   cssed : Improved seeds
   // 
   // Detailed description
@@ -2185,68 +3107,89 @@ Int_t AliTRDtrackerV1::ImproveSeedQuality(AliTRDtrackingChamber **stack, AliTRDs
   //
   // debug level: 7
   //
-       
+  
   // make a local working copy
-  AliTRDtrackingChamber *chamber = 0x0;
-  AliTRDseedV1 bseed[6];
-  Int_t nLayers = 0;
-  for (Int_t jLayer = 0; jLayer < 6; jLayer++) bseed[jLayer] = cseed[jLayer];
-       
-  Float_t lastquality = 10000.0;
-  Float_t lastchi2    = 10000.0;
-  Float_t chi2        =  1000.0;
+  AliTRDtrackingChamber *chamber = NULL;
+  AliTRDseedV1 bseed[AliTRDgeometry::kNlayer];
+
+  Float_t quality(1.e3), 
+          lQuality[] = {1.e3, 1.e3, 1.e3, 1.e3, 1.e3, 1.e3};
+  Int_t rLayers(0);
+  for(Int_t jLayer=AliTRDgeometry::kNlayer; jLayer--;){ 
+    bseed[jLayer] = cseed[jLayer];
+    if(!bseed[jLayer].IsOK()) continue;
+    rLayers++;
+    lQuality[jLayer] = bseed[jLayer].GetQuality(kTRUE);
+    quality    += lQuality[jLayer];
+  }
+  quality /= rLayers;
+  AliDebug(2, Form("Start N[%d] Q[%f] chi2[%f]", rLayers, quality, chi2));
 
   for (Int_t iter = 0; iter < 4; iter++) {
-    Float_t sumquality = 0.0;
-    Float_t squality[6];
-    Int_t   sortindexes[6];
-
-    for (Int_t jLayer = 0; jLayer < 6; jLayer++) {
-      squality[jLayer]  = bseed[jLayer].IsOK() ? bseed[jLayer].GetQuality(kTRUE) : -1.;
-      sumquality += squality[jLayer];
-    }
-    if ((sumquality >= lastquality) || (chi2       >     lastchi2)) break;
-
-    nLayers = 0;
-    lastquality = sumquality;
-    lastchi2    = chi2;
-    if (iter > 0) for (Int_t jLayer = 0; jLayer < 6; jLayer++) cseed[jLayer] = bseed[jLayer];
-
-    TMath::Sort(6, squality, sortindexes, kFALSE);
-    for (Int_t jLayer = 5; jLayer > 1; jLayer--) {
-      Int_t bLayer = sortindexes[jLayer];
+    // Try better cluster set
+    Int_t nLayers(0); Float_t qualitynew(0.);
+    Int_t  indexes[6];
+    TMath::Sort(Int_t(AliTRDgeometry::kNlayer), lQuality, indexes, kFALSE);
+    for(Int_t jLayer=AliTRDgeometry::kNlayer; jLayer--;) {
+      Int_t bLayer = indexes[jLayer];
+      bseed[bLayer].Reset("c");
       if(!(chamber = stack[bLayer])) continue;
-      bseed[bLayer].AttachClustersIter(chamber, squality[bLayer], kTRUE);
-      if(bseed[bLayer].IsOK()) nLayers++;
+      if(!bseed[bLayer].AttachClusters(chamber, kTRUE)) continue;
+      bseed[bLayer].Fit(1);
+      if(!bseed[bLayer].IsOK()) continue;
+      nLayers++;
+      lQuality[jLayer] = bseed[jLayer].GetQuality(kTRUE);
+      qualitynew    += lQuality[jLayer];
     }
-
-    chi2 = FitTiltedRieman(bseed, kTRUE);
-    if(AliTRDReconstructor::StreamLevel() >= 7){
+    if(rLayers > nLayers){
+      AliDebug(1, Form("Lost %d tracklets while improving.", rLayers-nLayers));
+      return iter>0?kTRUE:kFALSE;
+    } else rLayers=nLayers;
+    qualitynew /= rLayers;
+
+    if(qualitynew > quality){ 
+      AliDebug(4, Form("Quality[%f] worsen in iter[%d] to ref[%f].", qualitynew, iter, quality));
+      return iter>0?kTRUE:kFALSE;
+    } else quality = qualitynew;
+
+    // try improve track parameters
+    Float_t chi2new = FitTiltedRieman(bseed, kTRUE);
+    if(chi2new > chi2){ 
+      AliDebug(4, Form("Chi2[%f] worsen in iter[%d] to ref[%f].", chi2new, iter, chi2));
+      return iter>0?kTRUE:kFALSE;
+    } else chi2 = chi2new;
+
+    // store better tracklets
+    for(Int_t jLayer=AliTRDgeometry::kNlayer; jLayer--;) cseed[jLayer]=bseed[jLayer];
+    AliDebug(2, Form("Iter[%d] Q[%f] chi2[%f]", iter, quality, chi2));
+
+
+    if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 7 && fkReconstructor->IsDebugStreaming()){
       Int_t eventNumber                = AliTRDtrackerDebug::GetEventNumber();
       Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
       TLinearFitter *tiltedRieman = GetTiltedRiemanFitter();
-      TTreeSRedirector &cstreamer = *fgDebugStreamer;
+      TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
       cstreamer << "ImproveSeedQuality"
-               << "EventNumber="               << eventNumber
-               << "CandidateNumber="   << candidateNumber
-               << "Iteration="                         << iter
-               << "S0.="                                                       << &bseed[0]
-               << "S1.="                                                       << &bseed[1]
-               << "S2.="                                                       << &bseed[2]
-               << "S3.="                                                       << &bseed[3]
-               << "S4.="                                                       << &bseed[4]
-               << "S5.="                                                       << &bseed[5]
-               << "FitterT.="                          << tiltedRieman
-               << "\n";
+        << "EventNumber="              << eventNumber
+        << "CandidateNumber="  << candidateNumber
+        << "Iteration="                                << iter
+        << "S0.="                                                      << &cseed[0]
+        << "S1.="                                                      << &cseed[1]
+        << "S2.="                                                      << &cseed[2]
+        << "S3.="                                                      << &cseed[3]
+        << "S4.="                                                      << &cseed[4]
+        << "S5.="                                                      << &cseed[5]
+        << "FitterT.="                         << tiltedRieman
+        << "\n";
     }
   } // Loop: iter
-       
-  // we are sure that at least 2 tracklets are OK !
-  return nLayers+2;
+
+  // we are sure that at least 4 tracklets are OK !
+  return kTRUE;
 }
 
 //_________________________________________________________________________
-Double_t AliTRDtrackerV1::CalculateTrackLikelihood(AliTRDseedV1 *tracklets, Double_t *chi2){
+Double_t AliTRDtrackerV1::CalculateTrackLikelihood(Double_t *chi2){
   //
   // Calculates the Track Likelihood value. This parameter serves as main quality criterion for 
   // the track selection
@@ -2264,42 +3207,58 @@ Double_t AliTRDtrackerV1::CalculateTrackLikelihood(AliTRDseedV1 *tracklets, Doub
   //
   // debug level 2
   //
-
-  Double_t sumdaf = 0, nLayers = 0;
-  for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
-    if(!tracklets[iLayer].IsOK()) continue;
-    sumdaf += TMath::Abs((tracklets[iLayer].GetYfit(1) - tracklets[iLayer].GetYref(1))/ tracklets[iLayer].GetSigmaY2());
-    nLayers++;
+  
+  // Non-constrained Tilted Riemann
+  Double_t likeChi2TR = TMath::Exp(-chi2[0] * 0.0078);
+  // Constrained Tilted Riemann
+  Double_t likeChi2TC(1.);
+  if(chi2[1]>0.){
+    likeChi2TC = TMath::Exp(-chi2[1] * 0.677);
+    Double_t r = likeChi2TC/likeChi2TR;
+    if(r>1.e2){;}   // -> a primary track use TC
+    else if(r<1.e2) // -> a secondary track use TR
+      likeChi2TC =1.;
+    else{;}         // -> test not conclusive
   }
-  sumdaf /= Float_t (nLayers - 2.0);
-       
-  Double_t likeChi2Z  = TMath::Exp(-chi2[2] * 0.14);                   // Chi2Z 
-  Double_t likeChi2TC = TMath::Exp(-chi2[1] * 0.677);                  // Constrained Tilted Riemann
-  Double_t likeChi2TR = TMath::Exp(-chi2[0] * 0.78);                   // Non-constrained Tilted Riemann
-  Double_t likeAF     = TMath::Exp(-sumdaf * 3.23);
-  Double_t trackLikelihood     = likeChi2Z * likeChi2TR * likeAF;
-
-  if(AliTRDReconstructor::StreamLevel() >= 2){
+  // Chi2 only on Z direction
+  Double_t likeChi2Z  = TMath::Exp(-chi2[2] * 0.14);
+  // Chi2 angular resolution
+  Double_t likeChi2Phi= TMath::Exp(-chi2[3] * 3.23);
+
+  Double_t trackLikelihood     = likeChi2Z * likeChi2TR * likeChi2TC * likeChi2Phi;
+
+  AliDebug(2, Form("Likelihood [%e]\n"
+    "  Rieman : chi2[%f] likelihood[%6.2e]\n"
+    "  Vertex : chi2[%f] likelihood[%6.2e]\n"
+    "  Z      : chi2[%f] likelihood[%6.2e]\n"
+    "  Phi    : chi2[%f] likelihood[%6.2e]"
+    , trackLikelihood
+    , chi2[0], likeChi2TR
+    , chi2[1], likeChi2TC
+    , chi2[2], likeChi2Z
+    , chi2[3], likeChi2Phi
+  ));
+
+  if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
     Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
     Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
-    TTreeSRedirector &cstreamer = *fgDebugStreamer;
+    TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
     cstreamer << "CalculateTrackLikelihood0"
-             << "EventNumber="                 << eventNumber
-             << "CandidateNumber="     << candidateNumber
-             << "LikeChi2Z="                           << likeChi2Z
-             << "LikeChi2TR="                  << likeChi2TR
-             << "LikeChi2TC="                  << likeChi2TC
-             << "LikeAF="                                      << likeAF
-             << "TrackLikelihood=" << trackLikelihood
-             << "\n";
+        << "EventNumber="                      << eventNumber
+        << "CandidateNumber="  << candidateNumber
+        << "LikeChi2Z="                                << likeChi2Z
+        << "LikeChi2TR="                       << likeChi2TR
+        << "LikeChi2TC="                       << likeChi2TC
+        << "LikeChi2Phi="              << likeChi2Phi
+        << "TrackLikelihood=" << trackLikelihood
+        << "\n";
   }
-
+  
   return trackLikelihood;
 }
 
 //____________________________________________________________________
-Double_t AliTRDtrackerV1::CookLikelihood(AliTRDseedV1 *cseed, Int_t planes[4]
-                                        , Double_t *chi2)
+Double_t AliTRDtrackerV1::CookLikelihood(AliTRDseedV1 *cseed, Int_t planes[4])
 {
   //
   // Calculate the probability of this track candidate.
@@ -2324,59 +3283,64 @@ Double_t AliTRDtrackerV1::CookLikelihood(AliTRDseedV1 *cseed, Int_t planes[4]
   // The distributions for each type of probabilities are given below as of
   // (date). They have to be checked to assure consistency of estimation.
   //
+
   // ratio of the total number of clusters/track which are expected to be found by the tracker.
-  Float_t fgFindable = AliTRDReconstructor::RecoParam()->GetFindableClusters();
+       Double_t chi2y = GetChi2Y(&cseed[0]);
+  Double_t chi2z = GetChi2Z(&cseed[0]);
 
-       
-  Int_t nclusters = 0;
+  Float_t nclusters = 0.;
   Double_t sumda = 0.;
   for(UChar_t ilayer = 0; ilayer < 4; ilayer++){
     Int_t jlayer = planes[ilayer];
     nclusters += cseed[jlayer].GetN2();
-    sumda += TMath::Abs(cseed[jlayer].GetYfitR(1) - cseed[jlayer].GetYref(1));
+    sumda += TMath::Abs(cseed[jlayer].GetYfit(1) - cseed[jlayer].GetYref(1));
   }
-  Double_t likea     = TMath::Exp(-sumda*10.6);
+  nclusters *= .25;
+
+  Double_t likea     = TMath::Exp(-sumda * fkRecoParam->GetPhiSlope());
   Double_t likechi2y  = 0.0000000001;
-  if (chi2[0] < 0.5) likechi2y += TMath::Exp(-TMath::Sqrt(chi2[0]) * 7.73);
-  Double_t likechi2z = TMath::Exp(-chi2[1] * 0.088) / TMath::Exp(-chi2[1] * 0.019);
-  Int_t enc = Int_t(fgFindable*4.*fgNTimeBins);        // Expected Number Of Clusters, normally 72
-  Double_t likeN     = TMath::Exp(-(enc - nclusters) * 0.19);
-       
+  if (fkReconstructor->IsCosmic() || chi2y < fkRecoParam->GetChi2YCut()) likechi2y += TMath::Exp(-TMath::Sqrt(chi2y) * fkRecoParam->GetChi2YSlope());
+  Double_t likechi2z = TMath::Exp(-chi2z * fkRecoParam->GetChi2ZSlope());
+  Double_t likeN     = TMath::Exp(-(fkRecoParam->GetNMeanClusters() - nclusters) / fkRecoParam->GetNSigmaClusters());
   Double_t like      = likea * likechi2y * likechi2z * likeN;
 
-  //   AliInfo(Form("sumda(%f) chi2[0](%f) chi2[1](%f) likea(%f) likechi2y(%f) likechi2z(%f) nclusters(%d) likeN(%f)", sumda, chi2[0], chi2[1], likea, likechi2y, likechi2z, nclusters, likeN));
-  if(AliTRDReconstructor::StreamLevel() >= 2){
+  if(fkRecoParam->GetStreamLevel(AliTRDrecoParam::kTracker) >= 2 && fkReconstructor->IsDebugStreaming()){
     Int_t eventNumber = AliTRDtrackerDebug::GetEventNumber();
     Int_t candidateNumber = AliTRDtrackerDebug::GetCandidateNumber();
+    Int_t nTracklets = 0; Float_t meanNcls = 0;
+    for(Int_t iseed=0; iseed < kNPlanes; iseed++){
+       if(!cseed[iseed].IsOK()) continue;
+       nTracklets++;
+       meanNcls += cseed[iseed].GetN2();
+    }
+    if(nTracklets) meanNcls /= nTracklets;
     // The Debug Stream contains the seed 
-    TTreeSRedirector &cstreamer = *fgDebugStreamer;
+    TTreeSRedirector &cstreamer = *fkReconstructor->GetDebugStream(AliTRDrecoParam::kTracker);
     cstreamer << "CookLikelihood"
-             << "EventNumber="                 << eventNumber
-             << "CandidateNumber=" << candidateNumber
-             << "tracklet0.="                  << &cseed[0]
-             << "tracklet1.="                  << &cseed[1]
-             << "tracklet2.="                  << &cseed[2]
-             << "tracklet3.="                  << &cseed[3]
-             << "tracklet4.="                  << &cseed[4]
-             << "tracklet5.="                  << &cseed[5]
-             << "sumda="                                               << sumda
-             << "chi0="                                                << chi2[0]
-             << "chi1="                                                << chi2[1]
-             << "likea="                                               << likea
-             << "likechi2y="                           << likechi2y
-             << "likechi2z="                           << likechi2z
-             << "nclusters="                           << nclusters
-             << "likeN="                                               << likeN
-             << "like="                                                << like
-             << "\n";
+        << "EventNumber="                      << eventNumber
+        << "CandidateNumber=" << candidateNumber
+        << "tracklet0.="                       << &cseed[0]
+        << "tracklet1.="                       << &cseed[1]
+        << "tracklet2.="                       << &cseed[2]
+        << "tracklet3.="                       << &cseed[3]
+        << "tracklet4.="                       << &cseed[4]
+        << "tracklet5.="                       << &cseed[5]
+        << "sumda="                                            << sumda
+        << "chi2y="                                            << chi2y
+        << "chi2z="                                            << chi2z
+        << "likea="                                            << likea
+        << "likechi2y="                                << likechi2y
+        << "likechi2z="                                << likechi2z
+        << "nclusters="                                << nclusters
+        << "likeN="                                            << likeN
+        << "like="                                             << like
+        << "meanncls="        << meanNcls
+        << "\n";
   }
 
   return like;
 }
 
-
-
 //____________________________________________________________________
 void AliTRDtrackerV1::GetSeedingConfig(Int_t iconfig, Int_t planes[4])
 {
@@ -2601,150 +3565,240 @@ void AliTRDtrackerV1::GetExtrapolationConfig(Int_t iconfig, Int_t planes[2])
 //____________________________________________________________________
 AliCluster* AliTRDtrackerV1::GetCluster(Int_t idx) const
 {
+  if(!fClusters) return NULL;
   Int_t ncls = fClusters->GetEntriesFast();
-  return idx >= 0 || idx < ncls ? (AliCluster*)fClusters->UncheckedAt(idx) : 0x0;
+  return idx >= 0 && idx < ncls ? (AliCluster*)fClusters->UncheckedAt(idx) : NULL;
 }
 
 //____________________________________________________________________
-Float_t AliTRDtrackerV1::CalculateReferenceX(AliTRDseedV1 *tracklets){
-  //
-  // Calculates the reference x-position for the tilted Rieman fit defined as middle
-  // of the stack (middle between layers 2 and 3). For the calculation all the tracklets
-  // are taken into account
-  // 
-  // Parameters:       - Array of tracklets(AliTRDseedV1)
-  //
-  // Output:           - The reference x-position(Float_t)
-  //
-  Int_t nDistances = 0;
-  Float_t meanDistance = 0.;
-  Int_t startIndex = 5;
-  for(Int_t il =5; il > 0; il--){
-    if(tracklets[il].IsOK() && tracklets[il -1].IsOK()){
-      Float_t xdiff = tracklets[il].GetX0() - tracklets[il -1].GetX0();
-      meanDistance += xdiff;
-      nDistances++;
-    }
-    if(tracklets[il].IsOK()) startIndex = il;
-  }
-  if(tracklets[0].IsOK()) startIndex = 0;
-  if(!nDistances){
-    // We should normally never get here
-    Float_t xpos[2]; memset(xpos, 0, sizeof(Float_t) * 2);
-    Int_t iok = 0, idiff = 0;
-    // This attempt is worse and should be avoided:
-    // check for two chambers which are OK and repeat this without taking the mean value
-    // Strategy avoids a division by 0;
-    for(Int_t il = 5; il >= 0; il--){
-      if(tracklets[il].IsOK()){
-       xpos[iok] = tracklets[il].GetX0();
-       iok++;
-       startIndex = il;
-      }
-      if(iok) idiff++; // to get the right difference;
-      if(iok > 1) break;
-    }
-    if(iok > 1){
-      meanDistance = (xpos[0] - xpos[1])/idiff;
-    }
-    else{
-      // we have do not even have 2 layers which are OK? The we do not need to fit at all
-      return 331.;
-    }
-  }
-  else{
-    meanDistance /= nDistances;
-  }
-  return tracklets[startIndex].GetX0() + (2.5 - startIndex) * meanDistance - 0.5 * (AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());
+AliTRDseedV1* AliTRDtrackerV1::GetTracklet(Int_t idx) const
+{
+  if(!fTracklets) return NULL;
+  Int_t ntrklt = fTracklets->GetEntriesFast();
+  return idx >= 0 && idx < ntrklt ? (AliTRDseedV1*)fTracklets->UncheckedAt(idx) : NULL;
 }
 
-//_____________________________________________________________________________
-Int_t AliTRDtrackerV1::Freq(Int_t n, const Int_t *inlist
-                           , Int_t *outlist, Bool_t down)
-{    
-  //
-  // Sort eleements according occurancy 
-  // The size of output array has is 2*n 
-  //
+//____________________________________________________________________
+AliKalmanTrack* AliTRDtrackerV1::GetTrack(Int_t idx) const
+{
+  if(!fTracks) return NULL;
+  Int_t ntrk = fTracks->GetEntriesFast();
+  return idx >= 0 && idx < ntrk ? (AliKalmanTrack*)fTracks->UncheckedAt(idx) : NULL;
+}
 
-  if (n <= 0) {
-    return 0;
-  }
 
-  Int_t *sindexS = new Int_t[n];   // Temporary array for sorting
-  Int_t *sindexF = new Int_t[2*n];   
-  for (Int_t i = 0; i < n; i++) {
-    sindexF[i] = 0;
-  }
 
-  TMath::Sort(n,inlist,sindexS,down); 
-  Int_t last     = inlist[sindexS[0]];
-  Int_t val      = last;
-  sindexF[0]     = 1;
-  sindexF[0+n]   = last;
-  Int_t countPos = 0;
+// //_____________________________________________________________________________
+// Int_t AliTRDtrackerV1::Freq(Int_t n, const Int_t *inlist
+//           , Int_t *outlist, Bool_t down)
+// {    
+//   //
+//   // Sort eleements according occurancy 
+//   // The size of output array has is 2*n 
+//   //
+// 
+//   if (n <= 0) {
+//     return 0;
+//   }
+// 
+//   Int_t *sindexS = new Int_t[n];   // Temporary array for sorting
+//   Int_t *sindexF = new Int_t[2*n];   
+//   for (Int_t i = 0; i < n; i++) {
+//     sindexF[i] = 0;
+//   }
+// 
+//   TMath::Sort(n,inlist,sindexS,down); 
+// 
+//   Int_t last     = inlist[sindexS[0]];
+//   Int_t val      = last;
+//   sindexF[0]     = 1;
+//   sindexF[0+n]   = last;
+//   Int_t countPos = 0;
+// 
+//   // Find frequency
+//   for (Int_t i = 1; i < n; i++) {
+//     val = inlist[sindexS[i]];
+//     if (last == val) {
+//       sindexF[countPos]++;
+//     }
+//     else {      
+//       countPos++;
+//       sindexF[countPos+n] = val;
+//       sindexF[countPos]++;
+//       last                = val;
+//     }
+//   }
+//   if (last == val) {
+//     countPos++;
+//   }
+// 
+//   // Sort according frequency
+//   TMath::Sort(countPos,sindexF,sindexS,kTRUE);
+// 
+//   for (Int_t i = 0; i < countPos; i++) {
+//     outlist[2*i  ] = sindexF[sindexS[i]+n];
+//     outlist[2*i+1] = sindexF[sindexS[i]];
+//   }
+// 
+//   delete [] sindexS;
+//   delete [] sindexF;
+//   
+//   return countPos;
+// 
+// }
 
-  // Find frequency
-  for (Int_t i = 1; i < n; i++) {
-    val = inlist[sindexS[i]];
-    if (last == val) {
-      sindexF[countPos]++;
-    }
-    else {      
-      countPos++;
-      sindexF[countPos+n] = val;
-      sindexF[countPos]++;
-      last                = val;
-    }
-  }
-  if (last == val) {
-    countPos++;
-  }
 
-  // Sort according frequency
-  TMath::Sort(countPos,sindexF,sindexS,kTRUE);
+//____________________________________________________________________
+void AliTRDtrackerV1::ResetSeedTB()
+{
+// reset buffer for seeding time bin layers. If the time bin 
+// layers are not allocated this function allocates them  
 
-  for (Int_t i = 0; i < countPos; i++) {
-    outlist[2*i  ] = sindexF[sindexS[i]+n];
-    outlist[2*i+1] = sindexF[sindexS[i]];
+  for(Int_t isl=0; isl<kNSeedPlanes; isl++){
+    if(!fSeedTB[isl]) fSeedTB[isl] = new AliTRDchamberTimeBin();
+    else fSeedTB[isl]->Clear();
   }
+}
 
-  delete [] sindexS;
-  delete [] sindexF;
-  
-  return countPos;
 
+//_____________________________________________________________________________
+Float_t AliTRDtrackerV1::GetChi2Y(const AliTRDseedV1 * const tracklets) const
+{
+  //   Calculates normalized chi2 in y-direction
+  // chi2 = Sum chi2 / n_tracklets
+
+  Double_t chi2 = 0.; Int_t n = 0;
+  for(Int_t ipl = kNPlanes; ipl--;){
+    if(!tracklets[ipl].IsOK()) continue;
+    chi2 += tracklets[ipl].GetChi2Y();
+    n++;
+  }
+  return n ? chi2/n : 0.;
 }
 
 //_____________________________________________________________________________
-Float_t AliTRDtrackerV1::GetChi2Y(AliTRDseedV1 *tracklets) const
+Float_t AliTRDtrackerV1::GetChi2Z(const AliTRDseedV1 *const tracklets) const 
 {
-  //   Chi2 definition on y-direction
+  //   Calculates normalized chi2 in z-direction
+  // chi2 = Sum chi2 / n_tracklets
 
-  Float_t chi2 = 0;
-  for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
+  Double_t chi2 = 0; Int_t n = 0;
+  for(Int_t ipl = kNPlanes; ipl--;){
     if(!tracklets[ipl].IsOK()) continue;
-    Double_t distLayer = tracklets[ipl].GetYfit(0) - tracklets[ipl].GetYref(0); 
-    chi2 += distLayer * distLayer;
+    chi2 += tracklets[ipl].GetChi2Z();
+    n++;
   }
-  return chi2;
+  return n ? chi2/n : 0.;
 }
 
 //_____________________________________________________________________________
-Float_t AliTRDtrackerV1::GetChi2Z(AliTRDseedV1 *tracklets) const 
+Float_t AliTRDtrackerV1::GetChi2Phi(const AliTRDseedV1 *const tracklets) const 
 {
-  //   Chi2 definition on z-direction
+  //  Calculates normalized chi2 for angular resolution
+  // chi2 = Sum chi2 / n_tracklets
 
-  Float_t chi2 = 0;
-  for(Int_t ipl = 0; ipl < kNPlanes; ipl++){
-    if(!tracklets[ipl].IsOK()) continue;
-    Double_t distLayer = tracklets[ipl].GetMeanz() - tracklets[ipl].GetZref(0); 
-    chi2 += distLayer * distLayer;
+  Double_t chi2 = 0; Int_t n = 0;
+  for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
+    if(!tracklets[iLayer].IsOK()) continue;
+    chi2 += tracklets[iLayer].GetChi2Phi();
+    n++;
+  }
+  return n ? chi2/n: 0.;
+}
+
+//____________________________________________________________________
+Float_t AliTRDtrackerV1::CalculateReferenceX(const AliTRDseedV1 *const tracklets){
+       //
+       // Calculates the reference x-position for the tilted Rieman fit defined as middle
+       // of the stack (middle between layers 2 and 3). For the calculation all the tracklets
+       // are taken into account
+       //
+       // Parameters: - Array of tracklets(AliTRDseedV1)
+       //
+       // Output: - The reference x-position(Float_t)
+  // Only kept for compatibility with the old code
+       //
+       Int_t nDistances = 0;
+       Float_t meanDistance = 0.;
+       Int_t startIndex = 5;
+       for(Int_t il =5; il > 0; il--){
+       if(tracklets[il].IsOK() && tracklets[il -1].IsOK()){
+       Float_t xdiff = tracklets[il].GetX0() - tracklets[il -1].GetX0();
+           meanDistance += xdiff;
+           nDistances++;
+         }
+         if(tracklets[il].IsOK()) startIndex = il;
+       }
+       if(tracklets[0].IsOK()) startIndex = 0;
+       if(!nDistances){
+         // We should normally never get here
+         Float_t xpos[2]; memset(xpos, 0, sizeof(Float_t) * 2);
+         Int_t iok = 0, idiff = 0;
+         // This attempt is worse and should be avoided:
+         // check for two chambers which are OK and repeat this without taking the mean value
+         // Strategy avoids a division by 0;
+         for(Int_t il = 5; il >= 0; il--){
+           if(tracklets[il].IsOK()){
+             xpos[iok] = tracklets[il].GetX0();
+             iok++;
+             startIndex = il;
+           }
+           if(iok) idiff++; // to get the right difference;
+           if(iok > 1) break;
+         }
+         if(iok > 1){
+           meanDistance = (xpos[0] - xpos[1])/idiff;
+         }
+         else{
+           // we have do not even have 2 layers which are OK? The we do not need to fit at all
+           return 331.;
+       }
+       }
+       else{
+         meanDistance /= nDistances;
+       }
+       return tracklets[startIndex].GetX0() + (2.5 - startIndex) * meanDistance - 0.5 * (AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDtrackerV1::FitTiltedRiemanV1(AliTRDseedV1 *const tracklets){
+  //
+  // Track Fitter Function using the new class implementation of 
+  // the Rieman fit
+  //
+  AliTRDtrackFitterRieman fitter;
+  fitter.SetRiemanFitter(GetTiltedRiemanFitter());
+  fitter.Reset();
+  for(Int_t il = 0; il < AliTRDgeometry::kNlayer; il++) fitter.SetTracklet(il, &tracklets[il]);
+  Double_t chi2 = fitter.Eval();
+  // Update the tracklets
+  Double_t cov[15]; Double_t x0;
+  memset(cov, 0, sizeof(Double_t) * 15);
+  for(Int_t il = 0; il < AliTRDgeometry::kNlayer; il++){
+    x0 = tracklets[il].GetX0();
+    tracklets[il].SetYref(0, fitter.GetYat(x0));
+    tracklets[il].SetZref(0, fitter.GetZat(x0));
+    tracklets[il].SetYref(1, fitter.GetDyDxAt(x0));
+    tracklets[il].SetZref(1, fitter.GetDzDx());
+    tracklets[il].SetC(fitter.GetCurvature());
+    fitter.GetCovAt(x0, cov);
+    tracklets[il].SetCovRef(cov);
+    tracklets[il].SetChi2(chi2);
   }
   return chi2;
 }
 
+//____________________________________________________________________
+void AliTRDtrackerV1::UnsetTrackletsTrack(const AliTRDtrackV1 * const track)
+{
+  Int_t idx(-1);
+  for(Int_t il(0); il<kNPlanes; il++){
+    if((idx = track->GetTrackletIndex(il)) < 0) continue;
+    delete (fTracklets->RemoveAt(idx));
+  }
+}
+
+
 ///////////////////////////////////////////////////////
 //                                                   //
 // Resources of class AliTRDLeastSquare              //
@@ -2753,22 +3807,41 @@ Float_t AliTRDtrackerV1::GetChi2Z(AliTRDseedV1 *tracklets) const
 
 //_____________________________________________________________________________
 AliTRDtrackerV1::AliTRDLeastSquare::AliTRDLeastSquare(){
-  //
-  // Constructor of the nested class AliTRDtrackFitterLeastSquare
-  //
+//
+// Constructor of the nested class AliTRDtrackFitterLeastSquare
+//
+// Fast solving linear regresion in 2D
+//         y=a + bx
+// The data members have the following meaning
+// fParams[0] : a
+// fParams[1] : b
+// 
+// fSums[0] : S
+// fSums[1] : Sx
+// fSums[2] : Sy
+// fSums[3] : Sxy
+// fSums[4] : Sxx
+// fSums[5] : Syy
+// 
+// fCovarianceMatrix[0] : s2a
+// fCovarianceMatrix[1] : s2b
+// fCovarianceMatrix[2] : cov(ab)
+
   memset(fParams, 0, sizeof(Double_t) * 2);
-  memset(fSums, 0, sizeof(Double_t) * 5);
+  memset(fSums, 0, sizeof(Double_t) * 6);
   memset(fCovarianceMatrix, 0, sizeof(Double_t) * 3);
 
 }
 
 //_____________________________________________________________________________
-void AliTRDtrackerV1::AliTRDLeastSquare::AddPoint(Double_t *x, Double_t y, Double_t sigmaY){
+void AliTRDtrackerV1::AliTRDLeastSquare::AddPoint(const Double_t *const x, Double_t y, Double_t sigmaY){
   //
   // Adding Point to the fitter
   //
-  Double_t weight = 1/(sigmaY * sigmaY);
-  Double_t &xpt = *x;
+  
+  Double_t weight = 1/(sigmaY > 1e-9 ? sigmaY : 1e-9);
+  weight *= weight;
+  const Double_t &xpt = *x;
   //   printf("Adding point x = %f, y = %f, sigma = %f\n", xpt, y, sigmaY);
   fSums[0] += weight;
   fSums[1] += weight * xpt;
@@ -2779,12 +3852,14 @@ void AliTRDtrackerV1::AliTRDLeastSquare::AddPoint(Double_t *x, Double_t y, Doubl
 }
 
 //_____________________________________________________________________________
-void AliTRDtrackerV1::AliTRDLeastSquare::RemovePoint(Double_t *x, Double_t y, Double_t sigmaY){
+void AliTRDtrackerV1::AliTRDLeastSquare::RemovePoint(const Double_t *const x, Double_t y, Double_t sigmaY){
   //
   // Remove Point from the sample
   //
-  Double_t weight = 1/(sigmaY * sigmaY);
-  Double_t &xpt = *x; 
+
+  Double_t weight = 1/(sigmaY > 1e-9 ? sigmaY : 1e-9);
+  weight *= weight;
+  const Double_t &xpt = *x; 
   fSums[0] -= weight;
   fSums[1] -= weight * xpt;
   fSums[2] -= weight * y;
@@ -2794,29 +3869,39 @@ void AliTRDtrackerV1::AliTRDLeastSquare::RemovePoint(Double_t *x, Double_t y, Do
 }
 
 //_____________________________________________________________________________
-void AliTRDtrackerV1::AliTRDLeastSquare::Eval(){
+Bool_t AliTRDtrackerV1::AliTRDLeastSquare::Eval(){
   //
   // Evaluation of the fit:
   // Calculation of the parameters
   // Calculation of the covariance matrix
   //
-       
-  Double_t denominator = fSums[0] * fSums[4] - fSums[1] *fSums[1];
+  
+  Double_t det = fSums[0] * fSums[4] - fSums[1] *fSums[1];
+  if(det==0) return kFALSE;
+
   //   for(Int_t isum = 0; isum < 5; isum++)
   //           printf("fSums[%d] = %f\n", isum, fSums[isum]);
   //   printf("denominator = %f\n", denominator);
-  fParams[0] = (fSums[2] * fSums[4] - fSums[1] * fSums[3])/ denominator;
-  fParams[1] = (fSums[0] * fSums[3] - fSums[1] * fSums[2]) / denominator;
+  fParams[0] = (fSums[2] * fSums[4] - fSums[1] * fSums[3])/det;
+  fParams[1] = (fSums[0] * fSums[3] - fSums[1] * fSums[2])/det;
   //   printf("fParams[0] = %f, fParams[1] = %f\n", fParams[0], fParams[1]);
-       
+  
   // Covariance matrix
-  fCovarianceMatrix[0] = fSums[4] - fSums[1] * fSums[1] / fSums[0];
-  fCovarianceMatrix[1] = fSums[5] - fSums[2] * fSums[2] / fSums[0];
-  fCovarianceMatrix[2] = fSums[3] - fSums[1] * fSums[2] / fSums[0];
+  Double_t den = fSums[0]*fSums[4] - fSums[1]*fSums[1];
+  fCovarianceMatrix[0] = fSums[4] / den;
+  fCovarianceMatrix[1] = fSums[0] / den;
+  fCovarianceMatrix[2] = -fSums[1] / den;
+/*  fCovarianceMatrix[0] = fSums[4] / fSums[0] - fSums[1] * fSums[1] / (fSums[0] * fSums[0]);
+  fCovarianceMatrix[1] = fSums[5] / fSums[0] - fSums[2] * fSums[2] / (fSums[0] * fSums[0]);
+  fCovarianceMatrix[2] = fSums[3] / fSums[0] - fSums[1] * fSums[2] / (fSums[0] * fSums[0]);*/
+
+
+
+  return kTRUE;
 }
 
 //_____________________________________________________________________________
-Double_t AliTRDtrackerV1::AliTRDLeastSquare::GetFunctionValue(Double_t *xpos) const {
+Double_t AliTRDtrackerV1::AliTRDLeastSquare::GetFunctionValue(const Double_t *const xpos) const {
   //
   // Returns the Function value of the fitted function at a given x-position
   //
@@ -2831,3 +3916,335 @@ void AliTRDtrackerV1::AliTRDLeastSquare::GetCovarianceMatrix(Double_t *storage)
   memcpy(storage, fCovarianceMatrix, sizeof(Double_t) * 3);
 }
 
+//_____________________________________________________________________________
+void AliTRDtrackerV1::AliTRDLeastSquare::Reset(){
+  //
+  // Reset the fitter
+  //
+  memset(fParams, 0, sizeof(Double_t) * 2);
+  memset(fCovarianceMatrix, 0, sizeof(Double_t) * 3);
+  memset(fSums, 0, sizeof(Double_t) * 6);
+}
+
+///////////////////////////////////////////////////////
+//                                                   //
+// Resources of class AliTRDtrackFitterRieman        //
+//                                                   //
+///////////////////////////////////////////////////////
+
+//_____________________________________________________________________________
+AliTRDtrackerV1::AliTRDtrackFitterRieman::AliTRDtrackFitterRieman():
+  fTrackFitter(NULL),
+  fZfitter(NULL),
+  fCovarPolY(NULL),
+  fCovarPolZ(NULL),
+  fXref(0.),
+  fSysClusterError(0.)
+{
+  //
+  // Default constructor
+  //
+  fZfitter = new AliTRDLeastSquare;
+  fCovarPolY = new TMatrixD(3,3);
+  fCovarPolZ = new TMatrixD(2,2);
+  memset(fTracklets, 0, sizeof(AliTRDseedV1 *) * 6);
+  memset(fParameters, 0, sizeof(Double_t) * 5);
+  memset(fSumPolY, 0, sizeof(Double_t) * 5);
+  memset(fSumPolZ, 0, sizeof(Double_t) * 2);
+}
+
+//_____________________________________________________________________________
+AliTRDtrackerV1::AliTRDtrackFitterRieman::~AliTRDtrackFitterRieman(){
+  //
+  // Destructor
+  //
+  if(fZfitter) delete fZfitter;
+  if(fCovarPolY) delete fCovarPolY;
+  if(fCovarPolZ) delete fCovarPolZ;
+}
+
+//_____________________________________________________________________________
+void AliTRDtrackerV1::AliTRDtrackFitterRieman::Reset(){
+  //
+  // Reset the Fitter
+  //
+  if(fTrackFitter){
+    fTrackFitter->StoreData(kTRUE);
+    fTrackFitter->ClearPoints();
+  }
+  if(fZfitter){
+    fZfitter->Reset();
+  }
+  fXref = 0.;
+  memset(fTracklets, 0, sizeof(AliTRDseedV1 *) * AliTRDgeometry::kNlayer);
+  memset(fParameters, 0, sizeof(Double_t) * 5);
+  memset(fSumPolY, 0, sizeof(Double_t) * 5);
+  memset(fSumPolZ, 0, sizeof(Double_t) * 2);
+  for(Int_t irow = 0; irow < fCovarPolY->GetNrows(); irow++)
+    for(Int_t icol = 0; icol < fCovarPolY->GetNcols(); icol++){
+      (*fCovarPolY)(irow, icol) = 0.;
+      if(irow < 2 && icol < 2)
+        (*fCovarPolZ)(irow, icol) = 0.;
+    }
+}
+
+//_____________________________________________________________________________
+void AliTRDtrackerV1::AliTRDtrackFitterRieman::SetTracklet(Int_t itr, AliTRDseedV1 *tracklet){ 
+  //
+  // Add tracklet into the fitter
+  //
+  if(itr >= AliTRDgeometry::kNlayer) return;
+  fTracklets[itr] = tracklet; 
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::Eval(){
+  //
+  // Perform the fit
+  // 1. Apply linear transformation and store points in the fitter
+  // 2. Evaluate the fit
+  // 3. Check if the result of the fit in z-direction is reasonable
+  // if not
+  // 3a. Fix the parameters 3 and 4 with the results of a simple least
+  //     square fit
+  // 3b. Redo the fit with the fixed parameters
+  // 4. Store fit results (parameters and errors)
+  //
+  if(!fTrackFitter){
+    return 1e10;
+  }
+  fXref = CalculateReferenceX();
+  for(Int_t il = 0; il < AliTRDgeometry::kNlayer; il++) UpdateFitters(fTracklets[il]);
+  if(!fTrackFitter->GetNpoints()) return 1e10;
+  // perform the fit
+  fTrackFitter->Eval();
+  fZfitter->Eval();
+  fParameters[3] = fTrackFitter->GetParameter(3);
+  fParameters[4] = fTrackFitter->GetParameter(4);
+  if(!CheckAcceptable(fParameters[3], fParameters[4])) {
+    fTrackFitter->FixParameter(3, fZfitter->GetFunctionValue(&fXref));
+    fTrackFitter->FixParameter(4, fZfitter->GetFunctionParameter(1));
+    fTrackFitter->Eval();
+    fTrackFitter->ReleaseParameter(3);
+    fTrackFitter->ReleaseParameter(4);
+    fParameters[3] = fTrackFitter->GetParameter(3);
+    fParameters[4] = fTrackFitter->GetParameter(4);
+  }
+  // Update the Fit Parameters and the errors
+  fParameters[0] = fTrackFitter->GetParameter(0);
+  fParameters[1] = fTrackFitter->GetParameter(1);
+  fParameters[2] = fTrackFitter->GetParameter(2);
+
+  // Prepare Covariance estimation
+  (*fCovarPolY)(0,0) = fSumPolY[0]; (*fCovarPolY)(1,1) = fSumPolY[2]; (*fCovarPolY)(2,2) = fSumPolY[4];
+  (*fCovarPolY)(1,0) = (*fCovarPolY)(0,1) = fSumPolY[1];
+  (*fCovarPolY)(2,0) = (*fCovarPolY)(0,2) = fSumPolY[2];
+  (*fCovarPolY)(2,1) = (*fCovarPolY)(1,2) = fSumPolY[3];
+  fCovarPolY->Invert();
+  (*fCovarPolZ)(0,0) = fSumPolZ[0]; (*fCovarPolZ)(1,1) = fSumPolZ[2];
+  (*fCovarPolZ)(1,0) = (*fCovarPolZ)(0,1) = fSumPolZ[1];
+  fCovarPolZ->Invert();
+  return fTrackFitter->GetChisquare() / fTrackFitter->GetNpoints();
+}
+
+//_____________________________________________________________________________
+void AliTRDtrackerV1::AliTRDtrackFitterRieman::UpdateFitters(AliTRDseedV1 * const tracklet){
+  //
+  // Does the transformations and updates the fitters
+  // The following transformation is applied
+  //
+  AliTRDcluster *cl = NULL;
+  Double_t x, y, z, dx, t, w, we, yerr, zerr;
+  Double_t uvt[4];
+  if(!tracklet || !tracklet->IsOK()) return; 
+  Double_t tilt = tracklet->GetTilt();
+  for(Int_t itb = 0; itb < AliTRDseedV1::kNclusters; itb++){
+    if(!(cl = tracklet->GetClusters(itb))) continue;
+    if(!cl->IsInChamber()) continue;
+    if (!tracklet->IsUsable(itb)) continue;
+    x = cl->GetX();
+    y = cl->GetY();
+    z = cl->GetZ();
+    dx = x - fXref;
+    // Transformation
+    t = 1./(x*x + y*y);
+    uvt[0] = 2. * x * t;
+    uvt[1] = t;
+    uvt[2] = 2. * tilt * t;
+    uvt[3] = 2. * tilt * dx * t;
+    w = 2. * (y + tilt*z) * t;
+    // error definition changes for the different calls
+    we = 2. * t;
+    we *= TMath::Sqrt(cl->GetSigmaY2()+tilt*tilt*cl->GetSigmaZ2());
+    // Update sums for error calculation
+    yerr = 1./(TMath::Sqrt(cl->GetSigmaY2()) + fSysClusterError);
+    yerr *= yerr;
+    zerr = 1./cl->GetSigmaZ2();
+    for(Int_t ipol = 0; ipol < 5; ipol++){
+      fSumPolY[ipol] += yerr;
+      yerr *= x;
+      if(ipol < 3){
+        fSumPolZ[ipol] += zerr;
+        zerr *= x;
+      }
+    }
+    fTrackFitter->AddPoint(uvt, w, we);
+    fZfitter->AddPoint(&x, z, static_cast<Double_t>(TMath::Sqrt(cl->GetSigmaZ2())));
+  }
+}
+
+//_____________________________________________________________________________
+Bool_t AliTRDtrackerV1::AliTRDtrackFitterRieman::CheckAcceptable(Double_t offset, Double_t slope){
+  // 
+  // Check whether z-results are acceptable
+  // Definition: Distance between tracklet fit and track fit has to be
+  // less then half a padlength
+  // Point of comparision is at the anode wire
+  //
+  Bool_t acceptablez = kTRUE;
+  Double_t zref = 0.0;
+  for (Int_t iLayer = 0; iLayer < kNPlanes; iLayer++) {
+    if(!fTracklets[iLayer]->IsOK()) continue;
+    zref = offset + slope * (fTracklets[iLayer]->GetX0() - fXref);
+    if (TMath::Abs(fTracklets[iLayer]->GetZfit(0) - zref) > fTracklets[iLayer]->GetPadLength() * 0.5 + 1.0) 
+      acceptablez = kFALSE;
+  }
+  return acceptablez;
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetYat(Double_t x) const {
+  //
+  // Calculate y position out of the track parameters
+  // y:     R^2 = (x - x0)^2 + (y - y0)^2
+  //     =>   y = y0 +/- Sqrt(R^2 - (x - x0)^2)
+  //          R = Sqrt() = 1/Curvature
+  //     =>   y = y0 +/- Sqrt(1/Curvature^2 - (x - x0)^2)
+  //
+  Double_t y = 0;
+  Double_t disc = (x * fParameters[0] + fParameters[1]);
+  disc = 1 - fParameters[0]*fParameters[2] + fParameters[1]*fParameters[1] - disc*disc;
+  if (disc >= 0) {
+    disc = TMath::Sqrt(disc);
+    y    = (1.0 - disc) / fParameters[0];
+  }
+  return y;
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetZat(Double_t x) const {
+  //
+  // Return z position for a given x position
+  // Simple linear function
+  //
+  return fParameters[3] + fParameters[4] * (x - fXref);
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetDyDxAt(Double_t x) const {
+  //
+  // Calculate dydx at a given radial position out of the track parameters
+  // dy:      R^2 = (x - x0)^2 + (y - y0)^2
+  //     =>     y = +/- Sqrt(R^2 - (x - x0)^2) + y0
+  //     => dy/dx = (x - x0)/Sqrt(R^2 - (x - x0)^2) 
+  // Curvature: cr = 1/R = a/Sqrt(1 + b^2 - c*a)
+  //     => dy/dx =  (x - x0)/(1/(cr^2) - (x - x0)^2) 
+  //
+  Double_t x0 = -fParameters[1] / fParameters[0];
+  Double_t curvature = GetCurvature();
+  Double_t dy = 0;
+  if (-fParameters[2] * fParameters[0] + fParameters[1] * fParameters[1] + 1 > 0) {
+    if (1.0/(curvature * curvature) - (x - x0) * (x - x0) > 0.0) {
+     Double_t yderiv = (x - x0) / TMath::Sqrt(1.0/(curvature * curvature) - (x - x0) * (x - x0));
+      if (fParameters[0] < 0) yderiv *= -1.0;
+      dy = yderiv;
+    }
+  }
+  return dy;
+}
+
+//_____________________________________________________________________________
+Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::GetCurvature() const {
+  //
+  // Calculate track curvature
+  //
+  //
+  Double_t curvature =  1.0 + fParameters[1]*fParameters[1] - fParameters[2]*fParameters[0];
+  if (curvature > 0.0) 
+    curvature  =  fParameters[0] / TMath::Sqrt(curvature);
+  return curvature;
+}
+
+//_____________________________________________________________________________
+void AliTRDtrackerV1::AliTRDtrackFitterRieman::GetCovAt(Double_t x, Double_t *cov) const {
+  //
+  // Error Definition according to gauss error propagation
+  //  
+  TMatrixD transform(3,3);
+  transform(0,0) = transform(1,1) = transform(2,2) = 1;
+  transform(0,1) = transform(1,2) = x;
+  transform(0,2) = x*x;
+  TMatrixD covariance(transform, TMatrixD::kMult, *fCovarPolY);
+  covariance *= transform.T();
+  cov[0] = covariance(0,0);
+  TMatrixD transformZ(2,2);
+  transformZ(0,0) = transformZ(1,1) = 1;
+  transformZ(0,1) = x;
+  TMatrixD covarZ(transformZ, TMatrixD::kMult, *fCovarPolZ);
+  covarZ *= transformZ.T();
+  cov[1] = covarZ(0,0);
+  cov[2] = 0;
+}
+
+//____________________________________________________________________
+Double_t AliTRDtrackerV1::AliTRDtrackFitterRieman::CalculateReferenceX(){
+  //
+  // Calculates the reference x-position for the tilted Rieman fit defined as middle
+  // of the stack (middle between layers 2 and 3). For the calculation all the tracklets
+  // are taken into account
+  // 
+  // Parameters:       - Array of tracklets(AliTRDseedV1)
+  //
+  // Output:           - The reference x-position(Float_t)
+  //
+  Int_t nDistances = 0;
+  Float_t meanDistance = 0.;
+  Int_t startIndex = 5;
+  for(Int_t il =5; il > 0; il--){
+    if(fTracklets[il]->IsOK() && fTracklets[il -1]->IsOK()){
+      Float_t xdiff = fTracklets[il]->GetX0() - fTracklets[il -1]->GetX0();
+      meanDistance += xdiff;
+      nDistances++;
+    }
+    if(fTracklets[il]->IsOK()) startIndex = il;
+  }
+  if(fTracklets[0]->IsOK()) startIndex = 0;
+  if(!nDistances){
+    // We should normally never get here
+    Float_t xpos[2]; memset(xpos, 0, sizeof(Float_t) * 2);
+    Int_t iok = 0, idiff = 0;
+    // This attempt is worse and should be avoided:
+    // check for two chambers which are OK and repeat this without taking the mean value
+    // Strategy avoids a division by 0;
+    for(Int_t il = 5; il >= 0; il--){
+      if(fTracklets[il]->IsOK()){
+        xpos[iok] = fTracklets[il]->GetX0();
+        iok++;
+        startIndex = il;
+      }
+      if(iok) idiff++; // to get the right difference;
+      if(iok > 1) break;
+    }
+    if(iok > 1){
+      meanDistance = (xpos[0] - xpos[1])/idiff;
+    }
+    else{
+      // we have do not even have 2 layers which are OK? The we do not need to fit at all
+      return 331.;
+    }
+  }
+  else{
+    meanDistance /= nDistances;
+  }
+  return fTracklets[startIndex]->GetX0() + (2.5 - startIndex) * meanDistance - 0.5 * (AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());
+}