TRT_TrackSegmentsMaker_ECcosmics.cxx

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
 
//   Implementation file for class TRT_TrackSegmentsMaker_ECcosmics
// (c) ATLAS Detector software
 
 
 
#include "TrkSurfaces/Surface.h"
#include "TrkSurfaces/StraightLineSurface.h"
#include "TrkPseudoMeasurementOnTrack/PseudoMeasurementOnTrack.h"
#include "TrkRIO_OnTrack/RIO_OnTrack.h"
#include "TrkEventPrimitives/FitQuality.h"
#include "TRT_ReadoutGeometry/TRT_DetectorManager.h"
#include "InDetPrepRawData/TRT_DriftCircleContainer.h"
#include "RootUtils/WithRootErrorHandler.h"
#include "TGraphErrors.h"
#include "TF1.h"
#include "TVirtualFitter.h"
#include "TRT_TrackSegmentsTool_xk/TRT_TrackSegmentsMaker_ECcosmics.h"
 
#include "StoreGate/ReadHandle.h"
#include <cmath>
 
 
 
// Constructor
 
InDet::TRT_TrackSegmentsMaker_ECcosmics::TRT_TrackSegmentsMaker_ECcosmics
(const std::string& t,const std::string& n,const IInterface* p)
  : AthAlgTool(t,n,p)
{
  declareInterface<ITRT_TrackSegmentsMaker>(this);
}
 
// Destructor
 
InDet::TRT_TrackSegmentsMaker_ECcosmics::~TRT_TrackSegmentsMaker_ECcosmics()
= default;
 
 
// Fitting functions
 
Double_t fitf_ztanphi(const Double_t *x, const Double_t *par)
{
  Double_t f = par[0]*(x[0]+par[1])/(x[0]+par[2]);
  return f;
}
 
Double_t fitf_zphi(const Double_t *x, const Double_t *par)
{
  Double_t f = std::atan(par[0]*(x[0]+par[1])/(x[0]+par[2]));
  return f;
}
 
Double_t fitf_zphi_approx(const Double_t *x, const Double_t *par)
{
  Double_t f = par[0]+par[1]*x[0]+par[2]*x[0]*x[0];
  return f;
}
 
// Initialisation
 
StatusCode InDet::TRT_TrackSegmentsMaker_ECcosmics::initialize()
{
  StatusCode sc = AthAlgTool::initialize();
 
  // Initialize ReadHandle
  ATH_CHECK(m_trtname.initialize());
 
  // TRT
  if (detStore()->retrieve(m_trtid, "TRT_ID").isFailure()) {
    ATH_MSG_FATAL("Could not get TRT ID helper");
    return StatusCode::FAILURE;
  }
 
  // Get RIO_OnTrack creator with drift time information
  //
  if( m_riomakerD.retrieve().isFailure()) {
    ATH_MSG_FATAL("Failed to retrieve tool "<< m_riomakerD);
    return StatusCode::FAILURE;
  }
  ATH_MSG_DEBUG("Retrieved tool " << m_riomakerD);
 
  // Get RIO_OnTrack creator without drift time information
  //
 
  if( m_riomakerN.retrieve().isFailure()) {
    ATH_MSG_FATAL("Failed to retrieve tool "<< m_riomakerN);
    return StatusCode::FAILURE;
  }
  ATH_MSG_DEBUG("Retrieved tool " << m_riomakerN);
 
  // optional PRD to track association map
  //
  ATH_CHECK( m_prdToTrackMap.initialize( !m_prdToTrackMap.key().empty() ) );
 
 
  return sc;
}
 
 
void InDet::TRT_TrackSegmentsMaker_ECcosmics::setFitFunctions(TRT_TrackSegmentsMaker_ECcosmics::EventData &event_data) const {
  std::string fit_name1="ztanphi";
  std::string fit_name2="zphi";
  std::string fit_name3="zphi_ap";
 
  if(m_phaseMode){
    fit_name1+="_phase";
    fit_name2+="_phase";
    fit_name3+="_phase";
  }
 
  if(!m_prdToTrackMap.key().empty()){
    fit_name1+="_asso";
    fit_name2+="_asso";
    fit_name3+="_asso";
  }
 
  fit_name1+=name();
  fit_name2+=name();
  fit_name3+=name();
 
  event_data.m_fitf_ztanphi = new TF1(fit_name1.c_str(),fitf_ztanphi,-3000,3000,3);
  event_data.m_fitf_zphi = new TF1(fit_name2.c_str(),fitf_zphi,-3000,3000,3);
  event_data.m_fitf_zphi_approx = new TF1(fit_name3.c_str(),fitf_zphi_approx,-3000,3000,3);
}
 
// Finalize
 
StatusCode InDet::TRT_TrackSegmentsMaker_ECcosmics::finalize()
{
   StatusCode sc = AthAlgTool::finalize();
   return sc;
}
 
// Initialize tool for new event
 
std::unique_ptr<InDet::ITRT_TrackSegmentsMaker::IEventData>
InDet::TRT_TrackSegmentsMaker_ECcosmics::newEvent (const EventContext& /*ctx*/) const
{
 
  std::unique_ptr<TRT_TrackSegmentsMaker_ECcosmics::EventData>
     event_data = std::make_unique<TRT_TrackSegmentsMaker_ECcosmics::EventData>();
 
  setFitFunctions(*event_data);
  //sort into good/noise hits
  retrieveHits(*event_data);
 
  std::list<const InDet::TRT_DriftCircle*>::iterator it,itE;
  it=event_data->m_goodHits.begin();
  itE=event_data->m_goodHits.end();
 
  //loop over good hits and sort them into sectors
 
  for(;it!=itE;++it){
 
    int straw = m_trtid->straw((*it)->identify());
    const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(straw);
 
    int phi = int((std::atan2(sc.y(),sc.x())+M_PI)*8./M_PI);
 
    if     ( phi<0  ) phi = 15;
    else if( phi>15 ) phi = 0 ;
 
    int z=0;
    if(sc.z()<0) z=1;
 
    int zslice=int((std::abs(sc.z())-800.)/100.);
 
    event_data->m_sectors[z][zslice][phi].push_back(*it);
 
  }
 
  ATH_MSG_DEBUG("Number of good  driftcircles: "<<event_data->m_goodHits.size());
  ATH_MSG_DEBUG("Number of noise driftcircles: "<<event_data->m_noiseHits.size());
 
  return std::unique_ptr<InDet::ITRT_TrackSegmentsMaker::IEventData>(event_data.release());
}
 
// Initialize tool for new region
 
std::unique_ptr<InDet::ITRT_TrackSegmentsMaker::IEventData>
InDet::TRT_TrackSegmentsMaker_ECcosmics::newRegion
(const EventContext& /*ctx*/, const std::vector<IdentifierHash>& vTRT) const
{
  (void) vTRT;
  std::unique_ptr<TRT_TrackSegmentsMaker_ECcosmics::EventData>
     event_data = std::make_unique<TRT_TrackSegmentsMaker_ECcosmics::EventData>();
 
  setFitFunctions(*event_data);
 
  // @TODO here the retrieve_hits method should be called with the list of the idhash
 
 
  std::list<const InDet::TRT_DriftCircle*>::iterator it,itE;
  it=event_data->m_goodHits.begin();
  itE=event_data->m_goodHits.end();
 
  //loop over good hits and sort them into sectors
 
  for(;it!=itE;++it){
 
    int straw = m_trtid->straw((*it)->identify());
    const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(straw);
 
    int phi = int((std::atan2(sc.y(),sc.x())+M_PI)*8./M_PI);
 
    if     ( phi<0  ) phi = 15;
    else if( phi>15 ) phi = 0 ;
 
    int z=0;
    if(sc.z()<0) z=1;
    int zslice=int((std::abs(sc.z())-800.)/100.);
 
    event_data->m_sectors[z][zslice][phi].push_back(*it);
 
  }
 
  ATH_MSG_DEBUG("Number of good  driftcircles: "<<event_data->m_goodHits.size());
  ATH_MSG_DEBUG("Number of noise driftcircles: "<<event_data->m_noiseHits.size());
 
  return std::unique_ptr<InDet::ITRT_TrackSegmentsMaker::IEventData>(event_data.release());
}
 
// Inform tool about end of event or region investigation
 
void InDet::TRT_TrackSegmentsMaker_ECcosmics::endEvent (InDet::ITRT_TrackSegmentsMaker::IEventData &) const
{
}
 
 
 
// Helper function to sort the DC along z
 
namespace InDet{
  bool CompareDCz(const InDet::TRT_DriftCircle* x,const InDet::TRT_DriftCircle* y)
  {
    const Amg::Vector3D& sc = x->detectorElement()->center();
    double z1=sc.z();
 
 
    const Amg::Vector3D& sc2 = y->detectorElement()->center();
    double z2=sc2.z();
 
    return z1<z2;
  }
 
  bool CompareDCy(const InDet::TRT_DriftCircle* x,const InDet::TRT_DriftCircle* y)
  {
    const Amg::Vector3D& sc = x->detectorElement()->center();
    double y1=sc.y();
 
 
    const Amg::Vector3D& sc2 = y->detectorElement()->center();
    double y2=sc2.y();
 
    return y1>y2;
  }
 
  bool CompareDCzreverse(const InDet::TRT_DriftCircle* x,const InDet::TRT_DriftCircle* y)
  {
    const Amg::Vector3D& sc = x->detectorElement()->center();
    double z1=sc.z();
 
 
    const Amg::Vector3D& sc2 = y->detectorElement()->center();
    double z2=sc2.z();
 
    return z1>z2;
  }
}
 
 
 
// Methods of TRT segment reconstruction in one event
 
void InDet::TRT_TrackSegmentsMaker_ECcosmics::find(const EventContext & /*ctx*/,
                                                   InDet::ITRT_TrackSegmentsMaker::IEventData &virt_event_data,
                                                   InDet::TRT_DetElementLink_xk::TRT_DetElemUsedMap &) const
{
  TRT_TrackSegmentsMaker_ECcosmics::EventData &
     event_data  = TRT_TrackSegmentsMaker_ECcosmics::EventData::getPrivateEventData(virt_event_data);
 
 
 
  //loop over both endcaps
  for(int endcap=0;endcap<2;endcap++){
 
    // 1st step: find sector with the maximal number of hits until no one is left
    //           with at least 5 hits
 
    int max=m_minDCSeed;
 
    while(max>=m_minDCSeed){
      max=-1;
      int sector=-1;
      int zslice=-1;
 
      for(int j=0;j<20;j++){
    for(int i=0;i<16;i++){
      int count=event_data.m_sectors[endcap][j][i].size();
 
      if(count>0)
        ATH_MSG_VERBOSE("Endcap "<<endcap<<" zslice "<<j<<" sector "<<i<<" : "<<count);
 
      if(count>max){
        max=count;
        sector=i;
        zslice=j;
      }
    }
      }
 
      if(sector<0) continue; // no hits in this endcap ...
 
      max=event_data.m_sectors[endcap][zslice][sector].size();
 
      //check if enough driftcircles present
      if(max>=3){
        ATH_MSG_VERBOSE("Number of DCs in seed sector: "<<max);
 
        //2nd step: find seed among those driftcircles
 
        bool found=find_seed(endcap,zslice,sector,event_data);
 
        //if no seed is found we clear the sector
        if(!found){
          event_data.m_sectors[endcap][zslice][sector].clear();
        }
      }
 
    }
  }
 
  ATH_MSG_DEBUG("Found "<<event_data.m_seeds.size()<<" initial seeds !");
 
 
  //now loop over all seeds and try to create segments out of them
 
  std::vector<std::vector<const InDet::TRT_DriftCircle*> *>::iterator sit,sitE;
 
  sit=event_data.m_seeds.begin();
  sitE=event_data.m_seeds.end();
 
  for(;sit!=sitE;++sit){
    create_segment(*sit, event_data);
  }
 
 
  ATH_MSG_DEBUG("Found "<<event_data.m_segments.size()<<" TRT Segments");
 
  event_data.m_segiterator   = event_data.m_segments.begin();
}
 
 
// Find seeds
 
 
bool InDet::TRT_TrackSegmentsMaker_ECcosmics::find_seed(int endcap,
                                                        int zslice,
                                                        int sector,
                                                        TRT_TrackSegmentsMaker_ECcosmics::EventData &event_data) const
{
  double shift=0.;
  double phimin=10.;
  double phimax=-10.;
 
  std::vector<const InDet::TRT_DriftCircle*> dc;
  std::list<const InDet::TRT_DriftCircle*>::iterator it,itE;
 
  dc.reserve(event_data.m_sectors[endcap][zslice][sector].size());
  itE=event_data.m_sectors[endcap][zslice][sector].end();
  for(it=event_data.m_sectors[endcap][zslice][sector].begin();it!=itE;++it){
    dc.push_back(*it);
  }
  //sort them along z
 
  std::sort(dc.begin(),dc.end(), CompareDCz);
 
  std::vector<const InDet::TRT_DriftCircle*>::iterator vit,vitE;
  vit=dc.begin();
  vitE=dc.end();
 
  ATH_MSG_VERBOSE("Sorted driftcircles: "<<dc.size());
 
  for(;vit!=vitE;++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    ATH_MSG_VERBOSE("z="<<sc.z()<<" phi="<<sc.phi());
 
  }
 
 
  //sanity check: if more than 40 good hits per seed -> not a pure cosmic event!
 
  if(dc.size()>=40) return false;
 
  //fill arrays for the fit
 
  vit=dc.begin();
  vitE=dc.end();
 
 
  for(;vit!=vitE;++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    if(sc.phi()<phimin)
      phimin=sc.phi();
 
    if(sc.phi()>phimax)
      phimax=sc.phi();
  }
 
  shift=(phimax+phimin)/2.-M_PI_4;
  ATH_MSG_VERBOSE("Phimin="<<phimin<<" Phimax="<<phimax<<" -> shift = "<<shift);
 
  //protection for boundary at pi,-pi
  if(phimin<-M_PI_2 && phimax>M_PI_2){
    shift=3.*M_PI_4;
    ATH_MSG_VERBOSE("Boundary between pi and -pi!!! use the following shift: "<<shift);
  }
 
 
  int count=0;
  for(vit=dc.begin();vit!=vitE;++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    double orig=sc.phi();
 
    double corr=orig-shift;
 
    if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
    else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
    if(count>500){
      return false; // a seed cannot contain that many hits
    }
 
    event_data.m_a_z[count]=sc.z();
    event_data.m_a_phi[count]=corr;
    count++;
  }
 
  int maxdc=0;
  double p_best[3]={0,0,0};
  p_best[2]=shift;
 
  for(int i=0;i<count;i++){
    for(int j=i+1;j<count;j++){
 
      double p[3];
 
      p[2]=shift;
 
      if(event_data.m_a_z[i]==event_data.m_a_z[j]){
    p[0]=1e10;
    p[1]=event_data.m_a_z[i];
      }else{
    p[0]=(event_data.m_a_phi[i]-event_data.m_a_phi[j])/(event_data.m_a_z[i]-event_data.m_a_z[j]);
    p[1]=event_data.m_a_phi[j]-p[0]*event_data.m_a_z[j];
      }
 
 
 
      int match=evaluate_seed(endcap,zslice,sector,p,event_data);
 
      if(match>maxdc){
    maxdc=match;
    p_best[0]=p[0];
    p_best[1]=p[1];
      }
    }
  }
 
  ATH_MSG_VERBOSE("Number of matching dc from best seed: "<<maxdc);
 
 
  if(maxdc>=4){
    //ok, we've found a seed
 
    double zmin=1e4;
    double zmax=-1e4;
 
 
    int muster[3][3];
    for(auto & i : muster)
      for(int & j : i)
    j=0;
 
    std::vector<const InDet::TRT_DriftCircle*> *seed=new std::vector<const InDet::TRT_DriftCircle*>;
 
    for(int zsl=zslice-1;zsl<=zslice+1;zsl++){
      for(int ps=sector-1;ps<=sector+1;ps++){
 
    //make sure that the slices exist ...
    if(zsl<0 || zsl>=20) continue;
 
    int ps2=ps;
    if(ps2<0) ps2+=16;
    else if(ps2>15) ps2-=16;
 
    for(it=event_data.m_sectors[endcap][zsl][ps2].begin();it!=event_data.m_sectors[endcap][zsl][ps2].end();++it){
      int straw = m_trtid->straw((*it)->identify());
      const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(straw);
 
      double pred_phi=sc.z()*p_best[0]+p_best[1];
      double corr=sc.phi()-p_best[2];
 
      if(p_best[0]==1e10){
        if(sc.z()==p_best[1]) {
          pred_phi=corr; //z=const ...
        }else{
          pred_phi=corr+0.5;
        }
      }
      if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
      else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
 
      if(std::abs(phidiff(pred_phi,corr))<=4./650.){
        seed->push_back(*it);
        if(sc.z()<zmin) zmin=sc.z();
        if(sc.z()>zmax) zmax=sc.z();
        muster[zsl-zslice+1][ps-sector+1]=1;
      }
    }
      }
    }
 
    std::vector<const InDet::TRT_DriftCircle*>::iterator vit,vitE;
 
 
    //do we need to extend the range ??
 
    ATH_MSG_VERBOSE("Pattern:");
    ATH_MSG_VERBOSE("\t"<<muster[0][0]<<" "<<muster[1][0]<<" "<<muster[2][0]);
    ATH_MSG_VERBOSE("\t"<<muster[0][1]<<" "<<muster[1][1]<<" "<<muster[2][1]);
    ATH_MSG_VERBOSE("\t"<<muster[0][2]<<" "<<muster[1][2]<<" "<<muster[2][2]);
 
    int zsl=-1;
    if(muster[2][0] || muster[2][1] || muster[2][2]){
      //extend towards higher z-values
      zsl=zslice+2;
 
      for(int ps=sector-2;ps<=sector+2;ps++){
 
    //make sure that the slices exist ...
    if(zsl<0 || zsl>=20) continue;
 
    int ps2=ps;
    if(ps2<0) ps2+=16;
    else if(ps2>15) ps2-=16;
 
    for(it=event_data.m_sectors[endcap][zsl][ps2].begin();it!=event_data.m_sectors[endcap][zsl][ps2].end();++it){
      int straw = m_trtid->straw((*it)->identify());
      const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(straw);
 
      double pred_phi=sc.z()*p_best[0]+p_best[1];
      double corr=sc.phi()-p_best[2];
 
      if(p_best[0]==1e10){
        if(sc.z()==p_best[1]) {
          pred_phi=corr; //z=const ...
        }else{
          pred_phi=corr+0.5;
        }
      }
      if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
      else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
 
      if(std::abs(phidiff(pred_phi,corr))<=4./650.){
        if (msgLvl(MSG::VERBOSE)) msg()<<"extended hit at z= "<<sc.z()<<endmsg;
        if(sc.z()<zmin) zmin=sc.z();
        if(sc.z()>zmax) zmax=sc.z();
        seed->push_back(*it);
      }
    }
      }
    }
 
    if(muster[0][0] || muster[0][1] || muster[0][2]){
      //extend towards lower z-values
      zsl=zslice-2;
 
      for(int ps=sector-2;ps<=sector+2;ps++){
 
    //make sure that the slices exist ...
    if(zsl<0 || zsl>=20) continue;
 
    int ps2=ps;
    if(ps2<0) ps2+=16;
    else if(ps2>15) ps2-=16;
 
    for(it=event_data.m_sectors[endcap][zsl][ps2].begin();it!=event_data.m_sectors[endcap][zsl][ps2].end();++it){
      int straw = m_trtid->straw((*it)->identify());
      const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(straw);
 
      double pred_phi=sc.z()*p_best[0]+p_best[1];
      double corr=sc.phi()-p_best[2];
 
      if(p_best[0]==1e10){
        if(sc.z()==p_best[1]) {
          pred_phi=corr; //z=const ...
        }else{
          pred_phi=corr+0.5;
        }
      }
      if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
      else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
 
      if(std::abs(phidiff(pred_phi,corr))<=4./650.){
        ATH_MSG_VERBOSE("extended hit at z= "<<sc.z());
        if(sc.z()<zmin) zmin=sc.z();
        if(sc.z()>zmax) zmax=sc.z();
        seed->push_back(*it);
      }
    }
      }
    }
 
 
    if(seed->size()<(size_t)m_minDCSeed){
      ATH_MSG_VERBOSE("Seed has too few hits: "<<seed->size());
      seed->clear();
      delete seed;
      return false;
    }
 
 
    vit=seed->begin();
    vitE=seed->end();
 
    for(;vit!=vitE;++vit){
      int straw = m_trtid->straw((*vit)->identify());
      const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
      int phi = int((std::atan2(sc.y(),sc.x())+M_PI)*8./M_PI);
 
      if     ( phi<0  ) phi = 15;
      else if( phi>15 ) phi = 0 ;
 
      int z=0;
      if(sc.z()<0) z=1;
      int zslic=int((std::abs(sc.z())-800.)/100.);
 
      event_data.m_sectors[z][zslic][phi].remove(*vit);
 
    }
 
    //just to be sure: check also the noise hits in these 9 slices
 
    std::list<const InDet::TRT_DriftCircle*>::iterator lit,litE;
    lit=event_data.m_noiseHits.begin();
    litE=event_data.m_noiseHits.end();
 
    for(;lit!=litE;++lit){
 
      //don't add hits that really look like noise
      if((*lit)->timeOverThreshold()<m_cutToTLoose) continue;
 
      int straw = m_trtid->straw((*lit)->identify());
      const Amg::Vector3D& sc = (*lit)->detectorElement()->strawCenter(straw);
 
      int phi = int((std::atan2(sc.y(),sc.x())+M_PI)*8./M_PI);
 
      if     ( phi<0  ) phi = 15;
      else if( phi>15 ) phi = 0 ;
 
 
      int zsl=int((std::abs(sc.z())-800.)/100.);
 
      if(std::abs(zsl-zslice)<2){
    double pred_phi=sc.z()*p_best[0]+p_best[1];
    double corr=sc.phi()-p_best[2];
 
    if(p_best[0]==1e10){
      if(sc.z()==p_best[1]) {
        pred_phi=corr; //z=const ...
      }else{
        pred_phi=corr+0.5;
      }
    }
    if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
    else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
 
    if(std::abs(phidiff(pred_phi,corr))<=4./650.){
      if(sc.z()>zmin && sc.z()<zmax){
        seed->push_back(*lit);
        ATH_MSG_VERBOSE("\t\t noise hit matched seed! z="<< sc.z());
      }
    }
 
      }
 
 
    }
 
 
 
 
    event_data.m_seeds.push_back(seed);
 
    return true;
  }
 
 
  return false;
 
}
 
int InDet::TRT_TrackSegmentsMaker_ECcosmics::evaluate_seed(int endcap,
                                                           int zslice,
                                                           int sector,
                                                           const double *p,
                                                           TRT_TrackSegmentsMaker_ECcosmics::EventData &event_data) const
{
 
  std::list<const InDet::TRT_DriftCircle*>::iterator it,itE;
 
  int count=0;
 
  //look at all nearest neighbours ...
 
  for(int zsl=zslice-1;zsl<=zslice+1;zsl++){
    for(int ps=sector-1;ps<=sector+1;ps++){
 
      //make sure that the slices exist ...
      if(zsl<0 || zsl>=20) continue;
 
      int ps2=ps;
      if(ps2<0) ps2+=16;
      else if(ps2>15) ps2-=16;
 
 
      itE=event_data.m_sectors[endcap][zsl][ps2].end();
      for(it=event_data.m_sectors[endcap][zsl][ps2].begin();it!=itE;++it){
    int straw = m_trtid->straw((*it)->identify());
    const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(straw);
 
    double pred_phi=sc.z()*p[0]+p[1];
    double corr=sc.phi()-p[2];
 
    if(p[0]==1e10){
      if(sc.z()==p[1]) {
        pred_phi=corr; //z=const ...
      }else{
        pred_phi=corr+0.5;
      }
    }
    if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
    else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
 
    if(std::abs(phidiff(pred_phi,corr))<=4./650.){
      count=count+1;
    }
      }
    }
  }
 
 
  return count;
}
 
 
void InDet::TRT_TrackSegmentsMaker_ECcosmics::create_segment(std::vector<const InDet::TRT_DriftCircle*> *seed,
                                                             TRT_TrackSegmentsMaker_ECcosmics::EventData &event_data) const
{
 
  ATH_MSG_VERBOSE("Number of hits in initial seed: "<<seed->size());
 
  double shift=0.;
  double phimin=10.;
  double phimax=-10.;
 
  double zmin=1e5;
  double zmax=-1e5;
 
  std::vector<const InDet::TRT_DriftCircle*>::iterator vit,vitE;
 
  vit=seed->begin();
  vitE=seed->end();
 
  int count=0;
  for(;vit!=vitE;++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    if(sc.z()<zmin) zmin=sc.z();
    if(sc.z()>zmax) zmax=sc.z();
 
    if(count>500){
      return; // a seed cannot contain that many hits
    }
 
    event_data.m_a_z[count]=sc.z();
    event_data.m_a_phi[count]=sc.phi();
    event_data.m_a_tan[count]=std::tan(sc.phi());
    const auto cosPhi{std::cos(sc.phi())};
    event_data.m_a_tan_err[count]=(1.15/700.)/(cosPhi*cosPhi);
    event_data.m_a_z_err[count]=1.15; // 4/sqrt(12)
    event_data.m_a_phi_err[count]=1.15/700.; //take uncertainty at a radius of 700 mm
 
    if(sc.phi()<phimin)
      phimin=sc.phi();
 
    if(sc.phi()>phimax)
      phimax=sc.phi();
 
    count++;
  }
 
  shift=(phimax+phimin)/2.-M_PI_4;
  ATH_MSG_VERBOSE("Phimin="<<phimin<<" Phimax="<<phimax<<" shift="<<shift);
 
  //protection for boundary at pi,-pi
  if(phimin<-M_PI_2 && phimax>M_PI_2){
    shift=3.*M_PI_4;
    ATH_MSG_VERBOSE("Boundary between pi and -pi!!! use the following shift: "<<shift);
  }
 
 
  //correct the phi values
 
  for(int i=0;i<count;i++){
    double orig=event_data.m_a_phi[i];
 
    double corr=orig-shift;
    if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
    else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
    event_data.m_a_phi[i]=corr;
    event_data.m_a_tan[i]=std::tan(corr);
    const auto cosCorr{std::cos(corr)};
    event_data.m_a_tan_err[i]=(1.15/700.)/(cosCorr*cosCorr);
  }
 
  TF1 *fit=perform_fit(count, event_data);
  if(!fit) return;
 
  std::list<const InDet::TRT_DriftCircle*>::iterator lit,litE;
 
  //add the ones from the good list (but skip the ones that we already have)
  lit=event_data.m_goodHits.begin();
  litE=event_data.m_goodHits.end();
 
  std::vector<const InDet::TRT_DriftCircle*> tobeadded;
 
 
  for(;lit!=litE;++lit){
    int straw = m_trtid->straw((*lit)->identify());
    const Amg::Vector3D& sc = (*lit)->detectorElement()->strawCenter(straw);
 
    double fitted_phi=fit->Eval(sc.z(),0.,0.);
    fitted_phi+=shift;
 
    if     (fitted_phi > M_PI) fitted_phi = std::fmod(fitted_phi+M_PI,2.*M_PI)-M_PI;
    else if(fitted_phi <-M_PI) fitted_phi = std::fmod(fitted_phi-M_PI,2.*M_PI)+M_PI;
 
    if(std::abs(phidiff(fitted_phi,sc.phi()))<m_scaleTube*4./800.){
      //verify that this hit is not already included
 
      vit=seed->begin();
      vitE=seed->end();
      bool new_hit=true;
      for(;vit!=vitE && new_hit;++vit){
    if((*vit)==(*lit)){
      new_hit=false;
    }
      }
      if(new_hit){
    ATH_MSG_VERBOSE("\t\t good hit matched! fitted_phi="<<fitted_phi<<" z=" <<sc.z());
 
    if(sc.z()>zmin-200 && sc.z()<zmax+200){
      if(sc.z()<zmin) zmin=sc.z();
      if(sc.z()>zmax) zmax=sc.z();
 
      seed->push_back(*lit);
    }else{
      //not sure if this is really a good hit yet ...
      tobeadded.push_back(*lit);
    }
      }
    }
  }
 
  std::sort(tobeadded.begin(),tobeadded.end(), CompareDCz);
 
  int index1=-1,index2=-1;
 
  double z1=-1e5;
 
  count=0;
  ATH_MSG_VERBOSE("zmin="<<zmin<<"   zmax="<<zmax);
  for(vit=tobeadded.begin();vit!=tobeadded.end();++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
    ATH_MSG_VERBOSE("Shall we add hit at z="<<sc.z());
 
    if(sc.z()<zmin && sc.z()>z1) {
      z1=sc.z();
      index1=count;
    }
    if(sc.z()>zmax && index2==-1) {
      index2=count;
    }
    count++;
  }
 
  ATH_MSG_VERBOSE("index1="<<index1<<" index2="<<index2);
 
  if(index2>=0){
    for(int i=index2;i<count;i++){
      int straw = m_trtid->straw(tobeadded[i]->identify());
      const Amg::Vector3D& sc = tobeadded[i]->detectorElement()->strawCenter(straw);
      if(sc.z()<zmax+200){
    zmax=sc.z();
    seed->push_back(tobeadded[i]);
    ATH_MSG_VERBOSE(" added goot hit at z="<<sc.z());
      }else{
    ATH_MSG_VERBOSE(" rejected goot hit at z="<<sc.z());
    i=count;
      }
    }
  }
  if(index1>=0){
    for(int i=index1;i>=0;i--){
      int straw = m_trtid->straw(tobeadded[i]->identify());
      const Amg::Vector3D& sc = tobeadded[i]->detectorElement()->strawCenter(straw);
      if(sc.z()>zmin-200){
    zmin=sc.z();
    seed->push_back(tobeadded[i]);
    ATH_MSG_VERBOSE(" added goot hit at z="<<sc.z());
      }else{
    ATH_MSG_VERBOSE(" rejected goot hit at z="<<sc.z());
    i=-1;
      }
    }
  }
  tobeadded.clear();
 
 
 
  //fit again
  std::sort(seed->begin(),seed->end(), CompareDCz);
 
  vit=seed->begin();
  vitE=seed->end();
 
  count=0;
  for(;vit!=vitE;++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    if(count>500){
      return; // a seed cannot contain that many hits
    }
 
    event_data.m_a_z[count]=sc.z();
    event_data.m_a_phi[count]=sc.phi();
    event_data.m_a_tan[count]=std::tan(sc.phi());
    const auto cosPhi{std::cos(sc.phi())};
    event_data.m_a_tan_err[count]=(1.15/700.)/(cosPhi*cosPhi);
    event_data.m_a_z_err[count]=1.15; // 4/sqrt(12)
    event_data.m_a_phi_err[count]=1.15/700.; //take uncertainty at a radius of 700 mm
 
    if(sc.phi()<phimin)
      phimin=sc.phi();
 
    if(sc.phi()>phimax)
      phimax=sc.phi();
 
    count++;
  }
 
  shift=(phimax+phimin)/2.-M_PI_4;
  ATH_MSG_VERBOSE("Phimin="<<phimin<<" Phimax="<<phimax<<" shift="<<shift);
 
 //protection for boundary at pi,-pi
  if(phimin<-M_PI_2 && phimax>M_PI_2){
    shift=3.*M_PI_4;
    ATH_MSG_VERBOSE("Boundary between pi and -pi!!! use the following shift: "<<shift);
  }
 
  //correct the phi values
 
  for(int i=0;i<count;i++){
    double orig=event_data.m_a_phi[i];
    double corr=orig-shift;
 
    if     (corr > M_PI) corr = std::fmod(corr+M_PI,2.*M_PI)-M_PI;
    else if(corr <-M_PI) corr = std::fmod(corr-M_PI,2.*M_PI)+M_PI;
 
    event_data.m_a_phi[i]=corr;
    event_data.m_a_tan[i]=std::tan(corr);
    const auto cosCorr{std::cos(corr)};
    event_data.m_a_tan_err[i]=(1.15/700.)/(cosCorr*cosCorr);
  }
 
 
  fit=perform_fit(count, event_data);
  if(!fit) return;
 
  //add the ones from the noise list
  lit=event_data.m_noiseHits.begin();
  litE=event_data.m_noiseHits.end();
 
  for(;lit!=litE;++lit){
 
    //don't add hits that really look like noise
 
    int straw = m_trtid->straw((*lit)->identify());
    const Amg::Vector3D& sc = (*lit)->detectorElement()->strawCenter(straw);
 
    double z=sc.z();
    double phi=sc.phi();
    double fitted_phi=fit->Eval(sc.z(),0.,0.);
    fitted_phi+=shift;
 
    if     (fitted_phi > M_PI) fitted_phi = std::fmod(fitted_phi+M_PI,2.*M_PI)-M_PI;
    else if(fitted_phi <-M_PI) fitted_phi = std::fmod(fitted_phi-M_PI,2.*M_PI)+M_PI;
 
    //only look into the same endcap for noise hits
    if(z*event_data.m_a_z[0]<0) continue;
 
    if(std::abs(phidiff(fitted_phi,phi))<m_scaleTubeNoise*4./800.){
      vit=seed->begin();
      vitE=seed->end();
      bool new_hit=true;
      for(;vit!=vitE && new_hit;++vit){
    if((*vit)==(*lit)){
      new_hit=false;
    }
      }
      if(new_hit){
    if(sc.z()>zmin-50 && sc.z()<zmax+50){
      ATH_MSG_VERBOSE("\t\t noise hit matched! fitted_phi="<<fitted_phi<<" z=" <<sc.z());
      seed->push_back(*lit);
    }else{
      ATH_MSG_VERBOSE("\t\t noise hit matched but too far away! fitted_phi="<<fitted_phi<<" z=" <<sc.z());
    }
      }
    }
  }
 
  //first: sort along y
  std::sort(seed->begin(),seed->end(), CompareDCy);
 
  //check z-coordinate of first and last hit
  Amg::Vector3D firststraw=((*seed)[0]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[0]->identify()) ));
  Amg::Vector3D laststraw=((*seed)[seed->size()-1]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[seed->size()-1]->identify()) ));
  z1=firststraw.z();
  double z2=laststraw.z();
  double yfirst=firststraw.y();
  double ylast=laststraw.y();
 
  ATH_MSG_VERBOSE("zfirst="<<z1<<" zlast="<<z2);
 
  double Theta=0;
  int state=0;
 
  //sort again, but this time with the correct ordering
  if (std::abs(yfirst-ylast)>50){
    if(z1>z2) {
      std::sort(seed->begin(),seed->end(), CompareDCzreverse);
    }else{
      std::sort(seed->begin(),seed->end(), CompareDCz);
    }
  }
  else {
    if ((yfirst>0 && z1<0) || (yfirst<0 && z1>0)) std::sort(seed->begin(),seed->end(), CompareDCz);
    else std::sort(seed->begin(),seed->end(), CompareDCzreverse);
  }
  firststraw=(*seed)[0]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[0]->identify()) );
  laststraw=(*seed)[seed->size()-1]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[seed->size()-1]->identify()) );
  z1=firststraw.z();
  z2=laststraw.z();
 
 
  if(z1>z2) {
    Theta=M_PI-std::atan2(400.,std::abs(z1-z2));
    state=2;
  }else{
    Theta=std::atan2(400.,std::abs(z1-z2));
    state=1;
  }
 
  double globaly=((*seed)[0]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[0]->identify()) )).y();
  double firstphi=((*seed)[0]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[0]->identify()) )).phi();
 
 
  ATH_MSG_VERBOSE("Number of tube hits matching straight line: "<<seed->size());
 
 
  //estimate Segment parameters from first and last hit
 
  const Amg::Vector3D& sc_first = ((*seed)[0]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[0]->identify()) ));
  const Amg::Vector3D& sc_last = ((*seed)[seed->size()-1]->detectorElement()->strawCenter(  m_trtid->straw((*seed)[seed->size()-1]->identify()) ));
 
 
  double tx1,tx2,ty1,ty2;
 
  tx1=1050*std::cos(sc_first.phi());
  ty1=1050*std::sin(sc_first.phi());
 
  tx2=650*std::cos(sc_last.phi());
  ty2=650*std::sin(sc_last.phi());
 
  double tphi=std::atan2(ty2-ty1,tx2-tx1);
 
 
  ATH_MSG_VERBOSE("First hit: "<<sc_first<<" \nLast hit: "<<sc_last);
 
 
  ATH_MSG_VERBOSE(" (x1,y1) = ("<<tx1<<","<<ty1<<")");
  ATH_MSG_VERBOSE(" (x2,y2) = ("<<tx2<<","<<ty2<<")");
 
 
 
  //correct phi to point downwards
  if(tphi>0)
    tphi-=M_PI;
 
  //make sure that Theta is positive and less than Pi!
 
  while(Theta<0)
    Theta+=M_PI;
 
  while(Theta>M_PI)
    Theta-=M_PI;
 
  ATH_MSG_VERBOSE(" tphi="<<tphi);
 
  ATH_MSG_VERBOSE("globaly = "<<globaly<<" phi="<<firstphi<<" theta="<<Theta<<" --> state = "<<state);
 
 
  vit=seed->begin();
  vitE=seed->end();
 
  count=0;
  for(;vit!=vitE;++vit){
    count++;
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
    ATH_MSG_VERBOSE("Hit "<<count<<" z="<<sc.z()<<" phi="<<sc.phi()<<" y="<<sc.y());
  }
 
 
  if(m_useDriftTime){
 
    ATH_MSG_VERBOSE("drifttime should be used!!!");
 
    //refit the seed but this time including the drift time information
 
    //take the left-rigfht assignment from the tube fit and then fit again
    count=0;
 
    vit=seed->begin();
    vitE=seed->end();
 
    for(;vit!=vitE;++vit){
      int straw = m_trtid->straw((*vit)->identify());
      const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
      double fitted_phi=fit->Eval(sc.z(),0.,0.);
      fitted_phi+=shift;
 
      if     (fitted_phi > M_PI) fitted_phi = std::fmod(fitted_phi+M_PI,2.*M_PI)-M_PI;
      else if(fitted_phi <-M_PI) fitted_phi = std::fmod(fitted_phi-M_PI,2.*M_PI)+M_PI;
 
      int sign=1;
      if(fitted_phi<sc.phi()) sign=-1;
 
 
      double driftr  = (*vit)->localPosition()(Trk::driftRadius);
      double drifte  = 2*std::sqrt((*vit)->localCovariance()(0,0));
 
      double straw_r=640+400./std::abs(z2-z1)*std::abs(sc.z()-z1);
 
      double dphi=sign*driftr/straw_r;
 
 
      event_data.m_a_z[count]=sc.z();
      event_data.m_a_phi[count]=sc.phi()+dphi;
      event_data.m_a_phi_err[count]=drifte/straw_r;
 
      event_data.m_a_tan[count]=std::tan(event_data.m_a_phi[count]-shift);
      const auto cosPhiMinShift{std::cos(event_data.m_a_phi[count]-shift)};
      event_data.m_a_tan_err[count]=(event_data.m_a_phi_err[count])/(  cosPhiMinShift
                                                                     * cosPhiMinShift);
 
      event_data.m_a_z_err[count]=0.;
 
      ATH_MSG_VERBOSE(count<<" z="<<event_data.m_a_z[count]<<" phi="<<event_data.m_a_phi[count]<<" +- "<< event_data.m_a_phi_err[count]);
      count++;
    }
 
    ATH_MSG_VERBOSE("Number of hits in first fit (driftradius): "<<count);
 
    fit=perform_fit(count,event_data);
    if(!fit) return;
 
 
    //check if hits are matching
    vit=seed->begin();
    vitE=seed->end();
 
    count=0;
    for(;vit!=vitE;++vit){
      int straw = m_trtid->straw((*vit)->identify());
      const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
      double fitted_phi=fit->Eval(sc.z(),0.,0.);
      fitted_phi+=shift;
 
      double driftr  = (*vit)->localPosition()(Trk::driftRadius);
      double drifte  = 2*std::sqrt((*vit)->localCovariance()(0,0));
      int sign=1;
 
      if(fitted_phi<sc.phi()) sign=-1;
 
      double straw_r=640+400./std::abs(z2-z1)*std::abs(sc.z()-z1);
      double dphi=sign*driftr/straw_r;
 
      if(count>500){
      return; // a seed cannot contain that many hits
      }
 
      if (msgLvl(MSG::VERBOSE)) msg()<<"z="<<sc.z()<<" phi="<<sc.phi()<<" fitted_phi = "<<fitted_phi<<endmsg;
      if(std::abs(phidiff(fitted_phi,sc.phi()-dphi)) < m_scaleFactorDrift* drifte/straw_r){
        if (msgLvl(MSG::VERBOSE)) msg()<<"\t\t matched!!!"<<endmsg;
 
        event_data.m_a_z[count]=sc.z();
        event_data.m_a_phi[count]=sc.phi()+dphi;
        event_data.m_a_phi_err[count]=drifte/straw_r;
 
    event_data.m_a_tan[count]=std::tan(event_data.m_a_phi[count]-shift);
    const auto cosPhiMinShift{ std::cos(event_data.m_a_phi[count]-shift)};
    event_data.m_a_tan_err[count]=(event_data.m_a_phi_err[count])/( cosPhiMinShift
                                                                       *cosPhiMinShift);
 
        event_data.m_a_z_err[count]=0.;
        count++;
 
      }
    }
 
    //refit
 
    ATH_MSG_VERBOSE("Number of hits in second fit (driftradius): "<<count);
 
    if(count>4){
      fit=perform_fit(count,event_data);
      if(!fit) return;
    }
 
    vit=seed->begin();
    vitE=seed->end();
 
    count=0;
    for(;vit!=vitE;++vit){
      int straw = m_trtid->straw((*vit)->identify());
      const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
      double fitted_phi=fit->Eval(sc.z(),0.,0.);
      fitted_phi+=shift;
 
      if     (fitted_phi > M_PI) fitted_phi = std::fmod(fitted_phi+M_PI,2.*M_PI)-M_PI;
      else if(fitted_phi <-M_PI) fitted_phi = std::fmod(fitted_phi-M_PI,2.*M_PI)+M_PI;
 
      double driftr  = (*vit)->localPosition()(Trk::driftRadius);
      double drifte  = 2*std::sqrt((*vit)->localCovariance()(0,0));
      int sign=1;
 
      if(fitted_phi<sc.phi()) sign=-1;
 
      double straw_r=640+400./std::abs(z2-z1)*std::abs(sc.z()-z1);
      double dphi=sign*driftr/straw_r;
 
 
      ATH_MSG_VERBOSE("z="<<sc.z()<<" phi="<<sc.phi()<<" fitted_phi = "<<fitted_phi);
      if(std::abs(phidiff(fitted_phi,sc.phi()-dphi)) <  m_scaleFactorDrift* drifte/straw_r){
        ATH_MSG_VERBOSE("\t\t matched!!!");
        count++;
      }
    }
 
    ATH_MSG_VERBOSE("Number of hits matched after second fit: "<<count);
 
  }
 
 
  //create the segment
 
 
 
  if(count<m_minDCSeed) return; //too short segments don't make sense
 
  if(count>=400) return; //too long segments don't make sense
 
 
 
  // RIOonTrack production
  //
  auto rio = DataVector<const Trk::MeasurementBase>{};
 
  vit=seed->begin();
  vitE=seed->end();
 
  double chi2=0.;
 
  double initial_r=-10.;
  double initial_locz=0.;
 
  count=0;
  for(;vit!=vitE;++vit){
    const Trk::StraightLineSurface* line = (const Trk::StraightLineSurface*)
      (&((*vit)->detectorElement())->surface( (*vit)->identify()));
 
 
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    double z=sc.z();
    //    double phi=sc.phi();
 
    double locz=0.;
 
    if(std::abs(z2-z1)>0.000001){
      if(state==1){
    locz=400./std::abs(z2-z1)*std::abs(z-z1)-200.;
      }else{
    locz=200.-400./std::abs(z2-z1)*std::abs(z-z1);
      }
    }
    double fitted_phi=fit->Eval(z,0.,0.);
    fitted_phi+=shift;
 
    if     (fitted_phi > M_PI) fitted_phi = std::fmod(fitted_phi+M_PI,2.*M_PI)-M_PI;
    else if(fitted_phi <-M_PI) fitted_phi = std::fmod(fitted_phi-M_PI,2.*M_PI)+M_PI;
 
    double fitted_r=(phidiff(fitted_phi,sc.phi()))*(840+locz);
    double temp_phi=fitted_phi;
 
    if(initial_r==-10. && std::abs(fitted_r)<4.0){
      initial_r=fitted_r;
      initial_locz=locz;
    }
 
    if     (temp_phi > M_PI) temp_phi = std::fmod(temp_phi+M_PI,2.*M_PI)-M_PI;
    else if(temp_phi <-M_PI) temp_phi = std::fmod(temp_phi-M_PI,2.*M_PI)+M_PI;
 
    ATH_MSG_VERBOSE(count<<" fitted_r = "<<fitted_r<<" locz="<<locz<<" temp_phi="<<temp_phi);
 
 
    fitted_r*=-1.0;
 
 
    temp_phi=firstphi;
 
    const Trk::AtaStraightLine Tp(fitted_r,locz,tphi,Theta,.000000001,*line);
 
    //decide if drifttime should be used
 
 
 
 
    bool useDrift=false;
 
    if(m_useDriftTime){
      double driftr  = (*vit)->localPosition()(Trk::driftRadius);
      double drifte  = 2*std::sqrt((*vit)->localCovariance()(0,0));
      int sign=1;
 
      if(fitted_phi<sc.phi()) sign=-1;
 
      double straw_r=640+400./std::abs(z2-z1)*std::abs(sc.z()-z1);
      double dphi=sign*driftr/straw_r;
 
      if(std::abs(phidiff(fitted_phi,sc.phi()-dphi)) < 3* drifte/straw_r){
        useDrift=true;
        chi2+=(std::abs(fitted_r)-std::abs(driftr))*(std::abs(fitted_r)-std::abs(driftr))/(drifte*drifte);
      }
 
    }
 
 
    if(useDrift){
      ATH_MSG_VERBOSE("RIO using drift time!");
      rio.push_back(m_riomakerD->correct(*(*vit),Tp, Gaudi::Hive::currentContext()));
    }else{
      ATH_MSG_VERBOSE("RIO without using drift time!");
      chi2+=(fitted_r/1.15)*(fitted_r/1.15); // no drift time used
      ATH_MSG_VERBOSE(count<<"\t\t chi2 contribution: "<<(fitted_r/1.15)*(fitted_r/1.15));
      rio.push_back(m_riomakerN->correct(*(*vit),Tp, Gaudi::Hive::currentContext()));
    }
 
    count++;
 
    //add a pseudomeasurement for the first and the last hit constraining loc_z
    if(count==1 || (size_t)count==seed->size()){
      Trk::DefinedParameter dp(locz,Trk::locZ);
      Trk::LocalParameters par(dp);
      Amg::MatrixX cov(1,1);
      cov<<1.;
 
      //create new surface
      Amg::Vector3D C = line->transform().translation();
 
      if(state==2 || state==3){
        C[2]-=1.;
      }else{
        C[2]+=1.;
      }
      Amg::Transform3D            T    = Amg::Transform3D(line->transform().rotation()*Amg::Translation3D(C));
      Trk::StraightLineSurface* surface = new Trk::StraightLineSurface(T);
 
 
      Trk::PseudoMeasurementOnTrack *pseudo=new Trk::PseudoMeasurementOnTrack(
        std::move(par),
        std::move(cov),
        *surface);
 
      delete surface;
 
      rio.push_back(pseudo);
 
    }
  }
 
 
  //Track Segment production
 
  Trk::FitQuality      * fqu = new Trk::FitQuality(chi2,count-2);
  const Trk::Surface   * sur =  &((*seed)[0]->detectorElement())->surface((*seed)[0]->identify());
 
 
  //phi should always be negative!
 
  if(firstphi>0) firstphi=-firstphi;
 
 
  Trk::DefinedParameter dp0(initial_r,Trk::locR);
  Trk::DefinedParameter dp1(initial_locz,Trk::locZ);
  Trk::DefinedParameter dp2(tphi,Trk::phi);
  Trk::DefinedParameter dp3(Theta,Trk::theta);
  Trk::DefinedParameter dp4(0.00002,Trk::qOverP);
 
  std::array<Trk::DefinedParameter,5> defPar = {dp0,dp1,dp2,dp3,dp4};
 
  Trk::LocalParameters par(defPar);
 
 
  ATH_MSG_VERBOSE("Track parameters from segment:"<<par);
 
  double universal=1.15;
 
 
  Amg::MatrixX cov(5,5);
  cov<<
    universal*universal,          0., 0.,   0., 0.,
    0.                     , 160000./12., 0.,   0., 0.,
    0.                     ,          0., 0.1,  0., 0.,
    0.                     ,          0.,  0.,  1., 0.,
    0.                     ,          0.,  0.,  0., 1.;
  Trk::TrackSegment* segment = new Trk::TrackSegment(
    std::move(par), std::move(cov), sur, std::move(rio), fqu, Trk::Segment::TRT_SegmentMaker);
 
  //add segment to list of segments
 
  ATH_MSG_VERBOSE("Add segment to list");
  event_data.m_segments.push_back(segment);
 
 
}
 
 
 
// Pseudo iterator
 
Trk::TrackSegment* InDet::TRT_TrackSegmentsMaker_ECcosmics::next(InDet::ITRT_TrackSegmentsMaker::IEventData &virt_event_data) const
{
  TRT_TrackSegmentsMaker_ECcosmics::EventData &
     event_data  = TRT_TrackSegmentsMaker_ECcosmics::EventData::getPrivateEventData(virt_event_data);
 
  if(event_data.m_segiterator!=event_data.m_segments.end()) return (*event_data.m_segiterator++);
  return nullptr;
}
 
// Dumps relevant information into the MsgStream
 
MsgStream& InDet::TRT_TrackSegmentsMaker_ECcosmics::dump( MsgStream& out ) const
{
  return out;
}
 
 
// Dumps relevant information into the ostream
 
std::ostream& InDet::TRT_TrackSegmentsMaker_ECcosmics::dump( std::ostream& out ) const
{
  return out;
}
 
 
// retrieve Hits from StoreGate and sort into noise/good hits lists
 
void InDet::TRT_TrackSegmentsMaker_ECcosmics::retrieveHits(TRT_TrackSegmentsMaker_ECcosmics::EventData &event_data) const
{
 
  event_data.m_noiseHits.clear();
  event_data.m_goodHits.clear();
 
 
  SG::ReadHandle<InDet::TRT_DriftCircleContainer> trtcontainer(m_trtname);
  if (not trtcontainer.isValid()) {
    ATH_MSG_DEBUG("Could not get TRT_DriftCircleContainer");
    return;
  }
 
  SG::ReadHandle<Trk::PRDtoTrackMap> prd_to_track_map;
  const Trk::PRDtoTrackMap *prd_to_track_map_cptr=nullptr;
  if (!m_prdToTrackMap.key().empty()) {
    prd_to_track_map = SG::ReadHandle<Trk::PRDtoTrackMap>(m_prdToTrackMap);
    if (!prd_to_track_map.isValid()) {
      ATH_MSG_ERROR("Failed to read PRD to track association map: " << m_prdToTrackMap );
    }
    prd_to_track_map_cptr = prd_to_track_map.cptr();
  }
 
  const InDet::TRT_DriftCircleContainer*   mjo_trtcontainer = trtcontainer.get();
  if (!mjo_trtcontainer) return;
 
  InDet::TRT_DriftCircleContainer::const_iterator
    w = trtcontainer->begin(),we = trtcontainer->end();
  for(; w!=we; ++w) {
 
    Identifier ID = (*w)->identify();
    if(std::abs(m_trtid->barrel_ec(ID))!=2) continue; // only endcaps please!!!
 
    InDet::TRT_DriftCircleCollection::const_iterator
      c  = (*w)->begin(), ce = (*w)->end();
 
    for(; c!=ce; ++c) {
 
      if(prd_to_track_map_cptr &&  prd_to_track_map_cptr->isUsed(*(*c))) continue; //don't use hits that have already been used
 
      if( (*c)->isNoise() || (*c)->timeOverThreshold()<m_cutToTLoose) {
        event_data.m_noiseHits.push_back(*c);
      }else{
        event_data.m_goodHits.push_back(*c);
      }
 
    }
  }
 
  ATH_MSG_DEBUG("good hits in endcap: "<<event_data.m_goodHits.size());
  ATH_MSG_DEBUG("noise hits in endcap: "<<event_data.m_noiseHits.size());
 
 
  if(event_data.m_goodHits.size()>(size_t)m_hitLimit){
    // this event is too busy ...
    ATH_MSG_DEBUG("This event has more than "<<m_hitLimit<<" good hits. Aborting segment finding ...");
    event_data.m_goodHits.clear();
    event_data.m_noiseHits.clear();
    return;
  }
 
  //move isolated hits from the good hits vector to the noise hits vector
  //
  auto it=event_data.m_goodHits.begin();
  auto itE=event_data.m_goodHits.end();
  auto it_remove(it);
  bool remove=false;
  //
  const double dPhiLimit{0.03};
  const double dzLimit{31.};
  for(;it!=itE;++it){
    if(remove){
      event_data.m_goodHits.erase(it_remove);
      remove=false;
    }
    const bool accept=accepted(it, event_data.m_goodHits, dPhiLimit, dzLimit);
    if(!accept){
      event_data.m_noiseHits.push_back(*it);
      it_remove=it;
      remove=true;
    }
  }
  if(remove){
    event_data.m_goodHits.erase(it_remove);
    remove=false;
  }
 
  //2nd pass through good hits with increased ToT cut
 
  it=event_data.m_goodHits.begin();
  itE=event_data.m_goodHits.end();
 
  remove=false;
 
  for(;it!=itE;++it){
 
    if(remove){
      event_data.m_goodHits.erase(it_remove);
      remove=false;
    }
 
    if((*it)->timeOverThreshold()<m_cutToTTight || (*it)->timeOverThreshold()>m_cutToTUpper){
      event_data.m_noiseHits.push_back(*it);
      it_remove=it;
      remove=true;
    }
  }
  if(remove){
    event_data.m_goodHits.erase(it_remove);
    remove=false;
  }
 
 
  //2nd pass through good hits with loosened isolation criteria
 
  it=event_data.m_goodHits.begin();
  itE=event_data.m_goodHits.end();
 
  remove=false;
 
  for(;it!=itE;++it){
    if(remove){
      event_data.m_goodHits.erase(it_remove);
      remove=false;
    }
    const bool accept=accepted(it, event_data.m_goodHits, 0.25,  200.);
    if(!accept){
      ATH_MSG_DEBUG("Removing hit in 2nd pass isolation");
      event_data.m_noiseHits.push_back(*it);
      it_remove=it;
      remove=true;
    }
  }
 
  if(remove){
    event_data.m_goodHits.erase(it_remove);
    remove=false;
  }
 
  ATH_MSG_DEBUG("good hits in endcap: "<<event_data.m_goodHits.size());
  ATH_MSG_DEBUG("noise hits in endcap: "<<event_data.m_noiseHits.size());
 
}
 
bool
InDet::TRT_TrackSegmentsMaker_ECcosmics::accepted(
  const std::list<const InDet::TRT_DriftCircle*>::iterator it,
  std::list<const InDet::TRT_DriftCircle*> & container,
  double dPhiLimit, double dzLimit) const{
  //
  const auto id =  (*it)->identify();
  const auto ns = m_trtid->straw(id);
  const auto endcap= m_trtid->barrel_ec(id);
  const auto wheel = std::abs(m_trtid->layer_or_wheel(id));
  const Amg::Vector3D& sc = (*it)->detectorElement()->strawCenter(ns);
  //
  bool accept{false};
  for(auto it2=container.begin();it2!=container.end();++it2){
      if(it==it2) continue;
      Identifier id2 = (*it2)->identify();
      int endcap2=m_trtid->barrel_ec(id2);
      int wheel2=std::abs(m_trtid->layer_or_wheel(id2));
      //only look inside the same wheel
      if(endcap!=endcap2 || wheel2!=wheel) continue;
      int ns2 = m_trtid->straw(id2);
      const Amg::Vector3D& sc2 = (*it2)->detectorElement()->strawCenter(ns2);
      double dz=sc.z()-sc2.z();
      double dphi=phidiff(sc.phi(),sc2.phi());
      dphi*=300.0; // scale factor for dphi to get equal weight
      dz=std::abs(dz);
      dphi=std::abs(dphi/300.0);
      if(dphi<dPhiLimit and dz<dzLimit){
        accept=true;
        //break was not in original code...
        break; //...but no need to continue once accept has been set
      }
  } //end inner loop
  return accept;
}
 
// Perform the actual track fit to the coordinates
 
std::mutex InDet::TRT_TrackSegmentsMaker_ECcosmics::s_fitMutex;
 
TF1 *InDet::TRT_TrackSegmentsMaker_ECcosmics::perform_fit(int count,
                                                          TRT_TrackSegmentsMaker_ECcosmics::EventData &event_data) const
{
  // @TODO not thread-safe enough! need a globak root lock !
  std::lock_guard<std::mutex> lock(s_fitMutex);
  TVirtualFitter::SetMaxIterations(100000);
 
  RootUtils::WithRootErrorHandler hand ([] (int, bool, const char*, const char*) { return false; });
 
 
  event_data.m_fitf_ztanphi->SetParameter(0,0.);
  event_data.m_fitf_ztanphi->SetParameter(1,0.);
  event_data.m_fitf_ztanphi->SetParameter(2,0.);
 
  TGraphErrors *gre=new TGraphErrors(count,event_data.m_a_z,event_data.m_a_tan,event_data.m_a_z_err,event_data.m_a_tan_err);
  int fitresult1=gre->Fit(event_data.m_fitf_ztanphi,"Q");
 
  ATH_MSG_VERBOSE("Fit result (ztanphi): a0="<<event_data.m_fitf_ztanphi->GetParameter(0)
                  <<" a1="<<event_data.m_fitf_ztanphi->GetParameter(1)<<" a2="
                  <<event_data.m_fitf_ztanphi->GetParameter(2)<<" fitresult="<<fitresult1);
 
  //copy over the parameters
  event_data.m_fitf_zphi->SetParameter(0,event_data.m_fitf_ztanphi->GetParameter(0));
  event_data.m_fitf_zphi->SetParameter(1,event_data.m_fitf_ztanphi->GetParameter(1));
  event_data.m_fitf_zphi->SetParameter(2,event_data.m_fitf_ztanphi->GetParameter(2));
 
  delete gre;
 
  gre=new TGraphErrors(count,event_data.m_a_z,event_data.m_a_phi,event_data.m_a_z_err,event_data.m_a_phi_err);
  int fitresult2=gre->Fit(event_data.m_fitf_zphi_approx,"Q");
 
 
  ATH_MSG_VERBOSE( "Fit result (zphi): a0="<< event_data.m_fitf_zphi_approx->GetParameter(0)
                   <<" a1="<< event_data.m_fitf_zphi_approx->GetParameter(1)<<" a2="
                   << event_data.m_fitf_zphi_approx->GetParameter(2)<<" fitresult="<<fitresult2);
 
  double p1=event_data.m_fitf_ztanphi->GetProb();
  double p2=event_data.m_fitf_zphi_approx->GetProb();
 
  ATH_MSG_VERBOSE("tanphi prob: "<<p1<<" pol2 prob : "<<p2);
 
  delete gre;
 
 
  if(fitresult1!=0 && fitresult2!=0) return nullptr;
  if(fitresult1!=0 && fitresult2==0) return event_data.m_fitf_zphi_approx;
  if(fitresult1==0 && fitresult2!=0) return event_data.m_fitf_zphi;
 
 
  int match_tan=0;
  int match_phi=0;
  for(int i=0;i<count;i++){
    double phi1=event_data.m_fitf_zphi->Eval(event_data.m_a_z[i]);
    double phi2=event_data.m_fitf_zphi_approx->Eval(event_data.m_a_z[i]);
 
    if(std::abs(phi1-event_data.m_a_phi[i])<2*event_data.m_a_phi_err[i])
      match_tan++;
 
    if(std::abs(phi2-event_data.m_a_phi[i])<2*event_data.m_a_phi_err[i])
      match_phi++;
 
  }
 
 
  ATH_MSG_VERBOSE("Number of hits matching this fit: tan="<<match_tan<<" pol2="<<match_phi);
 
  if(match_tan>match_phi){
    return event_data.m_fitf_zphi;
  }else if(match_tan<match_phi){
    return event_data.m_fitf_zphi_approx;
  }
 
  if(p1>p2){
    return event_data.m_fitf_zphi;
  }else{
    return event_data.m_fitf_zphi_approx;
  }
 
}
 
// Provide the proper subtraction of two phi values
 
 
// @TODO unusued
bool InDet::TRT_TrackSegmentsMaker_ECcosmics::is_suspicious(const InDet::TRT_DriftCircle* dc,
                                                            std::vector<const InDet::TRT_DriftCircle*> *seed) const
{
 
  double mean=0,var=0;
  double meanz=0,varz=0;
 
  std::vector<const InDet::TRT_DriftCircle*>::iterator vit,vitE;
 
  vit=seed->begin();
  vitE=seed->end();
 
  double dcz[500];
  int count=0;
  int index=-1;
  for(;vit!=vitE;++vit){
    int straw = m_trtid->straw((*vit)->identify());
    const Amg::Vector3D& sc = (*vit)->detectorElement()->strawCenter(straw);
 
    if(dc==*vit) index=count;
    dcz[count++]=sc.z();
 
    meanz+=sc.z();
    varz+=sc.z()*sc.z();
  }
 
  if(count < 2) return true;
 
  varz=(count*varz-meanz*meanz);
  varz/=(double)(count*(count-1));
 
  meanz/=(double)count;
 
  varz=std::sqrt(varz);
 
  double zmin_sel=100000;
 
  for(int i=0;i<count;i++){
    double zmin=10000;
 
    if(i-1>=0)
      if(std::abs(dcz[i]-dcz[i-1])<zmin) zmin=std::abs(dcz[i]-dcz[i-1]);
    if(i+1<count)
      if(std::abs(dcz[i]-dcz[i+1])<zmin) zmin=std::abs(dcz[i]-dcz[i+1]);
 
    if(i==index)
      zmin_sel=zmin;
 
    mean+=zmin;
    var+=zmin*zmin;
  }
 
  var=(count*var-mean*mean);
  var/=(double)(count*(count-1));
 
  mean/=(double)count;
 
  var=std::sqrt(var);
 
  if(var<6) var=6;
 
  if(std::abs(zmin_sel-mean)>2*var){// || std::abs(dcz[index]-meanz)>2*varz){
    if(index>=0) {
    ATH_MSG_VERBOSE("Hit is suspicious, remove it! "<<std::abs(zmin_sel-mean)<<" , "<<2*var<<" -> "<<zmin_sel<< " : "<<dcz[index]<<" <-> "<<meanz<<" ("<<varz<<")");
    }
    return true;
  }else{
    if(index>=0) {
      ATH_MSG_VERBOSE("Hit seems to be ok: "<<std::abs(zmin_sel-mean)<<" < "<<2*var<<" && "<<std::abs(dcz[index]-meanz)<<" < "<<1.5*varz);
    }
  }
  return false;
}