source: git/modules/DualReadoutCalorimeter.cc@ fd4b326

/*
 *  Delphes: a framework for fast simulation of a generic collider experiment
 *  Copyright (C) 2012-2014  Universite catholique de Louvain (UCL), Belgium
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


/** \class DualReadoutCalorimeter
 *

  // ============  TODO  =========================================================
  // This implementation of dual calorimetry relies on several approximations:
  // - If hadronic energy is found in the tower the energy resolution then the full tower enrgy is smeared according to hadronic resolution (pessimistic for (e,n) or (pi+,gamma))
  // - While e+ vs pi+ (or gamma vs n) separation is in principle possible for single particles (using C/S, PMT timing, lateral shower profile) it is not obvious it can be done overlapping particles.
  //   Now we assume that regarless of the number of particle hits per tower we can always distinguish e+ vs pi+, which is probably not true in the case (e+,n) vs (pi+,gamma) without longitudinal segmentation.

 *
 *  \author M. Selvaggi - CERN
 *
 */

#include "modules/DualReadoutCalorimeter.h"

#include "classes/DelphesClasses.h"
#include "classes/DelphesFactory.h"
#include "classes/DelphesFormula.h"

#include "ExRootAnalysis/ExRootResult.h"
#include "ExRootAnalysis/ExRootFilter.h"
#include "ExRootAnalysis/ExRootClassifier.h"

#include "TMath.h"
#include "TString.h"
#include "TFormula.h"
#include "TRandom3.h"
#include "TObjArray.h"
#include "TDatabasePDG.h"
#include "TLorentzVector.h"

#include <algorithm>
#include <stdexcept>
#include <iostream>
#include <sstream>

using namespace std;

//------------------------------------------------------------------------------

DualReadoutCalorimeter::DualReadoutCalorimeter() :
  fECalResolutionFormula(0), fHCalResolutionFormula(0),
  fItParticleInputArray(0), fItTrackInputArray(0)
{

  fECalResolutionFormula = new DelphesFormula;
  fHCalResolutionFormula = new DelphesFormula;

  fECalTowerTrackArray = new TObjArray;
  fItECalTowerTrackArray = fECalTowerTrackArray->MakeIterator();

  fHCalTowerTrackArray = new TObjArray;
  fItHCalTowerTrackArray = fHCalTowerTrackArray->MakeIterator();

  fTowerTrackArray = new TObjArray;
  fItTowerTrackArray = fTowerTrackArray->MakeIterator();

}

//------------------------------------------------------------------------------

DualReadoutCalorimeter::~DualReadoutCalorimeter()
{

  if(fECalResolutionFormula) delete fECalResolutionFormula;
  if(fHCalResolutionFormula) delete fHCalResolutionFormula;

  if(fECalTowerTrackArray) delete fECalTowerTrackArray;
  if(fItECalTowerTrackArray) delete fItECalTowerTrackArray;

  if(fHCalTowerTrackArray) delete fHCalTowerTrackArray;
  if(fItHCalTowerTrackArray) delete fItHCalTowerTrackArray;

  if(fTowerTrackArray) delete fTowerTrackArray;
  if(fItTowerTrackArray) delete fItTowerTrackArray;

}

//------------------------------------------------------------------------------

void DualReadoutCalorimeter::Init()
{
  ExRootConfParam param, paramEtaBins, paramPhiBins, paramFractions;
  Long_t i, j, k, size, sizeEtaBins, sizePhiBins;
  Double_t ecalFraction, hcalFraction;
  TBinMap::iterator itEtaBin;
  set< Double_t >::iterator itPhiBin;
  vector< Double_t > *phiBins;

  // read eta and phi bins
  param = GetParam("EtaPhiBins");
  size = param.GetSize();
  fBinMap.clear();
  fEtaBins.clear();
  fPhiBins.clear();
  for(i = 0; i < size/2; ++i)
  {
    paramEtaBins = param[i*2];
    sizeEtaBins = paramEtaBins.GetSize();
    paramPhiBins = param[i*2 + 1];
    sizePhiBins = paramPhiBins.GetSize();

    for(j = 0; j < sizeEtaBins; ++j)
    {
      for(k = 0; k < sizePhiBins; ++k)
      {
        fBinMap[paramEtaBins[j].GetDouble()].insert(paramPhiBins[k].GetDouble());
      }
    }
  }

  // for better performance we transform map of sets to parallel vectors:
  // vector< double > and vector< vector< double >* >
  for(itEtaBin = fBinMap.begin(); itEtaBin != fBinMap.end(); ++itEtaBin)
  {
    fEtaBins.push_back(itEtaBin->first);
    phiBins = new vector< double >(itEtaBin->second.size());
    fPhiBins.push_back(phiBins);
    phiBins->clear();
    for(itPhiBin = itEtaBin->second.begin(); itPhiBin != itEtaBin->second.end(); ++itPhiBin)
    {
      phiBins->push_back(*itPhiBin);
    }
  }

  // read energy fractions for different particles
  param = GetParam("EnergyFraction");
  size = param.GetSize();

  // set default energy fractions values
  fFractionMap.clear();
  fFractionMap[0] = make_pair(0.0, 1.0);

  for(i = 0; i < size/2; ++i)
  {
    paramFractions = param[i*2 + 1];

    ecalFraction = paramFractions[0].GetDouble();
    hcalFraction = paramFractions[1].GetDouble();

    fFractionMap[param[i*2].GetInt()] = make_pair(ecalFraction, hcalFraction);
  }

  // read min E value for timing measurement in ECAL
  fTimingEnergyMin = GetDouble("TimingEnergyMin",4.);
  // For timing
  // So far this flag needs to be false
  // Curved extrapolation not supported
  fElectronsFromTrack = false;

  // read min E value for towers to be saved
  fECalEnergyMin = GetDouble("ECalEnergyMin", 0.0);
  fHCalEnergyMin = GetDouble("HCalEnergyMin", 0.0);
  fEnergyMin = GetDouble("EnergyMin", 0.0);

  fECalEnergySignificanceMin = GetDouble("ECalEnergySignificanceMin", 0.0);
  fHCalEnergySignificanceMin = GetDouble("HCalEnergySignificanceMin", 0.0);
  fEnergySignificanceMin = GetDouble("EnergySignificanceMin", 0.0);

  // switch on or off the dithering of the center of DualReadoutCalorimeter towers
  fSmearTowerCenter = GetBool("SmearTowerCenter", true);

  // read resolution formulas
  fECalResolutionFormula->Compile(GetString("ECalResolutionFormula", "0"));
  fHCalResolutionFormula->Compile(GetString("HCalResolutionFormula", "0"));

  // import array with output from other modules
  fParticleInputArray = ImportArray(GetString("ParticleInputArray", "ParticlePropagator/particles"));
  fItParticleInputArray = fParticleInputArray->MakeIterator();

  fTrackInputArray = ImportArray(GetString("TrackInputArray", "ParticlePropagator/tracks"));
  fItTrackInputArray = fTrackInputArray->MakeIterator();

  // create output arrays
  fTowerOutputArray = ExportArray(GetString("TowerOutputArray", "towers"));
  fPhotonOutputArray = ExportArray(GetString("PhotonOutputArray", "photons"));

  fEFlowTrackOutputArray = ExportArray(GetString("EFlowTrackOutputArray", "eflowTracks"));
  fEFlowPhotonOutputArray = ExportArray(GetString("EFlowPhotonOutputArray", "eflowPhotons"));
  fEFlowNeutralHadronOutputArray = ExportArray(GetString("EFlowNeutralHadronOutputArray", "eflowNeutralHadrons"));
}

//------------------------------------------------------------------------------

void DualReadoutCalorimeter::Finish()
{
  vector< vector< Double_t >* >::iterator itPhiBin;
  if(fItParticleInputArray) delete fItParticleInputArray;
  if(fItTrackInputArray) delete fItTrackInputArray;
  for(itPhiBin = fPhiBins.begin(); itPhiBin != fPhiBins.end(); ++itPhiBin)
  {
    delete *itPhiBin;
  }
}

//------------------------------------------------------------------------------

void DualReadoutCalorimeter::Process()
{
  Candidate *particle, *track;
  TLorentzVector position, momentum;
  Short_t etaBin, phiBin, flags;
  Int_t number;
  Long64_t towerHit, towerEtaPhi, hitEtaPhi;
  Double_t ecalFraction, hcalFraction;
  Double_t ecalEnergy, hcalEnergy;
  Double_t ecalSigma, hcalSigma, sigma;
  Double_t energyGuess, energy;
  Int_t pdgCode;

  TFractionMap::iterator itFractionMap;

  vector< Double_t >::iterator itEtaBin;
  vector< Double_t >::iterator itPhiBin;
  vector< Double_t > *phiBins;

  vector< Long64_t >::iterator itTowerHits;

  DelphesFactory *factory = GetFactory();
  fTowerHits.clear();
  fECalTowerFractions.clear();
  fHCalTowerFractions.clear();
  fECalTrackFractions.clear();
  fHCalTrackFractions.clear();

  // loop over all particles
  fItParticleInputArray->Reset();
  number = -1;
  while((particle = static_cast<Candidate*>(fItParticleInputArray->Next())))
  {
    const TLorentzVector &particlePosition = particle->Position;
    ++number;

    pdgCode = TMath::Abs(particle->PID);

    itFractionMap = fFractionMap.find(pdgCode);
    if(itFractionMap == fFractionMap.end())
    {
      itFractionMap = fFractionMap.find(0);
    }

    ecalFraction = itFractionMap->second.first;
    hcalFraction = itFractionMap->second.second;

    fECalTowerFractions.push_back(ecalFraction);
    fHCalTowerFractions.push_back(hcalFraction);

    if(ecalFraction < 1.0E-9 && hcalFraction < 1.0E-9) continue;

    // find eta bin [1, fEtaBins.size - 1]
    itEtaBin = lower_bound(fEtaBins.begin(), fEtaBins.end(), particlePosition.Eta());
    if(itEtaBin == fEtaBins.begin() || itEtaBin == fEtaBins.end()) continue;
    etaBin = distance(fEtaBins.begin(), itEtaBin);

    // phi bins for given eta bin
    phiBins = fPhiBins[etaBin];

    // find phi bin [1, phiBins.size - 1]
    itPhiBin = lower_bound(phiBins->begin(), phiBins->end(), particlePosition.Phi());
    if(itPhiBin == phiBins->begin() || itPhiBin == phiBins->end()) continue;
    phiBin = distance(phiBins->begin(), itPhiBin);

    flags = 0;
    flags |= (pdgCode == 11 || pdgCode == 22) << 1;

    // make tower hit {16-bits for eta bin number, 16-bits for phi bin number, 8-bits for flags, 24-bits for particle number}
    towerHit = (Long64_t(etaBin) << 48) | (Long64_t(phiBin) << 32) | (Long64_t(flags) << 24) | Long64_t(number);

    fTowerHits.push_back(towerHit);
  }

  // loop over all tracks
  fItTrackInputArray->Reset();
  number = -1;
  while((track = static_cast<Candidate*>(fItTrackInputArray->Next())))
  {
    const TLorentzVector &trackPosition = track->Position;
    ++number;

    pdgCode = TMath::Abs(track->PID);

    itFractionMap = fFractionMap.find(pdgCode);
    if(itFractionMap == fFractionMap.end())
    {
      itFractionMap = fFractionMap.find(0);
    }

    ecalFraction = itFractionMap->second.first;
    hcalFraction = itFractionMap->second.second;

    fECalTrackFractions.push_back(ecalFraction);
    fHCalTrackFractions.push_back(hcalFraction);

    // find eta bin [1, fEtaBins.size - 1]
    itEtaBin = lower_bound(fEtaBins.begin(), fEtaBins.end(), trackPosition.Eta());
    if(itEtaBin == fEtaBins.begin() || itEtaBin == fEtaBins.end()) continue;
    etaBin = distance(fEtaBins.begin(), itEtaBin);

    // phi bins for given eta bin
    phiBins = fPhiBins[etaBin];

    // find phi bin [1, phiBins.size - 1]
    itPhiBin = lower_bound(phiBins->begin(), phiBins->end(), trackPosition.Phi());
    if(itPhiBin == phiBins->begin() || itPhiBin == phiBins->end()) continue;
    phiBin = distance(phiBins->begin(), itPhiBin);

    flags = 1;

    // make tower hit {16-bits for eta bin number, 16-bits for phi bin number, 8-bits for flags, 24-bits for track number}
    towerHit = (Long64_t(etaBin) << 48) | (Long64_t(phiBin) << 32) | (Long64_t(flags) << 24) | Long64_t(number);

    fTowerHits.push_back(towerHit);
  }

  // all hits are sorted first by eta bin number, then by phi bin number,
  // then by flags and then by particle or track number
  sort(fTowerHits.begin(), fTowerHits.end());

  // loop over all hits
  towerEtaPhi = 0;
  fTower = 0;
  for(itTowerHits = fTowerHits.begin(); itTowerHits != fTowerHits.end(); ++itTowerHits)
  {
    towerHit = (*itTowerHits);
    flags = (towerHit >> 24) & 0x00000000000000FFLL;
    number = (towerHit) & 0x0000000000FFFFFFLL;
    hitEtaPhi = towerHit >> 32;

    if(towerEtaPhi != hitEtaPhi)
    {
      // switch to next tower
      towerEtaPhi = hitEtaPhi;

      // finalize previous tower
      FinalizeTower();

      // create new tower
      fTower = factory->NewCandidate();

      phiBin = (towerHit >> 32) & 0x000000000000FFFFLL;
      etaBin = (towerHit >> 48) & 0x000000000000FFFFLL;

      // phi bins for given eta bin
      phiBins = fPhiBins[etaBin];

      // calculate eta and phi of the tower's center
      fTowerEta = 0.5*(fEtaBins[etaBin - 1] + fEtaBins[etaBin]);
      fTowerPhi = 0.5*((*phiBins)[phiBin - 1] + (*phiBins)[phiBin]);

      fTowerEdges[0] = fEtaBins[etaBin - 1];
      fTowerEdges[1] = fEtaBins[etaBin];
      fTowerEdges[2] = (*phiBins)[phiBin - 1];
      fTowerEdges[3] = (*phiBins)[phiBin];

      fECalTowerEnergy = 0.0;
      fHCalTowerEnergy = 0.0;

      fECalTrackEnergy = 0.0;
      fHCalTrackEnergy = 0.0;
      fTrackEnergy = 0.0;

      fECalTrackSigma = 0.0;
      fHCalTrackSigma = 0.0;
      fTrackSigma = 0.0;

      fTowerTrackHits = 0;
      fTowerPhotonHits = 0;

      fECalTowerTrackArray->Clear();
      fHCalTowerTrackArray->Clear();
      fTowerTrackArray->Clear();

    }

    // check for track hits
    if(flags & 1)
    {
      ++fTowerTrackHits;

      track = static_cast<Candidate*>(fTrackInputArray->At(number));
      momentum = track->Momentum;
      position = track->Position;

      ecalEnergy = momentum.E() * fECalTrackFractions[number];
      hcalEnergy = momentum.E() * fHCalTrackFractions[number];
      energy = ecalEnergy + hcalEnergy;

      if(ecalEnergy > fTimingEnergyMin && fTower)
      {
        if(fElectronsFromTrack)
        {
          fTower->ECalEnergyTimePairs.push_back(make_pair<Float_t, Float_t>(ecalEnergy, track->Position.T()));
        }
      }


      // in Dual Readout we do not care if tracks are ECAL of HCAL
      if(fECalTrackFractions[number] > 1.0E-9 || fHCalTrackFractions[number] > 1.0E-9)
      {
        fTrackEnergy += energy;
        // this sigma will be used to determine whether neutral excess is significant. We choose the resolution according to bthe higest deposited fraction (in practice had for charged hadrons and em for electrons)
        sigma = 0.0;
        if(fHCalTrackFractions[number] > 0)
          sigma = fHCalResolutionFormula->Eval(0.0, fTowerEta, 0.0, momentum.E());
        else
          sigma = fECalResolutionFormula->Eval(0.0, fTowerEta, 0.0, momentum.E());

        if(sigma/momentum.E() < track->TrackResolution)
          energyGuess = ecalEnergy + hcalEnergy;
        else
          energyGuess = momentum.E();

        fTrackSigma += (track->TrackResolution)*energyGuess*(track->TrackResolution)*energyGuess;
        fTowerTrackArray->Add(track);

      }
      else
      {
        fEFlowTrackOutputArray->Add(track);
      }

      continue;
    }

    // check for photon and electron hits in current tower
    if(flags & 2) ++fTowerPhotonHits;

    particle = static_cast<Candidate*>(fParticleInputArray->At(number));
    momentum = particle->Momentum;
    position = particle->Position;

    // fill current tower
    ecalEnergy = momentum.E() * fECalTowerFractions[number];
    hcalEnergy = momentum.E() * fHCalTowerFractions[number];

    fECalTowerEnergy += ecalEnergy;
    fHCalTowerEnergy += hcalEnergy;

    if(ecalEnergy > fTimingEnergyMin && fTower)
    {
      if (abs(particle->PID) != 11 || !fElectronsFromTrack)
      {
        fTower->ECalEnergyTimePairs.push_back(make_pair<Float_t, Float_t>(ecalEnergy, particle->Position.T()));
      }
    }

    fTower->AddCandidate(particle);
  }

  // finalize last tower
  FinalizeTower();
}

//------------------------------------------------------------------------------

void DualReadoutCalorimeter::FinalizeTower()
{

  Candidate *track, *tower, *mother;
  Double_t energy, pt, eta, phi;
  Double_t ecalEnergy, hcalEnergy;
  Double_t ecalNeutralEnergy, hcalNeutralEnergy, neutralEnergy;

  Double_t ecalSigma, hcalSigma, sigma;
  Double_t ecalNeutralSigma, hcalNeutralSigma, neutralSigma;

  Double_t weightTrack, weightCalo, bestEnergyEstimate, rescaleFactor;

  TLorentzVector momentum;
  TFractionMap::iterator itFractionMap;

  Float_t weight, sumWeightedTime, sumWeight;

  if(!fTower) return;


  //if (fHCalTowerEnergy < 30 && fECalTowerEnergy < 30) return;
  //cout<<"----------- New tower ---------"<<endl;


  // here we change behaviour w.r.t to standard calorimeter. Start with worse case scenario. If fHCalTowerEnergy > 0, assume total energy smeared by HCAL resolution.
  // For example, if overlapping charged pions and photons take hadronic resolution as combined measurement

  // if no hadronic fraction at all, then use ECAL resolution

  //cout<<"fECalTowerEnergy: "<<fECalTowerEnergy<<", fHCalTowerEnergy: "<<fHCalTowerEnergy<<", Eta: "<<fTowerEta<<endl;

  // if no hadronic energy, use ECAL resolution
  if (fHCalTowerEnergy <= fHCalEnergyMin)
  {
    energy = fECalTowerEnergy;
    sigma  = fECalResolutionFormula->Eval(0.0, fTowerEta, 0.0, energy);
    //cout<<"em energy"<<energy<<", sigma: "<<sigma<<endl;
  }

  // if hadronic fraction > 0, use HCAL resolution
  else
  {
    energy = fECalTowerEnergy + fHCalTowerEnergy;
    sigma  = fHCalResolutionFormula->Eval(0.0, fTowerEta, 0.0, energy);
    //cout<<"had energy: "<<energy<<", sigma: "<<sigma<<endl;
  }

  energy = LogNormal(energy, sigma);
  //cout<<energy<<","<<ecalEnergy<<","<<hcalEnergy<<endl;

  if(energy < fEnergyMin || energy < fEnergySignificanceMin*sigma) energy = 0.0;

  // for now keep this the same
  ecalSigma = fECalResolutionFormula->Eval(0.0, fTowerEta, 0.0, fECalTowerEnergy);
  hcalSigma = fHCalResolutionFormula->Eval(0.0, fTowerEta, 0.0, fHCalTowerEnergy);

  ecalEnergy = LogNormal(fECalTowerEnergy, ecalSigma);
  hcalEnergy = LogNormal(fHCalTowerEnergy, hcalSigma);

  ecalSigma = fECalResolutionFormula->Eval(0.0, fTowerEta, 0.0, ecalEnergy);
  hcalSigma = fHCalResolutionFormula->Eval(0.0, fTowerEta, 0.0, hcalEnergy);

  if(ecalEnergy < fECalEnergyMin || ecalEnergy < fECalEnergySignificanceMin*ecalSigma) ecalEnergy = 0.0;
  if(hcalEnergy < fHCalEnergyMin || hcalEnergy < fHCalEnergySignificanceMin*hcalSigma) hcalEnergy = 0.0;

  //cout<<"Measured energy: "<<energy<<endl;

  if(fSmearTowerCenter)
  {
    eta = gRandom->Uniform(fTowerEdges[0], fTowerEdges[1]);
    phi = gRandom->Uniform(fTowerEdges[2], fTowerEdges[3]);
  }
  else
  {
    eta = fTowerEta;
    phi = fTowerPhi;
  }

  pt = energy / TMath::CosH(eta);

  // Time calculation for tower
  fTower->NTimeHits = 0;
  sumWeightedTime = 0.0;
  sumWeight = 0.0;

  for(size_t i = 0; i < fTower->ECalEnergyTimePairs.size(); ++i)
  {
    weight = TMath::Sqrt(fTower->ECalEnergyTimePairs[i].first);
    sumWeightedTime += weight * fTower->ECalEnergyTimePairs[i].second;
    sumWeight += weight;
    fTower->NTimeHits++;
  }

  if(sumWeight > 0.0)
  {
    fTower->Position.SetPtEtaPhiE(1.0, eta, phi, sumWeightedTime/sumWeight);
  }
  else
  {
    fTower->Position.SetPtEtaPhiE(1.0, eta, phi, 999999.9);
  }

  fTower->Momentum.SetPtEtaPhiE(pt, eta, phi, energy);
  fTower->Eem = ecalEnergy;
  fTower->Ehad = hcalEnergy;

  fTower->Edges[0] = fTowerEdges[0];
  fTower->Edges[1] = fTowerEdges[1];
  fTower->Edges[2] = fTowerEdges[2];
  fTower->Edges[3] = fTowerEdges[3];

  if(energy > 0.0)
  {
    if(fTowerPhotonHits > 0 && fTowerTrackHits == 0)
    {
      fPhotonOutputArray->Add(fTower);
    }
    fTowerOutputArray->Add(fTower);
  }

  // fill energy flow candidates

  fTrackSigma = TMath::Sqrt(fTrackSigma);
  neutralEnergy = max( (energy - fTrackEnergy) , 0.0);
  neutralSigma = neutralEnergy / TMath::Sqrt(fTrackSigma*fTrackSigma + sigma*sigma);

  //cout<<"trackEnergy: "<<fTrackEnergy<<", trackSigma: "<<fTrackSigma<<", Ntracks: "<<fTowerTrackArray->GetEntries()<<endl;

  //cout<<"neutralEnergy: "<<neutralEnergy<<", neutralSigma: "<<neutralSigma<<", :fEnergyMin "<<fEnergyMin<<", fEnergySignificanceMin: "<<fEnergySignificanceMin<<endl;

   // For now, if neutral excess is significant, simply create neutral EflowPhoton tower and clone each track into eflowtrack !!! -> Creating only photons !! EFlowNeutralHadron collection will be empy!!! TO BE FIXED
  if(neutralEnergy > fEnergyMin && neutralSigma > fEnergySignificanceMin)
  {

    //cout<<"significant neutral excess found:"<<endl;
    // create new photon tower
    tower = static_cast<Candidate*>(fTower->Clone());
    pt =  neutralEnergy / TMath::CosH(eta);
    //cout<<"Creating tower with Pt, Eta, Phi, Energy: "<<pt<<","<<eta<<","<<phi<<","<<neutralEnergy<<endl;
    tower->Momentum.SetPtEtaPhiE(pt, eta, phi, neutralEnergy);

    // if no hadronic energy, use ECAL resolution
    if (fHCalTowerEnergy <= fHCalEnergyMin)
    {
      tower->Eem = neutralEnergy;
      tower->Ehad = 0.0;
      tower->PID = 22;
    }

    // if hadronic fraction > 0, use HCAL resolution
    else
    {
      tower->Eem = 0;
      tower->Ehad = neutralEnergy;
      tower->PID = 130;
    }

    fEFlowPhotonOutputArray->Add(tower);


    //clone tracks
    fItTowerTrackArray->Reset();
    while((track = static_cast<Candidate*>(fItTowerTrackArray->Next())))
    {
      mother = track;
      track = static_cast<Candidate*>(track->Clone());
      track->AddCandidate(mother);
      fEFlowTrackOutputArray->Add(track);
    }
  }


  // if neutral excess is not significant, rescale eflow tracks, such that the total charged equals the best measurement given by the DualReadoutCalorimeter and tracking
  else if(fTrackEnergy > 0.0)
  {
    //cout<<"no significant neutral excess found:"<<endl;
    weightTrack = (fTrackSigma > 0.0) ? 1 / (fTrackSigma*fTrackSigma) : 0.0;
    weightCalo  = (sigma > 0.0) ? 1 / (sigma*sigma) : 0.0;

    bestEnergyEstimate = (weightTrack*fTrackEnergy + weightCalo*energy) / (weightTrack + weightCalo);
    rescaleFactor = bestEnergyEstimate/fTrackEnergy;

    //rescale tracks
    fItTowerTrackArray->Reset();
    while((track = static_cast<Candidate*>(fItTowerTrackArray->Next())))
    {
      mother = track;
      track = static_cast<Candidate *>(track->Clone());
      track->AddCandidate(mother);
      track->Momentum.SetPtEtaPhiM(track->Momentum.Pt()*rescaleFactor, track->Momentum.Eta(), track->Momentum.Phi(), track->Momentum.M());
      fEFlowTrackOutputArray->Add(track);
    }
  }


}

//------------------------------------------------------------------------------

Double_t DualReadoutCalorimeter::LogNormal(Double_t mean, Double_t sigma)
{
  Double_t a, b;

  if(mean > 0.0)
  {
    b = TMath::Sqrt(TMath::Log((1.0 + (sigma*sigma)/(mean*mean))));
    a = TMath::Log(mean) - 0.5*b*b;

    return TMath::Exp(a + b*gRandom->Gaus(0.0, 1.0));
  }
  else
  {
    return 0.0;
  }
}