PunchThroughTool.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
// class header
#include "PunchThroughTool.h"
 
// standard C++ libraries
#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
#include <vector>
#include <numeric>
#include <string_view>
#include <charconv>
 
// standard C libraries
#include <cmath>
 
// Control
#include "AthContainers/DataVector.h"
 
// HepMC
#include "AtlasHepMC/SimpleVector.h"
#include "AtlasHepMC/GenVertex.h"
#include "AtlasHepMC/GenParticle.h"
#include "AtlasHepMC/GenEvent.h"
#include "TruthUtils/MagicNumbers.h"
#include "TruthUtils/HepMCHelpers.h"
 
// CLHEP
#include "CLHEP/Random/RandFlat.h"
 
#include "XMLCoreParser/XMLCoreParser.h"
#include "XMLCoreParser/XMLCoreNode.h"
 
// ROOT
#include "TFile.h"
#include "TH2F.h"
#include "TAxis.h"
#include "TH1.h"
#include "TMath.h"
#include "TROOT.h"
#include "TKey.h"
#include "TClass.h"
 
// PathResolver
#include "PathResolver/PathResolver.h"
 
//ISF
#include "ISF_Event/ISFParticle.h"
#include "PDFcreator.h"
#include "PunchThroughParticle.h"
 
//Amg
#include "GeoPrimitives/GeoPrimitivesHelpers.h"
 
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
ISF::PunchThroughTool::PunchThroughTool( const std::string& type,
                                         const std::string& name,
                                         const IInterface*  parent )
: base_class(type, name, parent)
{
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
StatusCode ISF::PunchThroughTool::initialize()
{
  ATH_MSG_DEBUG( "initialize()" );
 
  // initialise punch through classifier
  if (m_punchThroughClassifier.retrieve().isFailure() )
  {
    ATH_MSG_ERROR (m_punchThroughClassifier.propertyName() << ": Failed to retrieve tool " << m_punchThroughClassifier.type());
    return StatusCode::FAILURE;
  }
 
  // resolving lookuptable file
  std::string resolvedFileName = PathResolverFindCalibFile (m_filenameLookupTable);
  if (resolvedFileName.empty()) {
    ATH_MSG_ERROR( "[ punchthrough ] Parametrisation file '" << m_filenameLookupTable << "' not found" );
    return StatusCode::FAILURE;
  }
  ATH_MSG_INFO( "[ punchthrough ] Parametrisation file found: " << resolvedFileName );
 
  // open the LookupTable file
  m_fileLookupTable = new TFile( resolvedFileName.c_str(), "READ");
  if (!m_fileLookupTable) {
    ATH_MSG_WARNING("[ punchthrough ] unable to open the lookup-table for the punch-through simulation (file does not exist)");
    return StatusCode::FAILURE;
  }
 
  if (!m_fileLookupTable->IsOpen()) {
    ATH_MSG_WARNING("[ punchthrough ] unable to open the lookup-table for the punch-through simulation (wrong or empty file?)");
    return StatusCode::FAILURE;
  }
 
  //retrieve inverse CDF config file
  if (!initializeInverseCDF(PathResolverFindCalibFile(m_filenameInverseCDF)))
  {
    ATH_MSG_WARNING("[ punchthrough ] unable to open or read the inverse CDF config");
    return StatusCode::FAILURE;
  }
 
  //retrieve inverse PCA config file
  if (!initializeInversePCA(PathResolverFindCalibFile(m_filenameInversePCA)))
  {
    ATH_MSG_WARNING("[ punchthrough ] unable to open or read the inverse PCA config");
    return StatusCode::FAILURE;
  }
 
  //check first the size of infoMap for both PCA and CDF, they should be equal
  if (!(m_xml_info_pca.size() == m_xml_info_cdf.size()))
  {
    ATH_MSG_WARNING("[ punchthrough ] size of infoMap for PCA and CDF differs! Something is wrong with input xml files.");
    return StatusCode::FAILURE;
  }
 
  m_gendata = std::make_shared<GenData>();
  
  // Geometry identifier service
  if ( !m_geoIDSvc.empty() && m_geoIDSvc.retrieve().isFailure())
    {
      ATH_MSG_FATAL ( "[ punchthrough ] Could not retrieve GeometryIdentifier Service. Abort");
      return StatusCode::FAILURE;
    }
 
  //envelope definition service
  if (m_envDefSvc.retrieve().isFailure() )
    {
      ATH_MSG_ERROR( "[ punchthrough ] Could not retrieve " << m_envDefSvc );
      return StatusCode::FAILURE;
    }
 
  //--------------------------------------------------------------------------------
  // register all the punch-through particles which will be simulated
  for ( unsigned int num = 0; num < m_punchThroughParticles.size(); num++ )
    {
      const int pdg = m_punchThroughParticles[num];
      // if no information is given on the creation of anti-particles -> do not simulate anti-particles
      const bool doAnti = ( num < m_doAntiParticles.size() ) ? m_doAntiParticles[num] : false;
      // if no information is given on the minimum energy -> take 50. MeV as default
      const double minEnergy = ( num < m_minEnergy.size() ) ? m_minEnergy[num] : 50.;
      // if no information is given on the maximum number of punch-through particles -> take -1 as default
      const int maxNum = ( num < m_minEnergy.size() ) ? m_maxNumParticles[num] : -1;
      // if no information is given on the scale factor for the number of particles -> take 1. as defaulft
      const double numFactor = ( num < m_numParticlesFactor.size() ) ? m_numParticlesFactor[num] : 1.;
      // if no information is given on the position angle factor -> take 1.
      const double posAngleFactor = ( num < m_posAngleFactor.size() ) ? m_posAngleFactor[num] : 1.;
      // if no information is given on the momentum angle factor -> take 1.
      const double momAngleFactor = ( num < m_momAngleFactor.size() ) ? m_momAngleFactor[num] : 1.;
      // if no information is given on the scale factor for the energy -> take 1. as default
      const double energyFactor = ( num < m_energyFactor.size() ) ? m_energyFactor[num] : 1.;
 
      // register the particle
      ATH_MSG_VERBOSE("[ punchthrough ] registering punch-through particle type with pdg = " << pdg );
      if ( registerParticle( pdg, doAnti, minEnergy, maxNum, numFactor, energyFactor, posAngleFactor, momAngleFactor )
           != StatusCode::SUCCESS)
        {
          ATH_MSG_ERROR("[ punchthrough ] unable to register punch-through particle type with pdg = " << pdg);
        }
    }
 
  // TODO: implement punch-through parameters for different m_pdgInitiators
  //       currently m_pdgInitiators is only used to filter out particles
 
  // check if more correlations were given than particle types were registered
  unsigned int numCorrelations = m_correlatedParticle.size();
  if ( numCorrelations > m_punchThroughParticles.size() )
    {
      ATH_MSG_WARNING("[ punchthrough ] more punch-through particle correlations are given, than punch-through particle types are registered (skipping the last ones)");
      numCorrelations = m_punchThroughParticles.size();
    }
 
  // now register correlation between particles
  for ( unsigned int num = 0; num < numCorrelations; num++ )
    {
      const int pdg1 = m_punchThroughParticles[num];
      const int pdg2 = m_correlatedParticle[num];
      const double fullCorrEnergy = ( num < m_fullCorrEnergy.size() ) ? m_fullCorrEnergy[num] : 0.;
      const double minCorrEnergy = ( num < m_minCorrEnergy.size() ) ?  m_minCorrEnergy[num] : 0.;
 
      // if correlatedParticle==0 is given -> no correlation
      if ( ! pdg2) continue;
      // register it
      if ( registerCorrelation(pdg1, pdg2, minCorrEnergy, fullCorrEnergy) != StatusCode::SUCCESS )
        {
          ATH_MSG_ERROR("[ punchthrough ] unable to register punch-through particle correlation for pdg1=" << pdg1 << " pdg2=" << pdg2 );
        }
    }
 
  // get the calo-MS border coordinates. Look at calo and MS geometry definitions, if same R and Z -> boundary surface
 
  const RZPairVector* rzMS = &(m_envDefSvc->getMuonRZBoundary());
  const RZPairVector* rzCalo = &(m_envDefSvc->getCaloRZBoundary());
 
  bool found1, found2;
  found1=false; found2=false;
 
  for ( size_t i=0; i<rzCalo->size();++i)
    {
      const double r_tempCalo = rzCalo->at(i).first;
      const double z_tempCalo = rzCalo->at(i).second;
 
      if (r_tempCalo> m_beamPipe)
        {
          for ( size_t j=0; j<rzMS->size();++j)
            {
              const double r_tempMS =rzMS->at(j).first;
              const double z_tempMS =rzMS->at(j).second;
 
              if (r_tempCalo==r_tempMS && z_tempCalo==z_tempMS && found1==false )
                {
                  m_R1=r_tempMS;
                  m_z1=std::fabs(z_tempMS);
                  found1=true;
                  continue;
                }
              else if (r_tempCalo==r_tempMS && z_tempCalo==z_tempMS && r_tempCalo!=m_R1 && std::fabs(z_tempCalo)!=m_z1)
                {
                  m_R2=r_tempMS;
                  m_z2=std::fabs(z_tempMS);
                  found2=true;
                }
            }
 
          if (found1==true && found2==true) break;
        }
    }
 
  //in case geometry description changes
  if (found1 == false) ATH_MSG_ERROR ("first coordinate of calo-MS border not found");
  if (found2 == false) ATH_MSG_ERROR ("second coordinate of calo-MS border not found; first one is: R1 ="<<m_R1<<" z1 ="<<m_z1);
 
  //now order the found values
  double r_temp, z_temp;
  if (m_R1>m_R2) { r_temp=m_R1; m_R1=m_R2; m_R2=r_temp; } //m_R1 - smaller one
  if (m_z1<m_z2) { z_temp=m_z1; m_z1=m_z2; m_z2=z_temp; } //m_z1 - bigger one
 
  if (m_R1==m_R2 || m_z1==m_z2) ATH_MSG_ERROR ("[punch-though] Bug in propagation calculation! R1="<<m_R1<<" R2 = "<<m_R2<<" z1="<<m_z1<<" z2= "<<m_z2 );
  else                  ATH_MSG_DEBUG ("calo-MS boundary coordinates: R1="<<m_R1<<" R2 = "<<m_R2<<" z1="<<m_z1<<" z2= "<<m_z2);
 
  // close the file with the lookuptable
  m_fileLookupTable->Close();
 
  ATH_MSG_INFO( "punchthrough initialization is successful" );
  return StatusCode::SUCCESS;
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
StatusCode ISF::PunchThroughTool::finalize()
{
  ATH_MSG_DEBUG( "[punchthrough] finalize() starting" );
  for(auto & each : m_particles) {
    delete each.second;
  }
 
  ATH_MSG_DEBUG( "[punchthrough] finalize() successful" );
 
  return StatusCode::SUCCESS;
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
const ISF::ISFParticleVector* ISF::PunchThroughTool::computePunchThroughParticles(const ISF::ISFParticle &isfp, const TFCSSimulationState& simulstate, CLHEP::HepRandomEngine* rndmEngine) const
{
  ATH_MSG_DEBUG( "[ punchthrough ] starting punch-through simulation");
 
  // create output particle collection
  auto isfpCont = std::make_unique<ISF::ISFParticleVector>();
 
  ATH_MSG_VERBOSE("[ punchthrough ] position of the input particle: r"<<isfp.position().perp()<<" z= "<<isfp.position().z() );
 
  //check if it points to the calorimeter - if not, don't simulate
 
  if ( m_geoIDSvc->identifyNextGeoID(isfp) != AtlasDetDescr::fAtlasCalo)
    {
      ATH_MSG_VERBOSE ("[ GeoIDSvc ] input particle doesn't point to calorimeter"<< "Next GeoID: "<<m_geoIDSvc->identifyNextGeoID(isfp) );
      return nullptr;
    }
 
 
  // check if the particle's pdg is registered as a punch-through-causing type
  {
    std::vector<int>::const_iterator pdgIt    = m_pdgInitiators.begin();
    std::vector<int>::const_iterator pdgItEnd = m_pdgInitiators.end();
 
    std::vector<int>::const_iterator minEnergyIt    = m_initiatorsMinEnergy.begin();
    // loop over all known punch-through initiators
    for ( ; pdgIt != pdgItEnd; ++pdgIt, ++minEnergyIt)
      {
        if (std::abs(isfp.pdgCode()) == *pdgIt){
          if(std::sqrt( isfp.momentum().mag2() + isfp.mass()*isfp.mass() ) < *minEnergyIt){
            ATH_MSG_DEBUG("[ punchthrough ] particle does not meet initiator min energy requirement. Dropping it in the calo.");
            return nullptr;
          }
          break;
        }
      }
 
    // particle will not cause punch-through -> bail out
    if (pdgIt == pdgItEnd)
      {
        ATH_MSG_DEBUG("[ punchthrough ] particle is not registered as punch-through initiator. Dropping it in the calo.");
        return nullptr;
      }
  }
 
  if(isfp.position().eta() < m_initiatorsEtaRange.value().at(0) || isfp.position().eta() > m_initiatorsEtaRange.value().at(1) ){
    ATH_MSG_DEBUG("[ punchthrough ] particle does not meet initiator eta range requirement. Dropping it in the calo.");
    return nullptr;
  }
 
  //Calculate probability of punch through using punchThroughClassifier
  double punchThroughProbability = m_punchThroughClassifier->computePunchThroughProbability(isfp, simulstate);
 
  //Draw random number to compare to probability
  double punchThroughClassifierRand = CLHEP::RandFlat::shoot(rndmEngine);
 
  ATH_MSG_DEBUG("[ punchthrough ] punchThroughProbability output: " << punchThroughProbability << " RandFlat: " << punchThroughClassifierRand );
 
  //If probability < random number then don't simulate punch through
  if( punchThroughClassifierRand > punchThroughProbability){
      ATH_MSG_DEBUG("[ punchthrough ] particle not classified to create punch through. Dropping it in the calo.");
      return nullptr;
  }
 
  //if initial particle is on ID surface, points to the calorimeter, is a punch-through initiator, meets initiator min enery and eta range
 
  // this is the place where the magic is done:
  // test for each registered punch-through pdg if a punch-through
  // occures and create these particles
  // -> therefore loop over all registered pdg ids
  // to keep track of the correlated particles which were already simulated:
  // first int is pdg, second int is number of particles created
 
  // calculate incoming energy and eta
  const double initEnergy = std::sqrt( isfp.momentum().mag2() + isfp.mass()*isfp.mass() );
  const double initEta = isfp.position().eta();
 
  // interpolate energy and eta
  const double interpEnergy = interpolateEnergy(initEnergy, rndmEngine);
  const double interpEta = interpolateEta(initEta, rndmEngine);
 
  std::map<int, int> corrPdgNumDone;
 
  int maxTries = 10;
  int nTries = 0;
 
  // loop over all particle pdgs
  while(isfpCont->empty() && nTries < maxTries) { //ensure we always create at least one punch through particle, maxTries to catch very rare cases
 
      for (const auto& currentParticle : m_particles)
        {
          // the pdg that is currently treated
          int doPdg = currentParticle.first;
          // get the current particle's correlated pdg
          int corrPdg = currentParticle.second->getCorrelatedPdg();
 
          // if there is a correlated particle type to this one
          if (corrPdg)
            {
              // find out if the current pdg was already simulated
              std::map<int,int>::iterator pos = corrPdgNumDone.find(doPdg);
              // if the current pdg was not simulated yet, find out if
              // it's correlated one was simulated
              if ( pos == corrPdgNumDone.end() ) pos = corrPdgNumDone.find(corrPdg);
 
              // neither this nor the correlated particle type was simulated
              // so far:
              if ( pos == corrPdgNumDone.end() )
                {
                  // -> roll a dice if we create this particle or its correlated one
                  if ( CLHEP::RandFlat::shoot(rndmEngine) > 0.5 ) doPdg = corrPdg;
                  // now create the particles with the given pdg and note how many
                  // particles of this pdg are created
                  corrPdgNumDone[doPdg] = getAllParticles(isfp, *isfpCont, rndmEngine, doPdg, interpEnergy, interpEta);
                }
 
              // one of the two correlated particle types was already simulated
              // 'pos' points to the already simulated one
              else
                {
                  // get the pdg of the already simulated particle and the number
                  // of these particles that were created
                  const int donePdg = pos->first;
                  const int doneNumPart = pos->second;
                  // set the pdg of the particle type that will be done
                  if (donePdg == doPdg) doPdg = corrPdg;
 
                  // now create the correlated particles
                  getCorrelatedParticles(isfp, *isfpCont, doPdg, doneNumPart, rndmEngine, interpEnergy, interpEta);
                  // note: no need to take note, that this particle type is now simulated,
                  // since this is the second of two correlated particles, which is
                  // simulated and we do not have correlations of more than two particles.
                }
 
              // if no correlation for this particle
              // -> directly create all particles with the current pdg
            }
          else getAllParticles(isfp, *isfpCont, rndmEngine, doPdg, interpEnergy, interpEta);
 
        } // for-loop over all particle pdgs
 
      nTries++;
  }
 
  if (!isfpCont->empty())  ATH_MSG_DEBUG( "[ punchthrough ] returning ISFparticle vector , size: "<<isfpCont->size() );
 
  for (ISF::ISFParticle *particle : *isfpCont) {
    ATH_MSG_DEBUG("codes of produced punch through particle: pdg = "<< particle->pdgCode());
    Amg::Vector3D position = particle->position();
    ATH_MSG_DEBUG("position of produced punch-through particle: x = "<< position.x() <<" y = "<< position.y() <<" z = "<< position.z());
    Amg::Vector3D momentum = particle->momentum();
    ATH_MSG_DEBUG("momentum of produced punch-through particle: px = "<< momentum.x() <<" py = "<< momentum.x() <<" pz = "<< momentum.x() <<" e = "<< particle->ekin() << " mass = " << particle->mass());
  }
 
  return isfpCont.release();
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
int ISF::PunchThroughTool::getAllParticles(const ISF::ISFParticle &isfp, ISFParticleVector& isfpCont, CLHEP::HepRandomEngine* rndmEngine, int pdg, double interpEnergy, double interpEta, int numParticles) const
{
 
  // get the current particle
  PunchThroughParticle *p = m_particles.at(pdg);
 
  // if no number of particles (=-1) was handed over as an argument
  //  -> get the number of particles from the pdf
  if ( numParticles < 0 )
    {
      // prepare the function arguments for the PDFcreator class
      std::vector<int> parameters;
      parameters.push_back( std::round(interpEnergy) );
      parameters.push_back( std::round(interpEta*100) );
      // the maximum number of particles which should be produced
      // if no maximum number is given, this is -1
      int maxParticles = p->getMaxNumParticles();
 
      // get the right number of punch-through particles
      // and ensure that we do not create too many particles
      do
        {
          numParticles = int( p->getNumParticlesPDF()->getRand(rndmEngine, parameters) );
 
          // scale the number of particles if requested
          numParticles = lround( numParticles *= p->getNumParticlesFactor() );
        }
      while ( (maxParticles >= 0.) && (numParticles > maxParticles) );
    }
 
  ATH_MSG_VERBOSE("[ punchthrough ] adding " << numParticles << " punch-through particles with pdg " << pdg);
 
  // now create the exact number of particles which was just computed before
  double energyRest = std::sqrt( isfp.momentum().mag2() + isfp.mass()*isfp.mass() );
  double minEnergy = p->getMinEnergy();
  int numCreated = 0;
 
  for ( numCreated = 0; (numCreated < numParticles) && (energyRest > minEnergy); numCreated++ )
    {
      // create one particle which fullfills the right energy distribution
      ISF::ISFParticle *par = getOneParticle(isfp, pdg, rndmEngine, interpEnergy, interpEta);
 
      // if something went wrong
      if (!par)
        {
          ATH_MSG_ERROR("[ punchthrough ] something went wrong while creating punch-through particles");
          return 0;
        }
 
      // get the energy of the particle which was just created
      const double restMass = m_gendata->particleMass(std::abs(pdg)).value();
      double curEnergy = std::sqrt(par->momentum().mag2() + restMass*restMass);
 
      // calculate the maximum energy to be available for all
      // following punch-through particles created
      energyRest -= curEnergy;
 
      // add this ISFparticle to the vector
      isfpCont.push_back( par );
    }
 
  // the number of particles which was created is numCreated
  return (numCreated);
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
int ISF::PunchThroughTool::getCorrelatedParticles(const ISF::ISFParticle &isfp, ISFParticleVector& isfpCont, int pdg, int corrParticles, CLHEP::HepRandomEngine* rndmEngine, double interpEnergy, double interpEta) const
{
  // get the PunchThroughParticle class
  PunchThroughParticle *p = m_particles.at(pdg);
 
  const double initEnergy = std::sqrt( isfp.momentum().mag2() + isfp.mass()*isfp.mass() );
 
  // (1.) decide if we do correlation or not
  double rand = CLHEP::RandFlat::shoot(rndmEngine)
    *(p->getFullCorrelationEnergy()-p->getMinCorrelationEnergy())
    + p->getMinCorrelationEnergy();
  if ( initEnergy < rand )
    {
      // here we do not do correlation
      return getAllParticles(isfp, isfpCont, rndmEngine, pdg, interpEnergy, interpEta);
    }
 
  // (2.) if this point is reached, we do correlation
  // decide which 2d correlation histogram to use
  double *histDomains = p->getCorrelationHistDomains();
  TH2F *hist2d = nullptr;
  // compute the center values of the lowE and highE
  // correlation histogram domains
  if ( initEnergy <  histDomains[1])
    {
      // initial energy lower than border between lowEnergy and highEnergy histogram domain
      //  --> choose lowEnergy correlation histogram
      hist2d = p->getCorrelationLowEHist();
    }
  else
    {
      double rand = CLHEP::RandFlat::shoot(rndmEngine)*(histDomains[2]-histDomains[1])
        + histDomains[1];
      hist2d = ( initEnergy < rand) ? p->getCorrelationLowEHist()
        : p->getCorrelationHighEHist();
    }
 
  // get the correlation 2d histogram
 
  // now find out where on the x-axis the the bin for number of
  // correlated particles is
  Int_t xbin = hist2d->GetXaxis()->FindFixBin(corrParticles);
  int numParticles = 0;
  int maxParticles = p->getMaxNumParticles();
  // now the distribution along the y-axis is a PDF for the number
  // of 'pdg' particles
  do
    {
      double rand = CLHEP::RandFlat::shoot(rndmEngine);
      double sum = 0.;
      for ( int ybin = 1; ybin <= hist2d->GetNbinsY(); ybin++ )
        {
          sum += hist2d->GetBinContent(xbin, ybin);
          // check if we choose the current bin or not
          if ( sum >= rand )
            {
              numParticles = ybin - 1;
              break;
            }
        }
      // scale the number of particles is requested
      numParticles = lround( numParticles * p->getNumParticlesFactor() );
    }
  while ( (maxParticles >= 0.) && (numParticles > maxParticles) );
 
  // finally create this exact number of particles
  return getAllParticles(isfp, isfpCont, rndmEngine, pdg, interpEnergy, interpEta, numParticles);
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
ISF::ISFParticle *ISF::PunchThroughTool::getOneParticle(const ISF::ISFParticle &isfp, int pdg, CLHEP::HepRandomEngine* rndmEngine, double interpEnergy, double interpEta) const
{
  // get a local copy of the needed punch-through particle class
  PunchThroughParticle *p = m_particles.at(pdg);
 
  // (0.) get the pca / cdf group based on pdgId and eta, eta times 100, e.g eta -4 to 4 is from eta -400 to 400
  int pcaCdfIterator = passedParamIterator(pdg, interpEta*100, m_xml_info_pca); //pca and cdf info should be of same size
 
  ATH_MSG_DEBUG("[ punchthrough ] passedPCAIterator ==> pcaCdfIterator = "<< pcaCdfIterator <<" , pdg = "<< pdg <<" , interpEnergy = "<< interpEnergy <<" MeV, interpEta(*100) = "<< interpEta*100);
 
  // (1.) decide if we create a particle or an anti-particle
  int anti = 1;
  if ( p->getdoAnti() )
    {
      // get a random-value
      double rand = CLHEP::RandFlat::shoot(rndmEngine);
      // 50/50 chance to be a particle or its anti-particle
      if (rand > 0.5) anti = -1;
    }
 
  // (2.) get the right punch-through distributions
  // prepare the function arguments for the PDFcreator class
  std::vector<int> parInitEnergyEta;
  parInitEnergyEta.push_back( std::round(interpEnergy) );
  parInitEnergyEta.push_back( std::round(interpEta*100) );
 
  //initialise variables to store punch through particle kinematics
  double energy = 0.;
  double deltaTheta = 0.;
  double deltaPhi = 0.;
  double momDeltaTheta = 0.;
  double momDeltaPhi = 0.;
 
  double principal_component_0 = 0.;
  double principal_component_1 = 0.;
  double principal_component_2 = 0.;
  double principal_component_3 = 0.;
  double principal_component_4 = 0.;
  std::vector<double> transformed_variables;
 
 
  principal_component_0 = p->getPCA0PDF()->getRand(rndmEngine, parInitEnergyEta);
  principal_component_1 = p->getPCA1PDF()->getRand(rndmEngine, parInitEnergyEta);
  principal_component_2 = p->getPCA2PDF()->getRand(rndmEngine, parInitEnergyEta);
  principal_component_3 = p->getPCA3PDF()->getRand(rndmEngine, parInitEnergyEta);
  principal_component_4 = p->getPCA4PDF()->getRand(rndmEngine, parInitEnergyEta);
 
  ATH_MSG_DEBUG("Drawn punch through kinematics PCA components: PCA0 = "<< principal_component_0 <<" PCA1 = "<< principal_component_1 <<" PCA2 = "<< principal_component_2 <<" PCA3 = "<< principal_component_3 <<" PCA4 = "<< principal_component_4 );
 
  std::vector<double> principal_components {
          principal_component_0, 
          principal_component_1, 
          principal_component_2, 
          principal_component_3, 
          principal_component_4
   };
 
  transformed_variables = inversePCA(pcaCdfIterator,principal_components);
 
  energy = inverseCdfTransform(transformed_variables.at(0), m_variable0_inverse_cdf[pcaCdfIterator]);
  deltaTheta = inverseCdfTransform(transformed_variables.at(1), m_variable1_inverse_cdf[pcaCdfIterator]);
  deltaPhi = inverseCdfTransform(transformed_variables.at(2), m_variable2_inverse_cdf[pcaCdfIterator]);
  momDeltaTheta = inverseCdfTransform(transformed_variables.at(3), m_variable3_inverse_cdf[pcaCdfIterator]);
  momDeltaPhi = inverseCdfTransform(transformed_variables.at(4), m_variable4_inverse_cdf[pcaCdfIterator]);
 
  ATH_MSG_DEBUG("Transformed punch through kinematics: energy = "<< energy <<" MeV deltaTheta = "<< deltaTheta <<" deltaPhi = "<< deltaPhi <<" momDeltaTheta = "<< momDeltaTheta <<" momDeltaPhi = "<< momDeltaPhi );
 
  energy *= p->getEnergyFactor(); // scale the energy if requested
  if (energy < p->getMinEnergy()) {
    energy = p->getMinEnergy() + 10;
  }
 
 
  // (2.2) get the particles delta theta relative to the incoming particle
  double theta = 0;
  // loop to keep theta within range [0,PI]
  do
    {
      // decide if delta positive/negative
      deltaTheta *=  ( CLHEP::RandFlat::shoot(rndmEngine) > 0.5 ) ? 1. : -1.;
      // calculate the exact theta value of the later created
      // punch-through particle
      theta = isfp.position().theta() + deltaTheta*p->getPosAngleFactor();
 
    }
  while ( (theta > M_PI) || (theta < 0.) );
  // (2.3) get the particle's delta phi relative to the incoming particle
 
  deltaPhi *=  ( CLHEP::RandFlat::shoot(rndmEngine) > 0.5 ) ? 1. : -1.;
 
  // keep phi within range [-PI,PI]
  double phi = isfp.position().phi() + deltaPhi*p->getPosAngleFactor();
  while ( std::fabs(phi) > 2*M_PI) phi /= 2.;
  while (phi >  M_PI) phi -= 2*M_PI;
  while (phi < -M_PI) phi += 2*M_PI;
 
  // (2.4) get the particle momentum delta theta, relative to its position
  //
  // loop to keep momTheta within range [0,PI]
 
  double momTheta = 0.;
  do
    {
      // decide if delta positive/negative
      momDeltaTheta *=  ( CLHEP::RandFlat::shoot(rndmEngine) > 0.5 ) ? 1. : -1.;
      // calculate the exact momentum theta value of the later created
      // punch-through particle
      momTheta = theta + momDeltaTheta*p->getMomAngleFactor();
 
    }
  while ( (momTheta > M_PI) || (momTheta < 0.) );
 
  // (2.5) get the particle momentum delta phi, relative to its position
 
  momDeltaPhi *=  ( CLHEP::RandFlat::shoot(rndmEngine) > 0.5 ) ? 1. : -1.;
 
  double momPhi = phi + momDeltaPhi*p->getMomAngleFactor();
  // keep momPhi within range [-PI,PI]
  while ( std::fabs(momPhi) > 2*M_PI) momPhi /= 2.;
  while (momPhi >  M_PI) momPhi -= 2*M_PI;
  while (momPhi < -M_PI) momPhi += 2*M_PI;
 
  // (**) finally create the punch-through particle as a ISFParticle
 
  ATH_MSG_DEBUG("createExitPs input parameters: doAnti? = "<< pdg*anti <<" energy = "<< energy <<" theta = "<< theta <<" phi = "<< phi <<" momTheta = "<< momTheta << " momPhi " << momPhi );
 
 
  ISF::ISFParticle *par = createExitPs( isfp, pdg*anti, energy, theta, phi, momTheta, momPhi);
 
  return par;
}
 
double ISF::PunchThroughTool::normal_cdf(double x) {
 
    return  0.5 * TMath::Erfc(-x * M_SQRT1_2);
}
 
std::vector<double> ISF::PunchThroughTool::dotProduct(const std::vector<std::vector<double>> &m, const std::vector<double> &v) 
{
    std::vector<double> result;
    result.reserve(m.size());
    for (const auto& r : m){
        result.push_back(std::inner_product(v.begin(), v.end(), r.begin(), 0.0));
    }
 
    return result;
}
 
template<typename T>
std::vector<T> str_to_list(const std::string_view str)
{
    constexpr char delimiters = ',';
    std::vector<T> tokens;
    // Skip delimiters at beginning.
    std::string_view::size_type lastPos = str.find_first_not_of(delimiters, 0);
    // Find first "non-delimiter".
    std::string_view::size_type pos = str.find_first_of(delimiters, lastPos);
 
    while (std::string_view::npos != pos || std::string_view::npos != lastPos) {
        // Found a token, add it to the vector.
        std::string_view numbStr = str.substr(lastPos, pos - lastPos);
        T num = -9999;
        std::from_chars(numbStr.data(), numbStr.data() + numbStr.size(), num);
        tokens.push_back(num);
        // Skip delimiters.  Note the "not_of"
        lastPos = str.find_first_not_of(delimiters, pos);
        // Find next "non-delimiter"
        pos = str.find_first_of(delimiters, lastPos);
    }
    return tokens;
}
 
int ISF::PunchThroughTool::passedParamIterator(int pid, double eta, const std::vector<InfoMap> &mapvect) const
{
    //convert the pid to absolute value and string for query
    int pidStrSingle = std::abs(pid);
    //STEP 1
    //filter items matching pid first
 
    for (int i = 0; const InfoMap& m : mapvect) {
      ++i;
      const std::vector<int>& v = m.pidStr;
      if(std::find(v.begin(), v.end(),pidStrSingle)==v.end()) continue;
      assert(m.etaMaxs.size() == m.etaMins.size());
      for (unsigned int j = 0; j < m.etaMins.size(); j++){ // assume size etaMinsVect == etaMaxsVect
        double etaMinToCompare = m.etaMins[j];
        double etaMaxToCompare = m.etaMaxs[j];
        if((eta >= etaMinToCompare) && (eta < etaMaxToCompare)){
          //PASS CONDITION
          //then choose the passing one and note it's iterator
          return i-1; //in case more than 1 match (ambiguous case)
        }
      }
    }
    return 0;
}
 
ISF::PunchThroughTool::InfoMap::InfoMap (const XMLCoreNode& node)
  : name (node.get_attrib ("name")),
    etaMins (str_to_list<double> (node.get_attrib ("etaMins"))),
    etaMaxs (str_to_list<double> (node.get_attrib ("etaMaxs"))),
    pidStr (str_to_list<int> (node.get_attrib ("pidStr")))
{
}
 
auto ISF::PunchThroughTool::getInfoMap(const std::string& mainNode, const XMLCoreNode& doc) -> std::vector<InfoMap>
{
  std::vector<InfoMap>  xml_info;
 
  for (const XMLCoreNode* node : doc.get_children (mainNode + "/info/item")) {
    xml_info.emplace_back(*node);
  }
 
  return xml_info;  
}
 
std::vector<double> ISF::PunchThroughTool::inversePCA(int pcaCdfIterator, std::vector<double> &variables) const
{
    std::vector<double> transformed_variables = dotProduct(m_inverse_PCA_matrix[pcaCdfIterator], variables);
 
    std::transform (transformed_variables.begin(), transformed_variables.end(), m_PCA_means[pcaCdfIterator].begin(), transformed_variables.begin(), std::plus<double>()); // + means
 
    return transformed_variables;
}
 
StatusCode ISF::PunchThroughTool::initializeInversePCA(const std::string & inversePCAConfigFile){
 
    XMLCoreParser p;
    std::unique_ptr<XMLCoreNode> doc = p.parse (inversePCAConfigFile);
 
    ATH_MSG_INFO( "[ punchthrough ] Loading inversePCA: " << inversePCAConfigFile);
 
    //check info first
    m_xml_info_pca = getInfoMap("PCAinverse", *doc);
 
    auto getRow = [] (const XMLCoreNode* node,
                      const std::string& attrib,
                      int imax)
      -> std::vector<double>
    {
      std::vector<double> row;
      for (int i = 0; i <= imax; ++i) {
        // Dynamically create property name
        std::string propName = attrib + std::to_string(i);
        row.push_back (node->get_double_attrib (propName));
      }
      return row;
    };
 
    for (unsigned int i = 0; i < m_xml_info_pca.size(); i++) {
      std::vector<std::vector<double>> PCA_matrix;
 
      if (const XMLCoreNode* node = doc->get_child ("PCAinverse/" + m_xml_info_pca[i].name)) {
        for (const XMLCoreNode* matrix : node->get_children ("PCAmatrix")) {
          PCA_matrix.push_back(getRow(matrix, "comp_", 4));
        }
        for (const XMLCoreNode* means : node->get_children ("PCAmeans")) {
          m_PCA_means.push_back(getRow(means, "mean_", 4));
        }
      }
 
      m_inverse_PCA_matrix.push_back(std::move(PCA_matrix));
    }
    
    return StatusCode::SUCCESS;
}
 
StatusCode ISF::PunchThroughTool::initializeInverseCDF(const std::string & inverseCdfConfigFile){
    //parse xml that contains config for inverse CDF for each of punch through particle kinematics
    XMLCoreParser p;
    std::unique_ptr<XMLCoreNode> doc = p.parse (inverseCdfConfigFile);
 
    ATH_MSG_INFO( "[ punchthrough ] Loading inverse CDF: " << inverseCdfConfigFile);
 
    //check info first
    m_xml_info_cdf = getInfoMap("CDFMappings", *doc);
 
    for (unsigned int i = 0; i < m_xml_info_cdf.size(); i++) {
      ATH_MSG_DEBUG( "[PunchThroughG4Tool] m_xml_info_cdf[" << i << "].name = " << m_xml_info_cdf[i].name);
 
      if (const XMLCoreNode* node = doc->get_child ("CDFMappings/" + m_xml_info_cdf[i].name)) {
        m_variable0_inverse_cdf.push_back(getVariableCDFmappings (node->get_child("variable0")));
        m_variable1_inverse_cdf.push_back(getVariableCDFmappings (node->get_child("variable1")));
        m_variable2_inverse_cdf.push_back(getVariableCDFmappings (node->get_child("variable2")));
        m_variable3_inverse_cdf.push_back(getVariableCDFmappings (node->get_child("variable3")));
        m_variable4_inverse_cdf.push_back(getVariableCDFmappings (node->get_child("variable4")));
      }
    }
 
    return StatusCode::SUCCESS;
}
 
std::map<double, double>
ISF::PunchThroughTool::getVariableCDFmappings(const XMLCoreNode* node){
 
    std::map<double, double>  mappings;
 
    if (node) {
      for (const XMLCoreNode* child : node->get_children ("CDFmap")) {
        double ref = child->get_double_attrib ("ref");
        double quant = child->get_double_attrib ("quant");
        mappings[ref] = quant;
      }
    }
 
    return mappings;
}
 
double ISF::PunchThroughTool::inverseCdfTransform(double variable, const std::map<double, double>& inverse_cdf_map) {
 
    double norm_cdf = normal_cdf(variable);
 
    auto upper = inverse_cdf_map.upper_bound(norm_cdf);
    auto lower = upper--;
 
    double m = (upper->second - lower->second)/(upper->first - lower->first);
    double c = lower->second - m * lower->first;
    double transformed = m * norm_cdf + c;
 
    return transformed;
 
}
 
double ISF::PunchThroughTool::interpolateEnergy(const double &energy, CLHEP::HepRandomEngine* rndmEngine) const{
 
    ATH_MSG_DEBUG("[ punchthrough ] interpolating incoming energy: " << energy);
 
    std::string energyPointsString;
    for (auto element:m_energyPoints){
        energyPointsString += std::to_string(element) + " ";
    }
 
    ATH_MSG_DEBUG("[ punchthrough ] available energy points: " << energyPointsString);
 
    auto const upperEnergy = std::upper_bound(m_energyPoints.begin(), m_energyPoints.end(), energy);
 
    if(upperEnergy == m_etaPoints.end()){ //if no energy greater than input energy, choose greatest energy
        ATH_MSG_DEBUG("[ punchthrough ] incoming energy > largest energy point, returning greatest energy point: " << m_energyPoints.back());
        return m_energyPoints.back();
    }
    else if(upperEnergy == m_etaPoints.begin()){ //if smallest energy greater than input energy, choose smallest energy
        ATH_MSG_DEBUG("[ punchthrough ] incoming energy < smallest energy point, returning smallest energy point: " << *upperEnergy);
        return *upperEnergy;
    }
 
    ATH_MSG_DEBUG("[ punchthrough ] energy points upper_bound: "<< *upperEnergy);
 
    double randomShoot = CLHEP::RandFlat::shoot(rndmEngine);
 
    ATH_MSG_DEBUG("[ punchthrough ] Shooting random number: "<< randomShoot);
 
    double midPoint = *std::prev(upperEnergy)*M_SQRT2;
 
    if(energy <  midPoint){ //if energy smaller than mid point in log(energy)
 
        double distance = std::abs(energy - *std::prev(upperEnergy))/((midPoint) - *std::prev(upperEnergy));
 
        ATH_MSG_DEBUG( "[ punchthrough ] incoming energy is closest to prev(upper_bound) in log(energy), distance: " << distance );
 
        if(randomShoot < distance){
            ATH_MSG_DEBUG( "[ punchthrough ] randomShoot < distance, returning upper_bound " << *upperEnergy );
            return *upperEnergy;
        }
        ATH_MSG_DEBUG( "[ punchthrough ] randomShoot > distance, returning prev(upper_bound) " << *std::prev(upperEnergy) );
 
        return *std::prev(upperEnergy);
    }
    else if(energy >  midPoint){ //if energy greater than mid point in log(energy)
 
        double distance = std::abs(energy - *upperEnergy)/((*upperEnergy - midPoint));
 
        ATH_MSG_DEBUG( "[ punchthrough ] incoming energy is closest to upper_bound in log(energy), distance: " << distance );
 
        if(randomShoot < distance){
            ATH_MSG_DEBUG( "[ punchthrough ] randomShoot < distance, returning prev(upper_bound) " << *std::prev(upperEnergy) );
            return *std::prev(upperEnergy);
        }
        ATH_MSG_DEBUG( "[ punchthrough ] randomShoot > distance, returning upper_bound " << *upperEnergy );
        return *upperEnergy;
    }
 
    return *upperEnergy;
}
 
double ISF::PunchThroughTool::interpolateEta(const double &eta, CLHEP::HepRandomEngine* rndmEngine) const{
 
    double absEta = std::abs(eta);
 
    ATH_MSG_DEBUG("[ punchthrough ] interpolating incoming abs(eta): " << absEta);
 
    std::string etaPointsString;
    for (auto element:m_etaPoints){
        etaPointsString += std::to_string(element) + " ";
    }
 
    ATH_MSG_DEBUG("[ punchthrough ] available eta points: " << etaPointsString);
 
    auto const upperEta = std::upper_bound(m_etaPoints.begin(), m_etaPoints.end(), absEta);
 
    if(upperEta == m_etaPoints.end()){
        ATH_MSG_DEBUG("[ punchthrough ] incoming abs(eta) > largest eta point, returning greatest eta point: " << m_etaPoints.back());
        return m_etaPoints.back();
    }
 
 
    ATH_MSG_DEBUG("[ punchthrough ] eta points upper_bound: "<< *upperEta);
 
    double randomShoot = CLHEP::RandFlat::shoot(rndmEngine);
 
    ATH_MSG_DEBUG("[ punchthrough ] Shooting random number: "<< randomShoot);
 
    if(std::abs(absEta - *upperEta) <  std::abs(absEta - *std::prev(upperEta))){
 
        double distance = std::abs(absEta - *upperEta)/((*upperEta - *std::prev(upperEta))/2);
 
        ATH_MSG_DEBUG( "[ punchthrough ] abs(eta) is closer to eta points upper_bound, distance: " << distance );
 
        if(randomShoot > distance){
            ATH_MSG_DEBUG( "[ punchthrough ] randomShoot > distance, returning upper_bound " << *upperEta );
            return *upperEta;
        }
 
        ATH_MSG_DEBUG( "[ punchthrough ] randomShoot < distance, returning prev(upper_bound) " << *std::prev(upperEta) );
 
        return *std::prev(upperEta);
    }
    else if(std::abs(absEta - *std::prev(upperEta)) <  std::abs(absEta - *upperEta)){
 
        if(std::prev(upperEta) == m_etaPoints.begin()){
            ATH_MSG_DEBUG( "[ punchthrough ] prev of upper bound is begin, returning that: " << *std::prev(upperEta) );
            return *std::prev(upperEta);
        }
 
        double distance = std::abs(absEta - *std::prev(upperEta))/((*std::prev(upperEta) - *std::prev(std::prev(upperEta)))/2);
 
        ATH_MSG_DEBUG( "[ punchthrough ] abs(eta) is closer to eta points prev(upper_bound), distance: " << distance );
 
        if(randomShoot > distance){
            ATH_MSG_DEBUG( "[ punchthrough ] randomShoot > distance, returning prev(prev(upper_bound)) " << *std::prev(std::prev(upperEta)) );
 
            return *std::prev(std::prev(upperEta));
        }
        ATH_MSG_DEBUG( "[ punchthrough ] randomShoot < distance, returning prev(upper_bound) " << *std::prev(upperEta) );
 
        return *std::prev(upperEta);
    }
 
    return *std::prev(upperEta);
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
StatusCode
ISF::PunchThroughTool::registerParticle(int pdg, bool doAntiparticle,
                                        double minEnergy, int maxNumParticles, double numParticlesFactor,
                                        double energyFactor, double posAngleFactor, double momAngleFactor)
{
    // read in the data needed to construct the distributions for the number of punch-through particles
 
      // (1.) get the distribution function for the number of punch-through particles
      std::unique_ptr<ISF::PDFcreator> pdf_num(readLookuptablePDF(pdg, "FREQ_PDG"));
      if (!pdf_num ) return StatusCode::FAILURE; // return error if something went wrong
 
      // (2.) get the PDF for the punch-through energy
      std::unique_ptr<PDFcreator> pdf_pca0 (readLookuptablePDF(pdg, "PCA0_PDG"));
      if (!pdf_pca0)
        {
          return StatusCode::FAILURE; // return error if something went wrong
        }
 
      // (3.) get the PDF for the punch-through particles difference in
      //      theta compared to the incoming particle
      std::unique_ptr<PDFcreator> pdf_pca1 (readLookuptablePDF(pdg, "PCA1_PDG"));
      if (!pdf_pca1)
        {
          return StatusCode::FAILURE;
        }
 
      // (4.) get the PDF for the punch-through particles difference in
      //      phi compared to the incoming particle
      std::unique_ptr<PDFcreator> pdf_pca2 (readLookuptablePDF(pdg, "PCA2_PDG"));
      if (!pdf_pca2)
        {
          return StatusCode::FAILURE;
        }
 
      // (5.) get the PDF for the punch-through particle momentum delta theta angle
      std::unique_ptr<PDFcreator> pdf_pca3 (readLookuptablePDF(pdg, "PCA3_PDG"));
      if (!pdf_pca3)
        {
          return StatusCode::FAILURE;
        }
 
      // (6.) get the PDF for the punch-through particle momentum delta phi angle
      std::unique_ptr<PDFcreator> pdf_pca4 (readLookuptablePDF(pdg, "PCA4_PDG"));
      if (!pdf_pca4)
        {
          return StatusCode::FAILURE;
        }
 
      // (7.) now finally store all this in the right std::map
      PunchThroughParticle *particle = new PunchThroughParticle(pdg, doAntiparticle);
      particle->setNumParticlesPDF(std::move(pdf_num));
      particle->setPCA0PDF(std::move(pdf_pca0));
      particle->setPCA1PDF(std::move(pdf_pca1));
      particle->setPCA2PDF(std::move(pdf_pca2));
      particle->setPCA3PDF(std::move(pdf_pca3));
      particle->setPCA4PDF(std::move(pdf_pca4));
 
      // (8.) set some additional particle and simulation properties
      const double restMass = m_gendata->particleMass(std::abs(pdg)).value();
      minEnergy = ( minEnergy > restMass ) ? minEnergy : restMass;
      particle->setMinEnergy(minEnergy);
      particle->setMaxNumParticles(maxNumParticles);
      particle->setNumParticlesFactor(numParticlesFactor);
      particle->setEnergyFactor(energyFactor);
      particle->setPosAngleFactor(posAngleFactor);
      particle->setMomAngleFactor(momAngleFactor);
 
      // (9.) insert this PunchThroughParticle instance into the std::map class member
      m_particles[pdg] = particle;
 
      return StatusCode::SUCCESS;
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
StatusCode ISF::PunchThroughTool::registerCorrelation(int pdgID1, int pdgID2,
                                                      double minCorrEnergy, double fullCorrEnergy)
{
  // find the given pdgs in the registered particle ids
  std::map<int, PunchThroughParticle*>::iterator location1 = m_particles.find(pdgID1);
  std::map<int, PunchThroughParticle*>::iterator location2 = m_particles.find(pdgID2);
 
  // if at least one of the given pdgs was not registered yet -> return an error
  if ( (location1 == m_particles.end()) || (location2 == m_particles.end()) )
    return StatusCode::FAILURE;
 
  // now look for the correlation histograms
  std::stringstream name;
  name << "NumExitCorrelations/x_PDG" << std::abs(pdgID1) << "__y_PDG" << std::abs(pdgID2) << "__lowE";
  TH2F *hist1_2_lowE = (TH2F*)m_fileLookupTable->Get(name.str().c_str());
  name.str("");
  name << "NumExitCorrelations/x_PDG" << std::abs(pdgID1) << "__y_PDG" << std::abs(pdgID2) << "__highE";
  TH2F *hist1_2_highE = (TH2F*)m_fileLookupTable->Get(name.str().c_str());
  name.str("");
  name << "NumExitCorrelations/x_PDG" << std::abs(pdgID2) << "__y_PDG" << std::abs(pdgID1) << "__lowE";
  TH2F *hist2_1_lowE = (TH2F*)m_fileLookupTable->Get(name.str().c_str());
  name.str("");
  name << "NumExitCorrelations/x_PDG" << std::abs(pdgID2) << "__y_PDG" << std::abs(pdgID1) << "__highE";
  TH2F *hist2_1_highE = (TH2F*)m_fileLookupTable->Get(name.str().c_str());
  // check if the histograms exist
  if ( (!hist1_2_lowE) || (!hist2_1_lowE) || (!hist1_2_highE) || (!hist2_1_highE) )
    {
      ATH_MSG_ERROR("[ punchthrough ] unable to retrieve the correlation data for PDG IDs " << pdgID1 <<  " and " << pdgID2);
      return StatusCode::FAILURE;
    }
 
  // TODO: if only one of the two histograms exists, create the other one
  //       by mirroring the data
 
  const double lowE = getFloatAfterPatternInStr( hist1_2_lowE->GetTitle(), "elow_");
  const double midE = getFloatAfterPatternInStr( hist1_2_lowE->GetTitle(), "ehigh_");
  //TODO: check if the same:
  // double midE = getFloatAfterPatternInStr( hist1_2_lowE->GetTitle(), "elow_");
  const double upperE = getFloatAfterPatternInStr( hist1_2_highE->GetTitle(), "ehigh_");
  // now store the correlation either way  id1->id2 and id2->id1
  m_particles[pdgID1]->setCorrelation(pdgID2, hist2_1_lowE, hist2_1_highE,
                                      minCorrEnergy, fullCorrEnergy,
                                      lowE, midE, upperE);
 
  m_particles[pdgID2]->setCorrelation(pdgID1, hist1_2_lowE, hist1_2_highE,
                                      minCorrEnergy, fullCorrEnergy,
                                      lowE, midE, upperE);
  return StatusCode::SUCCESS;
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *======================================================================*/
 
std::unique_ptr<ISF::PDFcreator> ISF::PunchThroughTool::readLookuptablePDF(int pdg, const std::string& folderName)
{
 
      // will hold the PDFcreator class which will be returned at the end
      // this will store the distributions for the punch through particles
      // (as map of energy & eta of the incoming particle)
      //PDFcreator *pdf = new PDFcreator();
      std::unique_ptr<ISF::PDFcreator> pdf = std::make_unique<ISF::PDFcreator>();
 
          //Get directory object
          std::stringstream dirName;
          dirName << folderName << pdg;
          pdf->setName(dirName.str().c_str());
 
          TDirectory * dir = (TDirectory*)m_fileLookupTable->Get(dirName.str().c_str());
          if(! dir)
          {
            ATH_MSG_ERROR( "[ punchthrough ] unable to retrieve directory object ("<< folderName << pdg << ")" );
            return nullptr;
          }
 
 
 
          //Get list of all objects in directory
          TIter keyList(dir->GetListOfKeys());
          TKey *key;
 
          while ((key = (TKey*)keyList())) {
 
            //Get histogram object from key and its name
            TH1* hist = nullptr;
 
            std::string histName;
            if(strcmp(key->GetClassName(), "TH1F") == 0){
              hist = (TH1*)key->ReadObj();
              histName = hist->GetName();
            }
 
            //extract energy and eta from hist name 6 and 1 to position delimeters correctly
            std::string strEnergy = histName.substr( histName.find_first_of('E') + 1, histName.find_first_of('_')-histName.find_first_of('E') - 1 );
            histName.erase(0, histName.find_first_of('_') + 1);
            std::string strEtaMin = histName.substr( histName.find("etaMin") + 6, histName.find_first_of('_') - histName.find("etaMin") - 6 );
            histName.erase(0, histName.find('_') + 1);
            std::string strEtaMax = histName.substr( histName.find("etaMax") + 6, histName.length());
 
            //create integers to store in map
            const int energy = std::stoi(strEnergy);
            const int etaMin = std::stoi(strEtaMin);
 
            //Add entry to pdf map
            pdf->addToEnergyEtaHist1DMap(energy, etaMin, hist);
 
            //create doubles to store energy and eta points for interpolation
            const double energyDbl = static_cast<double>(energy);
            const double etaDbl = static_cast<double>(etaMin)/100.;
 
            //create vectors to store the eta and energy points, this allows us to interpolate
            if (std::find(m_energyPoints.begin(), m_energyPoints.end(), energyDbl) == m_energyPoints.end()) {
                m_energyPoints.push_back(energyDbl);
            }
            if (std::find(m_etaPoints.begin(), m_etaPoints.end(), etaDbl) == m_etaPoints.end()) {
                m_etaPoints.push_back(etaDbl);
            }
 
          }
 
 
 
      return pdf;
}
 
/* =========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=========================================================================*/
 
ISF::ISFParticle* ISF::PunchThroughTool::createExitPs( const ISF::ISFParticle &isfp, int pdg,
                                                       double energy, double theta, double phi,double momTheta, double momPhi) const
{
  // the intersection point with Calo-MS surface
 
  const Amg::Vector3D pos = propagator(theta,phi);
 
  // set up the real punch-through particle at this position
  // set up the momentum vector of this particle as a GlobalMomentum
  // by using the given energy and mass of the particle and also using
  // the given theta and phi
 
  Amg::Vector3D mom;
  double mass = m_gendata->particleMass(std::abs(pdg)).value();
  Amg::setRThetaPhi( mom, std::sqrt(energy*energy - mass*mass), momTheta, momPhi);
  ATH_MSG_DEBUG("setRThetaPhi pre input parameters: energy = "<< energy <<" mass = "<< mass);
  ATH_MSG_DEBUG("setRThetaPhi input parameters: std::sqrt(energy*energy - mass*mass) = "<< std::sqrt(energy*energy - mass*mass) <<" momTheta = "<< momTheta <<" momPhi = "<< momPhi);
 
 
  double charge = MC::charge(std::abs(pdg));
  // since the PDT table only has abs(PID) values for the charge
  charge *= (pdg > 0.) ?  1. : -1.;
 
  const double pTime = 0;  
  const int status = 1 + HepMC::SIM_STATUS_THRESHOLD;
  const int id = HepMC::UNDEFINED_ID;
  // NB we are not considering the possibility that the punch-through
  // particle is the incoming particle having survived an interaction.
  ISF::ISFParticle* finalPar = new ISF::ISFParticle ( pos, mom, mass, charge, pdg, status, pTime, isfp, id);
  finalPar->setNextGeoID( AtlasDetDescr::fAtlasMS);
 
  // return the punch-through particle
  return finalPar;
}
 
/*=========================================================================
 *  DESCRIPTION OF FUNCTION:
 *  ==> see headerfile
 *=======================================================================*/
 
double ISF::PunchThroughTool::getFloatAfterPatternInStr(const char *cstr, const char *cpattern)
{
  double num = 0.;
 
  const std::string_view str( cstr);
  const std::string_view pattern( cpattern);
  const size_t pos = str.find(pattern);
 
  if ( pos == std::string::npos)
    {
      ATH_MSG_WARNING("[ punchthrough ] unable to retrieve floating point number from string");
      return -999999999999.;
    }
  const std::string_view substring = str.substr(pos+pattern.length());
  std::from_chars(substring.data(), substring.data() + substring.size(), num);
  return num;
}
 
Amg::Vector3D ISF::PunchThroughTool::propagator(double theta,double phi) const
{
  // phi, theta - direction of the punch-through particle coming into calo
  //particle propagates inside the calorimeter along the straight line
  //coordinates of this particles when exiting the calo (on calo-MS boundary)
 
  double x, y, z, r;
 
  // cylinders border angles
  const double theta1 = atan (m_R1/m_z1);
  const double theta2 = atan (m_R1/m_z2);
  const double theta3 = atan (m_R2/m_z2);
  //where is the particle
 
  if (theta >= 0 && theta < theta1)
    {
      z = m_z1;
      r = std::fabs (m_z1*tan(theta));
    }
  else if (theta >= theta1 && theta < theta2)
    {
      z = m_R1/tan(theta);
      r = m_R1;
    }
  else if (theta >= theta2 && theta < theta3)
    {
      z = m_z2;
      r = std::fabs(m_z2*tan(theta));;
    }
  else if (theta >= theta3 && theta < (TMath::Pi()-theta3) )
    {
      z = m_R2/tan(theta);
      r = m_R2;
    }
  else if (theta >= (TMath::Pi()-theta3) && theta < (TMath::Pi()-theta2) )
    {
      z = -m_z2;
      r = std::fabs(m_z2*tan(theta));
    }
  else if (theta >= (TMath::Pi()-theta2) && theta < (TMath::Pi()-theta1) )
    {
      z = m_R1/tan(theta);
      r = m_R1;
    }
  else if (theta >= (TMath::Pi()-theta1) && theta <= TMath::Pi() )
    {
      z = -m_z1;
      r = std::fabs(m_z1*tan(theta));
    }
 
  //parallel universe
  else
    {
      ATH_MSG_WARNING ( "Given theta angle is incorrect, setting particle position to (0, 0, 0)");
      x = 0.0; y = 0.0; z = 0.0; r = 0.0;
    }
 
  x = r*cos(phi);
  y = r*sin(phi);
  Amg::Vector3D pos(x, y, z);
 
  ATH_MSG_DEBUG("position of produced punch-through particle: x = "<< x <<" y = "<< y <<" z = "<< z<<" r = "<< pos.perp() <<"std::sqrt(x^2+y^2) = "<< std::sqrt(x*x+y*y) );
  ATH_MSG_DEBUG("GeoID thinks: Calo: "<< m_geoIDSvc->inside(pos, AtlasDetDescr::fAtlasCalo) <<" MS: "<< m_geoIDSvc->inside(pos,AtlasDetDescr::fAtlasMS));
 
  return pos;
}