EGammaClusterCoreCellRecovery.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
// Author: G. Unal (Guillaume.Unal@cern.ch)
// Decorate egamma objects with the energies in L2 and L3 that are in cells
// not included in the original supercluser due to the timing cut in topocluster
// building. This is an AOD fix for data (and mc, but effect is small for mc)
// produced with rel23 (and 24 ?)
 
#include "DerivationFrameworkCalo/EGammaClusterCoreCellRecovery.h"
#include "CaloEvent/CaloCell.h"
 
#include <TString.h>
#include <string>
namespace {}
 
// Athena initialize
StatusCode
DerivationFramework::EGammaClusterCoreCellRecovery::initialize()
{
  ATH_MSG_VERBOSE("initialize() ...");
 
  // The main tool
  ATH_CHECK(m_egammaCellRecoveryTool.retrieve());
 
  if (m_SGKey_photons.key().empty() && m_SGKey_electrons.key().empty()) {
    ATH_MSG_FATAL("No e-gamma collection provided for thinning. At least one "
                  "egamma collection (photons/electrons) must be provided!");
    return StatusCode::FAILURE;
  }
 
  ATH_CHECK(m_SGKey_electrons.initialize(SG::AllowEmpty));
  ATH_CHECK(m_SGKey_electrons_decorations.initialize(!m_SGKey_electrons.key().empty()));
  if (!m_SGKey_electrons.key().empty()) {
    ATH_MSG_DEBUG("Using " << m_SGKey_electrons.key() << " for electrons");
    if (msgLvl(MSG::DEBUG)) {
      ATH_MSG_DEBUG("Decorations for " << m_SGKey_electrons.key());
      for (const auto& s : m_SGKey_electrons_decorations)
        { ATH_MSG_DEBUG(s.key()); }
    }
  }
 
  // This tool needs the calo cells linked to the clusters...
  ATH_CHECK(m_SGKey_CaloCells.initialize());
 
  ATH_CHECK(m_SGKey_photons.initialize(SG::AllowEmpty));
  ATH_CHECK(m_SGKey_photons_decorations.initialize(!m_SGKey_photons.key().empty()));
  if (!m_SGKey_photons.key().empty()) {
    ATH_MSG_DEBUG("Using " << m_SGKey_photons.key() << " for photons");
    if (msgLvl(MSG::DEBUG)) {
      ATH_MSG_DEBUG("Decorations for " << m_SGKey_photons.key());
      for (const auto& s : m_SGKey_photons_decorations)
        { ATH_MSG_DEBUG(s.key()); }
    }
  }
 
  return StatusCode::SUCCESS;
}
 
 
// The decoration itself
StatusCode
DerivationFramework::EGammaClusterCoreCellRecovery::addBranches(const EventContext& ctx) const
{
 
  std::vector<SG::WriteDecorHandle<xAOD::EgammaContainer, char>> decon;
  std::vector<SG::WriteDecorHandle<xAOD::EgammaContainer, float>> decoE;
  decon.reserve(2);
  decoE.reserve(2);
 
  // Photon decorations
  if (!m_SGKey_photons.key().empty()) {
 
    for (int i = 0; i < 2; i++) {
      decon.emplace_back(m_SGKey_photons_decorations[i * 2], ctx);
      decoE.emplace_back(m_SGKey_photons_decorations[i * 2 + 1], ctx);
    }
 
    // Retrieve photon container
    SG::ReadHandle<xAOD::EgammaContainer> photonContainer(m_SGKey_photons, ctx);
 
    // Decorate photons
    for (const auto* photon : *photonContainer.ptr()) {
      IegammaCellRecoveryTool::Info res = decorateObject(photon);
      for (int i = 0; i < 2; i++) {
        decon[i](*photon) = res.nCells[i];
        decoE[i](*photon) = res.eCells[i];
      }
    }
  }
 
  // Electron decorations
  if (!m_SGKey_electrons.key().empty()) {
 
    decon.clear(); decon.reserve(2);
    decoE.clear(); decoE.reserve(2);
 
    for (int i = 0; i < 2; i++) {
      decon.emplace_back(m_SGKey_electrons_decorations[i * 2], ctx);
      decoE.emplace_back(m_SGKey_electrons_decorations[i * 2 + 1], ctx);
    }
 
    // Retrieve electron container
    SG::ReadHandle<xAOD::EgammaContainer> electronContainer(m_SGKey_electrons,
                                                            ctx);
 
    // Decorate electrons
    for (const auto* electron : *electronContainer.ptr()) {
      IegammaCellRecoveryTool::Info res = decorateObject(electron);
      for (int i = 0; i < 2; i++) {
        decon[i](*electron) = res.nCells[i];
        decoE[i](*electron) = res.eCells[i];
      }
    }
  }
 
  return StatusCode::SUCCESS;
}
 
IegammaCellRecoveryTool::Info
DerivationFramework::EGammaClusterCoreCellRecovery::decorateObject(
                                                                   const xAOD::Egamma*& egamma) const
{
  IegammaCellRecoveryTool::Info info{};
 
  ATH_MSG_DEBUG("Trying to recover cell for object of type " << egamma->type()
                << " pT = " << egamma->pt()
                << " eta = " << egamma->eta()
                << " phi = " << egamma->phi());
 
  const xAOD::CaloCluster *clus = egamma->caloCluster();
  if (!clus) {
    ATH_MSG_WARNING("No associated egamma cluster. Do nothing");
    return info;
  }
 
  // Find max energy cell in layer 2
  double etamax = -999., phimax = -999.;
  if (findMaxECell(clus,etamax,phimax).isFailure()) {
    ATH_MSG_WARNING("Problem in finding maximum energy cell in layer 2");
    return info;
  }
 
  info.etamax = etamax;
  info.phimax = phimax;
  if (m_egammaCellRecoveryTool->execute(*clus,info).isFailure()) {
    ATH_MSG_WARNING("Issue trying to recover cells");
  }
  return info;
}
 
StatusCode
DerivationFramework::EGammaClusterCoreCellRecovery::findMaxECell(
                                                                 const xAOD::CaloCluster *clus, double &etamax, double &phimax) const
{
  const CaloClusterCellLink* cellLinks = clus->getCellLinks();
  if (!cellLinks) {
    ATH_MSG_WARNING("No cell link for cluster. Do nothing");
    return StatusCode::FAILURE;
  }
 
  // First check :
  // if we run in MT, this would be nullptr without initializing a ReadHandleKey
  const CaloCellContainer *caloCells = cellLinks->getCellContainer();
  if (!caloCells) {
    ATH_MSG_WARNING("No cells for cluster. Do nothing");
    return StatusCode::FAILURE;
  }
 
  // Second check :
  // one might have used a custom cell container for the linked cells
  if (cellLinks->getCellContainerLink().dataID() != m_SGKey_CaloCells.key()) {
    ATH_MSG_ERROR("Wrong key for the calo cells");
    return StatusCode::FAILURE;
  }
 
  CaloClusterCellLink::const_iterator it_cell = cellLinks->begin(),
    it_cell_e = cellLinks->end();
 
  // find maximum cell energy in layer 2
  double emax = 0.;
  std::pair<const CaloCell*,double> maxcell{nullptr,0}; //just for debug
  for(; it_cell != it_cell_e; ++it_cell) {
    const CaloCell* cell = (*it_cell);
    if (cell) {
      if (!cell->caloDDE()) {
        ATH_MSG_WARNING("Calo cell without detector element ?? eta = "
                        << cell->eta() << " phi = " << cell->phi());
        continue;
      }
      int layer = cell->caloDDE()->getSampling();
      if (layer == CaloSampling::EMB2 || layer == CaloSampling::EME2) {
        double w     = it_cell.weight();
        double eCell = cell->energy();
        if (m_UseWeightForMaxCell) eCell *= w;
        if (eCell > emax) {
          emax           = eCell;
          maxcell.first  = cell;
          maxcell.second = w;
        }
      }
    }
  }
 
  if (emax > 0) {
    etamax = maxcell.first->caloDDE()->eta_raw();
    phimax = maxcell.first->caloDDE()->phi_raw();
    if (msgLvl(MSG::DEBUG)) {
      CaloSampling::CaloSample sam = maxcell.first->caloDDE()->getSampling();
      double etaAmax = clus->etamax(sam);
      double phiAmax = clus->phimax(sam);
      double vemax   = clus->energy_max(sam);
      ATH_MSG_DEBUG("Cluster energy in sampling 2 = " << clus->energyBE(2)
                    << " maximum layer 2 energy cell, E = " << maxcell.first->energy()
                    << " check E = " << vemax
                    << " w = " << maxcell.second << "\n"
                    << " in calo  frame, eta = " << etamax << " phi = " << phimax << "\n"
                    << " in ATLAS frame, eta = " << etaAmax << " phi = " << phiAmax);
    }
  } else {
    ATH_MSG_WARNING("No layer 2 cell with positive energy ! Should never happen");
    return StatusCode::FAILURE;
  }
  return StatusCode::SUCCESS;
}