findMaxECell.cxx

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/*
 Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
#include "egammaCaloUtils/findMaxECell.h"
 
#include "CaloEvent/CaloClusterCellLinkContainer.h"
#include "CaloEvent/CaloCellContainer.h"
 
namespace egammaCellUtils
{
  MaxECell::MaxECell(
   const xAOD::CaloCluster *clus,
   const std::string &cellCKey, bool UseWeightForMaxCell) :
    AthMessaging("egammaCellUtils::MaxECell") {
    
    const CaloClusterCellLink* cellLinks = clus->getCellLinks();
    if (!cellLinks) {
      ATH_MSG_WARNING("No cell link for cluster. Do nothing");
    } else {
    
      // First check :
      const CaloCellContainer *caloCells = cellLinks->getCellContainer();
      if (!caloCells) {
    ATH_MSG_WARNING("No cells for cluster. Do nothing");
      } else if (cellLinks->getCellContainerLink().dataID() != cellCKey) {
    // Second check :
    // one might have used a custom cell container for the linked cells
    ATH_MSG_ERROR("Wrong key for the calo cells");
      } else {
    
    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 (UseWeightForMaxCell) eCell *= w;
          if (eCell > emax) {
        emax           = eCell;
        maxcell.first  = cell;
        maxcell.second = w;
          }
        }
      }
    }
    
    if (emax > 0) {
      etaCell = maxcell.first->caloDDE()->eta_raw();
      phiCell = 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 = " << etaCell << " phi = " << phiCell << "\n"
              << " in ATLAS frame, eta = " << etaAmax << " phi = " << phiAmax);
      }
    } else {
      ATH_MSG_WARNING("No layer 2 cell with positive energy ! Should never happen");
      sc = StatusCode::FAILURE;
    }
    sc = StatusCode::SUCCESS;
      } // links OK, good cell container
    }   // no links 
  } // end function
}