[PWGJE] [PWGJE]Add offline time calibration for data in EMCalCorrectionTask (#8513)

Co-authored-by: Nicolas Strangmann <nicolas.strangmann@.cern.ch>

Author: nstrangm

PWGJE/TableProducer/emcalCorrectionTask.cxx

@@ -19,6 +19,9 @@
 #include <memory>
 #include <unordered_map>
 #include <cmath>
+#include <string>
+#include <tuple>
+#include <vector>
 
 #include "CCDB/BasicCCDBManager.h"
 #include "Framework/runDataProcessing.h"
@@ -87,7 +90,7 @@ struct EmcalCorrectionTask {
   Configurable<float> exoticCellInCrossMinAmplitude{"exoticCellInCrossMinAmplitude", 0.1, "Minimum energy of cells in cross, if lower not considered in cross"};
   Configurable<bool> useWeightExotic{"useWeightExotic", false, "States if weights should be used for exotic cell cut"};
   Configurable<bool> isMC{"isMC", false, "States if run over MC"};
-  Configurable<int> applyCellTimeShift{"applyCellTimeShift", 0, "apply shift to the cell time; 0 = off; 1 = const shift; 2 = eta-dependent shift"};
+  Configurable<int> applyCellTimeShift{"applyCellTimeShift", 0, "apply shift to the cell time for data and MC; For data: 0 = off; non-zero = log function extracted from data - For MC: 0 = off; 1 = const shift; 2 = eta-dependent shift"};
 
   // Require EMCAL cells (CALO type 1)
   Filter emccellfilter = aod::calo::caloType == selectedCellType;
@@ -264,7 +267,7 @@ struct EmcalCorrectionTask {
         }
         cellsBC.emplace_back(cell.cellNumber(),
                              amplitude,
-                             cell.time() + getCellTimeShift(cell.cellNumber()),
+                             cell.time() + getCellTimeShift(cell.cellNumber(), amplitude),
                              o2::emcal::intToChannelType(cell.cellType()));
         cellIndicesBC.emplace_back(cell.globalIndex());
       }
@@ -383,7 +386,7 @@ struct EmcalCorrectionTask {
         }
         cellsBC.emplace_back(cell.cellNumber(),
                              amplitude,
-                             cell.time() + getCellTimeShift(cell.cellNumber()),
+                             cell.time() + getCellTimeShift(cell.cellNumber(), amplitude),
                              o2::emcal::intToChannelType(cell.cellType()));
         cellIndicesBC.emplace_back(cell.globalIndex());
         cellLabels.emplace_back(cell.mcParticleIds(), cell.amplitudeA());
@@ -485,7 +488,7 @@ struct EmcalCorrectionTask {
       for (auto& cell : cellsInBC) {
         cellsBC.emplace_back(cell.cellNumber(),
                              cell.amplitude(),
-                             cell.time() + getCellTimeShift(cell.cellNumber()),
+                             cell.time() + getCellTimeShift(cell.cellNumber(), cell.amplitude()),
                              o2::emcal::intToChannelType(cell.cellType()));
         cellIndicesBC.emplace_back(cell.globalIndex());
       }
@@ -790,9 +793,10 @@ struct EmcalCorrectionTask {
     }
   }
 
-  // Apply shift of the cell time
-  // This has to be done to shift the cell time in MC (which is not calibrated to 0 due to the flight time of the particles to the EMCal surface (~15ns))
-  float getCellTimeShift(const int16_t cellID)
+  // Apply shift of the cell time in data and MC
+  // In MC this has to be done to shift the cell time, which is not calibrated to 0 due to the flight time of the particles to the EMCal surface (~15ns)
+  // In data this is done to correct for the time walk effect
+  float getCellTimeShift(const int16_t cellID, const float cellEnergy)
   {
     if (isMC) {
       if (applyCellTimeShift == 1) { // constant shift
@@ -810,7 +814,16 @@ struct EmcalCorrectionTask {
         return 0.f;
       }
     } else { // data
-      return 0.f;
+      if (applyCellTimeShift != 0) {
+        if (cellEnergy < 0.3) // Cells with tless than 300 MeV cannot be the leading cell in the cluster, so their time does not require precise calibration
+          return 0.f;
+        else if (cellEnergy < 4.)                                         // Low energy regime
+          return (0.57284 + 0.82194 * TMath::Log(1.30651 * cellEnergy));  // Parameters extracted from LHC22o (pp), but also usable for other periods
+        else                                                              // High energy regime
+          return (-0.05858 + 1.50593 * TMath::Log(0.97591 * cellEnergy)); // Parameters extracted from LHC22o (pp), but also usable for other periods
+      } else {                                                            // Dont apply cell time shift if applyCellTimeShift == 0
+        return 0.f;
+      }
     }
   }
 };