[StrangenessTracking] Pass ITS cluster info to AO2Ds

Author: Francesco Mazzaschi

DataFormats/Reconstruction/include/ReconstructionDataFormats/StrangeTrack.h

@@ -35,10 +35,49 @@ struct StrangeTrack {
   unsigned int mDecayRef = -1;
   std::array<float, 3> mDecayVtx;
   std::array<float, 3> mDecayMom;
-  std::array<float, 2> mMasses; // V0: hypertriton and hyperhydrongen4, cascade: Xi and Omega.
-  float mITSClusSize;
+  std::array<float, 2> mMasses;    // V0: hypertriton and hyperhydrongen4, cascade: Xi and Omega.
+  unsigned int mClusterSizes = 0u; // same encoding used for the ITS track
   float mMatchChi2;
   float mTopoChi2;
+
+  void setClusterSize(int l, int size)
+  {
+    if (l >= 8) {
+      return;
+    }
+    if (size > 15) {
+      size = 15;
+    }
+    mClusterSizes &= ~(0xf << (l * 4));
+    mClusterSizes |= (size << (l * 4));
+  }
+
+  int getClusterSize(int l) const
+  {
+    if (l >= 7) {
+      return 0;
+    }
+    return (mClusterSizes >> (l * 4)) & 0xf;
+  }
+
+  int getClusterSizes() const
+  {
+    return mClusterSizes;
+  }
+
+  float getAverageClusterSize() const
+  {
+    int nClusters = 0;
+    int nClustersSize = 0;
+    for (int i = 0; i < 7; ++i) {
+      int size = getClusterSize(i);
+      if (size > 0) {
+        nClustersSize += size;
+        nClusters++;
+      }
+    }
+    return nClusters > 0 ? static_cast<float>(nClustersSize) / nClusters : 0.f;
+  }
 };
 
 } // namespace dataformats

Detectors/AOD/src/AODProducerWorkflowSpec.cxx

@@ -545,6 +545,7 @@ void AODProducerWorkflowDPL::fillTrackTablesPerCollision(int collisionID,
     auto& sTrk = sTracks[collStrTrk.second];
     TrackExtraInfo extraInfo;
     extraInfo.itsChi2NCl = sTrk.mTopoChi2; // TODO: this is the total chi2 of adding the ITS clusters, the topology chi2 meaning might change in the future
+    extraInfo.itsClusterSizes = sTrk.getClusterSizes();
     addToTracksTable(tracksCursor, tracksCovCursor, sTrk.mMother, collisionID, aod::track::StrangeTrack);
     addToTracksExtraTable(tracksExtraCursor, extraInfo);
     mStrTrkIndices[collStrTrk.second] = mTableTrID;
@@ -1378,7 +1379,7 @@ void AODProducerWorkflowDPL::fillStrangenessTrackingTables(const o2::globaltrack
              sTrk.mMasses[1],
              sTrk.mMatchChi2,
              sTrk.mTopoChi2,
-             sTrk.mITSClusSize);
+             sTrk.getAverageClusterSize());
     } else if (sTrk.mPartType == dataformats::kStrkCascade) {
       cascCurs(mStrTrkIndices[sTrkID++],
                itsTableIdx,
@@ -1390,7 +1391,7 @@ void AODProducerWorkflowDPL::fillStrangenessTrackingTables(const o2::globaltrack
                sTrk.mMasses[1],
                sTrk.mMatchChi2,
                sTrk.mTopoChi2,
-               sTrk.mITSClusSize);
+               sTrk.getAverageClusterSize());
     } else {
       d3BodyCurs(mStrTrkIndices[sTrkID++],
                  itsTableIdx,
@@ -1402,7 +1403,7 @@ void AODProducerWorkflowDPL::fillStrangenessTrackingTables(const o2::globaltrack
                  sTrk.mMasses[1],
                  sTrk.mMatchChi2,
                  sTrk.mTopoChi2,
-                 sTrk.mITSClusSize);
+                 sTrk.getAverageClusterSize());
     }
   }
 }

Detectors/Vertexing/StrangenessTracking/src/StrangenessTracker.cxx

@@ -351,7 +351,6 @@ bool StrangenessTracker::matchDecayToITStrack(float decayR, StrangeTrack& strang
   auto nMinClusMother = trackClusters.size() < 4 ? 2 : mStrParams->mMinMotherClus;
 
   std::vector<ITSCluster> motherClusters;
-  std::vector<int> motherClusSizes;
   std::array<unsigned int, 7> nAttachments;
   nAttachments.fill(-1); // fill arr with -1
 
@@ -365,14 +364,15 @@ bool StrangenessTracker::matchDecayToITStrack(float decayR, StrangeTrack& strang
     double clusRad = sqrt(clus.getX() * clus.getX() - clus.getY() * clus.getY());
     auto diffR = decayR - clusRad;
     auto relDiffR = diffR / decayR;
+    auto lay = geom->getLayer(clus.getSensorID());
     // Look for the Mother if the Decay radius allows for it, within a tolerance
     LOG(debug) << "decayR: " << decayR << ", diffR: " << diffR << ", clus rad: " << clusRad << ", radTol: " << radTol;
     if (relDiffR > -radTol) {
-      LOG(debug) << "Try to attach cluster to Mother, layer: " << geom->getLayer(clus.getSensorID());
+      LOG(debug) << "Try to attach cluster to Mother, layer: " << lay;
       if (updateTrack(clus, strangeTrack.mMother)) {
         motherClusters.push_back(clus);
-        motherClusSizes.push_back(compClus);
-        nAttachments[geom->getLayer(clus.getSensorID())] = 0;
+        strangeTrack.setClusterSize(lay, compClus);
+        nAttachments[lay] = 0;
         isMotherUpdated = true;
         nUpdates++;
         LOG(debug) << "Cluster attached to Mother";
@@ -383,11 +383,11 @@ bool StrangenessTracker::matchDecayToITStrack(float decayR, StrangeTrack& strang
     // if Mother is not found, check for V0 daughters compatibility
     if (relDiffR < radTol && !isMotherUpdated) {
       bool isDauUpdated = false;
-      LOG(debug) << "Try to attach cluster to Daughters, layer: " << geom->getLayer(clus.getSensorID());
+      LOG(debug) << "Try to attach cluster to Daughters, layer: " << lay;
       for (int iDau{0}; iDau < daughterTracks.size(); iDau++) {
         auto& dauTrack = daughterTracks[iDau];
         if (updateTrack(clus, dauTrack)) {
-          nAttachments[geom->getLayer(clus.getSensorID())] = iDau + 1;
+          nAttachments[lay] = iDau + 1;
           isDauUpdated = true;
           break;
         }
@@ -419,9 +419,6 @@ bool StrangenessTracker::matchDecayToITStrack(float decayR, StrangeTrack& strang
     }
   }
 
-  // compute mother average cluster size
-  strangeTrack.mITSClusSize = float(std::accumulate(motherClusSizes.begin(), motherClusSizes.end(), 0)) / motherClusSizes.size();
-
   LOG(debug) << "Inward-outward refit finished, starting final topology refit";
   // final Topology refit