[PWGEM/PhotonMeson] Add gen mult histogram for bc wise analysis (#11227)

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

Author: nstrangm

PWGEM/PhotonMeson/TableProducer/bcWiseClusterSkimmer.cxx

@@ -75,6 +75,7 @@ struct bcWiseClusterSkimmer {
   Configurable<bool> cfgRequirekTVXinEMC{"cfgRequirekTVXinEMC", false, "Only store kTVXinEMC triggered BCs"};
   Configurable<bool> cfgRequireGoodRCTQuality{"cfgRequireGoodRCTQuality", false, "Only store BCs with good quality of T0 and EMC in RCT"};
   Configurable<bool> cfgStoreMu{"cfgStoreMu", false, "Calculate and store mu (probablity of a TVX collision in the BC) per BC. Otherwise fill with 0"};
+  ConfigurableAxis cfgMultiplicityBinning{"cfgMultiplicityBinning", {1000, 0, 10000}, "Binning used for the binning of the number of particles in the event"};
 
   aod::rctsel::RCTFlagsChecker isFT0EMCGoodRCTChecker{aod::rctsel::kFT0Bad, aod::rctsel::kEMCBad};
   parameters::GRPLHCIFData* mLHCIFdata = nullptr;
@@ -98,6 +99,8 @@ struct bcWiseClusterSkimmer {
     for (int iBin = 0; iBin < nEventBins; iBin++)
       mHistManager.get<TH1>(HIST("nBCs"))->GetXaxis()->SetBinLabel(iBin + 1, binLabels[iBin]);
 
+    mHistManager.add("CentralityVsGenMultiplicity", "Centrality vs number of generated MC particles;Centrality;#bf{#it{N}_{gen}}", HistType::kTH2F, {{102, 0., 102}, cfgMultiplicityBinning});
+
     LOG(info) << "BC wise cluster skimmer cuts:";
     LOG(info) << "------------------------------------";
     LOG(info) << "| Timing cut: " << cfgMinTime << " < t < " << cfgMaxTime;
@@ -310,6 +313,10 @@ struct bcWiseClusterSkimmer {
       auto mcCollisionsBC = mcCollisions.sliceBy(mcCollperBC, bc.globalIndex());
       for (const auto& mcCollision : mcCollisionsBC) {
         auto mcParticlesInColl = mcParticles.sliceBy(perMcCollision, mcCollision.globalIndex());
+        double centrality = 101.5;
+        if (collisionsInBC.size() > 0)
+          centrality = collisionsInBC.iteratorAt(0).centFT0M();
+        mHistManager.fill(HIST("CentralityVsGenMultiplicity"), centrality, mcParticlesInColl.size());
         for (const auto& mcParticle : mcParticlesInColl) {
           if (mcParticle.pdgCode() != 111 || std::abs(mcParticle.y()) > cfgRapidityCut || !isGammaGammaDecay(mcParticle, mcParticles) || mcParticle.pt() < cfgMinPtGenPi0)
             continue;

PWGEM/PhotonMeson/Tasks/mcGeneratorStudies.cxx

@@ -31,16 +31,23 @@ struct MCGeneratorStudies {
   HistogramRegistry mHistManager{"MCGeneratorStudyHistograms"};
   Configurable<int> cfgSelectedParticleCode{"cfgSelectedParticleCode", 111, "PDG code of the particle to be investigated"};
   Configurable<float> cfgMaxZVertex{"cfgMaxZVertex", 10, "Maximum absolute z-vertex distance (cm)"};
+  Configurable<float> cfgRapidityCut{"cfgRapidityCut", 0.8, "Maximum absolute rapditity of selected generated particles"};
+  ConfigurableAxis cfgMultiplicityBinning{"cfgMultiplicityBinning", {1000, 0, 10000}, "Binning used for the binning of the number of particles in the event"};
   expressions::Filter zVertexFilter = aod::mccollision::posZ < cfgMaxZVertex && aod::mccollision::posZ > -cfgMaxZVertex;
 
-  void init(InitContext const&) { mHistManager.add("YieldVsNParticles", "pT of selected particles in all MC collisions vs number of all generated particles in event;#bf{#it{p}_{T} (GeV/#it{c})};#bf{#it{N} (Multiplicity)};#bf{#it{N}}", HistType::kTH2F, {{200, 0, 20}, {1000, 0, 10000}}); }
+  void init(InitContext const&)
+  {
+    mHistManager.add("Multiplicity", "Number of generated particles per MC collision;#bf{#it{N} (Multiplicity)};#bf{#it{N}_{MC collisions}}", HistType::kTH1F, {cfgMultiplicityBinning});
+    mHistManager.add("YieldVsMultiplicity", "pT of selected particles in all MC collisions vs number of all generated particles in event;#bf{#it{p}_{T} (GeV/#it{c})};#bf{#it{N} (Multiplicity)};#bf{#it{N}}", HistType::kTH2F, {{200, 0, 20}, cfgMultiplicityBinning});
+  }
 
   void process(soa::Filtered<aod::McCollisions>::iterator const&, aod::McParticles const& mcParticles)
   {
     int nParticles = mcParticles.size();
+    mHistManager.fill(HIST("Multiplicity"), nParticles);
     for (auto& mcParticle : mcParticles) {
-      if (mcParticle.pdgCode() == cfgSelectedParticleCode && std::abs(mcParticle.y()) < 0.8f)
-        mHistManager.fill(HIST("YieldVsNParticles"), mcParticle.pt(), nParticles);
+      if (mcParticle.pdgCode() == cfgSelectedParticleCode && std::abs(mcParticle.y()) < cfgRapidityCut)
+        mHistManager.fill(HIST("YieldVsMultiplicity"), mcParticle.pt(), nParticles);
     }
   }
 };