Central PbPb generator with strangeness

Author: jesgum

MC/config/ALICE3/ini/central_strangeness_PbPb_552tev.ini

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+[Diamond]
+width[2]=6.0
+
+[GeneratorExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/pythia8/generator_pythia8_central_strangeness_gun_PbPb.C
+funcName=generatePYTHIA()
+
+[GeneratorPythia8]
+config=${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/pythia8/generator/pythia8_central_hi.cfg

MC/config/ALICE3/ini/tests/central_strangeness_PbPb_552tev.C

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+int External() 
+{
+  std::string path{"o2sim_Kine.root"};
+
+  TFile file(path.c_str(), "READ");
+  if (file.IsZombie()) {
+    std::cerr << "Cannot open ROOT file " << path << "\n";
+    return 1;
+  }
+
+  auto tree = (TTree *)file.Get("o2sim");
+  if (!tree) {
+    std::cerr << "Cannot find tree o2sim in file " << path << "\n";
+    return 1;
+  }
+
+  std::vector<o2::MCTrack> *tracks{};
+  tree->SetBranchAddress("MCTrack", &tracks);
+  auto nEvents = tree->GetEntries();
+  int nTracks = 0;
+  for (int i = 0; i < nEvents; i++) {
+    tree->GetEntry(i);
+    nTracks += tracks->size();
+  }
+
+  const int meanNTracksPerEvent = nTracks / nEvents;
+
+  // Expecting only events with a 0-10% centrality
+  // 0-100%  gives a mean of ~1350
+
+  if (meanNTracksPerEvent < 1300) {
+    return 1;
+  }
+
+  return 0;
+}

MC/config/ALICE3/pythia8/generator/pythia8_central_hi.cfg

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+### Specify beams
+Beams:idA = 1000822080
+Beams:idB = 1000822080            
+Beams:eCM = 5520.0                ### energy
+    
+Beams:frameType = 1
+ParticleDecays:limitTau0 = on
+ParticleDecays:tau0Max = 10.      ### match alice: 1cm/c = 10.0mm/c
+    
+### Initialize the Angantyr model to fit the total and semi-includive
+### cross sections in Pythia within some tolerance.
+HeavyIon:SigFitErr = 0.02,0.02,0.1,0.05,0.05,0.0,0.1,0.0
+
+### These parameters are typicall suitable for sqrt(S_NN)=5TeV
+HeavyIon:SigFitNGen = 0
+HeavyIon:SigFitDefPar = 13.88,1.84,0.22,0.0,0.0,0.0,0.0,0.0
+HeavyIon:bWidth = 4.43
+
+
+Random:setSeed = on

MC/config/ALICE3/pythia8/generator/pythia8_central_hi.cmnd

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+### beams
+Beams:idA 1000822080		# Pb
+Beams:idB 1000822080		# Pb
+Beams:eCM 5520. 		# GeV
+
+### heavy-ion settings (valid for Pb-Pb 5520 only)
+HeavyIon:SigFitNGen = 0
+HeavyIon:SigFitDefPar = 13.88,1.84,0.22,0.0,0.0,0.0,0.0,0.0
+HeavyIon:bWidth = 4.43
+
+### processes (apparently not to be defined)
+
+### decays
+ParticleDecays:limitTau0 on	
+ParticleDecays:tau0Max 0.001
+
+! 2) Seed settings
+! Seed is set inside the generator
+! If run on the grid, seed is set to job id
+! If run locally, seed is set to 0
+Random:setSeed = on                           ! Random seed on