[ALICE3] Add xi injector for pp and PbPb (#1939)

* Add xi injector for pp and PbPb

* Change to DPG_MC_CONFIG_ROOT

* Add simple test for the external generator

Author: jesgum

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

@@ -0,0 +1,46 @@
+int External()
+{
+  std::string path{"o2sim_Kine.root"};
+  int pdgToCheck = 3312;
+
+  TFile file(path.c_str(), "read");
+  if (file.IsZombie()) {
+    std::cerr << "Cannot open ROOT file " << path << std::endl;
+    return 1;
+  }
+
+  int nInjectedParticles = 0;
+  TTree* tree = (TTree*)file.Get("o2sim");
+  
+  if (!tree) {
+    std::cerr << "Cannot find tree o2sim in file " << path << std::endl;
+    return 1;
+  }
+
+  std::vector<o2::MCTrack> *tracks{};
+  tree->SetBranchAddress("MCTrack", &tracks);
+
+  int nEvents = tree->GetEntries();
+  for (int i = 0; i < nEvents; i++) {
+    tree->GetEntry(i);
+    for (auto& track : *tracks) {
+      auto pdgCode = track.GetPdgCode();
+      if (pdgCode == pdgToCheck) {
+        // not injecting anti-particle
+        nInjectedParticles++;
+      }
+    }
+  }
+
+  if (nInjectedParticles < nEvents) {
+    // Check that we are correctly injecting 15
+    // particle per event
+    return 1;
+  }
+
+  return 0;
+}
+
+
+
+

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

@@ -0,0 +1,46 @@
+int External()
+{
+  std::string path{"o2sim_Kine.root"};
+  int pdgToCheck = 3312;
+
+  TFile file(path.c_str(), "read");
+  if (file.IsZombie()) {
+    std::cerr << "Cannot open ROOT file " << path << std::endl;
+    return 1;
+  }
+
+  int nInjectedParticles = 0;
+  TTree* 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);
+
+  int nEvents = tree->GetEntries();
+  for (int i = 0; i < nEvents; i++) {
+    tree->GetEntry(i);
+    for (auto& track : *tracks) {
+      auto pdgCode = track.GetPdgCode();
+      if (pdgCode == pdgToCheck) {
+        // not injecting anti-particle
+        nInjectedParticles++;
+      }
+    }
+  }
+
+  if (nInjectedParticles < nEvents) {
+    // Check that we are correctly injecting one
+    // particle per event
+    return 1;
+  }
+
+  return 0;
+}
+
+
+
+

MC/config/ALICE3/ini/xi_PbPb.ini

@@ -0,0 +1,6 @@
+[GeneratorExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/pythia8/generator_pythia8_gun_PbPb.C
+funcName=generateNativeXi()
+
+[GeneratorPythia8]
+config=${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/pythia8/generator/config_custom_xicc.cfg

MC/config/ALICE3/ini/xi_pp.ini

@@ -0,0 +1,6 @@
+[GeneratorExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/pythia8/generator_pythia8_gun_pp.C
+funcName=generateNativeXi()
+
+[GeneratorPythia8]
+config=${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/pythia8/generator/config_custom_xicc.cfg