Implemented basic pythia8 generator with deep trigger forwarding

Author: jackal1-66

MC/config/examples/external/generator/pythia8_deep.C

@@ -0,0 +1,51 @@
+#if !defined(__CLING__) || defined(__ROOTCLING__)
+#include "Pythia8/Pythia.h"
+#include "FairGenerator.h"
+#include "FairPrimaryGenerator.h"
+#include "Generators/Trigger.h"
+#include <Generators/TriggerExternalParam.h>
+#include "Generators/GeneratorPythia8.h"
+#include <stdlib.h>
+#include "CommonUtils/ConfigurationMacroHelper.h"
+
+using namespace Pythia8;
+#endif
+
+// Basic implementation of deep-triggered Pythia8 as external generator
+
+class GeneratorPythia8Deep : public o2::eventgen::GeneratorPythia8
+{
+  // Settings are fed via the configuration file specified in the .ini file
+  // Triggers need to be handled like this otherwise the simulation with hybrid will
+  // not be able to recognise the provided triggers.
+
+public :
+
+  GeneratorPythia8Deep() : o2::eventgen::GeneratorPythia8()
+  {
+    mInterface = reinterpret_cast<void *>(&mPythia);
+    mInterfaceName = "pythia8";
+    o2::eventgen::DeepTrigger deeptrigger = nullptr;
+
+    // external trigger via ini file
+    auto &params = o2::eventgen::TriggerExternalParam::Instance();
+    LOG(info) << "Setting up external trigger for Pythia8 with following parameters";
+    LOG(info) << params;
+    auto external_trigger_filename = params.fileName;
+    auto external_trigger_func = params.funcName;
+    deeptrigger = o2::conf::GetFromMacro<o2::eventgen::DeepTrigger>(external_trigger_filename, external_trigger_func, "o2::eventgen::DeepTrigger", "deeptrigger");
+    if (!deeptrigger)
+    {
+      LOG(fatal) << "Failed to retrieve \'external trigger\': problem with configuration ";
+    } else {
+      LOG(info) << "External trigger for Pythia8 is set";
+      addDeepTrigger(deeptrigger);
+      setTriggerMode(o2::eventgen::Generator::kTriggerOR);
+    }
+  }
+};
+
+FairGenerator *generator_pythia8_deep()
+{
+  return new GeneratorPythia8Deep();
+}

MC/config/examples/ini/pythia8_impactb.ini

@@ -0,0 +1,16 @@
+### The setup uses an external event generator trigger which is
+### defined in the following file and it is retrieved and configured
+### according to the specified function call
+
+[GeneratorExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/external/generator/pythia8_deep.C
+funcName=generator_pythia8_deep()
+
+[TriggerExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/trigger/trigger_impactb.macro
+funcName=trigger_impactb_pythia8(0.,15.)
+
+### This part configures Pythia8
+
+[GeneratorPythia8]
+config = ${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/pythia8/generator/pythia8_hi.cfg

MC/config/examples/ini/tests/pythia8_impactb.C

@@ -0,0 +1,75 @@
+{
+  std::string path{"o2sim_Kine.root"};
+  // Check that file exists, can be opened and has the correct tree
+  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);
+
+  o2::dataformats::MCEventHeader *mcheader = nullptr;
+  tree->SetBranchAddress("MCEventHeader.", &mcheader);
+
+  // Check if all events are filled
+  auto nEvents = tree->GetEntries();  
+  for (Long64_t i = 0; i < nEvents; ++i)
+  {
+    tree->GetEntry(i);
+    if (tracks->empty())
+    {
+      std::cerr << "Empty entry found at event " << i << "\n";
+      return 1;
+    }
+  }
+  // Check if there are 100 events, as simulated in the o2dpg-test
+  if (nEvents != 100)
+  {
+    std::cerr << "Expected 100 events, got " << nEvents << "\n";
+    return 1;
+  }
+  // check if each event has two lead ions with the correct energy (based on Pythia simulation)
+  // exits if the particle is not lead 208
+  bool isvalid;
+  for (int i = 0; i < nEvents; i++)
+  {
+    auto check = tree->GetEntry(i);
+    int count = 0;
+    for (int idxMCTrack = 0; idxMCTrack < tracks->size(); ++idxMCTrack)
+    {
+      auto track = tracks->at(idxMCTrack);
+      double energy = track.GetEnergy();
+      // Check if track energy is right for the lead ions (a tolerance of 100 MeV is considered, straight equality does not work due to floating point precision)
+      if (std::abs(energy - 547158) < 1e-1) // Lead ion energy is 547158 MeV
+      {
+        if (track.GetPdgCode() != 1000822080)
+        {
+          std::cerr << "Found 547158 GeV particle with pdgID " << track.GetPdgCode() << "\n";
+          return 1;
+        }
+        count++;  
+      }
+    }
+    if (count < 2)
+    {
+      std::cerr << "Event " << i << " has less than 2 lead ions at 547158 GeV\n";
+      return 1;
+    }
+    // Check if event impact parameter is < 15 fm
+    double impactParameter = mcheader->getInfo<double>(o2::dataformats::MCInfoKeys::impactParameter, isvalid);
+    if (impactParameter > 15)
+    {
+      std::cerr << "Event " << i << " has impact parameter " << impactParameter << " fm outside range\n";
+      return 1;
+    }
+  }
+  return 0;
+}

MC/config/examples/pythia8/generator/pythia8_hi.cfg

@@ -0,0 +1,21 @@
+### random
+Random:setSeed = on
+Random:seed = 0
+
+### beams
+Beams:idA = 1000822080
+Beams:idB = 1000822080
+Beams:eCM = 5300.000000
+
+### 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 = 14.48
+
+### decays
+ParticleDecays:limitTau0 = on
+ParticleDecays:tau0Max = 10.
+
+### phase space cuts
+PhaseSpace:pTHatMin = 0.000000
+PhaseSpace:pTHatMax = -1.000000

MC/config/examples/trigger/trigger_impactb.macro

@@ -0,0 +1,45 @@
+#include "Generators/Trigger.h"
+#include "TParticle.h"
+#include <iostream>
+
+// a very simple trigger example, examining generated particles              
+o2::eventgen::Trigger trigger()
+{
+  //
+  return [](const std::vector<TParticle>& particles) -> bool {
+    std::cout << "Running trigger on event with size " << particles.size() << "\n";
+    if (particles.size() > 10000) {
+      return true;
+    }
+    return false;
+  };
+}
+
+#include "Pythia8/Pythia.h"
+#include "Pythia8/HIInfo.h"
+#include <fairlogger/Logger.h>
+// a deep trigger example, looking into the internal generator state
+o2::eventgen::DeepTrigger
+  trigger_impactb_pythia8(double bmin = 5., double bmax = 10.)
+{
+  return [bmin, bmax](void* interface, std::string name) -> bool {
+    if (!name.compare("pythia8")) {
+      auto py8 = reinterpret_cast<Pythia8::Pythia*>(interface);
+#if PYTHIA_VERSION_INTEGER < 8300
+      auto hiinfo = py8->info.hiinfo;
+#else
+      auto hiinfo = py8->info.hiInfo;
+#endif
+      if (!hiinfo) {
+        LOG(fatal) << "Cannot define impact parameter: is \'pythia8\' running in heavy-ion mode?";
+      }
+      auto b = hiinfo->b();
+      auto selected = (b > bmin && b < bmax);
+      LOG(info) << "Impact parameter = " << b << " fm: " << (selected ? "selected" : "rejected");
+      return selected;
+    } else {
+      LOG(fatal) << "Cannot define impact parameter for generator interface \'" << name << "\'";
+    }
+    return false;
+  };
+}