GenieGenerator.cxx

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#include "SimCore/Generators/GenieGenerator.h"
 
#include "SimCore/G4User/UserPrimaryParticleInformation.h"
 
// GENIE
#include "Framework/Conventions/Units.h"
#include "Framework/EventGen/EventRecord.h"
#include "Framework/EventGen/GEVGDriver.h"
#include "Framework/EventGen/GFluxI.h"
#include "Framework/EventGen/GMCJDriver.h"
#include "Framework/EventGen/GMCJMonitor.h"
#include "Framework/GHEP/GHepParticle.h"
#include "Framework/Interaction/Interaction.h"
#include "Framework/Messenger/Messenger.h"
#include "Framework/Ntuple/NtpWriter.h"
#include "Framework/Numerical/Spline.h"
#include "Framework/Utils/AppInit.h"
#include "Framework/Utils/CmdLnArgParser.h"
#include "Framework/Utils/PrintUtils.h"
#include "Framework/Utils/RunOpt.h"
#include "Framework/Utils/StringUtils.h"
#include "Framework/Utils/SystemUtils.h"
#include "Framework/Utils/XSecSplineList.h"
#include "GENIE/Framework/Interaction/InitialState.h"
#include "GENIE/Framework/Utils/RunOpt.h"
 
// Geant4
#include "G4Event.hh"
#include "G4PhysicalConstants.hh"
#include "Randomize.hh"
 
// ROOT
#include <TLorentzVector.h>
#include <TParticle.h>
 
// standard
#include <algorithm>
 
#include "SimCore/G4User/UserEventInformation.h"
 
namespace simcore {
namespace generators {
 
void GenieGenerator::fillConfig(const framework::config::Parameters& p) {
  energy_ = p.get<double>("energy");  // * GeV;
 
  targets_ = p.get<std::vector<int> >("targets");
  abundances_ = p.get<std::vector<double> >("abundances");
 
  time_ = p.get<double>("time");                          // * ns;
  position_ = p.get<std::vector<double> >("position");    // mm
  beam_size_ = p.get<std::vector<double> >("beam_size");  // mm
  direction_ = p.get<std::vector<double> >("direction");
  target_thickness_ = p.get<double>("target_thickness");  // mm
 
  tune_ = p.get<std::string>("tune");
  spline_file_ = p.get<std::string>("spline_file");
 
  message_threshold_file_ = p.get<std::string>("message_threshold_file");
}
 
bool GenieGenerator::validateConfig() {
  bool ret = true;
 
  if (targets_.size() == 0 || abundances_.size() == 0) {
    ldmx_log(error) << "targets and/or abundances sizes are zero." << "  "
                    << targets_.size() << ", " << abundances_.size();
    ret = false;
  }
  if (targets_.size() != abundances_.size()) {
    ldmx_log(error) << "targets and abundances sizes unequal." << "  "
                    << targets_.size() << " != " << abundances_.size();
    ret = false;
  }
 
  if (position_.size() != 3 || direction_.size() != 3) {
    ldmx_log(error) << "position and/or direction sizes are not 3." << "  "
                    << position_.size() << ", " << direction_.size();
    ret = false;
  }
 
  if (target_thickness_ < 0) {
    ldmx_log(warn) << "target thickness cannot be less than 0! (thickness="
                   << target_thickness_ << "). Taking absolute value.";
    target_thickness_ = std::abs(target_thickness_);
  }
 
  if (beam_size_.size() != 2) {
    if (beam_size_.size() == 0) {
      ldmx_log(info) << "beam size not set. Using zero.";
      beam_size_.resize(2);
      beam_size_[0] = 0.0;
      beam_size_[1] = 0.0;
    } else {
      ldmx_log(error) << "beam size is set, but does not have size 2." << " "
                      << beam_size_.size();
      ret = false;
    }
  } else if (beam_size_[0] < 0 || beam_size_[1] < 0) {
    ldmx_log(warn) << "Beam size set as negative value? " << "("
                   << beam_size_[0] << "," << beam_size_[1] << ")"
                   << ". Changing to positive.";
    beam_size_[0] = std::abs(beam_size_[0]);
    beam_size_[1] = std::abs(beam_size_[1]);
  }
 
  // normalize abundances
  float abundance_sum = 0;
  for (auto a : abundances_) {
    abundance_sum += a;
  }
 
  if (std::abs(abundance_sum) < 1e-6) {
    ldmx_log(error) << "abundances list sums to zero? " << abundance_sum;
    ret = false;
  }
 
  if (std::abs(abundance_sum - 1.0) > 2e-2) {
    ldmx_log(info) << "abundances list sums is not unity (" << abundance_sum
                   << " instead.) Will renormalize abundances to unity!";
  }
 
  for (size_t i_a = 0; i_a < abundances_.size(); ++i_a) {
    abundances_[i_a] = abundances_[i_a] / abundance_sum;
 
    ldmx_log(debug) << "Target=" << targets_[i_a]
                    << ", Abundance=" << abundances_[i_a];
  }
 
  float dir_total_sq = 0;
  for (auto d : direction_) dir_total_sq += d * d;
 
  if (dir_total_sq < 1e-6) {
    ldmx_log(error) << "direction vector is zero or negative? " << "("
                    << direction_[0] << "," << direction_[1] << ","
                    << direction_[2] << ")";
    ret = false;
  }
  for (size_t i_d = 0; i_d < direction_.size(); ++i_d)
    direction_[i_d] = direction_[i_d] / std::sqrt(dir_total_sq);
 
  xsec_by_target_.resize(targets_.size(), -999.);
  n_events_by_target_.resize(targets_.size(), 0);
 
  return ret;
}
 
void GenieGenerator::initializeGENIE() {
  // initialize some RunOpt by hacking the command line interface
  {
    char* in_arr[3] = {const_cast<char*>(""),
                       const_cast<char*>("--event-generator-list"),
                       const_cast<char*>("EM")};
    genie::RunOpt::Instance()->ReadFromCommandLine(3, in_arr);
  }
 
  // set message thresholds
  genie::utils::app_init::MesgThresholds(message_threshold_file_);
 
  // set tune info
  genie::RunOpt::Instance()->SetTuneName(tune_);
  if (!genie::RunOpt::Instance()->Tune()) {
    EXCEPTION_RAISE("ConfigurationException", "No TuneId in RunOption.");
  }
  genie::RunOpt::Instance()->BuildTune();
 
  // give it the splint file and require it
  genie::utils::app_init::XSecTable(spline_file_, true);
 
  // set GHEP print level (needed?)
  genie::GHepRecord::SetPrintLevel(0);
}
 
void GenieGenerator::calculateTotalXS() {
  // initializing...
  xsec_total_ = 0;
  ev_weighting_integral_.resize(targets_.size(), 0.0);
  evg_drivers_.resize(targets_.size());
 
  // calculate the total xsec per target...
  for (size_t i_t = 0; i_t < targets_.size(); ++i_t) {
    genie::InitialState initial_state(targets_[i_t], 11);
    evg_drivers_[i_t].SetEventGeneratorList(
        genie::RunOpt::Instance()->EventGeneratorList());
    evg_drivers_[i_t].SetUnphysEventMask(
        *genie::RunOpt::Instance()->UnphysEventMask());
    evg_drivers_[i_t].Configure(initial_state);
    evg_drivers_[i_t].UseSplines();
 
    // setup the initial election
    TParticle initial_e;
    initial_e.SetPdgCode(11);
    auto elec_i_p = std::sqrt(energy_ * energy_ -
                              initial_e.GetMass() * initial_e.GetMass());
    initial_e.SetMomentum(elec_i_p * direction_[0], elec_i_p * direction_[1],
                          elec_i_p * direction_[2], energy_);
    TLorentzVector e_p4;
    initial_e.Momentum(e_p4);
 
    xsec_by_target_[i_t] = evg_drivers_[i_t].XSecSum(e_p4);
    xsec_total_ += xsec_by_target_[i_t] * abundances_[i_t];
 
    ev_weighting_integral_[i_t] = xsec_total_;  // running sum
 
    // print...
    ldmx_log(debug) << "Target=" << targets_[i_t]
                    << "\tAbundance=" << abundances_[i_t] << "\tXSEC="
                    << xsec_by_target_[i_t] / genie::units::millibarn << "mb";
  }
  ldmx_log(debug) << "Total XSEC = " << xsec_total_ / genie::units::millibarn
                  << " mb";
 
  // renormalize our weighting integral
  for (size_t i_t = 0; i_t < ev_weighting_integral_.size(); ++i_t)
    ev_weighting_integral_[i_t] = ev_weighting_integral_[i_t] / xsec_total_;
}
 
GenieGenerator::GenieGenerator(const std::string& name,
                               const framework::config::Parameters& p)
    : PrimaryGenerator(name, p) {
  fillConfig(p);
 
  if (!validateConfig())
    EXCEPTION_RAISE("ConfigurationException", "Configuration not valid.");
 
  n_events_generated_ = 0;
  initializeGENIE();
  calculateTotalXS();
}
 
GenieGenerator::~GenieGenerator() {
  ldmx_log(info) << "--- GENIE Generation Summary BEGIN ---";
  double total_xsec = 0;
  for (size_t i_t = 0; i_t < targets_.size(); ++i_t) {
    ldmx_log(info) << "Target=" << targets_[i_t]
                   << "\tAbundance=" << abundances_[i_t] << "\tXSEC="
                   << xsec_by_target_[i_t] / genie::units::millibarn << " mb"
                   << "\tEvents=" << n_events_by_target_[i_t];
    if (n_events_by_target_[i_t] > 0)
      total_xsec += xsec_by_target_[i_t] * abundances_[i_t];
  }
 
  ldmx_log(info) << "Total events generated = " << n_events_generated_
                 << "\nTotal XSEC = " << total_xsec / genie::units::millibarn
                 << " mb";
 
  ldmx_log(info) << "--- GENIE Generation Summary *END* ---";
}
 
void GenieGenerator::GeneratePrimaryVertex(G4Event* event) {
  if (n_events_generated_ == 0) {
    // set random seed
    // have to do this here since seeds aren't properly set until we know the
    // run number
    auto seed = G4Random::getTheEngine()->getSeed();
    ldmx_log(debug) << "Initializing GENIE with seed " << seed;
    genie::utils::app_init::RandGen(seed);
  }
 
  auto nucl_target_i = 0;
 
  if (targets_.size() > 0) {
    double rand_uniform = G4Random::getTheGenerator()->flat();
 
    nucl_target_i = std::distance(
        ev_weighting_integral_.begin(),
        std::lower_bound(ev_weighting_integral_.begin(),
                         ev_weighting_integral_.end(), rand_uniform));
 
    ldmx_log(debug) << "Random number = " << rand_uniform << ", target picked "
                    << targets_.at(nucl_target_i);
  }
 
  auto x_pos = position_[0] +
               (G4Random::getTheGenerator()->flat() - 0.5) * beam_size_[0];
  auto y_pos = position_[1] +
               (G4Random::getTheGenerator()->flat() - 0.5) * beam_size_[1];
  auto z_pos = position_[2] +
               (G4Random::getTheGenerator()->flat() - 0.5) * target_thickness_;
 
  ldmx_log(debug) << "Generating interaction at (x_,y_,z_)=" << "(" << x_pos
                  << "," << y_pos << "," << z_pos << ")";
 
  // setup the initial election
  TParticle initial_e;
  initial_e.SetPdgCode(11);
  float elec_i_p =
      std::sqrt(energy_ * energy_ - initial_e.GetMass() * initial_e.GetMass());
  initial_e.SetMomentum(elec_i_p * direction_[0], elec_i_p * direction_[1],
                        elec_i_p * direction_[2], energy_);
  TLorentzVector e_p4;
  initial_e.Momentum(e_p4);
 
  ldmx_log(debug) << "Generating interation with (px,py,pz,e)=" << "("
                  << e_p4.Px() << "," << e_p4.Py() << "," << e_p4.Pz() << ","
                  << e_p4.E() << ")";
 
  n_events_by_target_[nucl_target_i] += 1;
 
  // GENIE magic — use the pre-configured driver for this target
  genie::EventRecord* genie_event = NULL;
  while (!genie_event)
    genie_event = evg_drivers_[nucl_target_i].GenerateEvent(e_p4);
 
  auto ev_info = new UserEventInformation;
  auto hepmc3_genie = hep_mc3_converter_.ConvertToHepMC3(*genie_event);
  ldmx::HepMC3GenEvent hepmc3_ldmx_genie;
  hepmc3_genie->write_data(hepmc3_ldmx_genie);
  ev_info->addHepMC3GenEvent(hepmc3_ldmx_genie);
  event->SetUserInformation(ev_info);
 
  // setup the primary vertex now
 
  G4PrimaryVertex* vertex = new G4PrimaryVertex();
  vertex->SetPosition(x_pos, y_pos, z_pos);
  vertex->SetWeight(genie_event->Weight());
 
  // loop over the entries and add to the G4Event
  int n_entries = genie_event->GetEntries();
 
  ldmx_log(debug) << "---------- " << "Generated Event "
                  << n_events_generated_ + 1 << " ----------";
 
  for (int i_p = 0; i_p < n_entries; ++i_p) {
    genie::GHepParticle* p = (genie::GHepParticle*)(*genie_event)[i_p];
 
    // make sure it's a final state particle
    if (p->Status() != 1) continue;
 
    ldmx_log(debug) << "\tAdding particle " << p->Pdg() << " with status "
                    << p->Status() << " energy " << p->E() << " ...";
 
    G4PrimaryParticle* primary = new G4PrimaryParticle();
    primary->SetPDGcode(p->Pdg());
 
    // this sets the 4momentum. But may not respect masses in G4...
    // primary->Set4Momentum(p->Px() * CLHEP::GeV, p->Py() * CLHEP::GeV,
    //                       p->Pz() * CLHEP::GeV, p->E() * CLHEP::GeV);
 
    // for now, do this to set the masses to be the G4 ones, through the PDG
    // code
    primary->SetMomentum(p->Px() * CLHEP::GeV, p->Py() * CLHEP::GeV,
                         p->Pz() * CLHEP::GeV);
 
    primary->SetProperTime(time_ * CLHEP::ns);
 
    UserPrimaryParticleInformation* primary_info =
        new UserPrimaryParticleInformation();
    primary_info->setHepEvtStatus(1);
    primary->SetUserInformation(primary_info);
 
    vertex->SetPrimary(primary);
  }
 
  // add the vertex to the event
  event->AddPrimaryVertex(vertex);
 
  // Apply beam spot smearing if configured for this generator
  if (useBeamspot()) {
    smearBeamspot(vertex);
  }
 
  ++n_events_generated_;
  delete genie_event;
}
 
void GenieGenerator::RecordConfig(const std::string& id, ldmx::RunHeader& rh) {
  rh.setStringParameter(id + " Class", "simcore::generators::GenieGenerator");
  rh.setStringParameter(id + "GenieTune", tune_);
}
 
}  // namespace generators
}  // namespace simcore
 
DECLARE_GENERATOR(simcore::generators::GenieGenerator)