diff --git a/trackers/simple_tracking.cxx b/trackers/simple_tracking.cxx
new file mode 100644
index 0000000000000000000000000000000000000000..d9c465b6c5fbfd792e84da7a6ed1c21aa1e822aa
--- /dev/null
+++ b/trackers/simple_tracking.cxx
@@ -0,0 +1,124 @@
+//R__LOAD_LIBRARY(libfmt.so)
+//#include "fmt/core.h"
+R__LOAD_LIBRARY(libDDG4IO.so)
+//
+//#include "DD4hep/Detector.h"
+#include "DDG4/Geant4Data.h"
+//#include "DDRec/CellIDPositionConverter.h"
+//#include "DDRec/SurfaceManager.h"
+//#include "DDRec/Surface.h"
+#include "ROOT/RDataFrame.hxx"
+//
+//#include "lcio2/MCParticleData.h"
+//#include "lcio2/ReconstructedParticleData.h"
+
+//#include "Math/Vector3D.h"
+//#include "Math/Vector4D.h"
+//#include "Math/VectorUtil.h"
+#include "TCanvas.h"
+//#include "TLegend.h"
+//#include "TMath.h"
+//#include "TRandom3.h"
+//#include "TFile.h"
+//#include "TH1F.h"
+//#include "TH1D.h"
+//#include "TTree.h"
+#include "TChain.h"
+//#include "TF1.h"
+#include <random>
+//#include "lcio2/TrackerRawDataData.h"
+//#include "lcio2/TrackerRawData.h"
+
+void simple_tracking(const char* fname = "data/roman_pot_out.root"){
+
+  ROOT::EnableImplicitMT(); // Tell ROOT you want to go parallel
+  //using namespace lcio2;
+  double degree = TMath::Pi()/180.0;
+
+  TChain* t = new TChain("EVENT");
+  t->Add(fname);
+
+  ROOT::RDataFrame d0(*t);//, {"GEMTrackerHintits","MCParticles"});
+
+  //std::cout << t->GetBranch("GEMTrackerHits")->GetClassName() << std::endl;
+  //std::vector<dd4hep::sim::Geant4Tracker::Hit*>
+  
+  // -------------------------
+  // Get the DD4hep instance
+  // Load the compact XML file
+  // Initialize the position converter tool
+  //dd4hep::Detector& detector = dd4hep::Detector::getInstance();
+  //detector.fromCompact("gem_tracker_disc.xml");
+  //dd4hep::rec::CellIDPositionConverter cellid_converter(detector);
+
+  //// -------------------------
+  //// Get the surfaces map
+  //dd4hep::rec::SurfaceManager& surfMan = *detector.extension<dd4hep::rec::SurfaceManager>() ;
+  //auto surfMap = surfMan.map( "world" ) ;
+  
+  auto nhits = [] (std::vector<dd4hep::sim::Geant4Tracker::Hit*>& hits){ return (int) hits.size(); };
+  //auto hit_position = [&](const std::vector<dd4hep::sim::Geant4Tracker::Hit*>& hits){
+  //for(const auto& h: hits){
+  //  //std::cout << (h->position/10.0) << std::endl;
+  //  //std::cout << cellid_converter.position(h->cellID) << std::endl;
+  //  //dd4hep::rec::SurfaceMap::const_iterator
+  //  const auto si = _surfMap.find( cellid_converter.findContext(h->cellID)->identifier ); //identifier=volumeID
+  //  dd4hep::rec::ISurface* surf = (si != _surfMap.end() ?  si->second  : 0);
+  //  dd4hep::rec::Vector3D pos =  surf->origin();//fit_global(pivot[0],pivot[1],pivot[2]);
+  //  //std::cout << pos.x() << ", " << pos.y() << ", " << pos.z()<< std::endl;
+  //  // transform lcio units to dd4hep units, see documentation for other functions              
+  //  //DDSurfaces::Vector2D fit_local = surf->globalToLocal( dd4hep::mm * fit_global );
+  //}
+  //  return hits.size(); };
+
+  //auto digitize_gem_hits = 
+  //  [&](const std::vector<dd4hep::sim::Geant4Tracker::Hit*>& hits) {
+  //    std::vector<lcio2::TrackerRawDataData> digi_hits;
+  //    std::normal_distribution<> time_dist(0,2.0);
+  //    std::normal_distribution<> adc_dist(5.0,3.0);
+
+  //    std::map<int64_t,lcio2::TrackerRawDataData> hits_by_id;
+  //    for(const auto& h: hits) {
+  //      //lcio2::TrackerRawDataData ahit;
+  //      auto& ahit = hits_by_id[(int64_t)h->cellID];
+  //      auto pos = h->position/10.0; //cm
+
+  //      ahit.cellID0   = h->cellID;
+  //      ahit.cellID1   = h->cellID;
+  //      ahit.channelID = h->cellID;
+  //      //fmt::print("{} vs {} vs {}\n", id1, id2,id3);
+  //      fmt::print("{} vs {}\n", h->cellID, ahit.cellID0);
+  //      // time is not kept from dd4hep hit, instead using z position as crude substitute
+  //      ahit.time = pos.z() + time_dist(gen);
+  //      ahit.adc  = adc_dist(gen);
+  //      //digi_hits.push_back(ahit);
+  //    }
+  //    for (auto& [cell, hit] : hits_by_id) {
+  //      //fmt::print("{} vs {}\n", cell, hit.cellID0);
+  //      digi_hits.push_back(hit);
+  //    }
+  //    return digi_hits;
+  //  };
+
+  auto d1 = d0.Define("nhits", nhits, {"ForwardRomanPotHits"})
+              //.Filter([](int n){ return (n>4); },{"nhits"})
+              //.Define("delta",hit_position, {"GEMTrackerHits"})
+              //.Define("RawTrackerHits", digitize_gem_hits, {"GEMTrackerHits"})
+              ;
+
+  auto h0 = d1.Histo1D(TH1D("h0", "nhits; ", 20, 0,20), "nhits");
+
+  auto n0 = d1.Filter([](int n){ return (n>0); },{"nhits"}).Count();
+
+  TCanvas* c = new TCanvas();
+
+  //d1.Snapshot("digitized_EVENT","test_gem_tracker_digi.root");
+  h0->DrawClone();
+  std::cout << *n0 << " events with nonzero hits\n";
+
+  if(*n0<5) {
+    std::quick_exit(1);
+  }
+
+}
+