void Import_GDML_Export_ROOT()
{
  //TString richGeoFilename = "rich_v18_1e.gdml";                 // wide pipe (SIS100), all mirrors - default
  //TString richGeoFilename = "rich_v18_1e_nobpmt.gdml";        // wide pipe (SIS100), no most inner mirrors
  //TString richGeoFilename = "rich_v18_3e.gdml";                 // narrow pipe (SIS300), no most inner mirrors - default
  TString richGeoFilename = "rich_v18_3e_full_mirror.gdml";   // narrow pipe (SIS300), all mirrors

  TGeoManager *gdml = new TGeoManager("gdml", "FAIRGeom");

  cout << "Importing '" << richGeoFilename << "'." << endl;

  TGDMLParse parser;
  // Define your input GDML file HERE
  TGeoVolume* gdmlTop = parser.GDMLReadFile(richGeoFilename);
  TGeoVolume* rootTop = new TGeoVolumeAssembly("TOP");

  gGeoManager->SetTopVolume(rootTop);

  // Starting from the version v18a position is defined inside the GDML file
  // Define your position HERE
    // Z coordinate for v16a = 270, for v17a = 258.75, for v18a = 0.
  TGeoRotation* rot = new TGeoRotation ("rot", 0., 0., 0.);
  TGeoCombiTrans* posrot = new TGeoCombiTrans (0., 0., 0., rot);// v16a - 270, v17a - 258.75, v18a - 0

  rootTop->AddNode (gdmlTop, 1, posrot);

  gGeoManager->CloseGeometry();
  gGeoManager->CheckOverlaps();

  // Just print the name of the rich volume
  // One may compare it to the file name
  TGeoNode* richNode = gGeoManager->GetTopVolume()->GetNodes()->At(0);
  cout << richNode->GetVolume()->GetName() << endl;

  // Extract name to form output file name
  TString richGeoOutFilename;
  if (richGeoFilename.EndsWith(".gdml")) {
    richGeoOutFilename = richGeoFilename(0, richGeoFilename.Length()-5) + ".geo.root";
  } else {
    richGeoOutFilename = richGeoFilename + ".geo.root";
  }

  cout << "Exporting '" << richGeoOutFilename << "'." << endl;

  // Define you output ROOT file HERE
  TFile* outfile = new TFile(richGeoOutFilename, "RECREATE");
  rootTop->Write();
  outfile->Close();
}