void make_shield_geo() {

  double TARGET = 0.;  //NEDS TO BE SETTABLE
  double LENGTH = 75.;
  

  gROOT->Macro("$VMCWORKDIR/gconfig/rootlogon.C");

  //----------------------- INIT --------------------------------------

  //get geometry definitions:
  FairGeoLoader* loader = new FairGeoLoader("TGeo", "FairGeoLoader");
  FairGeoBuilder* builder = loader->getGeoBuilder();

  FairGeoInterface* geoIFC = loader->getGeoInterface();
  TString workdir = gSystem->Getenv("VMCWORKDIR");
  cout << workdir.Data() << endl;
  geoIFC->setMediaFile(workdir+"/geometry/media_pnd.geo");
  geoIFC->readMedia();
  //geoIFC->print();
  FairGeoMedia* media = geoIFC->getMedia();
  TGeoManager* geoMan = (TGeoManager*) gROOT->FindObject("FAIRGeom");

  //------------------ LOAD MATERIALS ----------------------------------
  FairGeoMedium* lead = media->getMedium("FOPIPassLead");
  builder->createMedium(lead);
  FairGeoMedium* air = media->getMedium("FOPISensAir");
  builder->createMedium(air);

  // ------------------ DEFINE GEO -------------------------------------

  TGeoVolume* top = new TGeoVolumeAssembly("TPCSHIELD");
  TGeoVolumeAssembly* topAss = new TGeoVolumeAssembly("TPCSHIELD");

  TGeoVolumeAssembly* shield = new TGeoVolumeAssembly("Shield");
  
  double air_pars[3] = {20.4, 20.49., LENGTH};
  double shield_pars[3] = {20.5, 30., LENGTH};

  TGeoTube* shA = new TGeoTube(air_pars);
  TGeoVolume* shAV = new TGeoVolume("FOPISensAirV", shA, 
				    gGeoManager->GetMedium(TString("FOPISensAir")));
  shield->AddNode(shAV,0);
  
  TGeoTube* shL = new TGeoTube(shield_pars);
  TGeoVolume* shLV = new TGeoVolume("ShieldLeadV", shL, 
				    gGeoManager->GetMedium(TString("FOPIPassLead")));
  shield->AddNode(shLV,0);


  TGeoTranslation* glob = new TGeoTranslation(0,0,TARGET + LENGTH/2.);
  topAss->AddNode(shield,0,glob);

  TGeoVoxelFinder* voxels = top->GetVoxels();
  if (voxels) { voxels->SetNeedRebuild(); }
  
  geoMan->SetTopVolume(topAss);
  
  top->AddNode(topAss, 0);
  geoMan->CloseGeometry();  
  
  
  TEveManager::Create();
  
  TEveGeoTopNode* meh = new TEveGeoTopNode(geoMan, geoMan->GetTopNode());
  gEve->AddGlobalElement(meh);

  //  gEve->Redraw3D(kTRUE);
  
  TFile outfile("$VMCWORKDIR/geometry/FOPI_TPC_SHIELD.root", "recreate");
  outfile.cd();
  top->Write();

}