{
  gSystem->Load("libGeom");
  /*   c1 = new TCanvas("c1","3D Viewer",100,500,1200,600); */
  /*   c1->SetFillColor(0); */
  /*   c1->cd(); */

  const float ColLength50L = 32.;  // cm.
  const float IndLength50L = 32.;  // cm.
  const float DriftLength50L = 47.; // cm.

  // 50L placed in WANF beam. Angles respect NOMAD
  const float Theta50L = -.532;   // rad. = 30.48 deg.
  const float Phi50L = .024;      // rad. = 1.375 deg.
  
  // const float Coor50L[3] = {3.,-51.,-418.}; // cm.
  // This values come from FPP fortran file NomadTo50LTPC.f
  // and are respect to NOMAD RS.
  const float Coor50L[3] = {2.08,-31.69,-418.}; // cm.

  //--- Definition of a simple geometry
  TGeoManager *geom = new TGeoManager("50L Geometry", "Simple geometry");

  // define the vacuum material
  TGeoMaterial *matVacuum = new TGeoMaterial("Vacuum", 0,0,0);
  TGeoMedium *Vacuum = new TGeoMedium("Vacuum",1, matVacuum);
  
  // Shapes dimensions (half lengths) in cm.
  float TopDim[3] = {1000.,210.,210.};
  float NomadRoomDim[3] = { 500., 205., 205.};
  float NomadCalDim[3] = {50.,180., 180.};
  float NomadDriftDim[3] = {250.,180., 180.};
  float the50LChamberDim[3] = {ColLength50L/2.,IndLength50L/2.,DriftLength50L/2.};
  float Cryo50LDim[3] = {25.,30.,40.};
  
  // Shapes definitions
  TGeoVolume *top = geom->MakeBox("TOP", Vacuum, TopDim[0],TopDim[1],TopDim[2]);
  TGeoVolume *NomadRoom = geom->MakeBox("NomadRoom", Vacuum,NomadRoomDim[0],NomadRoomDim[1],NomadRoomDim[2]);
  TGeoVolume *NomadCal = geom->MakeBox("NomadCal", Vacuum,NomadCalDim[0],NomadCalDim[1],NomadCalDim[2]);
  TGeoVolume *NomadDrift = geom->MakeBox("Nomad", Vacuum,NomadDriftDim[0],NomadDriftDim[1],NomadDriftDim[2]);
  TGeoVolume *Cryo50L = geom->MakeTube("Cryo50L",Vacuum,Cryo50LDim[0],Cryo50LDim[1],Cryo50LDim[2]);
  TGeoVolume *the50Lchamber = geom->MakeBox("the50LChamber",Vacuum,the50LChamberDim[0],the50LChamberDim[1],the50LChamberDim[2]);
  
  NomadRoom->SetLineColor(kBlue);
  NomadCal->SetLineColor(kBlack);
  NomadDrift->SetLineColor(kRed);
  Cryo50L->SetLineColor(kCyan);
  the50Lchamber->SetLineColor(kGreen);
  
  // Traslations and rotations
  TGeoRotation *identity = new TGeoRotation("identity", 0., 0., 0.);
  
  // Repect to Nomad SR the first Cal was placed at -279 cm. in Z axis.
  // and the 50L chamber at -418 cm.
  const double CalZPos = -279.;  // cm.
  
  // Position of NOMAD RS respect to top
  TGeoTranslation *trasNomad = new TGeoTranslation("trasNomad",200.,0,0);
  // Position of the Nomamd iron
  TGeoTranslation *trasCal = new TGeoTranslation("trasCal",CalZPos+NomadCalDim[0],0,0);
  // Position of Nomamd driftchambers
  TGeoTranslation *trasDrift = new TGeoTranslation("trasDrift",CalZPos+2.*NomadCalDim[0]+NomadDriftDim[0],0,0);
  // 50L rotation 
  TGeoRotation *rot1 = new TGeoRotation("rot1", Theta50L*180./TMath::Pi(), 0., 0.);
  // Position of 50L 
  TGeoTranslation *tras50l = new TGeoTranslation("tras50l",Coor50L[2],Coor50L[0],Coor50L[1]);	  
  TGeoCombiTrans *t50l = new TGeoCombiTrans(*tras50l, *rot1);	 
  
  top->AddNode(NomadRoom,1,trasNomad);	  
  NomadRoom->AddNode(NomadCal,1,trasCal);
  NomadRoom->AddNode(NomadDrift,1,trasDrift);
  NomadRoom->AddNode(Cryo50L,1,t50l);
  Cryo50L->AddNode(the50Lchamber,1,identity);
  
  geom->SetTopVolume(top);

  //--- close the geometry
  geom->CloseGeometry();
  geom->SetVisOption(0);
  geom->SetVisLevel(4);
  top->Draw();


}