diff --git a/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.cxx b/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.cxx
index 96971e087ab78a3faca5b56f9a2b3d7b5c285222..b98cc9d2876aa22b3ad15ebbc5f018b39f40a0a7 100644
--- a/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.cxx
+++ b/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 ///////////////////////////////////////////////////////////////////
@@ -20,16 +20,9 @@
 #include "G4PVPlacement.hh"
 #include "globals.hh"
 
-// G4 material : vacuum setup
-G4Material* G4DetectorConstruction::s_g4vacuum = new G4Material("Vacuum",1.,1.01*CLHEP::g/CLHEP::mole,
-                                                                     CLHEP::universe_mean_density,
-                                                                     kStateGas,0.1*CLHEP::kelvin, 1.e-19*CLHEP::pascal);
-
 G4DetectorConstruction::G4DetectorConstruction()
   :   m_worldLog(nullptr),
-      //m_detectorLog(nullptr),
       m_worldPhys(nullptr)
-      ///m_detectorPhys(nullptr),
 {}
 
 
@@ -44,8 +37,15 @@ void G4DetectorConstruction::dummyDetector()
   // (1) WORLD
   // create the world setup
   G4Box* worldBox = new G4Box("WorldBox",25000.,25000.,25000.);
-  m_worldLog      = m_worldLog ? new(m_worldLog) G4LogicalVolume(worldBox,s_g4vacuum,"WorldLogical", 0, 0, 0) :
-    new G4LogicalVolume(worldBox,s_g4vacuum,"WorldLogical", 0, 0, 0);
+  
+  // G4 material : vacuum setup
+  G4Material* g4vacuum = G4Material::GetMaterial("Vacuum",false);
+  if(!g4vacuum) g4vacuum = new G4Material("FatrasDummyVacuum",1.,1.01*CLHEP::g/CLHEP::mole,
+                                           CLHEP::universe_mean_density,
+                                           kStateGas,0.1*CLHEP::kelvin, 1.e-19*CLHEP::pascal);
+  
+  m_worldLog      = m_worldLog ? new(m_worldLog) G4LogicalVolume(worldBox,g4vacuum,"WorldLogical", 0, 0, 0) :
+    new G4LogicalVolume(worldBox,g4vacuum,"WorldLogical", 0, 0, 0);
   m_worldPhys     = m_worldPhys ? new(m_worldPhys) G4PVPlacement(0,G4ThreeVector(0.,0.,0),"WorldPhysical",m_worldLog,0,false,0) :
     new G4PVPlacement(0,materialPosition,"WorldPhysical",m_worldLog,0,false,0);
 
diff --git a/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.h b/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.h
index 885f2b3222a45631bf583305b46284daa8225ad3..90107de37e12aa43248f9130dde989d7fc8f5e33 100644
--- a/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.h
+++ b/Simulation/ISF/ISF_Geant4/ISF_Geant4Tools/src/G4DetectorConstruction.h
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 ///////////////////////////////////////////////////////////////////
@@ -36,17 +36,10 @@ private:
   // Logical volumes
   //
   G4LogicalVolume*          m_worldLog;
-  //G4LogicalVolume*          m_detectorLog;
 
   // Physical volumes
   //
   G4VPhysicalVolume*        m_worldPhys;
-  //G4VPhysicalVolume*        m_detectorPhys;
-
-  // Vaccum material
-  //
-  static G4Material*        s_g4vacuum;
-
 };
 
 #endif