diff --git a/Armory/ClassAnasen.h b/Armory/ClassAnasen.h
index db892b7..ff7bd1e 100644
--- a/Armory/ClassAnasen.h
+++ b/Armory/ClassAnasen.h
@@ -108,17 +108,21 @@ inline void ANASEN::Construct3DModel(int anodeID1, int anodeID2, int cathodeID1,
   geom = new TGeoManager("Detector", "ANASEN");
 
   //--- define some materials
-  TGeoMaterial *matVacuum = new TGeoMaterial("Vacuum", 0,0,0);
+  TGeoMaterial *matVacuum = new TGeoMaterial("Vacuum", 0,0,0); //name, A, Z, density
+  TGeoMaterial *matHe = new TGeoMaterial("He", 4.0026, 2, 0.000861);
   TGeoMaterial *matAl = new TGeoMaterial("Al", 26.98,13,2.7);
+  TGeoMaterial *matSi = new TGeoMaterial("Si", 28.085,14,2.33);
   //--- define some media
-  TGeoMedium *Vacuum = new TGeoMedium("Vacuum",1, matVacuum);
+  TGeoMedium *Vacuum = new TGeoMedium("Vacuum",1, matVacuum); //name, number of materials, material
+  TGeoMedium *He = new TGeoMedium("He",2, matHe);
   TGeoMedium *Al = new TGeoMedium("Root Material",2, matAl);
+  TGeoMedium *Si = new TGeoMedium("Si",3, matSi);
 
   //--- make the top container volume 
   Double_t worldx = 200.; //mm
   Double_t worldy = 200.; //mm
   Double_t worldz = 200.; //mm
-  worldBox = geom->MakeBox("ROOT", Vacuum, worldx, worldy, worldz);
+  worldBox = geom->MakeBox("ROOT", He, worldx, worldy, worldz); // name, medium, x half-length, y half-length, z half-length
   geom->SetTopVolume(worldBox);
 
   //--- making axis
@@ -183,7 +187,7 @@ inline void ANASEN::Construct3DModel(int anodeID1, int anodeID2, int cathodeID1,
                                                     new TGeoRotation("rot1", wirePhi , wireTheta, 0.)));
   }
 
-  TGeoVolume * sx3Det = geom->MakeBox("box", Al, 0.1, sx3->GetWidth()/2, sx3->GetLength()/2);
+  TGeoVolume * sx3Det = geom->MakeBox("box", Si, 0.1, sx3->GetWidth()/2, sx3->GetLength()/2);
   sx3Det->SetLineColor(kGreen+3);
 
   for( int i = 0; i < sx3->GetNumDet(); i++){
@@ -243,7 +247,7 @@ inline  void ANASEN::DrawTrack(TVector3 pos, TVector3 direction, bool drawEstima
   Track->SetLineColor(kRed);
   worldBox->AddNode(Track, 1, new TGeoCombiTrans( pos.X(), pos.Y(), pos.Z(), new TGeoRotation("rotA", phi +  90, theta, 0.)));
 
-  TGeoVolume * startPos = geom->MakeSphere("startPos", 0, 0, 3);
+  TGeoVolume * startPos = geom->MakeSphere("startPos", 0, 0, 3); 
   startPos->SetLineColor(kBlack);
   worldBox->AddNode(startPos, 3, new TGeoCombiTrans( pos.X(), pos.Y(), pos.Z(), new TGeoRotation("rotA", 0, 0, 0.)));