void test()
{
	// load libraries and open the TGeo manager
	gSystem->Load("libGeom");
	TGeoManager *geom = new TGeoManager("ITS", "Simple ITS geometry");
	TGeoMaterial *matVacuum = new TGeoMaterial("Vacuum", 0, 0, 0);
	TGeoMaterial *matAl = new TGeoMaterial("Al", 26.98, 13, 2.7);
	TGeoMedium *Vacuum = new TGeoMedium("vacuum", 1, matVacuum);
	TGeoMedium *Al = new TGeoMedium("al", 2, matAl);
	
	TGeoVolume *top  = geom->MakeBox("CONT", Vacuum, 50.0, 50.0, 50.0);
	TGeoVolume *box1 = geom->MakeBox("BOX1", Al, 20.0, 20.0, 20.0);
	TGeoVolume *box2 = geom->MakeBox("BOX2", Al, 20.0, 20.0, 20.0);
	
	TGeoTranslation *t1 = new TGeoTranslation(-15.0, -5.0, 0.0);
	TGeoTranslation *t2 = new TGeoTranslation( 15.0,  5.0, 0.0);
	
	box1->SetLineColor(kRed);
	box2->SetLineColor(kBlue);
	
	geom->SetTopVolume(top);
	
	top->AddNode(box1, 1, t1);
	top->AddNode(box2, 2, t2);
	
	geom->CloseGeometry();
	top->Draw();
	geom->CheckOverlaps(0.1, "s");
}