staveVol->AddNode(hstaveVol, 0, new TGeoTranslation(-xpos, ypos, 0));
staveVol->AddNode(hstaveVol, 1, new TGeoTranslation( xpos, ypos+fgkOBHalfStaveYTrans, 0));
fHierarchy[kHalfStave] = 2; // RS
staveVol->AddNode(hstaveVol, 0, new TGeoTranslation(-xpos, ypos, 0));
staveVol->AddNode(hstaveVol, 1, new TGeoTranslation( xpos, ypos+fgkOBHalfStaveYTrans, 0));
fHierarchy[kHalfStave] = 2; // RS