CMS rotating shielding around beam pipe

The forward shielding of CMS comprises all shielding elements along the beam line between the endcap and the cavern head-wall. The rotating shielding is a mechanical device divided in 4 half cylinders. It shields the cavern and detector from particles coming from the forward region. An upgrade campaign is ongoing at CMS to consolidate this shielding. First of all, the geometry of closure is improved. Then due to the new design of beam pipe support, the rotating shielding is modified to comply with and increase its shielding capability in some specific area.