a body of material intended to reduce the intensity of radiation entering a region, a structure made of shielding material to reduce radiation levels, protective use of low atomic number materials to thermalize strong neutron beams, or concrete, lead or other heavy materials to shield against gamma radiation when it might be harmful to operator or measuring system. Concrete is commonly used for large areas and lead for smaller., dense material, such as depleted uranium, concrete or steel, used to reduce the intensity of ionizing radiation and thereby provide protection for people from radiation