What type of shielding material is commonly used to protect against gamma radiation?

Gamma radiation is a highly penetrating form of electromagnetic radiation that requires dense materials for effective shielding. Lead is commonly used in radiation protection because of its high atomic number and density, which allow it to absorb and attenuate gamma rays efficiently. When gamma radiation encounters lead, the probability of interactions such as photoelectric absorption and Compton scattering is much higher than with less dense materials, significantly reducing radiation exposure.

Other materials like cellophane, plastic, and paper have much lower densities and atomic numbers, making them inadequate for shielding against gamma radiation. They can only attenuate low-energy radiation, such as alpha and beta particles, but they are virtually ineffective when it comes to the high-energy gamma rays that can penetrate through many materials. Therefore, lead is the preferred choice for protection against gamma radiation in various environments, including medical, industrial, and nuclear settings.