Which material is considered an effective shield for neutron radiation?

Plastic is considered an effective shield for neutron radiation primarily due to its hydrogen content. Neutrons are uncharged particles, which makes them different from charged radiation like alpha and beta particles. When neutrons interact with matter, they are more effectively slowed down or moderated by materials that contain a significant amount of hydrogen atoms.

Plastic, particularly types of polyethylene, contains a high percentage of hydrogen, which is very efficient at scattering neutrons. This interaction reduces the energy of the neutrons, effectively shielding the surrounding environment from their potential harmful effects. By slowing down the neutrons, plastic helps to attenuate the neutron dose that an individual might receive.

While materials such as lead, concrete, and steel can provide additional shielding for other types of radiation (like gamma and x-rays), they are not as effective at slowing down neutrons due to their higher atomic mass and lack of hydrogen content. Therefore, when it comes to neutron radiation specifically, plastic is the superior choice for shielding.