For neutron radiation, which shielding material is most effective?

For neutron radiation, which shielding material is most effective?

• A. Lead
• B. Plastic
• C. Foil
• D. Water

Answer: (D)

Neutron shielding works best when you slow and capture neutrons using hydrogen-rich material. Fast neutrons lose energy most efficiently in elastic collisions with light nuclei, especially protons. Water contains a lot of hydrogen, and its density means a given thickness provides many hydrogen targets for neutron collisions, effectively slowing fast neutrons to thermal energies. Once slowed, neutrons are more likely to be captured and removed from the beam, especially if the water is doped with neutron-absorbing elements like boron. Lead, while great for gamma shielding, doesn’t slow neutrons well and can even generate secondary gamma radiation when hit by neutrons. Foil is too thin to provide meaningful neutron attenuation. Plastic can slow neutrons thanks to hydrogen, but water typically offers more hydrogen per volume and is easier to implement as shielding, making it the most effective choice among the options.

Neutron shielding works best when you slow and capture neutrons using hydrogen-rich material. Fast neutrons lose energy most efficiently in elastic collisions with light nuclei, especially protons. Water contains a lot of hydrogen, and its density means a given thickness provides many hydrogen targets for neutron collisions, effectively slowing fast neutrons to thermal energies. Once slowed, neutrons are more likely to be captured and removed from the beam, especially if the water is doped with neutron-absorbing elements like boron.

Lead, while great for gamma shielding, doesn’t slow neutrons well and can even generate secondary gamma radiation when hit by neutrons. Foil is too thin to provide meaningful neutron attenuation. Plastic can slow neutrons thanks to hydrogen, but water typically offers more hydrogen per volume and is easier to implement as shielding, making it the most effective choice among the options.