Which material is a preferred neutron shielding material?

• A. Boron
• B. Lead
• C. Aluminum
• D. Concrete

Answer: (A)

Neutron shielding works best when you both slow the neutrons down and then capture them. Boron-10 has a very high probability (cross-section) of absorbing thermal neutrons, so materials containing boron are highly efficient at removing neutrons from a beam without producing a lot of extra radiation. That’s why boron-containing shields, like borated plastics or boron carbide, are preferred: they absorb the slowed neutrons effectively and convert their energy to harmless particles.

In contrast, lead is excellent for shielding gamma rays, not neutrons. Aluminum isn’t particularly good at absorbing neutrons, and concrete, while it slows neutrons because it’s hydrogen-rich, isn’t as effective at absorption unless it’s formulated with boron or another absorber. So, for neutron shielding, materials rich in boron (often paired with a moderator to slow neutrons first) are the best choice.