Why might tungsten be chosen over lead for gamma shielding in certain applications?

• A. Tungsten offers very high density and a high melting point, which can allow thinner shielding but at higher cost than lead.
• B. Tungsten is lighter than lead, making handling easier.
• C. Tungsten provides better gamma attenuation at all energies with no trade-offs.
• D. Tungsten is not suitable for shielding in any case.

Answer: (A)

The important idea is how material properties influence gamma shielding and the trade-offs in material choice. A shield’s effectiveness per thickness depends strongly on density and how well the material can stand up to the environment where shielding is used. Tungsten’s density is about 19.3 g/cm3, compared with lead’s 11.3 g/cm3. That higher density means more atoms packed into a given thickness, so gamma rays have a greater chance of interacting as they pass through, allowing you to achieve the same level of attenuation with a thinner layer. The high density also coincides with good structural stability, and tungsten’s melting point is around 3422 C, far above lead’s ~327 C, so it remains solid and intact in hotter conditions or where shielding absorbs significant heat.

However, this comes with a cost: tungsten is much more expensive and harder to machine into shielding shapes than lead, so you trade reduced thickness for higher material cost and more complex fabrication. It’s not that tungsten is better at all energies with no downsides; the choice depends on whether reduced shielding thickness and heat resistance justify higher cost and manufacturing challenges for a given application.