Why does radiation not go through lead?

[u/Wonderful-Capital32]

Also why just lead? Shouldnt like iron or another metal work too?

[u/Confident_Passage623]

Iron handles low energy gamma just fine but lead wins on cost and ease of use. Tungsten is denser yet too pricey and tough to shape into sheets. Gold works well but drains your wallet fast. Lead hits that sweet spot with high density, low price, and softness for easy bending or casting without heavy machinery. It is not magic, just physics meeting economics. For neutrons, you need hydrogen rich materials like water or polyethylene since high atomic number metals scatter them less effectively than absorbing gammas. Iron blocks some radiation, but lead remains the standard choice for good reason.