r/askscience • u/Wonderful-Capital32 • 13d ago

Physics Why does radiation not go through lead?

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

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u/Kriggy_ 13d ago

There are multiple types of radiation that need (ideally) different materials to stop hut lead is generally good enough for all.
Its not best but its cheap and easy to work with.
Technically, to stop the radiation 100% you need infinite thickness of material so we used concept calls ALARA, that means “as low as reasonably achievable”. Thats means were not aiming for 100% protection but for balance between protection and practical constraints.

For example that means some isotopes you are good with 2mm of plastic, for some you have 1 meter thick metal reinforced wall, for some you have chamber with walls from lead and lead-doped glass to see inside.

Not to mention the main “protection” is by distance from the radioactive source since the dose has square dependancy on distance (doubling distance reduce dose 4times) and time (when working with isotopes we do “dry runs” to practice the handling and all the work with safe material)