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Pb-210 is a lead isotope that's a byproduct of uranium decay. When mined, all lead contains some Pb-210 as a result of U238 decay[0]. The lead can be refined to
by flashman 10y ago
Pb-210 is a lead isotope that's a byproduct of uranium decay. When mined, all lead contains some Pb-210 as a result of U238 decay[0]. The lead can be refined to remove the U238, but not to remove Pb-210. So all 'fresh' lead contains some Pb-210 with a half-life of 22 years. If you use this for shielding in your experiment, you have to deal with its natural radioactivity.
(Now, what confuses me is how the Romans removed U238 from lead, because they must have done so in order to end up with lead that could decay over 2000 years. Maybe it happened as part of the smelting process.)
[0]https://www.scientificamerican.com/article/ancient-roman-lead-physics-archaeology-controversy/ https://www.scientificamerican.com/article/ancient-roman-lea...
- jacquesm 10y agoMost old lead objects are cast, casting is a process where a liquid is poured into a mold where it is left to solidify. Presumably because both the melting crucible and the cast are under the influence of gravity while the metal is in the liquid phase the heavier elements will sort themselves to one end of the end-product, maybe even into the flues that will get cut off from the final product. It would be much harder to keep the U238 evenly distributed throughout the lead during such a process.