Posted on 06/11/2010 4:45:54 PM PDT by SunkenCiv
The 120 lead ingots, each weighing about 33 kilograms, come from a larger load recovered 20 years ago from a Roman shipwreck, the remains of a vessel that sank between 80 B.C. and 50 B.C. off the coast of Sardinia. As a testimony to the extent of ancient Rome's manufacturing and trading capacities, the ingots are of great value to archaeologists, who have been preserving and studying them at the National Archaeological Museum in Cagliari, southern Sardinia. What makes the ingots equally valuable to physicists is the fact that over the past 2,000 years their lead has almost completely lost its natural radioactivity. It is therefore the perfect material with which to shield the CUORE (Cryogenic Underground Observatory for Rare Events) detector, which Italy's National Institute of Nuclear Physics (INFN) is building at the Gran Sasso laboratory... Lead is, in principle, a shield against radiation, but freshly mined lead is itself slightly radioactive because it contains an unstable isotope, lead-210. "We could never use it for our experiment, which is exactly about keeping background radioactivity to a minimum," says Ettore Fiorini, a physicist at the University of Milan-Bicocca and coordinator of the CUORE experiment. After it is extracted from the ground, however, lead-210 decays into more stable isotopes, with the concentration of the radioactive isotope halving every 22 years. The lead in the Roman ingots has now lost almost all traces of its radioactivity... The ship was in fact a navis oneraria magna, a specialized cargo vessel often used to transport heavy loads such as lead or other metals. It carried more than 1,000 ingots, or 33 tonnes of metal.
(Excerpt) Read more at nature.com ...
Only the inscriptions on the lead ingots will be preserved. -- INFN/Cagliari Archeological SuperintendenceAfter a few years' absence, I've added Mirabilis.ca back onto the links list, and that's the source of the link for this story. Turns out my old Mirabilis link was to an archived page -- that's why it didn't change. You have read that the brain shrinks as you get older, right?
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Old gold.
I’d like to cast some bullets from that lead.
OK this may be a stupid question, but why does mining the lead cause it to start to decay? Would it not decay equally while still in the ground? If the half life is 22 years, the lead has presumably been in the ground since the earth formed billions of years ago, so why is *any* of it still radioactive?
Shh! I think the writer of the article *may have effed that up*. :’)
Since lead water pipes were used in Caesar`s Rome, all the population was aglow.
Great!!!!!!!!!!!!!!
Yeah, that cinched it.
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