Washington: The properties of the lead bricks recovered from ancient Roman shipwrecks are ideal for experiments in particle physics and scientists have begun to use them to study dark matter and neutrinos, but archaeologists have raised alarm about the destruction and trading of cultural heritage that lies behind this.
Two thousand years ago, a Roman vessel with ingots of lead extracted from the Sierra of Cartagena sank across the waters from the coast of Sardinia. Since 2011, more than a hundred of these ingots have been used to build the `Cryogenic Underground Observatory for Rare Events` (CUORE), an advanced detector of neutrinos- almost weightless subatomic particles- at the Gran Sasso National Laboratory in Italy.
In the 18th century, another ship loaded with lead ingots was wrecked on the French coast. A company of treasure hunters retrieved this material and, despite problems with French authorities, managed to sell it to the Cryogenic Dark Matter Search (CDMS) team. This detector located in a mine in Minnesota (USA) looks for signs of the enigmatic dark matter, which is believed to constitute a quarter of the universe.
These two examples have served as reference for the discussion that two researchers have opened between archaeologists, worried by the destruction of underwater cultural heritage, and particle physicists, pleased to have found a unique material for research on neutrinos and dark matter.
Elena Perez-Alvaro from the University of Birmingham said Roman lead is essential for conducting these experiments because it offers purity and such low levels of radioactivity-all the more so the longer it has spent underwater-which current methods for producing this metal cannot reach.
The underwater archaeologist and the physicists are encouraging dialogue between both collectives, as well as developing legislation that regulates these kinds of activities, without limiting them exclusively to archaeologists, and including scientists.
The study was published in the journal Science.