Controversy over the use of Roman ingots to investigate dark matter and neutrinos

Nov 29, 2013
Bou Ferrer shipwreck with roman lead ingots. Credit: De Juan / D. G. de Cultura - Generalitat Valenciana

The properties of these lead bricks recovered from ancient shipwrecks are ideal for experiments in particle physics. Scientists from the CDMS dark matter detection project in Minnesota (USA) and from the CUORE neutrino observatory at the Gran Sasso Laboratory in Italy have begun to use them, but archaeologists have raised alarm about the destruction and trading of cultural heritage that lies behind this. The journal Science has expressed this dilemma formulated by two Spanish researchers in the United Kingdom.

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 , and , pleased to have found a unique material for research on neutrinos and .

As Elena Perez-Alvaro explains to SINC from the University of Birmingham: "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."

Bou Ferrer shipwreck - a roman lead ingot. Credit: De Juan/D. G. de Cultura - Generalitat Valenciana

"Lead extracted today is naturally contaminated with the isotope Pb-210, which prevents it from being used as shielding for particle detectors", adds physicist Fernando González Zalba from the University of Cambridge.

The two researchers have published a study in the journal 'Rosetta', also commented upon this month in Science, which poses a dilemma: Should we sacrifice part of our cultural heritage in order to achieve greater knowledge of the universe and the origin of humankind? Should we yield part of our past to discover more about our future?

"Underwater archaeologists see destruction of heritage as a loss of our past, our history, whilst physicists support basic research to look for answers we do not yet have," remarks Perez-Alvaro, "although this has led to situations in which, for example, private companies like Odyssey trade lead recovered from sunken ships." This is the company that had to return the treasure of the frigate Nuestra Señora de las Mercedes to Spain.

Dialogue between underwater archaeologists and particle physicists

The underwater archaeologist and the physicist 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. "Recovery for knowledge in both fields, and not merely for commercial reasons," the scientists stress.

The jury is still out. In the case of the CUORE detector, for example, in principle the lead from the least well-preserved Roman ingots is used, although their inscriptions are cut and preserved. Some archaeologists also suggests that there are other pieces of valuable metal, such as anchor stocks, rings or tackles for fishing that we should assess whether or not to "sacrifice for science". The problem is that they are protected by UNESCO's 2001 Convention on the protection of underwater cultural heritage if they have been under water more than 10 years and the 2003 Convention for safeguarding intangible cultural heritage.

Regarding the habitual use that Romans made of these ingots, Pérez Álvaro points out that there are many theories, "but they were generally used as water-resistant material for pipes, water tanks or roofs, but also in the manufacture of arms and ammunition."

A special case are the large lead bricks recovered from the largest Roman ship of the excavation of the Mediterranean, the wreck of the Bou Ferrer, which sunk very close to the port of La Vila Joiosa (Alicante). A series of engravings (IMP. GER. AVG) enable specialists to determine that their owner was the Emperor of Rome himself, probably Caligula, Claudius or Nero.

Explore further: Scientists crank up the voltage, create better dark-matter search

More information: Perez-Alvaro, E. (with González-Zalba, F.) "Experiments on Particle Physics Using Underwater Cultural Heritage: The Dilemma". Rosetta 13.5: 40-46, 2013. Reference in News de Science 342, 1 November 2013.

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Sean_W
2.2 / 5 (12) Nov 29, 2013
Maybe we should build a vault under the sea with some of our lead in it so people in 2000years will have something useful. Does it have to be in contact with the water or is it just the shielding from other radiation which let's it become less radioactive.

It's a tough call but I feel the benefits of having ingots in a museum are fewer than expanding human knowledge. Save a fraction of them.
Doug_Huffman
1.4 / 5 (10) Nov 29, 2013
Like steel salvaged from the Scapa Flow fleet sank during WW-I.
Doug_Huffman
1.4 / 5 (9) Nov 29, 2013
No. The lead and the steel were smelted before the first nuclear bomb tests and are free of radioactive contamination.
kochevnik
1.4 / 5 (11) Nov 29, 2013
No. The lead and the steel were smelted before the first nuclear bomb tests and are free of radioactive contamination.
And the article claims "Naturally contaminated?"
gurloc
5 / 5 (6) Nov 29, 2013
In nature lead occurs with uranium and other radioactive elements, in fact a lot of the lead is created by radioactive decay of heavier elements like uranium. Because of that when you mine lead some fraction of it is the unstable isotope lead-210 which has a half life of about 22 years.

However lead can be smelted quite easily to yield a fairly pure product with low uranium contamination, even using ancient techniques. And the lead-210 will decay away over the centuries to non-radioactive lead-206. That is why ancient lead is sought after for shielding experiments looking for rare events.

Having the lead underwater is a bonus because the water helps block cosmic rays and cosmic rays hitting lead can create new radioactive isotopes. But its the lead-210 that is the major issue.
mzso
1.8 / 5 (12) Nov 29, 2013
"r the discussion that two researchers have opened between archaeologists, worried by the destruction of underwater cultural heritage,"
Bah... cultural heritage, my ass. At least they found some value for ancient garbage.
gurloc
4.6 / 5 (10) Nov 29, 2013
Its also worth mentioning that calling this lead archaeologically significant is a bit of a stretch, these are ingots of raw material not a finished product. Just because something is old doesn't make it historically important.

The only thing on the ingots are some production and ownership stamps. Any portion with markings is removed and preserved and the rest of the lead then used for shielding.

In some cases the only reason this lead is recovered in the first place is because particle physics experiments fund archaeological expeditions to find it. Its not as if people are digging up roman artifacts in the back yard and melting them in the basement, this lead only reaches the physicists after the archaeologists are done with it.
Humpty
1 / 5 (11) Nov 29, 2013
Oh fuck it - as a resource for some special and rare experiments - it's hard to beat...

BUT - it's just a bar of fucking lead, taking up space in a warehouse.... Melt another one up out of tyre balancing weights and kick it around some, toss it in the ocean for a few weeks and no one will be any the wiser.

Well they could also stamp "Recreation 2013" on the underside of it....

hudres
1.1 / 5 (7) Nov 29, 2013
Given the necessity for the purity level and freedom from radioisotopes, it is technologically feasible to employ conventional isotope extraction techniques, such as normally used with Uranium, to produce lead of the needed purity. Expensive? Definitely. But it does not harm archeological artifacts. Lead is easier to separate than Uranium, so it should not be so costly. Neutrino and drak matter research are in the area known as "Big Science" let's just spend some more money to be politically correct.
meerling
4.2 / 5 (5) Nov 29, 2013
This is getting ridiculous. Just because it's old, or sunken, doesn't give it significant intrinsic value. I agree with preserving samples and recordings of the engraving (if any) on an ingot, but not the ingot. It's not art, it's not literature, it's not even unique, it's just a basic resource in a convenient form, waiting to be turned into something useful. Sitting untouched on the ocean floor is a waste, and people are supposed to be able to recover and use it, thus the international salvage laws.
If the original makers of those ingots heard that people weren't being allowed to use them because they were lost for a time, I'm sure they'd laugh and declare those people insane.
PhotonX
3.7 / 5 (3) Nov 29, 2013
I'm all for preserving artifacts whenever possible, but it's hard to imagine that this is a sacrosanct piece of cultural heritage. I also believe we have a mandate to learn as much as possible about the Universe around us, and this material furthers that end. Both purposes can be served, though. Sacrifice one end of an ingot, mill out the inside, refill it with modern lead, and stamp the end accordingly. Future archeologists will marvel at the combined work of science and technology over the millennia to achieve a common goal, the outsides of the ingots are preserved, and the physicists get the material they need. Problem solved.
Humpty
1 / 5 (8) Nov 30, 2013
OK pure lead samples... like from a mine?

So how does being many hundreds of meters under ground make it ultra contaminated from nukes and shit - and given how lead and it's isotopes - are break down products from Yewrainium - WTF does it really matter?

To be sure that I am not that clevera about Higgs's bottom, nor his top dom - or even the sphinxtrix penetrators, and neutrinos etc...

But store some away - like leave it on the seabed and use up some for research.

Like if no one had of found it - it would have probably sat on the bottom of the ocean for eternity....

Doug_Huffman
1.3 / 5 (9) Nov 30, 2013
Elemental lead rarely occurs in nature, the radioactive contamination occurs during refinement to remove the usual copper, silver and zinc. Lead ore is usually <10% Pb.

I did a process that monitored a liquid flow for radioactivity using a lead enclosure for the pipe and detector. The lead's inherent radioactivity had to be established with each daily calculation of the detector's sensitivity. It was so sensitive that the effects of the rising and setting Sun could be seen in the output. If the fluid approached the criterion for "contaminated," then it would be dumped - cheaper to replace than clean all the machinery.
gwrede
1 / 5 (8) Nov 30, 2013
I fail to see what the big problem would be if you know the radioactivity of your lead. Basically you would subtract a certain percentage of "hits" from your data. Where's the big deal?
bluehigh
1.9 / 5 (13) Nov 30, 2013
All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?

Lead ingots?

All right, but apart from lead ingots, the sanitation ....
mzso
1 / 5 (10) Nov 30, 2013
All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?

Lead ingots?

All right, but apart from lead ingots, the sanitation ....

They didn't do any of those "for us". As a matter of fact much of that was unlearned in the middle ages and then re-learned more than a millennia later.
bluehigh
1.7 / 5 (12) Nov 30, 2013
It's a reference from a Monty Python film. Life of Brian. Science doesn't exclude historical humour or does it? Forget I asked.
Why so serious? - *smirks *
KBK
1.7 / 5 (9) Dec 01, 2013
All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?

Lead ingots?

All right, but apart from lead ingots, the sanitation ....

They didn't do any of those "for us". As a matter of fact much of that was unlearned in the middle ages and then re-learned more than a millennia later.


The Aqueduct?
carl_badgley
1 / 5 (8) Dec 02, 2013
i am admittedly a bit stunned at the bias being exhibited here. this is not simply about lead ingots. this conversation will shape many other areas in the use or abuse of cultural artifacts in the future. we can't create the lead needed now. but neither do we need an answer to dark matter /now/. it's incredibly important, but it's not life saving or vital to our survival.
mzso
1 / 5 (9) Dec 03, 2013
i am admittedly a bit stunned at the bias being exhibited here. this is not simply about lead ingots. this conversation will shape many other areas in the use or abuse of cultural artifacts in the future. we can't create the lead needed now. but neither do we need an answer to dark matter /now/. it's incredibly important, but it's not life saving or vital to our survival.


What we absolutely don't need and is unimportant is junk from old times. Doesn't matter if it's a hundred years old or 10 thousand.
Zephir_fan
Dec 03, 2013
This comment has been removed by a moderator.
Urgelt
not rated yet Dec 09, 2013
Carl, they're just lead ingots. There isn't a lot of information to be gleaned from them, but archeologists are welcome to get first crack before they go to physicists, far as I'm concerned.

You *might* be wrong about the implications for human survival. Dark matter research is basic research, as basic as it gets. Which means we don't know what we'll learn or how we'll be able to put what we learn to use.

Don't look now, but the survival of our civilization is in question. There are too many of us. The oceans are being depleted of edible fish; they may be gone by 2050. Energy isn't as cheap and is getting pricier. Species extinctions due to climate change are accelerating. The trend lines are troubling.

If physics can come up with cheap, safe energy sources, it'll help keep us going. We don't *know* if this research will net us a win like that, but we're well-advised to engage in basic research as much as we can. It might not be enough, but it's worth trying.
Q-Star
not rated yet Dec 09, 2013
i am admittedly a bit stunned at the bias being exhibited here. this is not simply about lead ingots.


Bias? What do ya mean by bias? It's a judgment call on what will be best served in using these lead ingots to further science, or letting them be used for "?". How interesting is a stack of old leads ingot to look at from outside a glass case? Is there anything that can be learned from them by looking at them again and again?

this conversation will shape many other areas in the use or abuse of cultural artifacts in the future. we can't create the lead needed now. but neither do we need an answer to dark matter /now/. it's incredibly important, but it's not life saving or vital to our survival.


So join the conversation.What good do they serve now? What is their value now as is? Make a case of why it is more important not to use them than to use them. Sentimental attachment is valued how?

I'm thinking the fellow with the rusty cars makes a good point.