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Nuclear dating for antics

Posted by iKnowHOW on October 30, 2006

An adjunct programme of the International Atomic Energy Agency fosters the use of nuclear methods to address historic and artistic riddles like verifying the origin and authenticity of art objects. William J. Broad reports

(From top) A Tang dynasty figurine, Statue of Mars of Todi, a Corinthian vase

Eager for precision in a field notorious for ambiguity and frustration, curators at top museums in Europe and the US have long reached for the instruments of nuclear science to hit treasures of art with invisible rays. The resulting clues have helped answer vexing questions of provenance, age and authenticity.

Now such insights are going global. The International Atomic Energy Agency (IAEA), best known for fighting the spread of nuclear arms, is working hard to foster such methods in the developing world. This is to make scientists in places like Peru, Ghana and Kazakhstan act as better custodians of their cultural heritage.

Scientific papers and abstracts describe how research projects had used nuclear methods to address historic and artistic riddles. For instance, Chinese scientists had fired the subatomic particles known as neutrons at ancient pottery from the Tang dynasty, which ruled China from AD 618 to 906. The analysis is helping them uncover the art works’ origins in regional workshops.

In an interview, Feng Songlin, a scientist at the Institute of High Energy Physics in Beijing, said he found the agency’s programme “very helpful for Chinese archaeology research and for me”. He said it had helped him ascertain the best analytical methods, prepare samples and learn how to interpret the findings.

Mexican scientists have also applied such methods to colonial-era pottery. Pieces once thought to have been imported from Spain turned out to have been made locally.

The methods used, some of the most fundamental in nuclear science, include neutron activation analysis, proton-induced X-ray emission, accelerator mass spectrometry and X-ray fluorescence spectrometry. The advances are striking because the world of art often finds itself hard pressed to achieve basic goals like verifying the origins of pieces. The standard historical approach of comparing style and iconography, even when coupled with painstaking detective work in archives and distant collections, has often proved inconclusive or at times even deceptive.

The atomic methods, some applied to artistic analysis for the first time in the 1970s and 80s, have revolutionised the field of art history. For instance, the Metropolitan Museum of Art in New York gained a wealth of insights into the provenance of old sculptures in its collection, including some sculptured heads separated from torsos during the French Revolution. The trouble arose when radicals, mistaking statues of religious figures for royalty, developed a taste for decapitation.

The museum’s detective work began at a nuclear reactor, where operators would bombard detached bits of the artwork with speeding neutrons. The resulting showers of gamma rays revealed the presence of trace elements in distinct patterns.

These identifying signatures let museum curators make matches with similarly revealed signatures of European churches, quarries and carvings. For instance, they recently found that one of the sculptured heads in a current exhibition came from a quarry that supplied statuary to either Notre Dame or another 13th century Parisian church.

The Louvre in Paris has a very long accelerator in its basement that fires subatomic particles at artwork to discover compositional clues. Maria Filomena Guerra, a specialist there in ancient gold artefacts, travelled to Vienna last month to help the IAEA with its outreach programme.

The agency is now fostering the development of such techniques in Hungary and other countries. In Budapest, scientists are using a cousin of the neutron technique to study Stone Age pottery, including a graceful bowl from a cave in the Bukk mountains. The method is known as prompt gamma activation analysis.

The Hungarian scientists are using the gamma method to compare pottery from eight sites with a variety of clay samples in hope of establishing where the pots arose. The trace elements so far identified include vanadium, neodymium, samarium and gadolinium. The scientists plan to expand the number of investigated sites and soils to produce a comprehensive portrait of artistic evolution in Stone Age Hungary.

Dr Matthias Rossbach of IAEA said he had recently administered a kind of proficiency test to the programme’s members. They were sent bits of powdered Chinese porcelain for analysis, and the results were compared with the agency’s findings. “It was,” he said, “like a teacher grading a report. The objective was to help them improve their method.”

At a display, the scientists set up an instrument, a portable X-ray fluorescence spectrometre, a device little bigger than a golf bag. When in operation, its beam of X-rays stimulates material under observation to glow at various wavelengths, allowing the identification of constituent elements.

The method is cheaper, easier and faster than the neutron technique, though slightly less precise. The scientists said the agency had developed the portable device for use in art museums, and they demonstrated how it worked by training it on a piece of painted canvas.

To the naked eye of an observer, admittedly no art expert, the paint looked dull and drab, almost too plain for words. But the X-rays revealed a kaleidoscope of pigment elements, rendered on the computer monitor as a series of wiggly lines. The scientists identified the peaks as sulphur, calcium, titanium, iron and zinc. Such chemical signatures, they said, could help confirm whether the pigment and painting were actually made at an advertised date, because paint formulas often changed over the decades.

Dr Rossbach said the programme excited him because in the process of teaching he discovered so much about global art as well as its diverse ranks of scientific custodians.

“I’ve learned about pottery in China and icons in Poland,” he said. “I know the techniques they’re using and can discuss whether they’re doing it right. So that, I think, is a very good exchange.”

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8 Responses to “Nuclear dating for antics”

  1. Per Lee said

    I hate nuclear chemistry and wish to tell you that I think your proposal is a useless sack of garbage with a twisty tie on top. 😉

  2. Per Lee said

    Hey Karlie 🙂

  3. Brenda Tiber said

    Hi Perrr 🙂
    you know not to call me that on the internet 😉

  4. Per Lee said

    Ahhh ya minx I’m sorry but this nuclear dating got me all riled up !

  5. Brenda Tiber said

    I know it gets you going 😉
    why create a little chemical reaction of our ownn..

  6. Marlene Barton said

    you kids are up to no good 😉

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  8. http://www.scoop.it

    Nuclear dating for antics

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