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How a particle accelerator in France has revolutionized artifact analysis


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Each year roughly 6,000 scientists run experiments at the European Synchrotron Radiation Facility in Grenoble, France. Recently, archaeologists have joined physicists, biologists, and materials scientists who use the particle accelerator to examine objects at a molecular scale. (Erich Lessing/Art Resource)

Some of the greatest discoveries in the future of archaeology may lie within the molecules of excavated artifacts. Thanks to the extremely powerful X-ray beams produced by a type of particle accelerator called a synchrotron, scientists can now look within artifacts at an unprecedented degree of detail. A synchrotron beam, for example, has identified the ingredients in the brilliant blue pigment with which the Maya painted their elaborate murals. Other analyses identified the earliest evidence of oil paint in murals dating to the mid-seventh-century A.D. in caves near the ruins of Afghanistan's giant Bamiyan Buddha statues (both stories were featured in "Top 10 Discoveries of 2008," January/February 2009).

The European Synchrotron Radiation Facility (ESRF) in Grenoble, France, creates a tightly focused beam of electromagnetic radiation that wiggles and undulates through a circular tunnel half a mile in circumference until it reaches a velocity approaching the speed of light. As the beam accelerates and gains energy, it throws off a field of X-rays tens of billions of times more intense than that of a standard medical X-ray machine. Powerful magnets shape the X-rays into beams and funnel them into 40 separate workstations where scientists use them to create images of samples of material down to their molecules. "The synchrotron provides a very small beam," says Marine Cotte, a research scientist at ESRF. "You can work on very, very small fragments, which is rather important in archaeology because if you are allowed to take a sample from an artifact, usually it's very, very small." The radiation does not damage the artifact being examined, and can be applied to samples smaller than the diameter of a human hair. Synchrotron radiation was discovered in 1947, but archaeologists have only started using it in the past decade or so. A look at some of the most intriguing discoveries that ESRF has made over the past few years shows the promise of molecular excavations.

Victoria Schlesinger is a freelance writer in San Francisco.

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