New ion beam research provides links to past

Author: Alexandra Kilpatrick, South Bend Tribune

SOUTH BEND -- From discovering the origins of early Native American pottery in Notre Dame's Snite Museum to analyzing the silver content of Roman coins, Notre Dame nuclear astrophysicists apply new research involving accelerated ion beams to real life in more ways than one and, in turn, uncover more about the area's local history.


"A lot of the work that's done on early (Native American) settlements around here is to find out if a lot of the pottery was local or if they'd come from somewhere else," said Philippe Collon, a Notre Dame physics professor.

It's important work, he said, because it "can give you information on migration, on trade and things like that ... by analyzing specific trace elements."

While scientists often have to partially destroy a painting to discover its authenticity, new applied physics techniques use ion beams in a nondestructive way to uncover counterfeit artwork. However, Notre Dame's department focuses more on the composition of the artwork than the authenticity.

"There are techniques that can (reveal counterfeit artwork)," said Collon, adding there are labs that do this sort of thing "for bread and butter. It's not to say that we can't do it or we wouldn't do it. But what we've mostly been doing is analyzing various artifacts from the Snite Museum, from various collectors, and what they were more interested in is, what was the composition of the pigments?"

In addition to researching paintings and pottery from the museum, the astrophysics researchers also study Roman coins.

"By comparing the silver content in Roman coins, you can actually correlate that to the state of the Roman economy," Collon said. "The poorer, the worse it was, the less silver you had in the coins and things like that."

Collon claims the physics research attracts undergraduate students because of its application to the real world.

"What we were interested in here is to go away a little bit from just doing nuclear astrophysics and doing some more applied work," Collon said, "because it's extremely interesting. It's something different to do. It's something that's very helpful for students."

A whole number of different techniques are based in physics, he added, "from X-raying a painting to usingX-raysto analyze pigments."

Notre Dame's nuclear astrophysics department uses the same accelerators to research the moon, sky and stars, and to analyze artifacts, merely producing different beams that cater to studying objects that are smaller and closer than those they study in the sky.

"In order to do the research for stars, we use accelerators," Collon said. "They basically present beams of energetic particles that have a specific velocity. And what we do is we study nuclear reactions. However, you can use those same machines and produce specific beams and use those to analyze artifacts and a whole host of different applied techniques."

The department uses two different applied techniques in their lab, one called accelerated mass spectrometry, or AMS, which dates anything from paintings to coins. The applied physics researchers also use proton-inducedX-rayemissions, or PIXE, which identify various pigments in a piece of artwork or artifact.

Although such programs have been around for decades, physicists have only begun using them in recent years to study paintings and artifacts. Notre Dame's physics department is one of the first to involve students in art archaeology research using accelerated ion beams.

Not only physics students but also anthropology students, specifically archaeology majors, research the accelerated ion beams with Collon to analyze various artifacts.


"We get a lot of students that are not necessarily physics students into the lab," Collon said, "because they are anthropology students, they are archaeology majors. ... And they basically learn about physics, because what they're doing is using nuclear physics but to understand what they're looking for, so that's great fun and so it's a sort of extra avenue."

While Collon and his research team mainly use AMS specifically for nuclear astrophysics, rather than to date artifacts, the Notre Dame department does offer a class, Physics Methods in Art and Archaeology, which demonstrates how the program can be applied for art archaeology. The research team actively uses PIXE to reveal pigments in artifacts and artwork, specifically that found in the Snite Museum.

"What happens is as the protons go through the various pigments of the artifact, they produce X-rays and those X-rays are very specific to specific elements that are in the pigments," Collon said. "And so, I can, in a nondestructive way, not only see that it's a blue pigment, but I can actually find out what type of blue pigment. And that can help in identifying if something is of a specific period or not, the specific pigments we use and things like that."

Collon emphasizes the applied nature of the work he and his research team do in the physics lab and in turn, the diversity of student majors the research draws.

"The fun thing about AMS is that it's a needle-in-the-haystack technique," he said. "And so, it allows you to do some nuclear physics, basic nuclear physics, using that technique but then also to apply it to different fields and that's great fun."

Appeared in the South Bend Tribune Monday, August 13.