Synchrotron reveals lost archaeological information

Tereza Pultarova

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640 synchrotron medalScientists were able to obtain images of these medals without opening the box in which they were lying [Credit: ESRF]

French archaeologists used one of the world’s most powerful X-ray machines to read information inside a 17th century artefact thought lost due to material degradation. 

The team excavating a large site at Grenoble’s Saint Laurent church found a small metallic box inside a grave, which was too damaged even to be manually opened.

The archaeologists brought the 4cm box to the European Synchrotron Radiation Facility (ESRF), which houses one of the world’s most powerful sources of X-rays. The particle accelerator enabled the team to virtually look inside the box without opening it.

The team was even able to read inscriptions on three circular medals found inside the box using an X-ray micro-tomography technique, similar to medical tomography. “It was only supposed to be a small feasibility study to produce an image for an exhibition,” said ESRF scientist Paul Tafforeau. “However, the results were so astounding that it turned into a full scale research project.”

The researchers were able to obtain 3D images of the interior of the box, which revealed three circular medals made of clay and two pearls. Although the medals were stuck together and badly damaged, the researchers were able to reconstruct engravings of Christ on the cross and an image of resurrection that were used to decorate them.

Although synchrotron X-ray imaging has been used frequently for paleontological research since its development in 2000, its use for the study of objects like this box is a novelty that opens new paths and collaborations in the field of archaeology.

Synchrotron can shed light on archaeological secrets that have been kept intact since excavation, a common approach to valuable historical artefacts.

This minimal restoration, which was also applied to archaeological relics to preserve their authenticity in a state as extracted from the earth, today allows us to perform non-destructive investigations with astounding results,” said archaeologist Renée Colardelle who has been leading the excavation at Grenoble’s Saint Laurent church for the past 20 years.