SUBSURFACE METAL LATTICE COIN IMAGES

New Groundbreaking Scientific Technique Unlocks Mysteries of a 1792 Judd-9 Silver Disme
By Robert Rodriguez

At the 2023 ANS Coinage of the Americas Conference, I presented, History Recovered: Saga of the 1792 Silver Disme, on September 22. As a result of our investigations, my colleague, Tony Lopez, and I conclude that the following 1792 Judd-9 silver disme is the Design Work Surface that was used to design the 1793 half cent. To arrive at this conclusion, our journey of discovery required the most extensive and intensive scientific investigation ever conducted in the field of numismatics that took place over a period of nearly 4 1/2 years.

In this presentation, the numismatic and antiquities communities were introduced to the power and capabilities of synchrotron-radiation-based X-ray micro-diffraction. At the Argonne National Laboratory's Advanced Photon Source synchrotron, we recovered the first successful subsurface metal lattice image from the interior of a coin. Nearly 600 hours of scans were executed that culminated in the recovery of stunning images of surface features that can no longer be seen or are illegible on the surface. They were recovered from a depth of approximately 50 microns using high-intensity X-rays that are about one million times stronger than that which would occur in a doctor's office. Three physicists, Dr. Wenjun Liu, Dr. Jon Tischler and Dr. Ruqing Xu, conducted the scanning investigations.

As an example of this new powerful scientific investigation technique, this remarkable image was recovered from the subsurface of a 1792 Judd-9a after a 28-hour scan. The date has not been seen since it was effaced away in 1792.

The presentation may be viewed at the following link: https://www.youtube.com/watch?v=0ap8tHI1QrQ. Our paper will be published later this year as part of the proceedings from the 2023 ANS COAC.

We believe this new scientific investigation technique has the ability to unlock mysteries that were thought to be permanently lost. The Advanced Photon Source is now undergoing a two-year upgrade program that will make it the premiere synchrotron of its type in the world.

"When we recovered the very first image, there was quite a bit of excitement among the three physicists since this had never been achieved before. During the height of Covid, I needed an image that had never been published before from the British Museum. I sent a cold call email to Tom Hockenhull, Curator Director of Coins and Medals. When he saw the date recapture, it blew him away. He drove into the BM that was closed, took a photo with his iPhone and said that if it was not good enough, he would inform the BM's publicity department to do whatever I needed. His photo was perfect, and I used it in the largest edge study of the 1783 Treaty of Paris medal, Betts-614. It has opened a few doors for me. When the date was captured, we were all stunned by it.

"The manuscript for the second project at the Argonne will take me 8-12 months since it is 5x more complex than this research project on the 1792 disme. It will entail around five different papers and will likely become a book. Over 700 hours of X-ray micro-diffraction were involved, along with several other research endeavors. When the Argonne re-opens in 2025, I have a continuing project that will be completed.

"I'm not sure whether the numismatic community will understand the significance of this new scientific technique of investigation. Over time, I hope so."