X-ray Technique Provides a New Tool For Nuclear Forensics Investigations

LLNL and Lawrence Berkeley National Laboratory scientists described how synchrotron-based scanning transmission X-ray microscopy (STXM) can identify chemical states and material impurities at the scale of individual particles — a resolution never before achieved. With this technique, the authors identified and quantified the most common uranium oxides.

The method uses an X-ray beam — focused down to a pinprick that is only tens of nanometers wide — from a synchrotron to scan across a uranium sample. The characteristics of this beam, generated at the Advanced Light Source, allow the team to achieve that superior resolution. As the X-rays pass through the sample, detectors measure how many X-rays are absorbed at each point in the material for multiple X-ray energies.

According to one of the scientists Rachel Lim, STXM allows us to see details in chemical states and impurities of individual particles of nuclear materials that is a major advance for nuclear forensics capabilities. Because each element has its own unique absorption profile — like a fingerprint — STXM can create detailed images and identify the specific elements and their chemical states in very small regions of the sample. 

STXM can be used to analyze minute amounts of nuclear materials quickly and safely without damaging the sample. However, for the correct interpretation of the results, datasets will be required to connect STXM signatures to a material’s provenance and history.