It provides a powerful tool for studying complex materials non-destructively, and could be used in fields such as nuclear engineering, battery development or archaeology.
The method, Neutron Resonance Transmission Imaging (NRTI), relies on higher energy epithermal neutrons, which are only produced by a few facilities globally.
As neutrons interact with the nucleus, they are inherently sensitive to different isotopes. Neutron techniques are also non-destructive, whereas other methods for isotope analysis, such as mass spectrometry, involve destroying the sample. Such destructive sampling might not be possible on rare historical artefacts. It also means any information about where the isotopes are located in the sample is lost.
To demonstrate how NRTI can be used, the researchers examined a sample of silver flakes containing two silver isotopes, Ag-109 and Ag-107. Conventional neutron imaging using cold neutrons on the IMAT beamline was able to show the thickness of the sample, for instance where two flakes overlapped, but could not distinguish between isotopes. NRTI, in contrast, produced a two dimensional map of the flakes highlighting the location each of the isotopes.
NRTI uses time-of-flight measurements of the transmitted neutron beam as it passes through the sample. Each isotope shows a characteristic negative dip in the transmission curve, which can be compared to cross-sections available in dedicated nuclear databases to identify the elements and isotopes present.
During data analysis, the researchers are able to select specific neutron energy ranges that correspond to the dips in the transmitted spectrum, and map the distribution of the isotopes in 2D.
The project to implement NRTI at ISIS has been running since 2007, as part of a CNR-STFC collaboration and the Ancient Charm project, which was supported by the European Union's New and Emerging Science and Technology (NEST) programme. More recently, significant progress in the implementation of NRTI has been achieved through a PhD thesis and postdoctoral research from the University of Milano-Bicocca, in close collaboration with the ISIS team.
ISIS is now able to offer NRTI to users on the INES beamline.
Related publication: G. Marcucci (ISIS, Università degli Studi di Milano-Bicocca and INFN Sezione di Milano-Bicocca) A. Scherillo, D. Raspino, (ISIS), D. Di Martino (Università degli Studi di Milano-Bicocca and INFN Sezione di Milano-Bicocca). Isotopic imaging with epithermal neutrons at the ISIS Neutron and Muon Source. Sci Rep 15, 19344 (2025). https://doi.org/10.1038/s41598-025-04283-y
