Bringing a Proven Technique into the Digital Era – BIPM and NIM Collaboration
A pioneering radioactivity measurement method has been brought firmly into the 21st century through a joint project between the BIPM and the National Institute of Metrology (NIM), China.
Together, the institutes have modernized Selective Sampling—a technique first developed at the BIPM in the 1980s to improve the accuracy of activity measurements of beta-emitting radionuclides.
The BIPM’s 4πβ(LS)–γ detection system has been the central platform for applying this method. The upgrade replaces cumbersome analogue procedures with a streamlined digital system—using a high-speed CAEN digitizer and in-house software.
This improves how the instrument processes signals and will ensure more reliable results in applications for nuclear medicine, environmental monitoring, radiation safety and more.
By simplifying the architecture, improving background correction, and making the system easier to operate, the project opens the door for more National Metrology Institutes (NMIs) to benefit from a method that was once too complex to adopt.
Beyond the benefits of this specific project, this collaborative effort demonstrates how earlier-generation equipment can be adapted in a cost-effective way, ensuring useful techniques remain relevant and accessible to NMIs worldwide.
The New System
Image caption: Diagram and component overview of the 4πβ(LS)–γ digital selective sampling system.
Thank you
The BIPM warmly acknowledges the contribution of Dr Haoran Liu of the National Institute of Metrology (China), who spent 3 months on secondment at the BIPM to support this project. Bringing his expertise in radionuclide metrology and digital acquisition, Dr Liu worked side-by-side with colleagues to modernise the Selective Sampling system—helping to demonstrate how this technique can be given new life with today’s digital tools.
Photo caption: Dr Haoran Liu (NIM) and Dr Romain Coulon (BIPM) working on Digital Selective Sampling at the BIPM headquarters in Sèvres.
As his secondment comes to an end, the BIPM extends its thanks for his dedication and technical insight, which have left a lasting impact on the project and the wider metrology community.