Solution-processed flexible Neutron Converter Foils

The cost increase of helium-3 has sparked the development of alternative detection technologies, specifically the use of boron carbide converters is one of the pillars of next-generation neutron detectors. While producing high-quality films, sputter-coating is limited in deposition area, and requires costly and energy-intensive vacuum processing. Lithium fluoride can reach a similar performance to boron carbide, yet requiring thicker layers. The field of functional printing offers several advantages to improve cost efficiency, deposition possibilities over large areas and to explore a larger palette of materials applied to mechanically flexible substrates. We investigated the deposition of boron carbide and lithium fluoride materials via bar coating to fabricate high-performance neutron-sensing flexible films. By understanding and characterization of film properties, neutron detection efficiency and outgassing, fabrication processes have been established. First mechanically flexible coated samples of boron carbide and lithium fluoride films have been produced for layer heights between 2 mum 50 mum and binder concentrations between 10 % and 30 % by weight. They show encouraging results in terms of performance and mechanical stability. Due to the industrial readiness of printing technologies we expect a potential pathway towards developing a new generation of neutron converter foils to support the development of state-of-the-art large-area instruments. Lower costs, more detectors, better research.