Fabrication and experimental evaluation of microstructured 6Li silicate fiber arrays for high spatial resolution neutron imaging

This research presents the fabrication and experimental evaluation of instrumentation designed to enable higher spatial resolution neutron radiography for users at neutron scattering facilities. The properties of novel X-ray opaque materials, like those used energy storage systems, precision manufacturing technologies, aerospace components, and metallic additive manufacturing, are often described using simulation tools lacking experimentally grounded models, and are based on first-principle calculations and theoretical assumptions alone. Thus, ongoing material characterization relies on neutron scattering instrumentation to verify performance predictions and add structure to future models. Despite the successes that neutron scattering science facilities have achieved in recent years, even higher-impact research into microstructure evolution, thermodynamic, and mechanical properties of advanced materials is limited by the current spatial resolution of neutron sensing instrumentation. Herein, we describe a proof-of-concept array of microstructured silicate fibers with 6Li doped cores that shows progress towards micron resolution neutron radiography. The multicore fiber was fabricated by drawing stacked unit elements of Guardian Glass (Nucsafe Inc., Oak Ridge, TN, USA), a 6Li scintillating core glass, and a silicate cladding glass. These structured fibers function as an array of sub-10-micron waveguides for scintillation light. Measurements have shown a significantly increased integrated charge distribution in response to neutrons, and the spatial resolution of the radiographs is described by edge response and line spread functions of 48 +- 2 m and 59 +- 4 m, respectively.