Cold neutron radiography, as a complementary technique of X-ray radiography, has been proven to be a very effective non-destructive method because of the unique ability of neutrons to penetrate dense materials, while remaining sensitive to low atomic mass materials. The imaging detector is one of the key components that affects the imaging quality in cold neutron radiography. In such a detector, the high spatial resolution, high imaging contrast, high signal-to-noise ratio (SNR), and high neutron detection efficiency are keenly desired. Structured scintillation screens are a very promising solution to fabricate a high spatial resolution imaging detector at the same time maintaining a high neutron detection efficiency.

CIRP carried out an optimization of the neutron imaging detector through manufacturing the novel Gd2O3 glass fiber arrays with different diameters and deploying the infinity corrected optics.

Schematic of the cold neutron imaging system based on Gd 2 O 3 glass
fiber arrays and the infinity corrected optics

Theoretical analysis and experimental works have been carried out to investigate the factors affecting the spatial resolution, imaging contrast, SNR, and the neutron detection efficiency. The characterization results show that the cold neutron imaging detector made of 0.3-mm-thick Tb³⁺/Ce³⁺ co-doped Gd₂O₃ scintillation glass fiber array with a fiber diameter of 6 mm achieved a spatial resolution of 28.8 lp/mm (17.4 µm), an SNR of 28.6:1, and a cold neutron detection efficiency of 31.6%, i.e., a cold neutron absorption efficiency of 81.0%. In future research, the core glass composition will be further optimized to increase the light yield and reduce interdiffusion during the manufacturing process.

Contact: official@cirp.org.cn