Development of a converter made of scintillator and wavelength-shifting fibers for fast neutron radiography

Wavelength-shifting fiber (WSF) converter is a novel converter for fast neutron (FN) radiography, which has high light output, high detection efficiency and low gamma sensitivity. In order to improve the performance of WSF converter, we optimized the WSF converter design with a simple model and manufactured it with a new method, which can increase the scintillation material concentration. The light output and gamma sensitivity of WSF converters were measured on accelerator-based fast neutron sources, and gamma sensitivity was measured with an activated indium gamma source. FN radiographs were taken with WSF converter and some other traditional converters for comparison. We found that the light output of the new WSF converter is more than 5 times that of a 2 mm polypropylene (PP) converter for 5.8 MeV neutron beam, while its relative gamma sensitivity is still low.