Wavelength-shifting-fibre-based neutron image detector with a fibre-optic taper to increase the spatial resolution

The effective pixel size of a two-dimensional wavelength-shifting-fibre (WLS-fibre)-based neutron image detector was improved from 0.5 to 0.16 mm by including a fibre-optic taper (FOT) between the scintillator screen and the WLS fibre. The WLS-fibre-based detector consisted of a thin ZnS/6LiF screen, a FOT and WLS ribbons crossed in the x and y directions. The demonstrator detector had 16 fibre channels in each direction, and the light signals in each fibre were read out individually. The FOT was constructed from fine glass fibres with a taper ratio of 3.1 and served as an image magnifier. The prototype detector equipped with the FOT exhibited a spatial resolution of 0.3 mm, compared to the spatial resolution of 0.8 mm of the original detector without the FOT.