Development of wavelength-shifting-fiber neutron image detector with a fiber-optic taper with a high spatial resolution

The neutron image detector that was based on wavelength-shifting-fibers (WLS fibers) equipped with the fiber-optic taper was developed. By inserting the FOT in between the scintillator and WLS fibers the measured neutron image was magnified on the WLS fibers. We have tested two FOTs; a square-shaped one with a size of 2.6 × 2.6 mm and a round shaped with a diameter of 20 mm. Both FOTs have identical magnification ratios of 3.1. By implementing the larger FOT the detector has the neutron-sensitive area of 314 mm2 with the effective pixel size of 0.17 × 0.17 mm² while the light transmission rate decreased 20% less compared to that with the small FOT. The detector equipped with the larger FOT exhibited a spatial resolution of 0.26 ±0.07 mm, which was similar to that of the one with the small FOT.