High spatial resolution cold neutron imaging with new Tb~(3+)/Ce~(3+) co-doped Gd_2O_3 scintillation glass fiber arrays

摘要

The fiber-array-structured scintillation detectors can achieve both high detection efficiency and high spatial resolution for cold neutron radiography. Three novel Tb3+/Ce3+ co-doped Gd2O3 scintillation glass fiber arrays with different thicknesses (0.3, 0.4, 0.5 mm) have been fabricated and tested. These arrays were composed of 10 mu m diameter Tb3+/Ce3+ co-doped Gd2O3 glass fibers, cladding glass, and extra-mural absorption (EMA) glass. The spatial resolution and the cold neutron absorption efficiency of the imaging system made of 0.4 mm thick fiber array and an optical readout system were measured to be 10 lp/mm (line pairs per millimeter) and 93.4% for cold neutrons, respectively. The optical readout system consists of a cooled Andor iKon-LDZ936 charge-coupled device, a mirror, and a Nikon Nikkor 135 mm lens. The spatial resolution of the cold neutron imaging system is mainly limited by the low resolution of the optical readout system. To further characterize the spatial resolution of these arrays, a higher resolution optical readout system is desired.