A comparative study of promising filter materials for neutron imaging facilities

Abstract

The effect of sapphire and bismuth single-crystal filters and their combinations on the quality of neutron radiographic images and neutron tomography data has been studied. The parameters of the contrast of the neutron image were analyzed depending on the monocrystalline filters. Neutron transmission spectra were obtained for sapphire and bismuth single crystals. Additionally, the effect of filters on the overall intensity of the thermal neutron beam and the background of gamma-rays was investigated. Based on the obtained data, we assume that a single-crystal sapphire filter can be most effectively used for radiographic and tomographic installations using thermal neutrons.

Progress in commissioning a neutron/X-ray radiography and tomography systems at IAEA NSIL

“…On this scope, single-crystal sapphire and bismuth filters are strongly recommended. Not only they have high neutron-attenuation coefficient, but also their monocrystal characteristics offer proven improvements on the quality parameters of neutron radiographic images and tomographic data [14]. However, the cost of a suitable single crystal is far higher than for simple cast material and it must be well-cooled if it is to retain its monocrystal characteristics under irradiation.…”

Experimental evaluation of transition rate of sapphire crystal for thermal and fast neutrons using MNSR vertical neutron beam line

“…For single-crystal sapphire filters, a sharp increase in the neutron transmission curve from 53 % to 80 % is observed in the (0.8–2 Å) neutron wavelength range. In the cold neutron range (3.2 Å to 8 Å), the transmittance curve of sapphire is observed to decrease monotonically from 78 % to 58 % [ 7 ].…”