Lithium fluoride crystal as a novel high dynamic neutron imaging detector with microns scale spatial resolution

Abstract

Recently, a new field of application of optically stimulated luminescence of color centers (CCs) in lithium fluoride (LiF) crystals was proposed – using them for high‐performance neutron imaging – and promising results were obtained (Matsubayashi et al., Nucl. Instrum. Methods A 622, 637 (2010) and Matsubayashi et al., Nucl. Instrum. Methods A 651, 90 (2011)). Here we present the overview of main findings, which clearly demonstrated that the LiF crystal performs efficiently as neutron imaging detector in areas, where a high spatial resolution with a high image gradation resolution is needed. It was shown that the obtained neutron images are almost free from granular noises, have spatial resolution of ∼ 6 μm, and have practically linear response with the dynamic range of at least 103. It was also found that the LiF crystal detector offers a fairly good sensitivity. Moreover, detailed evaluation using a standard sensitivity indicator for neutron radiography showed that two holes with less than 2% transmittance differences could be distinguished. Additionally, we recently demonstrated that the high resolution neutron imaging with LiF crystals could be useful for quantitative characterizations of neutron sources and electric devices, comprising of low‐Z elements, for example, such as fuel cells. All of this gives new opportunity for microns scale spatial resolution imaging by neutrons (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Using LiF crystals for high-performance neutron imaging with micron-scale resolution

“…The procedures for neutron irradiation of different samples and the readout process were described in detail in Refs. [33][34][35][36].…”

“…In image readout, luminescence from the LiF crystal was observed with a laser scanning confocal luminescence microscope. The λ = 488 nm line of an argon laser was used for excitation and luminescence from the CCs at λ > 510 nm [33][34][35][36] . …”

“…(b) A schematic drawing of a small fuel cell and the neutron image of it [35] . Tiny details with sizes of at least ∼12 µm of the fuel cell structure and its inhomogeneity along and perpendicular to the anode-cathode directions are evidently resolved.…”

“…As is seen from Figure 8(b), such information can be obtained by neutron irradiation of cells and registration of the image by the LiF crystal imaging detector [35] . A spatial resolution of better than 12 µm can be undoubtedly seen along the full field of view of ∼1.5 × 4.5 (mm) and allows us to distinguish the most minute details of the cell structure.…”

“…They have also started to be widely used for characterization intensity profiles or focusing properties of x-ray laser or high-order harmonic beams [23][24][25][26][27][28][29][30] . Dislocations, point defect clusters and cavities in crystals irradiated by neutrons have been investigated already for many decades [31,32] , but only recently we proposed to use LiF crystals as highperformance neutron imaging detectors [33][34][35][36] . In this paper we will give an overview of our main results performed for characterization of such a detector and its use as a highspatial-resolution thermal neutron radiography and discuss the applications of such a detector in areas where a high spatial resolution with a high image gradation resolution is needed.…”