Investigation of the neutron imaging applications using fine-grained nuclear emulsion

TL;DR

This paper explores the use of fine-grained nuclear emulsion detectors for high-resolution neutron imaging, demonstrating effective imaging of gadolinium gratings with micrometer precision and analyzing optimal track densities.

Contribution

It introduces the application of fine-grained nuclear emulsion for neutron imaging, determining optimal track densities, and successfully resolving grating structures with sub-micrometer resolution.

Findings

Track density of ~10^4 tracks per 100x100 μm^2 is sufficient for imaging.

Gadolinium-based gratings were successfully imaged with micrometer resolution.

Edge response of 0.945 μm was achieved in the imaging process.

Abstract

Neutron imaging is a non-destructive inspection technique with a wide range of applications. One of the important aspects concerning neutron imaging is achieving micrometer-scale spatial resolution. Developing a neutron detector with a high resolution is a challenging task. Neutron detectors, based on fine-grained nuclear emulsion, may be suitable for high resolution neutron imaging applications. High track density is a necessary requirement to improve the quality of neutron imaging. However, the available track analysis methods are difficult to apply under high track density conditions. Simulated images were used to determine the required track density for neutron imaging. It was concluded that a track density of the order of $10^4$ tracks per 100 $\times$ 100 $\mu$m$^2$ is sufficient to utilize neutron detectors for imaging applications. The contrast resolution was also investigated for the image data sets with various track densities and neutron transmission rates. Moreover, experiments were performed for neutron imaging of the gadolinium-based gratings with known geometries. The structure of gratings was successfully resolved. The calculated 1$\sigma$ 10-90 \% edge response, using the gray scale optical images of the grating slit with a periodic structure of 9 $\mu$m, was 0.945 $\pm$ 0.004 $\mu$m.