High Spatial Resolution Neutron Transmission Imaging Using a Superconducting Two-Dimensional Detector

TL;DR

This paper demonstrates high-resolution neutron transmission imaging using a superconducting CB-KID detector with delay-line readout, enabling detailed isotope-specific imaging and single-crystal visualization within a Gd-Al alloy.

Contribution

The study introduces a superconducting delay-line CB-KID detector for neutron imaging, achieving high spatial resolution and isotope selectivity with minimal readout channels.

Findings

Successful imaging of Gd-Al alloy and single crystals

Detection of Gd isotope resonance dips at 0.03 nm wavelength

Gd distribution imaging with 15x12 μm resolution

Abstract

Neutron imaging is one of the most powerful tools for nondestructive inspection owing to the unique characteristics of neutron beams, such as high permeability for many heavy metals, high sensitivity for certain light elements, and isotope selectivity owing to a specific nuclear reaction between an isotope and neutrons. In this study, we employed a superconducting detector, current-biased kinetic-inductance detector (CB-KID) for neutron imaging using a pulsed neutron source. We employed the delay-line method, and high spatial resolution imaging with only four reading channels was achieved. We also performed wavelength-resolved neutron imaging by the time-of-flight method for the pulsed neutron source. We obtained the neutron transmission images of a Gd-Al alloy sample, inside which single crystals of GdAl3 were grown, using the delay-line CB-KID. Single crystals were well imaged, in both shapes and distributions, throughout the Al-Gd alloy. We identified Gd nuclei via neutron transmissions that exhibited characteristic suppression above the neutron wavelength of 0.03 nm. In addition, the ^{155}Gd resonance dip, a dip structure of the transmission caused by the nuclear reaction between an isotope and neutrons, was observed even when the number of events was summed over a limited area of 15 X 12 um^2. Gd selective imaging was performed using the resonance dip of ^{155}Gd, and it showed clear Gd distribution even with a limited neutron wavelength range of 1 pm.