Narrow-area Bragg-edge transmission of iron samples using superconducting neutron sensor

Abstract

This study investigates a current-biased kinetic inductance detector (CB-KID) performance by investigating Bragg-edge spectra from the restricted-area neuron transmission of materials. Iron samples with a size of 5 × 5 ×2 mm3 were used as typical test materials. The ergodic theorem was used to obtain a visible transmission spectrum so that a long-time averaging of a transmission spectrum can alternatively be evaluated using a space average of independently selected area spectra with the same ensemble size. The most visible edges were observed with a limited area sample of 0.43 mm2 using a minimum time bin of 25 μs in a time-of-flight (ToF) spectrum or a wavelength resolution of 0.0007 nm of each neutron pulse at beamline BL10 of the Japan Proton Accelerator Research Complex (J-PARC) center. The main Bragg edge of iron as a sum of random 100 ensembles (with an ensemble size of 3.1 × 2.3 μm2) thus obtained has a distinctive signal-to-noise ratio and can be fitted well with the Rietveld Imaging of Transmission Spectra (RITS) program with Miller indices. We consider that our CB-KID system is, in principle, able to analyze the Bragg edge of samples as small as 3.1 × 2.3 μm2.

Neutron transmission imaging system with a superconducting kinetic inductance detector

“…We note that the energy resolution of our detector [25] is good enough to discriminate a dip selectively using an aggregate of FeS2 crystals. The wavelength-sensitive imaging demonstrated here can be used to inspect various practical test samples of interests in material sciences.…”

Superconducting neutron transmission imaging for investigating a sequential change in phase separations of low-melting Wood’s metal

“…A spatial resolution of neutron imaging was achieved down to 16 µm and a detection efficiency was 1% at 25 meV [16,17]. We already demonstrated that the most-visible Bragg edge of Fe sample can be discerned even with a very narrow sampling area of 3.1 2.3 m 2 in the neutron transmission spectrum with wavelength resolution of 0.0007 nm [18]. We confirmed that the energy resolution is good enough to obtain the resonance absorption dips to reveal mosaic crystalline structure appeared in Sm-Sn mixed metal [19].…”