ED3-3

Narrow-area Bragg-edge transmission of iron samples using superconducting neutron sensor
*The Dang Vu1,2, Hiroaki Shishido3,4, Kazuya Aizawa2, Takayuki Oku2, Kenichi Oikawa2, Masahide Harada2, Kenji M. Kojima4,5, Shigeyuki Miyajima6, Kazuhiko Soyama2, Tomio Koyama4, Mutsuo Hidaka7, Soh Y. Suzuki8, Manobu M. Tanaka9, Alex Malins10, Masahiko Machida10, Takekazu Ishida1,4

Neutron imaging has been recognized as one of the most powerful tools for conducting nondestructive inspection of a wide range of materials. We first proposed the idea of a superconducting neutron detector called a current-biased kinetic inductance detector (CB-KID) [1] and reported systematic investigations of the CB-KID characteristics to optimize the operating conditions in recent years [2,3]. A delay-line technique of the four-terminal CB-KID was successful in achieving neutron imaging with a spatial resolution of 16 µm [4]. We revealed that neutron transmission images of practical test samples (various different sized Gd islands) with CB-KID were in good accordance with SEM images [5]. It is a particular advantage of CB-KID to be able to choose a tunable pixel size for analyses. Since neutrons behave as waves, they provide information of the wave-length sensitive properties of materials. In this paper, we intend to examine the CB-KID performance for investigating Bragg-edge spectra from restricted areas of neuron transmission of materials. As a typical test sample, we employed iron samples of the size 3×3×1.5 mm3. We can observe the most visible edges with a single sample area of 450×450 µm2, with a minimum time bin of 50 µs in ToF spectrum or a wave-length resolution of 0.0014 nm of each neutron pulse at beam line BL10 of J-PARC center. Our next interest is to determine how narrow we can choose a test area to investigate the Bragg edges. Because of the limitation of available beam time at the facility, we instead utilize the Ergodic theorem to obtain a visible transmission spectrum. In other words, we assumed that a long time average of a transmission spectrum can be evaluated by space average of independently-chosen area spectra with the same ensemble size. A Bragg edge spectrum as a sum of random 1000 ensembles (with an ensemble size 9×9 μm2) thus obtained has a good signal-to-noise ratio and can be fitted well with RITS (Rietveld Imaging of Transmission Spectra) program with Miller indices [6]. We consider that our CB-KID system is in principle able to analyze the Bragg edge of a sample as small as 9×9 μm2.

This work is partially supported by Grant-in-Aid for Scientific Research (Nos. JP16H02450, JP21H04666, JP21K14566) from JSPS

References
[1] Ishida T, Yoshioka N, Narukami Y, Shishido H, Miyajima S, Fujimaki A, Miki S, Wang Z, Hidaka M 2014 J Low Temp Phys 176 216
[2] Vu T D, Iizawa Y, Nishimura K, Shishido H, Kojima K M, Oikawa K, Harada M, Miyajima S, Hidaka M,Oku T, Soyama K, Aizawa K, Koyama T and Ishida T 2019 J. Phys.: Conf. Ser. 1293 012051.
[3] Vu T D, Nishimura K, Shishido H, Harada M, Oikawa K, Miyajima S, Hidaka M, Oku T, Soyama K, Aizawa K, Kojima K M, Koyama T, Malins A, Machida M and Ishida T 2019 J. Phys.: Conf. Ser. 1293 012051
[4] Iizawa Y, Shishido H, Nishimura K, Vu T D, Kojima K M, Koyama T, Oikawa K, Harada M, Miyajima S, Hidaka M, Oku T, Soyama K, Aizawa K, Suzuki S Y and Ishida T 2019 Supercond. Sci. Technol. 32 12500
[5] Vu T D, Shishido H, Aizawa K, Kojima K, Koyam T, Oikawa K, Harada M, Oku T, Soyama K, Miyajima S, Hidaka M, Suzuki S Y, Tanaka M M, Malins A, Machida M, Kawamata S, Ishida T 2021 Nucl. Instrum. Meth. Phys. Res. A 1006 165411
[6] Sato H 2018 J. Imaging 4 7

Keywords: Superconducting neutron detector, CB-KID, Bragg-edge, Neutron image