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論文

Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor

Vu, TheDang; 宍戸 寛明*; 相澤 一也; 小嶋 健児*; 小山 富男*; 及川 健一; 原田 正英; 奥 隆之; 曽山 和彦; 宮嶋 茂之*; et al.

Nuclear Instruments and Methods in Physics Research A, 1006, p.165411_1 - 165411_8, 2021/08

 被引用回数:0 パーセンタイル:0.03(Instruments & Instrumentation)

We found that the sizes of the Gd islands determined from the transmission image correlated strongly with those determined from the SEM image. We demonstrated the CB-KID could be used to identify (1) tiny voids in a thermally sprayed continuous Gd$$_2$$O$$_3$$ film in and (2) various mosaic morphologies and different eutectic microstructures in Wood's metal samples. The fact that the CB-KID system could be used to identify features of samples with a wide distribution of sizes and thicknesses is promising for real application of the device for imaging samples of interest to material scientists. Operating the CB-KID at higher temperatures appreciably improved the efficiency for simultaneously identifying the X and Y positions of hotspots. We also compared the detection efficiency with the PHITS simulations. We now plan to improve the detection efficiency by increasing the thickness of the $$^{10}$$B neutron conversion layer

論文

Homogeneity of neutron transmission imaging over a large sensitive area with a four-channel superconducting detector

Vu, TheDang; 宍戸 寛明*; 小嶋 健児*; 小山 富男*; 及川 健一; 原田 正英; 宮嶋 茂之*; 奥 隆之; 曽山 和彦; 相澤 一也; et al.

Superconductor Science and Technology, 34(1), p.015010_1 - 015010_10, 2021/01

 被引用回数:2 パーセンタイル:72.02(Physics, Applied)

We demonstrated that a four-readout superconducting neutron imaging system shows good spatial heterogeneity and linearity using the delay-line method. We examined the precise pattern of a $$^{10}$$B-dot-array absorber and found the X-direction pitch (Px) = 250.7 um with a scatter of (Hx)= 5.4 um and the Y-direction pitch (Py)= 249.1 um with a scatter of (Hy)= 3.4 um while the $$^{10}$$B dot array was fully extended toward the X direction across the detector sensitive area. We consider that this demonstrates detection with good spatial homogeneity and conclude. The transmission-imaging system is suitable for use at pulsed neutron facilities. We also reported a clear transmission image of tiny screws and nuts, and ladybug (insect). We recognize that further efforts to improve the detection efficiency are necessary to make using the detector more practical.

論文

Kinetic inductance neutron detector operated at near critical temperature

Vu, TheDang; 西村 和真*; 宍戸 寛明*; 原田 正英; 及川 健一; 宮嶋 茂之*; 日高 睦夫*; 奥 隆之; 曽山 和彦; 相澤 一也; et al.

Journal of Physics; Conference Series, 1590, p.012036_1 - 012036_9, 2020/07

 被引用回数:0 パーセンタイル:0.01

Our CB-KID neutron imager detects high spatial resolution neutrons transmission images by using a delay-line technique. We found that the number of events was remarkably increased with increasing the detector temperature until close to the critical temperature Tc. We investigated the properties of CB-KID at near Tc. We observed systematic changes of neutron signals as a function of the detector temperature from 4 K to Tc. The simulations modeled the sequential physical processes for $$^{10}$$B(n,$$alpha$$)$$^{7}$$Li reactions and energy deposition by particles within CB-KID, including neutrons, $$^{4}$$He particles, $$^{7}$$Li particles, photon and electron transport.

論文

Temperature dependent characteristics of neutron signals from a current-biased Nb nanowire detector with $$^{10}$$B converter

Vu, TheDang; 飯澤 侑貴*; 西村 和真*; 宍戸 寛明*; 小嶋 健児*; 及川 健一; 原田 正英; 宮嶋 茂之*; 日高 睦夫*; 奥 隆之; et al.

Journal of Physics; Conference Series, 1293, p.012051_1 - 012051_9, 2019/10

 被引用回数:4 パーセンタイル:97.68

We succeeded in designed and fabricated a neutron detector by using a superconducting current-biased kinetic inductance detector (CB-KID), which is constructed by two perpendicular Nb-based superconducting meander-lines and an enriched $$^{10}$$B neutron conversion layer. We rebuilt completely a neutron image of a $$^{10}$$B dot array contain in the stainless-steel mesh. To improve the resolution of neutron images, the characteristics of a superconducting neutron detector have been studied carefully. In this study, we present the dependence of neutron signals in the temperature of detector. We found that when the temperature of a neutron detector is as close as the critical temperature of superconductivity, the intensity of signal increase as a function of temperature. We consider that the ratio of noise and signal is decrease which is very useful to improve the resolution of neutron images.

論文

Multiple-wavelength neutron holography with pulsed neutrons

林 好一*; 大山 研司*; 八方 直久*; 松下 智裕*; 細川 伸也*; 原田 正英; 稲村 泰弘; 仁谷 浩明*; 宍戸 統悦*; 湯葢 邦夫*

Science Advances (Internet), 3(8), p.e1700294_1 - e1700294_7, 2017/08

Local structures around impurities in solids provide important information for understanding the mechanisms of material functions, because most of them are controlled by dopants. For this purpose, the X-ray absorption fine structure method, which provides radial distribution functions around specific elements, is most widely used. However, a similar method using neutron techniques has not yet been developed. If one can establish a method of local structural analysis with neutrons, then a new frontier of materials science can be explored owing to the specific nature of neutron scattering-that is, its high sensitivity to light elements and magnetic moments. Multiple-wavelength neutron holography using the time-of-flight technique with pulsed neutrons has great potential to realize this. We demonstrated multiple-wavelength neutron holography using a Eu-doped CaF$$_{2}$$ single crystal and obtained a clear three-dimensional atomic image around trivalent Eu substituted for divalent Ca, revealing an interesting feature of the local structure that allows it to maintain charge neutrality. The new holography technique is expected to provide new information on local structures using the neutron technique.

論文

Neutron flux spectrum revealed by Nb-based current-biased kinetic inductance detector with a $$^{10}$$B conversion layer

宮嶋 茂之*; 宍戸 寛明*; 鳴神 吉人*; 吉岡 直人*; 藤巻 朗*; 日高 睦夫*; 及川 健一; 原田 正英; 奥 隆之; 新井 正敏*; et al.

Nuclear Instruments and Methods in Physics Research A, 842, p.71 - 75, 2017/01

 被引用回数:12 パーセンタイル:84.86(Instruments & Instrumentation)

We successfully derived the time-dependent flux of pulsed neutrons using a superconducting Nb-based current biased kinetic inductance detector (CB-KID) with a $$^{10}$$B conversion layer at Japan Proton Accelerator Research Complex. Our CB-KID is a meander line made of a 40-nm-thick Nb thin film with 1-$$mu$$m line width, which is covered with a 150-nm-thick $$^{10}$$B conversion layer. The detector works at a temperature below 4 K. The evaluated detection efficiency of the CB-KID in this experiment is 0.23% at the neutron energy of 25.4 meV. The time-dependent flux spectra of pulsed neutrons thus obtained are in good agreement with the results obtained by the Monte Carlo simulations.

論文

Cyclotron resonance study of quasiparticle mass and scattering rate in the hidden-order and superconducting phases of URu$$_2$$Si$$_2$$

利根川 翔*; 橋本 顕一郎*; 井加田 洸輔*; 鶴原 悠悟*; Lin, Y.-H.*; 宍戸 寛明*; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; et al.

Physical Review B, 88(24), p.245131_1 - 245131_13, 2013/12

 被引用回数:12 パーセンタイル:53.54(Materials Science, Multidisciplinary)

Detailed analyses of the cyclotron resonance lines in a uranium compound URu$$_2$$Si$$_2$$ are reported. The analyses of the resonance profiles reveals that the heavier branch of the split line has a larger scattering rate, providing evidence for the existence of hot-spot along the [110] direction. The result is consistent with the broken fourfold symmetry in the hidden-order phase.

論文

Cyclotron resonance in the hidden-order phase of URu$$_2$$Si$$_2$$

利根川 翔*; 橋本 顕一郎*; 井加田 洸輔*; Lin, Y.-H.*; 宍戸 寛明*; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; 池田 浩章*; et al.

Physical Review Letters, 109(3), p.036401_1 - 036401_5, 2012/07

 被引用回数:51 パーセンタイル:88.95(Physics, Multidisciplinary)

First observation of cyclotron resonance in the hidden-order phase of ultra clean URu$$_2$$Si$$_2$$ is reported. An anomalous splitting of the sharpest resonance line under in-plane magnetic field rotation was found. This is most naturally explained by the domain formation, which breaks the fourfold rotational symmetry of the underlying tetragonal lattice. The result is consistent with the "nematic" Fermi liquid state, in which itinerant electrons have unidirectional correlations.

論文

Anomalous low-field diamagnetic response in ultraclean URu$$_2$$Si$$_2$$ superconductor

岡崎 竜二*; 下澤 雅明*; 宍戸 寛明*; Konczykowski, M.*; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; 柳瀬 陽一*; 芝内 孝禎*; et al.

Journal of Physics; Conference Series, 273, p.012081_1 - 012081_4, 2011/02

 被引用回数:3 パーセンタイル:66.37

The low critical field $$H_{rm c1}$$ in ultraclean URu$$_2$$Si$$_2$$ single crystals with residual resistivity ration exceeding 700 is precisely determined. The whole $$H_{rm c1}$$ for $$H parallel a$$ can be explained by the two-gap with line and point nodes. In contrast, for $$H parallel c$$ a distinct kink in the slope of $$H_{rm c1}$$ was found at 1.2 K, which cannot be accounted for by the two-gap. This outstanding anomaly demonstrates a highly unusual superconducting state embedded in the hidden order state possibly related to the time reversal symmetry breaking.

論文

Lower critical fields and the anisotropy in PrFeAsO$$_{1-y}$$ single crystals

岡崎 竜二*; Konczykowski, M.*; Van der Beek, C. J.*; 加藤 智成*; 橋本 顕一郎*; 下澤 雅明*; 宍戸 寛明*; 山下 穣*; 石角 元志; 鬼頭 聖*; et al.

Physica C, 470(Suppl.1), p.S485 - S486, 2010/12

 被引用回数:0 パーセンタイル:0(Physics, Applied)

鉄系オキシニクタイドPrFeAsO$$_{1-y}$$単結晶における$$H$$ $$parallel$$ $$c$$$$H$$ $$parallel$$ $$ab$$-planesのより下部臨界磁場$$H_{c1}$$を報告する。磁束ピン止めによって$$H_{c1}$$決定の困難さを回避することで、センサーの位置ごとの局所の磁気誘導を評価できる小型のホールセンサーアレイを使った新方式を開発した。結晶の縁に置かれたホールセンサーは、マイスナーの状態から最初の磁束侵入を明瞭に解明した。$$H$$ $$parallel$$ $$c$$による$$H_{c1}$$の温度依存性は、面内侵入の深さによって計測され、完全ギャップの超伝導状態と一致する。低温での$$H_{c1}$$の異方性は$$sim$$3であると評価され、それは$$H_{c2}$$よりさらに小さいものである。これは、マルチバンド超伝導性を意味し、超伝導性のアクティヴバンドはより二次元的である。

論文

Disorder and flux pinning in superconducting pnictide single crystals

Van der Beek, C. J.*; Rizza, G.*; Konczykowski, M.*; Fertey, P.*; Monnet, I.*; 岡崎 竜二*; 加藤 智成*; 橋本 顕一郎*; 下澤 雅明*; 宍戸 寛明*; et al.

Physica C, 470(Suppl.1), p.S385 - S386, 2010/12

 被引用回数:1 パーセンタイル:7.06(Physics, Applied)

ニクタイド超伝導体PrFeAsO$$_{1-x}$$中の結晶の乱れが、磁束の新入の磁気光学可視化,透過型電子顕微鏡,放射光X線回折を用いて調べられた。磁束分布の臨界状態,臨界電流の大きさと温度依存性が、すべての温度で酸素欠陥によるバルクの磁束ピン止めを示す。

論文

Fermi surface properties of ferromagnet UCu$$_2$$Si$$_2$$

松田 達磨; 池田 修悟*; 山本 悦嗣; 芳賀 芳範; 宍戸 寛明*; 山上 浩志; 摂待 力生*; 大貫 惇睦

Journal of the Physical Society of Japan, 79(11), p.114712_1 - 114712_4, 2010/11

 被引用回数:4 パーセンタイル:34.86(Physics, Multidisciplinary)

Snフラックス法により正方晶UCu$$_2$$Si$$_2$$の単結晶育成及びドハース・ファンアルフェン効果測定に成功した。UCu$$_2$$Si$$_2$$は、温度106K以下において反強磁性転移し、続く100K以下において強磁性転移する。この強磁性状態において、5$$times$$10$$^6$$から7$$times$$10$$^7$$ Oeのドハース・ファンアルフェンシグナルを観測した。それぞれに対応するサイクロトロン有効質量は、1.4から4.2$$m_0$$で、電子比熱係数の値$$gamma=$$20mJ/K$$^2cdot$$molと矛盾がない。これらの実験結果は、5$$f$$電子を遍歴とした、スピン及び軌道分極モデルでおおまかに説明される。

論文

Exotic superconducting state embedded in the hidden order state of URu$$_2$$Si$$_2$$

松田 祐司*; 岡崎 竜二*; 笠原 裕一*; 宍戸 寛明*; 芝内 孝禎*; 芳賀 芳範; 松田 達磨; 大貫 惇睦

Physica C, 470(20), p.1013 - 1017, 2010/11

 被引用回数:1 パーセンタイル:7.06(Physics, Applied)

We report charge and thermal transport measurements on ultra clean single crystals of the superconductor with the hidden-order state URu$$_2$$Si$$_2$$. The results provide strong evidence for a new type of unconventional superconductivity with two distinct gaps having different nodal topology. We propose a gap function with chiral $$d$$-wave form. We also demonstrate that a distinct flux line lattice melting transition with outstanding characters occurs well below the upper critical fields even at sub-Kelvin temperature.

論文

Anomalous temperature dependence of lower critical field in ultraclean URu$$_2$$Si$$_2$$

岡崎 竜二*; 下澤 雅明*; 宍戸 寛明*; Konczykowski, M.*; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; 柳瀬 陽一*; 芝内 孝禎*; et al.

Journal of the Physical Society of Japan, 79(8), p.084705_1 - 084705_7, 2010/08

 被引用回数:15 パーセンタイル:67.1(Physics, Multidisciplinary)

Lower critical field $$H_{rm c1}$$ of the heavy fermion superconductor URu$$_2$$Si$$_2$$ has been investigated on a ultra clean sample. The whole $$H_{rm c1}$$ ($$T$$) along the $$a$$ axis is well explained by the two superconducting gap structures with line and point nodes. On the other hand, $$H_{rm c1}$$ along the $$c$$ axis shows a distinct kink around 1 K, well below the superconducting transition temperature. The observed anomalous response is possibly related to a peculiar vortex dynamics associated with chiral domains.

論文

Recent progress in the energy recovery linac project in Japan

坂中 章悟*; 明本 光生*; 青戸 智浩*; 荒川 大*; 浅岡 聖二*; 榎本 収志*; 福田 茂樹*; 古川 和朗*; 古屋 貴章*; 芳賀 開一*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

日本においてERL型放射光源を共同研究チームで提案している。電子銃,超伝導加速空洞などの要素技術開発を進めている。また、ERL技術の実証のためのコンパクトERLの建設も進めている。これら日本におけるERL技術開発の現状について報告する。

論文

Lower critical fields of superconducting PrFeAsO$$_{1-y}$$ single crystals

岡崎 竜二*; Konczykowski, M.*; Van der Beek, C. J.*; 加藤 智成*; 橋本 顕一郎*; 下澤 元幸*; 宍戸 寛明*; 山下 穣*; 石角 元志; 鬼頭 聖*; et al.

Physical Review B, 79(6), p.064520_1 - 064520_6, 2009/02

 被引用回数:55 パーセンタイル:88.03(Materials Science, Multidisciplinary)

鉄砒素系超伝導体PrFeAsO$$_{1-y}$$超伝導単結晶の下部臨界磁場とその異方性の評価を行った。

論文

Single crystal growth and the fermi surface property in LuCoGa$$_5$$

松田 達磨; 芳賀 芳範; 酒井 宏典; 青木 大*; 池田 修悟; 山本 悦嗣; 宍戸 寛明*; 摂待 力生*; 播磨 尚朝*; 大貫 惇睦

Journal of the Physical Society of Japan, 77(2), p.024704_1 - 024704_6, 2008/02

 被引用回数:1 パーセンタイル:12.17(Physics, Multidisciplinary)

HoCoGa$$_5$$-型正方晶をとるLuCoGa$$_5$$の純良単結晶育成に成功した。得られた単結晶を用いて、結晶構造パラメータを決定し、さらに抵抗,比熱,ドハース・ファンアルフェン効果測定を行った。フェルミ面は、シリンダー状に近いトポロジーを有しており、これらの特徴はFLAPW法によるエネルギーバンド計算によって非常によく説明できることが明らかとなった。

論文

Flux line lattice melting and the formation of a coherent quasiparticle bloch state in the ultraclean URu$$_2$$Si$$_2$$ superconductor

岡崎 竜二*; 笠原 裕一*; 宍戸 寛明*; Konczykowski, M.*; Behnia, K.*; 芳賀 芳範; 松田 達磨; 大貫 惇睦; 芝内 孝禎*; 松田 祐司*

Physical Review Letters, 100(3), p.037004_1 - 037004_4, 2008/01

 被引用回数:27 パーセンタイル:77.32(Physics, Multidisciplinary)

We find that in ultraclean heavy-fermion superconductor URu$$_2$$Si$$_2$$ ($$T_c0 = 1.45$$ K) a distinck flux line lattice melting transition with outstanding characters occurs well below the mean-field upper critical fields. We show that a very small number of carriers with heavy mass in this system results in exceptionally large thermal fluctuations even at subkelvin temperatures, which are witnessed by a sizable region of the flux line liquid phase. The uniqueness is further highlighted by an enhancement of the quasiparticle mean free path below the melting transition, implying a possible formation of a quasiparticle Bloch state in the periodic flux line lattice.

論文

Exotic superconducting properties in the electron-hole-compensated heavy-fermion "semimetal" URu$$_2$$Si$$_2$$

笠原 裕一*; 岩澤 卓矢*; 宍戸 寛明*; 芝内 孝禎*; Behnia, K.*; 芳賀 芳範; 松田 達磨; 大貫 惇睦; Sigrist, M.*; 松田 祐司*

Physical Review Letters, 99(116), p.116402_1 - 116402_4, 2007/09

 被引用回数:166 パーセンタイル:97.08(Physics, Multidisciplinary)

We show that the charge and thermal transport measurements on ultraclean crystals of URu$$_2$$Si$$_2$$ reveal a number of unprecedented superconducting properties. The uniqueness is best highlighted by the peculiar field dependence of thermal conductivity including the first order transition at $$H_{rm c2}$$ with a reduction of entropy flow. This is a consequence of multi-band superconductivity with compensated electronic structure in the hidden order state of this system. We provide strong evidence for a new type of unconventional superconductivity with two distinct gaps having different nodal topology.

論文

Single crystal growth and fermi surface property in ThRhIn$$_5$$

松田 達磨; 芳賀 芳範; 山本 悦嗣; 池田 修悟; 宍戸 寛明*; 摂待 力生*; 播磨 尚朝*; 大貫 惇睦

Journal of the Physical Society of Japan, 76(6), p.064712_1 - 064712_7, 2007/06

 被引用回数:11 パーセンタイル:57.39(Physics, Multidisciplinary)

HoCoGa$$_5$$-タイプの正方晶構造を持つThRhIn$$_5$$の単結晶育成を世界で初めて成功した。この単結晶を用いたX線構造解析から、格子定数等の構造パラメータを決定した。また、電気抵抗とドハース・ファンアルフェン効果測定を行った。ドハース・ファンアルフェン効果測定から得られたメインブランチは、4$$f$$電子状態が遍歴的であると考えられる超伝導物質CeCoIn$$_5$$のフェルミ面から得られる特徴に酷似している。一方で、サイクロトロン有効質量は、1$$sim$$2桁近くも違っていることを明らかにし、またこのフェルミ面の特性は、FLAPW法によるエネルギーバンド計算によってよく説明されることを明らかにした。

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