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New precise measurement of muonium hyperfine structure interval at J-PARC

上野 恭裕*; 青木 正治*; 深尾 祥紀*; 東 芳隆*; 樋口 嵩*; 飯沼 裕美*; 池戸 豊*; 石田 啓一*; 伊藤 孝; 岩崎 雅彦*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 被引用回数:1 パーセンタイル:17.79

MuSEUM is an international collaboration aiming at a new precise measurement of the muonium hyperfine structure at J-PARC (Japan Proton Accelerator Research Complex). Utilizing its intense pulsed muon beam, we expect a ten-fold improvement for both measurements at high magnetic field and zero magnetic field. We have developed a sophisticated monitoring system, including a beam profile monitor to measure the 3D distribution of muonium atoms to suppress the systematic uncertainty.


Non-destructive elemental analysis of a carbonaceous chondrite with direct current Muon beam at MuSIC

寺田 健太郎*; 佐藤 朗*; 二宮 和彦*; 川島 祥孝*; 下村 浩一郎*; 吉田 剛*; 河井 洋輔*; 大澤 崇人; 橘 省吾*

Scientific Reports (Internet), 7(1), p.15478_1 - 15478_6, 2017/11


 被引用回数:1 パーセンタイル:100(Multidisciplinary Sciences)

電子やX線を用いた特性X線分析は基礎的化学分析手法として様々な分野で用いられている。近年、その高い透過性からミュオン捕獲特性X線を用いた分析手法が注目を集めている。我々はここに最新の強力なDCミュオン源であるMuSICを用いて行った炭素質コンドライトの分析結果について報告する。炭素を約2%含むJbilet Winselwan隕石を測定した結果、Mg, Si, Fe, O, S, Cからのミュオン捕獲特性X線を検出し、元素存在度のパターンはCMコンドライトとして無矛盾であった。本非破壊分析手法は炭素に高い感度を持つことから、C型小惑星からのサンプルが持ち帰られた場合にも、それを分析する強力な新手法となりえる。


Excited configurations of hydrogen in the BaTiO$$_{3-x}$$H$$_x$$ perovskite lattice associated with hydrogen exchange and transport

伊藤 孝; 幸田 章宏*; 下村 浩一郎*; 髭本 亘; 松崎 禎市郎*; 小林 洋治*; 陰山 洋*

Physical Review B, 95(2), p.020301_1 - 020301_5, 2017/01

 被引用回数:2 パーセンタイル:66.33(Materials Science, Multidisciplinary)

Excited configurations of hydrogen in the oxyhydride BaTiO$$_{3-x}$$H$$_x$$ ($$x=0.1-0.5$$), which are considered to be involved in its hydrogen transport and exchange processes, were investigated by $$mu^+$$SR spectroscopy using muonium (Mu) as a pseudoisotope of hydrogen. Muons implanted into BaTiO$$_{3-x}$$H$$_x$$ were mainly found in two metastable states. One was assigned to a highly mobile interstitial protonic state, which is commonly observed in perovskite oxides. The other was found to form an entangled two spin-$$frac{1}{2}$$ system with the nuclear spin of an H$$^-$$ ion at the anion site. The structure of the (H,Mu) complex agrees well with that of a neutralized center containing two H$$^-$$ ions at a doubly charged oxygen vacancy, which was predicted to form in SrTiO$$_{3-delta}$$ by a computational study. Above 100 K, interstitial Mu$$^+$$ diffusion and retrapping to a deep defect were observed, which could be a rate-limiting step of macroscopic Mu/H transport in BaTiO$$_{3-x}$$H$$_x$$.


New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; 青木 正治*; 深尾 祥紀*; 東 芳隆*; 樋口 嵩*; 飯沼 裕美*; 池戸 豊*; 石田 啓一*; 伊藤 孝; 岩崎 雅彦*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 被引用回数:3 パーセンタイル:10.17

At the Muon Science Facility (MUSE) of J-PARC (Japan Proton Accelerator Research Complex), the MuSEUM collaboration is planning new measurements of the ground state hyperfine structure (HFS) of muonium both at zero field and at high magnetic field. The previous measurements were performed both at LAMPF (Los Alamos Meson Physics Facility) with experimental uncertainties mostly dominated by statistical errors. The new high intensity muon beam that will soon be available at MUSE H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation, and the results of a first commissioning test experiment at zero field are presented.


Electronic structure of hydrogen donors in semiconductors and insulators probed by muon spin rotation

下村 浩一郎*; 伊藤 孝

Journal of the Physical Society of Japan, 85(9), p.091013_1 - 091013_5, 2016/09

 パーセンタイル:100(Physics, Multidisciplinary)

Hydrogen in semiconductors and insulators plays a crucial role in their electric conductivity. Substantial experimental and theoretical efforts have been made to establish this hypothesis in the last decade, and the muon spin rotation technique has played a pioneering role. Positive muons implanted into such low-carrier systems often form a muonium (a hydrogen analogue). Although its dynamical aspect may be different from the heavier hydrogen, the electronic structure of the muonium is expected to be identical to that of hydrogen after a small correction of the reduced mass. Since the discovery of a shallow muonium in CdS, its properties have been intensively studied in many semiconductors and insulators, and then it was interpreted as a possible origin of $$n$$-type conductivity under the context of a classical shallow donor model. In this article, we will describe the principle of muonium experiments and survey recent achievements in this field.


Online monitoring of negative muon beam profiles at J-PARC MUSE using a gated image intensifier

伊藤 孝; 髭本 亘; 二宮 和彦*; 久保 謙哉*; 河村 成肇*; 下村 浩一郎*

JPS Conference Proceedings (Internet), 8, p.036014_1 - 036014_5, 2015/09

We report on negative muon beam imaging at J-PARC MUSE using a newly-developed online muon beam profile monitor. A beam spot of a 3.8-MeV pulsed negative muon beam was clearly visualized in a few minutes. Decay electron background was significantly reduced owing to high-speed gating capability of a gated image intensifier installed in the muon beam profile monitor. A 3D map of negative muon intensity distribution was obtained at around the beam exit in the D2 experimental area, using a movable feature of this instrument.


Tuning of ultra-slow muon transport system

足立 泰平*; 池戸 豊*; 西山 樟生*; 薮内 敦*; 長友 傑*; Strasser, P.*; 伊藤 孝; 髭本 亘; 小嶋 健児*; 牧村 俊助*; et al.

JPS Conference Proceedings (Internet), 8, p.036017_1 - 036017_4, 2015/09

We report on the tuning of the ultra-slow muon beam line at J-PARC MUSE using Li impurities in a tungsten muonium production target in place of positive muons. Li ions were evaporated from the tungsten target by heating it up to 2000K and were transported in the ultra-slow muon beam line. The Li ion beam was monitored by micro channel plates installed at several points in the beam line. The Li beam was successfully transported to the end of the beam line after optimization of beam line parameters.


Nondestructive elemental depth-profiling analysis by muonic X-ray measurement

二宮 和彦*; 久保 謙哉*; 長友 傑*; 髭本 亘; 伊藤 孝; 河村 成肇*; Strasser, P.*; 下村 浩一郎*; 三宅 康博*; 鈴木 栄男*; et al.

Analytical Chemistry, 87(9), p.4597 - 4600, 2015/05

 被引用回数:7 パーセンタイル:58.47(Chemistry, Analytical)

Elemental analysis of materials is fundamentally important to science and technology. Many elemental analysis methods have been developed, but three-dimensional nondestructive elemental analysis of bulk materials has remained elusive. Recently, we developed a nondestructive depth-profiling elemental analysis method after a decade of research. This new method utilizes a new type of probe; a negative muon particle and high-energy muonic X-rays emitted after the muon stops in a material. We performed elemental depth profiling on an old Japanese gold coin (Tempo-Koban) using a low-momentum negative muon beam and successfully determined that the Au concentration in the coin gradually decreased with depth over a micrometer length scale.



伊藤 孝; 髭本 亘; 幸田 章宏*; 下村 浩一郎*

四季, 26, P. 5, 2015/03



Online full two-dimensional imaging of pulsed muon beams at J-PARC MUSE using a gated image intensifier

伊藤 孝; 豊田 晃久*; 髭本 亘; 田島 美典*; 松田 恭幸*; 下村 浩一郎*

Nuclear Instruments and Methods in Physics Research A, 754, p.1 - 9, 2014/08

 被引用回数:4 パーセンタイル:51.53(Instruments & Instrumentation)

A new muon beam profile monitor (MBPM) was developed to diagnose pulsed muon beams in J-PARC MUSE, mainly composed of a scintillation screen, a gated image intensifier (II), and a cooled CCD camera. The MBPM was designed to be compact so that it could be inserted into the bore of the $$mu$$SR spectrometer in the D1 area and used concurrently. The spatial resolution of the MBPM was evaluated to be in the range from one to two line-pair/mm, depending on II gain. Such high-resolution muon beam profiles were obtained online for a positive muon beam with a kinetic energy of $$sim$$ 4 MeV. The contribution from decay positrons was significantly reduced owing to II gating. The linearity of the MBPM was evaluated on the bases of the number of decay positrons monitored by the $$mu$$SR spectrometer. A linear response within five percent deviations was confirmed over more than two orders of magnitude. In addition, 3D imaging capability, use in vacuum, and immunity against moderate magnetic fields were demonstrated.


Shallow donor level associated with hydrogen impurities in undoped BaTiO$$_3$$

伊藤 孝; 髭本 亘; 松田 達磨*; 幸田 章宏*; 下村 浩一郎*

Applied Physics Letters, 103(4), p.042905_1 - 042905_4, 2013/07

 被引用回数:4 パーセンタイル:73.07(Physics, Applied)

The influence of hydrogen impurities on electronic properties of undoped BaTiO$$_3$$ was studied from a microscopic point of view using the muon spin rotation and relaxation technique. Electron localization around an implanted positive muon, by analogy an hydrogen impurity, was observed below $$sim$$80 K. The effective electron binding energy was estimated to be $$sim10^{-2}$$ eV, indicating that the hydrogen-induced defect forms a shallow donor level. At room temperature, the weakly bound electron is excited into a conduction band and behaves as a free carrier, which causes insulation degradation undesirable for capacitor application.


Development of nondestructive and quantitative elemental analysis method using calibration curve between muonic X-ray intensity and elemental composition in bronze

二宮 和彦; 長友 傑*; 久保 謙哉*; 伊藤 孝; 髭本 亘; 喜多 真琴*; 篠原 厚*; Strasser, P.*; 河村 成肇*; 下村 浩一郎*; et al.

Bulletin of the Chemical Society of Japan, 85(2), p.228 - 230, 2012/02

 被引用回数:7 パーセンタイル:66.74(Chemistry, Multidisciplinary)



Development of elemental analysis by muonic X-ray measurement in J-PARC

二宮 和彦; 長友 傑*; 久保 謙哉*; Strasser, P.*; 河村 成肇*; 下村 浩一郎*; 三宅 康博*; 齋藤 努*; 髭本 亘

Journal of Physics; Conference Series, 225, p.012040_1 - 012040_4, 2010/06

 被引用回数:8 パーセンタイル:4.95



J-PARC muon facility, MUSE

三宅 康博*; 下村 浩一郎*; 河村 成肇*; Strasser, P.*; 牧村 俊助*; 幸田 章宏*; 藤森 寛*; 中原 一隆*; 竹下 聡史*; 小林 庸男*; et al.

Journal of Physics; Conference Series, 225, p.012036_1 - 012036_7, 2010/06

 被引用回数:2 パーセンタイル:24.85

The science facility (MUSE) along with the neutron, hadron and neutrino facilities is one of the experimental areas PF the J-PARC project, which was approved for construction in a period from 2001 to 2008. Construction of the MLF building was started in the beginning of 2004, and was completed at the end of the 2006 fiscal year. On September 19th, 2008, the graphite target for muon production was placed into the 3 GeV proton beam line. On September 26th, 2008, we finally succeeded to extract surface muon beams. We also succeeded in the extraction of the decay muons on December 25th, 2008.


J-PARC decay muon channel construction status

Strasser, P.*; 下村 浩一郎*; 幸田 章宏*; 河村 成肇*; 藤森 寛*; 牧村 俊助*; 小林 庸男*; 中原 一隆*; 加藤 峯夫*; 竹下 聡史*; et al.

Journal of Physics; Conference Series, 225, p.012050_1 - 012050_8, 2010/06

 被引用回数:7 パーセンタイル:6.01

The new Muon Science Facility (MUSE) that is now under construction at J-PARC in the Materials and Life Sciences Facility (MLF) building will comprise four types of muon channels. In the first stage, a conventional superconducting decay muon channel (D-Line) was constructed, which can extract surface (positive) muons with an expected muon yield of $$10^7$$ /s and decay positive/negative muon up to 120 MeV/c, with an expected muon yield of a few $$10^6$$/s at 60 MeV/c for both positive and negative muons. This channel will be used for various kinds of muon experiments like $$mu$$SR, muon catalyzed fusion and nondestruction elements analysis.


JAEA-ASRC muon research at J-PARC MUSE

髭本 亘; 伊藤 孝; 二宮 和彦; Heffner, R.*; 下村 浩一郎*; 西山 樟生*; 三宅 康博*

Journal of Physics; Conference Series, 225, p.012012_1 - 012012_4, 2010/06

 被引用回数:2 パーセンタイル:24.85




酒井 健二; 大井 元貴; 甲斐 哲也; 渡辺 聡彦; 中谷 健; 髭本 亘; 下村 浩一郎*; 木下 秀孝; 神永 雅紀

JAEA-Technology 2009-042, 44 Pages, 2009/08




Birth of an intense pulsed muon source, J-PARC MUSE

三宅 康博*; 下村 浩一郎*; 河村 成肇*; Strasser, P.*; 牧村 俊助*; 幸田 章宏*; 藤森 寛*; 中原 一隆*; 門野 良典*; 加藤 峯夫*; et al.

Physica B; Condensed Matter, 404(5-7), p.957 - 961, 2009/04

 被引用回数:8 パーセンタイル:57.16(Physics, Condensed Matter)



JAEA-ASRC $$mu$$SR project at J-PARC MUSE

髭本 亘; Heffner, R. H.; 下村 浩一郎*; 西山 樟生*; 三宅 康博*

Nuclear Instruments and Methods in Physics Research A, 600(1), p.182 - 184, 2009/02

 被引用回数:1 パーセンタイル:85.42(Instruments & Instrumentation)

原子力機構先端基礎研究センターではJ-PARC MLFミュオン科学実験施設において「$$mu$$SR計画」を進めている。この計画では、ミュオン取り出し部分と分光器を、崩壊表面ミュオンビームラインの支流として設置し、29MeV/cのビームによりミュオンスピン回転・緩和実験を行うことになっている。主たる対象になる科学は強相関電子系、特にf電子系物質の解明であり、この強力な$$mu$$SR分光器において新たな知見が得られるものと期待する。


J-PARC muon control system

髭本 亘; 下村 浩一郎*; 小林 庸男*; 牧村 俊助*; 三宅 康博*; 甲斐 哲也; 酒井 健二

Nuclear Instruments and Methods in Physics Research A, 600(1), p.179 - 181, 2009/02

 パーセンタイル:100(Instruments & Instrumentation)


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