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廃炉環境国際共同研究センター; 大阪大学*
JAEA-Review 2020-050, 69 Pages, 2021/01
JAEA-Review-2020-050.pdf:3.79MB
日本原子力研究開発機構(JAEA)廃炉環境国際共同研究センター(CLADS)では、令和元年度英知を結集した原子力科学技術・人材育成推進事業(以下、「本事業」という)を実施している。本事業は、東京電力ホールディングス福島第一原子力発電所の廃炉等をはじめとした原子力分野の課題解決に貢献するため、国内外の英知を結集し、様々な分野の知見や経験を、従前の機関や分野の壁を越えて緊密に融合・連携させた基礎的・基盤的研究及び人材育成を推進することを目的としている。平成30年度の新規採択課題から実施主体を文部科学省からJAEAに移行することで、JAEAとアカデミアとの連携を強化し、廃炉に資する中長期的な研究開発・人材育成をより安定的かつ継続的に実施する体制を構築した。本研究は、研究課題のうち、「単一微粒子質量分析法に基づくアルファ微粒子オンラインモニタリングに向けた基礎検討」の令和元年度の研究成果について取りまとめたものである。本研究では、福島第一原発の燃料デブリ切削の際に飛散する恐れのあるアルファ微粒子のオンラインモニタリングを目指し、単一微粒子質量分析技術の適用性について基礎検討を行うことが目的である。本年度、アルファ微粒子発生のための模擬試料として固体酸化物の(U,Zr)O
試料、ならびに酸性と塩基性のU溶液試料を調製した。また、アブレーション法による微粒子生成に向けたレーザー照射光学系を構築するとともに、噴霧法で発生する微小液滴を乾燥し固体エアロゾルを生成する装置を製作した。さらに単一微粒子質量分析計を整備し、測定に向けた準備を整えた。
Ge(n,
) cross sections and implications for stellar nucleosynthesisLederer-Woods, C.*; Battino, U.*; Ferreira, P.*; Gawlik, A.*; 木村 敦; n_TOF Collaboration*; 他128名*
Physics Letters B, 790, p.458 - 465, 2019/03
被引用回数：5 パーセンタイル：61.83(Astronomy & Astrophysics)
cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at 
=30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of Ge produced in stars, which would explain the low isotopic abundance of Ge in the solar system.
Gd(n,) induced by thermal and epithermal neutronsMastromarco, M.*; Manna, A.*; Aberle, O.*; Andrzejewski, J.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他116名*
European Physical Journal A, 55(1), p.9_1 - 9_20, 2019/01
被引用回数：14 パーセンタイル：93.24(Physics, Nuclear)Neutron capture cross section measurements on 
Gd and 
Gd were performed using the time-of-flight technique at the n_TOF facility at CERN on isotopically enriched samples. The measurements were carried out in the n TOF experimental area EAR1, at 185m from the neutron source, with an array of 4 C
D liquid scintillation detectors. At a neutron kinetic energy of 0.0253eV, capture cross sections of 62.2(2.2) and 239.8(8.4) kilobarn have been derived for Gd and Gd, respectively, with up to 6% deviation relative to values presently reported in nuclear data libraries, but consistent with those values within 1.6 standard deviations. A resonance shape analysis has been performed in the resolved resonance region up to 181eV and 307eV, respectively for Gd and Gd, where on average, resonance parameters have been found in good agreement with evaluations. Above these energies and up to 1keV, the observed resonance-like structure of the cross section has been analysed and characterised. From a statistical analysis of the observed neutron resonances we deduced: neutron strength function of 2.01(28) 
10
and 2.17(41) 10; average total radiative width of 106.8(14)meV and 101.1(20)meV and s-wave resonance spacing 1.6(2)eV and 4.8(5)eV for n + Gd and n + Gd systems, respectively.
Be(n,p)Li reaction and the cosmological lithium problem; Measurement of the cross section in a wide energy range at n_TOF at CERNDamone, L.*; Barbagallo, M.*; Mastromarco, M.*; Cosentino, L.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他152名*
Physical Review Letters, 121(4), p.042701_1 - 042701_7, 2018/07
被引用回数：33 パーセンタイル：93.14(Physics, Multidisciplinary)We report on the measurement of the Be(n,p)Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and they showed a large discrepancy between each other. The measurement was performed with a Si telescope and a high-purity sample produced by implantation of a Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low energy, relative to current evaluations, in the region of BBN interest, the present results are consistent with the values inferred from the time-reversal Li(p,n)Be reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near threshold neutron production in the p+Li reaction is also discussed.
Pu in the resonance region at the CERN n_TOF-EAR1 facilityLerendegui-Marco, J.*; Guerrero, C.*; Mendoza, E.*; Quesada, J. M.*; Eberhardt, K.*; Junghans, A. R.*; 木村 敦; n_TOF Collaboration*; 他126名*
Physical Review C, 97(2), p.024605_1 - 024605_21, 2018/02
被引用回数：13 パーセンタイル：85.61(Physics, Nuclear)This paper presents a new time-of-flight capture measurement on Pu carried out at n_TOF-EAR1(CERN), focusing on the analysis and statistical properties of the resonance region, below 4 keV. The Pu(n,)reaction on a sample containing 95(4) mg enriched to 99.959% was measured with an array of four CD detectors and applying the total energy detection technique. The high neutron energy resolution of n_TOF-EAR1 and the good statistics accumulated have allowed us to extend the resonance analysis up to 4 keV, obtaining new individual and average resonance parameters from a capture cross section featuring a systematic uncertainty of 5%, fulfilling the request of the NEA.
Cs as a part of the ImPACT projectHales, B. P.; 中村 詔司; 木村 敦; 岩本 修
JAEA-Conf 2017-001, p.199 - 203, 2018/01
As part of the ImPACT project, it is currently planned to measure the neutron cross-section of 
Cs (half-life 
y), a long-lived fission product (LLFP), via neutron time-of-flight (TOF) method at the Japan Proton Accelerator Research Complex (J-PARC). Both Cs (natural Cs, stable) and 
Cs (half-life 
y) are unavoidable contaminants in the Cs sample. In working towards the measurement of Cs, a measurement of non-radioactive Cs has been conducted. The neutron capture cross-section of Cs in the thermal to epithermal energy region was experimentally measured via neutron TOF method at J-PARC. Measured results show good agreement with JENDL in the energy region below 10 eV.
木村 敦
核データニュース(インターネット), (118), p.36 - 42, 2017/10
欧州原子核研究機構(CERN)にあるn_TOF実験施設において、Research Centre for Energy, Environment and Technology (CIMAT)と共同代表としてCm-244,246の中性子捕獲断面積測定研究を進めており、2017年夏n_TOF実験施設で測定実験を行った。本稿では堅苦しい学術的な話ではなく、読者の広場だからこそ書けるn_TOF実験施設での実験の様子や訪問の際に知っていれば便利だと思うことを紹介する。
Pu(n,f) cross-section at the CERN n_TOF facility; First results from experimental area II (EAR-2)Stamatopoulos, A.*; Tsinganis, A.*; Colonna, N.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他126名*
EPJ Web of Conferences, 146, p.04030_1 - 04030_4, 2017/09
被引用回数：6 パーセンタイル：97.85The accurate knowledge of the neutron-induced fission cross-sections of actinides and other isotopes involved in the nuclear fuel cycle is essential for the design of advanced nuclear systems, such as Generation-IV nuclear reactors. Such experimental data can also provide the necessary feedback for the adjustment of nuclear model parameters used in the evaluation process, resulting in the further development of nuclear fission models. In the present work, the Pu(n,f) cross-section was measured at CERN n_TOF facility relative to the well-known 
U(n,f) cross section, over a wide range of neutron energies, from meV to almost MeV, using the time-of-flight technique and a set-up based on Micromegas detectors. This measurement was the first experiment to be performed at n_TOF new experimental area (EAR-2), which offers a significantly higher neutron flux compared to the already existing experimental area (EAR-1).Preliminary results as well as the experimental procedure, including a description of the facility and the data handling and analysis, are presented.
Lerendegui-Marco, J.*; Cort
s-Giraldo, M. A.*; Guerrero, C.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他114名*
EPJ Web of Conferences, 146, p.03030_1 - 03030_4, 2017/09
被引用回数：0 パーセンタイル：0.08Monte Carlo (MC) simulations are an essential tool to determine fundamental features of a neutron beam, such as the neutron flux or the ray background, that sometimes can not be measured or at least not in every position or energy range. Until recently, the most widely used MC codes in this field had been MCNPX and FLUKA. However, the Geant4 toolkit has also become a competitive code for the transport of neutrons after the development of the native Geant4 format for neutron data libraries, G4NDL. In this context, we present the Geant4 simulations of the neutron spallation target of the n TOF facility at CERN, done with version 10.1.1 of the toolkit. The first goal was the validation of the intra-nuclear cascade models implemented in the code using, as benchmark, the characteristics of the neutron beam measured at the first experimental area (EAR1), especially the neutron flux and energy distribution, and the time distribution of neutrons of equal kinetic energy, the so-called Resolution Function. The second goal was the development of a Monte Carlo tool aimed to provide useful calculations for both the analysis and planning of the upcoming measurements at the new experimental area (EAR2) of the facility.
Be(n,
) and Be(n,p) cross-section measurement for the cosmological lithium problem at the n_TOF facility at CERNBarbagallo, M.*; Colonna, N.*; Aberle, O.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他125名*
EPJ Web of Conferences, 146, p.01012_1 - 01012_4, 2017/09
被引用回数：1 パーセンタイル：69.68The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called "Spite plateau" in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the Be(n,) and Be(n,p) reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range._1
Chiaveri, E.*; Aberle, O.*; Andrzejewski, J.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他111名*
EPJ Web of Conferences, 146, p.03001_1 - 03001_4, 2017/09
被引用回数：1 パーセンタイル：69.68The CERN n_TOF neutron beam facility is characterized by a very high instantaneous neutron flux, excellent TOF resolution at the 185m long flight path (EAR-1), low intrinsic background and coverage of a wide range of neutron energies, from thermal to a few GeV. The overall efficiency of the experimental program and the range of possible measurements has been expanded with the construction of a second experimental area (EAR-2), located 20m on the vertical of the n_TOF spallation target. This upgrade, which benefits from a neutron flux 30 times higher than in EAR-1, provides a substantial extension in measurement capabilities, opening the possibility to collect data on neutron cross-section of isotopes with short half-lives or available in very small amounts. We will discuss the innovative features of the EAR-2 neutron beam that make possible to perform very challenging measurements on short-lived radioisotopes or sub-mg samples, out of reach up to now at other neutron facilities around the world. Finally, the future perspectives of the facility will be presented.
Pm and 
Tm for astrophysicsGuerrero, C.*; Lerendegui-Marco, J.*; Domingo-Pardo, C.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他113名*
EPJ Web of Conferences, 146, p.01007_1 - 01007_4, 2017/09
被引用回数：1 パーセンタイル：69.68The neutron capture cross section of several key unstable isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n,) measurement, for which high neutron fluxes and effective background rejection capabilities are required. Capture cross section of Pm and Tm have been measured for time-of-flight measurements at the CERN n_TOF facility using the 19 and 185m beam lines. Activation experiments on the same Pm and Tm targets with a high-intensity 30 keV quasi-Maxwellian flux of neutrons will be performed using the SARAF accelerator and the Liquid-Lithium Target (LiLiT) in order to extract the corresponding Maxwellian Average Cross Section (MACS). The status of these experiments and preliminary results will be presented and discussed as well.
Gunsing, F.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他141名*
European Physical Journal Plus (Internet), 131(10), p.371_1 - 371_13, 2016/10
被引用回数：23 パーセンタイル：61.39(Physics, Multidisciplinary)Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. CERN's neutron time-of-flight facility, n_TOF, has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement program in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at n_TOF will be presented.
Be(
He reaction and the cosmological lithium problem; Measurement of the cross section in a wide energy range at n_TOF at CERNBarbagallo, M.*; Musumarra, A.*; Cosentino, L.*; Maugeri, E.*; Heinitz, S.*; Mengoni, A.*; Dressler, R.*; Schumann, D.*; K
ppeler, F.*; 原田 秀郎; et al.
Physical Review Letters, 117(15), p.152701_1 - 152701_7, 2016/10
被引用回数：61 パーセンタイル：95.07(Physics, Multidisciplinary)The energy-dependent cross section of the Be(He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. Coincidences between the two alpha particles have been recorded in two Si-Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.
Ge spectrometer小泉 光生; 長 明彦; 藤 暢輔; 木村 敦; 水本 元治; 大島 真澄; 井頭 政之*; 大崎 敏郎*; 原田 秀郎*; 古高 和禎*; et al.
Nuclear Instruments and Methods in Physics Research A, 562(2), p.767 - 770, 2006/06
被引用回数：6 パーセンタイル：45.27(Instruments & Instrumentation)原子核科学研究グループにおいては、文部科学省公募型特会事業において、マイナーアクチニドの中性子捕獲断面積を測ることを目的として、4Geスペクトロメータを使った実験装置の準備を行っている。実験は、京大炉の電子LINAC施設で行う予定で、TOF中性子ビームラインの整備はほぼ完了している。4Geスペクトロメータの建設は進行中である。並行して、デジタル処理テクニックに基づく新しいデータ収集システムの開発を行った。以上この事業の現状について紹介する。
岸田 則生*; 村田 徹*; 浅見 哲夫*; 小迫 和明*; 真木 紘一*; 原田 秀郎*; Lee, Y.*; Chang, J.*; 千葉 敏; 深堀 智生
AIP Conference Proceedings 769, p.199 - 202, 2005/05
光核反応に対する核データは、高エネルギー電子加速器の遮蔽設計及び高エネルギー線治療の分野に必要である。JENDL光核反応データファイルは、シグマ委員会の光核反応データ評価ワーキンググループによって整備された。われわれは多くの文献サーベイから、評価に必要な十分な実験データが圧倒的に不足しているので、光核反応データファイルを実験データのみから作成するのは困難であるという結論を得た。したがって、評価は統計模型核反応モデルの助けを借りて実施した。JENDL光核反応データファイルに格納される断面積データ等の物理量は、光吸収断面積,中性子,陽子,重陽子,三重陽子,
He粒子,粒子の収量及び二重微分断面積,同位体生成断面積である。アクチノイド核種に対しては、これに光核分裂断面積を加える。格納される
Hから
Npまでの68核種に対する最大光子入射エネルギーは140MeVである。
渡辺 大裕*; Che, D.-C.*; 福山 哲也*; 橋之口 道宏*; 寺岡 有殿; 笠井 俊夫*
Review of Scientific Instruments, 76(5), p.055108_1 - 055108_5, 2005/05
被引用回数：6 パーセンタイル：34.77(Instruments & Instrumentation)強いパルス超熱分子ビームを得るための分子ビーム技術が開発された。そのビーム源はパルスバルブ,冷却水管(これは高温ノズルからの伝熱からパルスバルブを保護する),ヒーター付きのノズルから構成される。実際にHCl分子のパルスHTMBが生成されて、その特徴が(2+1)共鳴増感多光子イオン化法と生成イオンの飛行時間分析によって評価された。
間柄 正明; 臼田 重和; 桜井 聡; 渡部 和男; 江坂 文孝; 平山 文夫; Lee, C. G.; 安田 健一郎; 河野 信昭; 伊奈川 潤; et al.
Proceedings of INMM 46th Annual Meeting (CD-ROM), 8 Pages, 2005/00
原研では、国際保障措置制度の堅持に貢献するため、環境試料分析のための極微量核物質の分析法を開発している。スワイプ試料のバルク及びパーティクル分析の基本技術については開発を終了し、2003年にIAEAからIAEAネットワーク分析所として認証され、現在ネットワーク分析所の一員として活動している。今回、マイナーアクチノイドや核分裂生成物,フィッショントラック法を用いたパーティクル分析法の開発を行い、ICP-TOFMAを使った効率的なパーティクル分析法,蛍光エックス線を用いたスクリーニング法の開発を開始したので、その概要と現状について報告する。
丸山 龍治*; 田崎 誠司*; 日野 正裕*; 武田 全康; 海老澤 徹*; 川端 祐司*
Nuclear Instruments and Methods in Physics Research A, 530(3), p.505 - 512, 2004/09
被引用回数：9 パーセンタイル：54.8(Instruments & Instrumentation)中性子共鳴スピンエコー法は中性子準弾性散乱を高いエネルギー分解能で測定することのできる手法である。この中性子共鳴スピンエコー法をパルス中性子と組合せて使うと、非常に広範囲なスピンエコータイムをカバーすることができるため、原子炉で使用するよりも多くの利点がある。われわれは、すでに開発済みのパルス中性子用の共鳴フリッパーを利用して、0.3nmから0.9nmの範囲のパルス中性子に対して、スピンエコーシグナルを観測することに成功した。
北村 敏勝; 外川 織彦; 荒巻 能史; 鈴木 崇史; 甲 昭二*
第15回タンデム加速器及びその周辺技術の研究会報告集, p.1 - 6, 2003/03
平成9年4月、海洋環境における放射性核種の移行挙動にかかわる研究を目的としてタンデトロン加速器質量分析装置(HVEE社製 Model 4130-AMS)を導入した。本装置は最大加速電圧3MVのタンデム加速器で炭素及びヨウ素の同位体比測定に用いられる。炭素ラインは、平成10年6月、
C/
C比及び
C/Cの測定精度を確認(0.5%以下)し、平成11年12月からCの定常測定を開始した。また、ヨウ素ラインは、平成12年7月に
I/
I比の繰返し測定精度を確認(~1.6%)した。昨年10月、Iの定常運転を行うため調整を開始したが飛行時間(TOF:Time of Flight)型検出器のMCP(Micro Channel Plate)に不具合が見つかり調整を中断した。本講演では、平成13年度の運転状況,整備状況等について紹介する。
