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論文

Measurement of the neutron capture cross section of $$^{185}$$Re in the keV energy region

片渕 竜也*; 佐藤 八起*; 武部 花凛*; 井頭 政之*; 梅澤 征悟*; 藤岡 諒*; 齋藤 辰宏*; 岩本 信之

Journal of Nuclear Science and Technology, 6 Pages, 2024/00

Measurements of the neutron capture cross section of $$^{185}$$Re have been limited in the keV energy region. In addition, existing measured data have discrepancies. In this study, the neutron time-of-flight method was employed to measure the capture cross section of $$^{185}$$Re at Tokyo Institute of Technology. The capture $$gamma$$-rays were detected with a large volume NaI(Tl) detector. The pulse-height weighting technique was applied to obtain the capture yield. The present results were corrected for neutron scattered effects and impurities in the sample. The measured cross sections were determined with the standard capture cross section of gold in the energy range from 15 to 90 keV, and compared with measured and evaluated data. The results of the measurement provided improved accuracy relative to previous studies in the keV energy range.

論文

Measurements of neutron total and capture cross sections of $$^{139}$$La and evaluation of resonance parameters

遠藤 駿典; 河村 しほり*; 奥平 琢也*; 吉川 大幹*; Rovira Leveroni, G.; 木村 敦; 中村 詔司; 岩本 修; 岩本 信之

European Physical Journal A, 59(12), p.288_1 - 288_12, 2023/12

ランタン(La)-139の断面積と共鳴パラメータは、原子力分野への応用や基礎核物理の研究にとって重要である。本論文では、大強度陽子加速器施設(J-PARC)のANNRIにてLaの中性子全断面積と捕獲断面積を測定した。Negative共鳴を含む4つの共鳴の共鳴パラメータを、共鳴解析コードREFITを用いて求めた。その結果いくつかの共鳴パラメータにおいて、評価済み核データライブラリとの不一致が見られた。さらに全断面積を再現するために、スピン依存する散乱半径もフィットした。得られた散乱半径は、評価済み核データライブラリで記録されたものよりも大きいことがわかった。

論文

第35回NEA核データ評価国際協力ワーキングパーティ(WPEC)会合報告

岩本 修; 岩本 信之; 木村 敦; 多田 健一; 横山 賢治

核データニュース(インターネット), (136), 6 Pages, 2023/10

OECD/NEA/NSC主催のWPEC(Working Party on International Nuclear Data Evaluation Co-operation)の本会合及び関連するサブグループ(SG)、専門家グループ(EG)会合が、2023年5月15日$$sim$$5月17日の日程で、NEA本部とWebでのハイブリッド形式によって実施された。日本からは2名(岩本(修)、多田)が対面で、その他がオンラインで参加した。日本を含め、米国や欧州、中国、IAEA、NEAから出席があり、対面でのWPEC本会合への参加は30名程度であった。以下に、核データ測定、評価及びEG、SGの活動状況について報告する。

論文

Neutron capture cross section and capture $$gamma$$-ray spectrum of $$^{88}$$Sr in the stellar nucleosynthesis energy region

片渕 竜也*; 井頭 政之*; 鎌田 創*; 田近 道英*; 岩本 信之; 河野 俊彦*

Physical Review C, 108(3), p.034610_1 - 034610_12, 2023/09

The neutron capture cross section and the capture $$gamma$$-ray spectrum of $$^{88}$$Sr were measured in the keV energy regions. Above 34 keV, the present data are larger than evaluated cross sections which are based on a set of resonance parameters measured in past experiments. To investigate the impact of the present results to the stellar nucleosynthesis, the Maxwellian averaged neutron capture cross section (MACS) was calculated using the present experimental results. The calculated MACS was about 10% smaller than the values widely used in stellar nucleosynthesis calculations and it is found that this difference arises from a problem in calculating the direct capture process in the previous study. In fact, the present and previous MACS become in good agreement when the contribution from the direct neutron capture process that has been theoretically calculated is removed from the previous MACS. This indicates that the previous work overestimated the contribution of the direct capture process. The present experimental capture $$gamma$$-ray spectrum shows that primary transition intensities to the low-lying states of $$^{89}$$Sr drastically changes with the neutron energy.

論文

JENDL photonuclear data file 2016

岩本 信之; 小迫 和明*; 深堀 智生

Journal of Nuclear Science and Technology, 60(8), p.911 - 922, 2023/08

 被引用回数:0 パーセンタイル:79.09(Nuclear Science & Technology)

Nuclear reactions of gamma-rays with materials have attracted much attention for various application fields. To allow the use in those fields, JENDL photonuclear data file was updated from former JENDL/PD-2004 and were opened as JENDL/PD-2016 in 2017. The nuclear data were revised by adopting resonance analysis-like method for light nuclides and applying nuclear reaction models to the evaluations for heavier nuclides. In JENDL/PD-2016, standard and expanded versions are provided up to an incident energy of 140 MeV, covering 181 and 2681 nuclides, respectively. The evaluated results show better reproducibility to measured data, relative to JENDL/PD-2004. JENDL/PD-2016 is freely available from a website.

論文

Neutron total and capture cross-section measurements of $$^{155}$$Gd and $$^{157}$$Gd in the thermal energy region with the Li-glass detectors and NaI(Tl) spectrometer installed in J-PARC$$cdot$$MLF$$cdot$$ANNRI

木村 敦; 中村 詔司; 遠藤 駿典; Rovira Leveroni, G.; 岩本 修; 岩本 信之; 原田 秀郎; 片渕 竜也*; 寺田 和司*; 堀 順一*; et al.

Journal of Nuclear Science and Technology, 60(6), p.678 - 696, 2023/06

 被引用回数:2 パーセンタイル:59.27(Nuclear Science & Technology)

Neutron total and capture cross-section measurements of $$^{155}$$Gd and $$^{157}$$Gd were performed in the ANNRI at the MLF of the J-PARC. The neutron total cross sections were determined in the energy region from 5 to 100 meV. At the thermal neutron energy, the total cross sections were obtained to be 59.4$$pm$$1.7 and 251.9$$pm$$4.6 kilobarn for $$^{155}$$Gd and $$^{157}$$Gd, respectively. The neutron capture cross sections were determined in the energy region from 3.5 to 100 meV with an innovative method by taking the ratio of the detected capture event rate between thin and thick samples. At the thermal energy, the capture cross sections were obtained as 59.0$$pm$$2.5 and 247.4$$pm$$3.9 kilobarn for $$^{155}$$Gd and $$^{157}$$Gd, respectively. The present total and capture cross sections agree well within the standard deviations. The results for $$^{155}$$Gd were found to be consistent with the values in JENDL-4.0 and the experimental data given by Mastromarco et al. and Leinweber et al. within one standard deviation. Moreover, the present results for $$^{157}$$Gd agreed with the evaluated data in JENDL-4.0 and the experimental data by M${o}$ller et al. within one standard deviation and agreed with the data by Mastromarco et al. within 1.4 standard deviations. However, they disagree (11% larger) with the experimental result by Leinweber et al.

論文

Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

Goux, P.*; Glessgen, F.*; Gazzola, E.*; Singh Reen, M.*; Focillon, W.*; Gonin, M.*; 田中 智之*; 萩原 開人*; Ali, A.*; 須藤 高志*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2023(6), p.063H01_1 - 063H01_15, 2023/06

 被引用回数:0 パーセンタイル:0.01(Physics, Multidisciplinary)

We investigated the angular correlation of two $$gamma$$-rays emitted in neutron capture at the Materials and Life Science Experimental Facility of J-PARC. The 14 Ge crystals in a cluster detector and one coaxial Ge crystal were employed. We obtained angular correlation functions for two $$gamma$$-rays emerging in the electromagnetic transitions of the capture reactions on $$^{155}$$Gd and $$^{157}$$Gd. We found mild angular correlations for the strong, but rare transitions from the resonance state to two excited levels with known spin and parities. In contrast, angular correlations was negligibly small for arbitrary pairs of two $$gamma$$-rays produced in the majority of transitions in continuum states.

論文

General-purpose nuclear data library JENDL-5 and to the next

岩本 修; 岩本 信之; 国枝 賢; 湊 太志; 中山 梓介; 木村 敦; 中村 詔司; 遠藤 駿典; 長家 康展; 多田 健一; et al.

EPJ Web of Conferences, 284, p.14001_1 - 14001_7, 2023/05

Japanese Evaluated Nuclear Data Library version 5 (JENDL-5) was released in 2021. JENDL-5 is intended to extend its generality from JENDL-4.0 by covering a wide variety of nuclear data for applications not only to nuclear design and decommissioning, but also to radiation-related fields. Overview of JENDL-5 and a future plan for the next of JENDL-5 are presented. JENDL-5 includes up-to-date neutron reaction cross sections incorporating other various types of data such as newly evaluated nuclear decay, fission yield, and thermal neutron scattering law. The neutron induced reaction cross sections especially on minor actinides in the resonance regions are improved by the experimental data measured at ANNRI. The extensive benchmark analyses on neutron nuclear data were made and the performance of JENDL-5 was confirmed by benchmark tests of ICSBEP and IRPhEP as well as fast reactors, radiation shielding calculations, and so on. So far, several JENDL special-purpose files have been developed for various applications. The data cover neutron, charged particles, and photon induced reactions. As the neutron induced reaction files, two special purpose files of JENDL/AD-2017 and JENDL/ImPACT-2018 were released to meet needs of nuclear backend applications including activation evaluation for nuclear facilities and nuclear transmutations of high-level radioactive wastes of long-lived fission products, respectively. Furthermore, the photon, proton and deuteron data were released as JENDL/PD-2016.1, JENDL-4.0/HE and JENDL/DEU-2020, respectively, for accelerator applications. With updating the data, they were incorporated in JENDL-5 as sub-libraries for facilitation of usability of JENDL. As the next step of JENDL-5, provision of the proper and sufficient covariance will be a major challenge, where cross correlations across different reactions or data-types may play a significant role in connection with data assimilation for various applications.

論文

$$^{241}$$Am neutron capture cross section in the keV region using Si and Fe-filtered neutron beams

Rovira Leveroni, G.; 木村 敦; 中村 詔司; 遠藤 駿典; 岩本 修; 岩本 信之; 片渕 竜也*; 児玉 有*; 中野 秀仁*

Journal of Nuclear Science and Technology, 60(5), p.489 - 499, 2023/05

 被引用回数:0 パーセンタイル:59.27(Nuclear Science & Technology)

The neutron capture cross-section of $$^{241}$$Am was measured in the keV neutron range using the recently implemented neutron filtering system of the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) beamline in the Materials and Life Science (MLF) facility of the Japan Proton Accelerator Research Complex (J-PARC). Filter arrays consisting of 20 cm of $$^{nat}$$Fe and $$^{nat}$$Si were employed in separate measurements to provide filtered neutron beams with averaged neutron energies of 23.5 (Fe), 51.5 and 127.7 (Si) keV. The present $$^{241}$$Am results were obtained relative to the $$^{197}$$Au neutron capture yield by applying the total energy detection principle together with the pulse-height weighting technique. The $$^{241}$$Am neutron capture cross section was determined as 2.72 $$pm$$ 0.29 b at 23.5 keV, 2.14 $$pm$$ 0.26 b at 51.5 keV and 1.32 $$pm$$ 0.10 b at 127.7 keV with total uncertainties in the range of 8 to 12$$%$$, much lower in comparison to the latest time-of-flight experimental data available.

論文

Covariance of resonance parameters ascribed to systematic uncertainties in experiments

遠藤 駿典; 木村 敦; 中村 詔司; 岩本 修; 岩本 信之; Rovira Leveroni, G.

EPJ Web of Conferences, 281, p.00012_1 - 00012_5, 2023/03

In resonance analysis, experimental uncertainties affect the accuracy of resonance parameters. A resonance analysis code REFIT can consider the statistical uncertainty of the experimental data in evaluation of the resonance parameter uncertainty. On the other hand, since the systematic uncertainties of the sample thickness and normalization, which is proportional to the cross-section, are not independent at each measurement point, they must be treated differently from the statistical uncertainty. However, their treatment has not been discussed in detail so far. In this study, we evaluated the effect of the systematic uncertainties of experimental data on deduced resonance parameters by varying sample-thickness values used for the REFIT code. Covariance of resonance parameters ascribed to systematic uncertainties were evaluated from the neutron transmission data of natural zinc measured at the J-PARC MLF ANNRI. We will introduce this evaluation method and discuss the feature of obtained correlations.

論文

Fast-neutron capture cross section data measurement of minor actinides for development of nuclear transmutation systems

片渕 竜也*; 岩本 修; 堀 順一*; 木村 敦; 岩本 信之; 中村 詔司; Rovira Leveroni, G.; 遠藤 駿典; 芝原 雄司*; 寺田 和司*; et al.

EPJ Web of Conferences, 281, p.00014_1 - 00014_4, 2023/03

Long-lived minor actinides (MA) in nuclear waste from nuclear power plants are a long-standing issue to continue nuclear energy production. To solve the issue, researchers have suggested nuclear transmutation, in which long-lived radionuclides are transmuted into stable or shorter-life nuclides via neutron-induced nuclear reactions. Development of nuclear transmutation systems as an accelerator-driven system requires accurate neutron nuclear reaction data. The present research project entitled "Study on accuracy improvement of fast-neutron capture reaction data of long-lived MAs for development of nuclear transmutation systems" have been conducted as a joint collaboration, including Tokyo Tech, Japan Atomic Energy Agency and Kyoto University. This project focuses on the neutron capture reaction of MAs, especially $$^{237}$$Np, $$^{241}$$Am and $$^{243}$$Am, in the fast neutron energy region. The final goal of this project is to improve the accuracies of the neutron capture cross sections of $$^{237}$$Np, $$^{241}$$Am and $$^{243}$$Am employing a high-intensity neutron beam from a spallation source of the Japan Proton Accelerator Research Complex (J-PARC) that reduces uncertainties of measurement. To achieve the goal, a neutron beam filter system in J-PARC, sample characteristic assay, and theoretical reaction model study were developed. In this contribution, the overview and results of the project will be presented.

論文

Japanese Evaluated Nuclear Data Library version 5; JENDL-5

岩本 修; 岩本 信之; 国枝 賢; 湊 太志; 中山 梓介; 安部 豊*; 椿原 康介*; 奥村 森*; 石塚 知香子*; 吉田 正*; et al.

Journal of Nuclear Science and Technology, 60(1), p.1 - 60, 2023/01

 被引用回数:17 パーセンタイル:99.99(Nuclear Science & Technology)

The fifth version of Japanese Evaluated Nuclear Data Library, JENDL-5, was developed. JENDL-5 aimed to meet a variety of needs not only from nuclear reactors but also from other applications such as accelerators. Most of the JENDL special purpose files published so far were integrated into JENDL-5 with revisions. JENDL-5 consists of 11 sublibraries: (1) Neutron, (2) Thermal scattering law, (3) Fission product yield, (4) Decay data, (5) Proton, (6) Deuteron, (7) Alpha-particle, (8) Photonuclear, (9) Photo-atomic, (10) Electro-atomic, and (11) Atomic relaxation. The neutron reaction data for a large number of nuclei in JENDL-4.0 were updated ranging from light to heavy ones, including major and minor actinides which affect nuclear reactor calculations. In addition, the number of nuclei of neutron reaction data stored in JENDL-5 was largely increased; the neutron data covered not only all of naturally existing nuclei but also their neighbor ones with half-lives longer than 1 day. JENDL-5 included the originally evaluated data of thermal scattering law and fission product yield for the first time. Light charged-particle and photon induced reaction data were also included for the first time as the JENDL general purpose file.

論文

$$^{241}$$Am neutron capture cross section measurement using the NaI(Tl) spectrometer of the ANNRI beamline of J-PARC

Rovira Leveroni, G.; 木村 敦; 中村 詔司; 遠藤 駿典; 岩本 修; 岩本 信之; 片渕 竜也*; 児玉 有*; 中野 秀仁*; 佐藤 八起*

Journal of Nuclear Science and Technology, 19 Pages, 2023/00

The neutron capture cross-section of $$^{241}$$Am was measured from 10 meV to about 1 MeV using the NaI(Tl) spectrometer of the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) beamline in the Materials and Life Science (MLF) facility of the Japan Proton Accelerator Research Complex (J-PARC). The total energy detection principle was applied in conjunction with the pulse-height weighting technique to derive the neutron capture yield. The present cross-section results were normalized using a $$^{197}$$Au sample measurement by applying the saturated resonance method. The thermal cross section was measured to be 708 $$pm$$ 22 b, in agreement within uncertainties to the present evaluation in JENDL-5 of 709 b. Moreover, the results of a shape resonance analysis of the resolved resonance region are also provided in the present dissertation.

論文

Measurements of the neutron total and capture cross sections and derivation of the resonance parameters of $$^{181}$$Ta

遠藤 駿典; 木村 敦; 中村 詔司; 岩本 修; 岩本 信之; Rovira Leveroni, G.; 藤 暢輔; 瀬川 麻里子; 前田 亮

Nuclear Science and Engineering, 18 Pages, 2023/00

The neutron transmission ratio and capture yield for $$^{181}$$Ta were measured in J-PARC MLF ANNRI to improve the accuracy of resonance parameters. The total cross section was determined from the transmission ratio in the energy range from 0.2 to 150 eV. The capture cross section was obtained from the capture yield using the pulse height weighting technique (PHWT) in the energy range from thermal to 150 eV. The obtained transmission ratio and capture cross-section were fitted by the resonance analysis code, REFIT, and the resonance parameters were determined below 150 eV. It was also discussed the correlations caused by fitting based on statistical uncertainty and correlations for systematic uncertainty based on sample thickness in the transmission measurements.

論文

$$^{241}$$Am neutron capture cross section measurement and resonance analysis

Rovira Leveroni, G.; 木村 敦; 中村 詔司; 遠藤 駿典; 岩本 修; 岩本 信之; 片渕 竜也*; 児玉 有*; 中野 秀仁*; 佐藤 八起*

JAEA-Conf 2022-001, p.91 - 96, 2022/11

Neutron capture cross section measurements were performed in the Accurate Neutron Nucleus Reaction Measurement Instrument (ANNRI) at the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The time-of-flight (TOF) methodology was employed in a non-filter condition experiment to determine the neutron capture cross section from thermal to about 100 eV. Moreover, experiments were performed using the neutron filtering system to determine the neutron capture cross section at the energy of 23.5 keV using Fe as filter material. In this study, the preliminary results of the $$^{241}$$Am neutron capture cross section from 10 meV to about 100 eV determined in TOF experiments and at 23.5 keV from Fe filter experiments are presented. In the TOF experiments, the $$^{241}$$Am neutron capture cross section was normalized by means of the saturated resonance method using a Au sample with a mass of 1.5 g. In addition, for the Fe filter experiments, the capture cross section of $$^{241}$$Am at the energy of 23.5 keV was determined relative to the $$^{197}$$Au yield obtained from a measurement using the same Au sample. Moreover, early-stage results of a resonance analysis of the $$^{241}$$Am capture resonances are also presented.

論文

The Optical potential for neutron-nucleus scattering derived by Bayesian optimization

渡辺 証斗*; 湊 太志; 木村 真明*; 岩本 信之

JAEA-Conf 2022-001, p.103 - 108, 2022/11

We are working on a combination of nuclear reaction calculation code CCONE and machine learning libraries to generate nuclear data and improve their accuracy. The angular distributions of elastic and inelastic scatterings to the first excited state on $$^{54}$$Fe at several incident energies were calculated using CCONE, and the optical potential parameters were optimized to reproduce the experimental data by Bayesian optimization. The optimized parameters were the depth of the real volume and imaginary surface parts of the potential, their energy dependence, radius, and diffuseness. Using the obtained optical potential, we estimated the angular distributions at energies different from those used on the optimization, and found that the results were in good agreement with the experiment data. In this presentation, we will introduce these calculation results and future prospects.

論文

Nuclear data generation by machine learning, 1; application to angular distributions for nucleon-nucleus scattering

渡辺 証斗*; 湊 太志; 木村 真明*; 岩本 信之

Journal of Nuclear Science and Technology, 59(11), p.1399 - 1406, 2022/11

 被引用回数:0 パーセンタイル:0.01(Nuclear Science & Technology)

In order to increase the efficiency of nuclear data evaluation, we have tested a combination of a nuclear reaction model and machine learning algorithm. We calculated nucleon-nucleus elastic scattering angular distributions by using the nuclear reaction model code, and optimized the potential parameters of an optical model to reproduce experimental data by means of the Bayesian optimization. We present optimization cases with the single parameter and two or more parameters, and show that our framework gives the angular distributions which are in good agreement with the observed ones.

論文

第34回NEA核データ評価国際協力ワーキングパーティ(WPEC)会合報告

岩本 修; 岩本 信之; 木村 敦; 多田 健一; 菅原 隆徳; 横山 賢治

核データニュース(インターネット), (133), p.1 - 6, 2022/10

OECD/NEA/NSC主催のWPEC(Working Party on International Nuclear Data Evaluation Co-operation)の本会合及び関連するサブグループ(SG),専門家グループ(EG)会合が、2022年5月10日$$sim$$5月13日の日程で、パリのOECDカンファレンスセンターとWebでのハイブリッド形式によって実施された。WPEC本会合については、日本からの5名(岩本(修), 岩本(信), 木村, 多田, 東京工業大学・片渕氏)を含め、米国や欧州, 中国, IAEA, NEAから40名近い参加があった。アジアからの参加者はすべてオンラインであったが、米国からは現地での参加が多数あった。横山と菅原はSG-46会合へ参加した。本会合の概要を報告する。

論文

JENDL-5の放射化断面積データ

岩本 信之

核データニュース(インターネット), (133), p.55 - 62, 2022/10

JENDL-5に収録された放射化断面積データは、中性子サブライブラリの派生データの一つで、794核種に対して基底状態やアイソマー状態の生成断面積を収録している。断面積は最大入射エネルギー20MeVでENDF-6フォーマットにより個別の反応チャンネルごとに整備された。本稿では、放射化断面積データの概要、JENDL-5崩壊データサブライブラリとの関係について説明する。

論文

Reduction and resource recycling of high-level liquid radioactive waste through nuclear transmutation, 4; ImPACT/LLFP-2018: A New nuclear data library for a challenge on transmutation of long-lived fission products

国枝 賢; 古立 直也*; 湊 太志; 岩本 信之; 岩本 修

NEA/NSC/R(2020)4 (Internet), p.329 - 331, 2022/10

長寿命核分裂生成核種の核変換研究のために、新たな核データライブラリImPACT/LLFP-2018を開発した。測定データの少ない不安定核種の核反応断面積を推定するために、微視的理論に基づく核構造モデルをCCONEコードに導入した。また、理化学研究所で得られた最新の断面積測定データを用いて高エネルギー反応で重要な前平衡パラメータを決定した。開発したライブラリには$$^{79}$$Se, $$^{93}$$Zr, $$^{107}$$Pdおよび$$^{135}$$Csを含む160核種に対する中性子および陽子入射の断面積が200MeVをエネルギー上限に格納されている。さらに、既存の安定核種に対する測定値と比較することにより調査した結果、本ライブラリは他のライブラリと比べて実験データへの再現性が高いことが判った。

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