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Pb, the heaviest 
-process; Only isotope in the solar systemCasanovas-Hoste, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 133(5), p.052702_1 - 052702_8, 2024/07
被引用回数：1 パーセンタイル：53.15(Physics, Multidisciplinary)Tl(n, 
) cross section was measured at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of Tl produced at the Institute Laue Langevin high flux reactor. At the -process temperatures of kT 
8 keV and kT 30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new Tl MACS, the uncertainty arising from the Tl(n, ) cross section on the -process abundance of Pb has been reduced from 
30% down to +8%/-6%, and the -process calculations are in agreement with the latest solar system abundance of Pb reported by K. Lodders in 2021.
-rays from slow neutron-induced fission of 
U with STEFFWright, T.*; 原田 秀郎; 木村 敦; 他121名*
European Physical Journal A, 60(3), p.70_1 - 70_11, 2024/03
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)The average energy and multiplicity of prompt -rays from slow neutron-induced fission of U have been measured using the STEFF spectrometer at the neutron time-of-flight facility n_TOF. The individual responses from 11 NaI scintillators were corrected for multiple -ray interactions, prompt fission neutrons and background counts before being deconvolved to estimate the emitted spectrum of prompt fission -rays. The results give an average -ray energy 
of 1.71(5) MeV and multiplicity 
of 2.66(18) considering -rays emitted within the energy range from 0.8 to 6.8 MeV. The n_TOF data has a slightly larger and smaller than other recent measurements, however the product of the two is in agreement within the quoted uncertainties.
Ce(n, ) cross section at n_TOF and its astrophysical implications for the chemical evolution of the universeAmaducci, S.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 132(12), p.122701_1 - 122701_8, 2024/03
被引用回数：2 パーセンタイル：72.87(Physics, Multidisciplinary)Ce(n,) is a key reaction for slow neutron-capture (-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty 5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
Th at the CERN n_TOF facilityMichalopoulou, V.*; 原田 秀郎; 木村 敦; 他134名*
Physical Review C, 108(1), p.014616_1 - 014616_15, 2023/07
被引用回数：2 パーセンタイル：28.72(Physics, Nuclear)The neutron-induced fission cross section of Th has been measured at the neutron time-of-flight facility n_TOF located at CERN. The experiment was performed at the experimental area EAR-1 with a neutron flight path of 185 m, using Micromegas detectors for the detection of the fission fragments. The Th(n,f) cross section was determined relative to the U(n, f) one, covering the energy range from the fission threshold up to 400 MeV. The results from the present work are compared with existing cross-section datasets and the observed discrepancies are discussed and analyzed.
Gd and 
Gd in the thermal energy region with the Li-glass detectors and NaI(Tl) spectrometer installed in J-PARC
MLFANNRI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：30.61(Nuclear Science & Technology)Neutron total and capture cross-section measurements of Gd and 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
1.7 and 251.94.6 kilobarn for Gd and 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 59.02.5 and 247.43.9 kilobarn for Gd and Gd, respectively. The present total and capture cross sections agree well within the standard deviations. The results for 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 Gd agreed with the evaluated data in JENDL-4.0 and the experimental data by M
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.
N(n, p)C cross section at the CERN n_TOF facility from subthermal energy to 800 keVTorres-S
nchez, P.*; 原田 秀郎; 木村 敦; 他129名*
Physical Review C, 107(6), p.064617_1 - 064617_15, 2023/06
被引用回数：1 パーセンタイル：28.72(Physics, Nuclear)The N(n, p)C reaction cross section has been measured at the CERN neutron time-of-flight facility n_TOF from subthermal energy to 800 keV. The experiment was performed at the experimental area EAR-2 with a stack of micromesh gaseous structure detectors (MicroMegas). 
B(n,
)
Li and U(n, f) reactions were used as references. A thermal cross section was obtained (1.809 0.045 b) that is lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 andJEFF-3.3 evaluations.
Se(n,) cross section up to 200 keV at the n_TOF facility at CERNSosnin, N. V.*; 原田 秀郎; 木村 敦; 他128名*
Physical Review C, 107(6), p.065805_1 - 065805_9, 2023/06
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)The Se(n,) reaction is of importance for Se abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the Se radiative neutron capture cross section at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections up to 200 keV. Maxwellian-averaged cross sections were calculated for stellar temperatures between kT = 5 keV and kT = 100 keV, with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in Se abundances produced through the slow neutron capture process in selected stellar models, compared to using previous recommendation of the cross section.
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：0.00(Physics, Multidisciplinary)We investigated the angular correlation of two -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 -rays emerging in the electromagnetic transitions of the capture reactions on Gd and 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 -rays produced in the majority of transitions in continuum states.
Ge(n,) cross section below 70 keV measured at n_TOF CERNLederer-Woods, C.*; 原田 秀郎; 木村 敦; 他128名*
European Physical Journal A, 58(12), p.239_1 - 239_9, 2022/12
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Neutron capture reaction cross sections on Ge are of importance to determine Ge production during the astrophysical slow neutron capture process. We present new resonance data on Ge(n,) reactions below 70 keV neutron energy. We calculate Maxwellian averaged cross sections, combining our data below 70 keV with evaluated cross sections at higher neutron energies. Our stellar cross sections are in agreement with a previous activation measurement performed at Forschungszentrum Karlsruhe by Marganiec et al., once their data has been re-normalised to account for an update in the reference cross section used in that experiment.
I(n, ) using fast neutron source in the "YAYOI" reactor中村 詔司; 藤 暢輔; 木村 敦; 初川 雄一*; 原田 秀郎
Journal of Nuclear Science and Technology, 59(7), p.851 - 865, 2022/07
被引用回数：1 パーセンタイル：10.40(Nuclear Science & Technology)本研究は、東京大学の高速中性子源炉「弥生」を用いて、評価済み核データライブラリーを検証するために放射化法によりIの積分実験を行った。Iと中性子束モニタを、弥生炉のグローリー孔にて照射した。反応率は、
Iから放出されるガンマ線の収量から求めた。中性子束モニタの反応率の実験値と計算値との比較から、高速中性子スペクトルの確かさを確認した。Iの反応率の実験値を、評価済み核データライブラリーを用いて求めた計算値と比較した。本研究で、評価済みライブラリーJENDL-4.0に採用されている中性子エネルギー10keVから3MeV領域の中性子捕獲断面積データは、18%程、過大評価されていることが分かった。また、本研究の結果は、100keV以下では、Noguere等による報告データを支持した。
中村 詔司; 初川 雄一*; 木村 敦; 藤 暢輔; 原田 秀郎
Journal of Nuclear Science and Technology, 58(12), p.1318 - 1329, 2021/12
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)本研究は、東大の高速中性子源炉「弥生」を用いて、放射化法により
Tcの積分実験を行った。Tc試料を、気送管システムを用いて照射した。Tcの反応率は、
Tcから放出されるガンマ線を測定して求めた。中性子束は、Au箔を用いてモニタした。本研究におけるTcの反応率の結果は、JENDL-4.0を支持した。
Ge(n,) cross section at the n_TOF facility at CERNGawlik, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review C, 104(4), p.044610_1 - 044610_7, 2021/10
被引用回数：5 パーセンタイル：52.80(Physics, Nuclear)The Ge(n,) reaction has been measured at the n_TOF facility at CERN via the time-of-flight technique. Neutron capture cross sections on Ge are of interest to a variety of low-background experiments, such as neutrinoless double 
decay searches, and to nuclear astrophysics. We have determined resonance capture kernels up to 52 keV neutron energy and used the new data to calculate Maxwellian-averaged neutron capture cross sections for k
T values of 5 to 100 keV.
-ray emitter 
Al in massive stars; Study of the key Al(n,) reactionLederer-Woods, C.*; 原田 秀郎; 木村 敦; 他123名*
Physical Review C, 104(3), p.L032803_1 - L032803_6, 2021/09
被引用回数：8 パーセンタイル：64.85(Physics, Nuclear)Neutron destruction reactions of the cosmic -ray emitter Al are of importance to determine the amount of Al ejected into our galaxy by supernova explosions and for Al production in asymptotic giant branch stars. We performed a new measurement of the Al(n,) reaction up to 160-keV neutron energy at the neutron time-of-flight facilities n_TOF at CERN and GELINA at EC-JRC. We provide strengths for ten resonances, six of them for the first time. We use our data to calculate astrophysical reactivities for stellar temperatures up to 0.7 GK. Our results resolve a discrepancy between the two previous direct measurements of this reaction, and indicate higher stellar destruction rates than the most recently recommended reactivity.
-ray emitter Al in massive stars; Study of the key Al(n, p) reactionLederer-Woods, C.*; 原田 秀郎; 木村 敦; 他121名*
Physical Review C, 104(2), p.L022803_1 - L022803_7, 2021/08
被引用回数：8 パーセンタイル：68.98(Physics, Nuclear)The Al(n,p)Mg reaction is the key reaction impacting on the abundances of the cosmic -ray emitter Al produced in massive stars and impacts on the potential pollution of the early solar system with Al by asymptotic giant branch stars. We performed a measurement of the Al(n,p)Mg cross section at the high-flux beam line EAR-2 at the n_TOF facility (CERN). We report resonance strengths for eleven resonances, nine being measured for the first time, while there is only one previous measurement for the other two. Our resonance strengths are significantly lower than the only previous values available. Our cross-section data range to 150 keV neutron energy, which is sufficient for a reliable determination of astrophysical reactivities up to 0.5 GK stellar temperature.
原田 秀郎
Applied Sciences (Internet), 11(14), p.6558_1 - 6558_20, 2021/07
被引用回数：0 パーセンタイル：0.00(Chemistry, Multidisciplinary)中性子放射化分析と中性子捕獲断面積の精度向上のために、Westcott記法のg因子とs因子のバイアス効果について検討した。バイアス要因として、接合関数形状,中性子温度,試料温度を調べた。2つの1/v則に従う同位体(
Au, 
Co)と6つの非1/v同位体(
Am, 
Eu, 
Rh, 
In, 
Hf, 
Ra)について、定量的な計算を行った。詳細なモンテカルロ シミュレーションによって推定された最新の接合関数で計算したs因子を、Westcottによる従来の接合関数で計算したs因子と比較した。この結果、サンプル温度によって誘発されるバイアスは、g因子の場合で0.1%のオーダー、s因子の場合で1%のオーダーと小さいことを示した。一方、接合関数の形状の差に起因するs因子のバイアスは、同位体と中性子温度の両方に大きく依存することを示した。この結果、反応率にも大きな影響が生じることも示した。この効果を明示するため、熱外中性子インデックスr=0.1の場合に、検討した8種類すべての同位体について、反応率に生じるバイアスを定量的に与えた。
川瀬 頌一郎*; 木村 敦; 原田 秀郎; 岩本 信之; 岩本 修; 中村 詔司; 瀬川 麻里子; 藤 暢輔
Journal of Nuclear Science and Technology, 58(7), p.764 - 786, 2021/07
被引用回数：4 パーセンタイル：41.66(Nuclear Science & Technology)The neutron capture cross sections of 
Cm and 
Cm were measured for the neutron energy range of 1-1000 eV via the neutron time-of-flight method with ANNRI at MLF of the J-PARC. The world's most intense neutron pulses from the Japan Spallation Neutron Source enable the accurate measurement of neutron capture cross sections. Besides, single-bunched neutron pulses allow the analysis in a higher neutron energy region than the previous measurement at ANNRI. The resonance analyses were performed up to 1000 eV by using a resonance shape analysis code REFIT. The spectra of prompt gamma-rays from neutron capture reactions of Cm and Cm were also obtained, and 43 and 10 prompt gamma-ray peaks from Cm(n,) and Cm(n,) reactions were newly observed, respectively.
Babiano-Surez, V.*; 原田 秀郎; 木村 敦; 他132名*
European Physical Journal A, 57(6), p.197_1 - 197_17, 2021/06
被引用回数：16 パーセンタイル：85.85(Physics, Nuclear)i-TED is an innovative detection system which exploits Compton imaging techniques to achieve a superior signal-to-background ratio in (n,) cross-section measurements using time-of-flight technique. This work presents the first experimental validation of the i-TED apparatus for high resolution time-of-flight experiments and demonstrates for the first time the concept proposed for background rejection. To this aim, the Au(n,) and 
Fe(n,) reactions were studied at CERN n_TOF using an i-TED demonstrator based on three position-sensitive detectors. The i-TED prototype built for this study shows a factor of about 3 times higher detection sensitivity than traditional 
detectors in the 10 keV neutron-energy region. This paper explores also the perspectives of further enhancement in performance attainable with the final i-TED array consisting of twenty position-sensitive detectors and new analysis methodologies based on Machine-Learning techniques.
原田 秀郎
核データニュース(インターネット), (129), p.35 - 43, 2021/06
核データの精度を高めるために実施した国際核データ評価ワーキングパーティ(WPEC)のサブグループSG-41の活動について概説する。この中で、ばらつくデータの対処法に焦点を当て、複数の測定結果から推奨値を導出する手法についてレビューする。また、SG-41で採用した推奨値を導出方法について、演習問題を含め解説した。
Ce(n,)
Ce cross-section measurement at n_TOFAmaducci, S.*; 原田 秀郎; 木村 敦; 他127名*
Universe (Internet), 7(6), p.200_1 - 200_11, 2021/06
被引用回数：5 パーセンタイル：33.94(Astronomy & Astrophysics)An accurate measurement of the Ce(n,) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. For this measurement, we used a sample of cerium oxide enriched in Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the Ce Maxwellian-averaged cross-section.
Ge(n,) cross section over a wide neutron energy range at the CERN n_TOF facilityDietz, M.*; 原田 秀郎; 木村 敦; 他121名*
Physical Review C, 103(4), p.045809_1 - 045809_8, 2021/04
被引用回数：7 パーセンタイル：59.44(Physics, Nuclear)The Ge(n,) cross section was measured for neutron energies up to 300 keV at the neutron time-of-flight facility n_TOF (CERN). The measurement was performed at the high-resolution beamline EAR-1, using an isotopically enriched Ge sample. The prompt capture rays were detected with four liquid scintillation detectors, optimized for low neutron sensitivity. We determined resonance capture kernels up to a neutron energy of 43 keV, and averaged cross sections from 43 to 300 keV. Maxwellian-averaged cross section values were calculated from kT = 5 to 100 keV, with uncertainties between 3.2% and 7.1%. The new results significantly reduce uncertainties of abundances produced in the slow neutron capture process in massive stars.
