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相澤 直人*; 渡邉 友章; 千葉 豪*; 多田 健一; 藤田 達也*; 山本 章夫*
Nuclear Engineering and Technology, 58(5), p.104176_1 - 104176_16, 2026/05
被引用回数:0 パーセンタイル:0.00(Nuclear Science & Technology)A quick neutron spectrum reconstruction module based on proper orthogonal decomposition (POD) and a regression model for fast reactors is developed for the general-purpose burnup calculation code SWAT-X. This module enables burnup calculations to be performed quickly for arbitrary conditions based on a few parameters, eliminating the need for computationally intensive calculation codes. Reduced-order and regression models are constructed by applying the POD technique to the snapshot data of the multi-group neutron fluxes calculated using randomly-sampled parameter sets for a single hexagonal pin-cell of a sodium-cooled fast reactor. The neutron spectrum is reconstructed using a linear combination of POD basis vectors with the coefficients obtained from the regression model. The applicability of a pin-cell model, the accuracy of the reconstruction module itself, and its integration with SWAT-X are verified by comparing with the calculation results from the reactor physics code system CBZ.
渡邉 友章; 相澤 直人*; 千葉 豪*; 多田 健一; 藤田 達也*; 山本 章夫*
Journal of Nuclear Science and Technology, 63(2), p.166 - 186, 2026/02
被引用回数:1 パーセンタイル:50.28(Nuclear Science & Technology)中性子スペクトルの再構築に基づく高速な燃焼計算手法を新たに提案する。本手法では、燃料燃焼中の中性子スペクトルを推定するために、固有直交分解(POD)と回帰モデルを用いて構築された簡易モデル(ROM)を使用する。このROMは、さまざまな条件下で実施された詳細な燃焼および中性子輸送計算から得られたスナップショットデータをもとに構築され、燃焼計算では各燃焼ステップにおいてROMを用いて中性子スペクトルを高速に再構築する。その再構築されたスペクトルを用いて、背景断面積をもとに得られた多群実効断面積から1群断面積を計算する。本手法は、燃焼計算中に中性子輸送計算を繰り返す必要がないため、計算時間を大幅に短縮できる。提案手法の性能を、PWRのUO
燃料ピンセルモデルを用いて検証した。結果として、第6次のPOD基底までを使用した場合、参照解であるモンテカルロ計算と比較して、核種インベントリを
5%以内の平均誤差で計算できることが示された。また、誤差の要因分析の結果、計算精度に対する影響として、PODの次数や多群断面積計算の不確かさに比べて回帰モデルの精度の影響が大きいことが明らかとなった。
多田 健一; 相澤 直人*; 藤田 達也*; 福島 昌宏; Pyeon, C. H.*
Journal of Nuclear Science and Technology, 63(1), p.1 - 2, 2026/01
被引用回数:0 パーセンタイル:0.00(Nuclear Science & Technology)本稿は、Journal of Nuclear Science and Technology誌に掲載された「現在及び将来の原子炉物理学の課題の進捗に関する特集号」の序文である。
He neutron spin filter at J-PARC高橋 慎吾; 鬼柳 亮嗣; 奥平 琢也*; 高田 秀佐*; 小林 龍珠; 奥泉 舞桜; 猪野 隆*; 浅井 寛太*; 土川 雄介; 及川 健一; et al.
Nuclear Instruments and Methods in Physics Research A, 1075, p.170410_1 - 170410_8, 2025/06
被引用回数:2 パーセンタイル:51.17(Instruments & Instrumentation)This study developed a compact and portable in-situ
He neutron spin filter (
He NSF) utilizing spin-exchange optical pumping at MLF of J-PARC. Its performance as an incident neutron polarizer was evaluated at MLF, where it achieved a
He polarization exceeding 0.6, corresponding to a neutron polarization greater than 0.8 at 1.8
. Notably, the
He NSF demonstrated stable operation for 110 h. These outcomes signify that the developed in-situ
He NSF facilitates and promotes polarized pulsed neutron experiments at MLF.
C
reaction at 1.8 GeV/
with the Superconducting Kaon spectrometer市川 裕大; 藤田 真奈美; 長谷川 勝一; 今井 憲一*; 七村 拓野; 成木 恵; 佐藤 進; 佐甲 博之; 田村 裕和; 谷田 聖; et al.
Progress of Theoretical and Experimental Physics (Internet), 2024(9), p.091D01_1 - 091D01_13, 2024/09
被引用回数:4 パーセンタイル:56.92(Physics, Multidisciplinary)We conducted a measurement of the inclusive missing-mass spectrum in the
C
reaction at an incident beam momentum of 1.8 GeV/
. This measurement was carried out utilizing the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Hall in J-PARC. Remarkably, our experimental setup yielded an exceptionaly good energy resolution of 8.2 MeV (FWHM), enabling us to observe significant enhancements in the vicinity of the
Be threshold region. In order to estimate the spectrum information, we employed several fitting parameters assumptions. The best agreement with the spectrum shape was obtained with combining quasi-free (QF) component and two-Gaussian functions, with the experimental resolution
being held constant. The peak positions were obtained to be
(stat.)
(syst.) MeV and
(stat.)
(syst.) MeV. Another model assumption, utilizing quasi-free (QF) and one Breit-Wigner function with
(stat.)
(syst.) MeV and
(stat.)
(syst.) MeV, also yielded a similar
value.
三輪 浩司*; 藤田 真奈美; 原田 健志; 長谷川 勝一; 細見 健二; 市川 真也; 今井 憲一*; 佐甲 博之; 佐藤 進; 田村 裕和; et al.
EPJ Web of Conferences, 271, p.04001_1 - 04001_7, 2022/11
A new hyperon-proton scattering experiment, dubbed J-PARC E40, was performed to measure differential cross sections of the
,
elastic scatterings and the
scattering by identifying a lot of
particles in the momentum ranging from 0.4 to 0.8 GeV/
produced by the
reactions. We successfully measured the differential cross sections of these three channels with a drastically improved accuracy with a fine angular step. These new data will become important experimental constraints to improve the theories of the two-body baryon-baryon interactions. Following this success, we proposed a new experiment to measure the differential cross sections and spin observables by using a highly polarized
beam for providing quantitative information on the
interaction. The results of three
channels and future prospects of the
scattering experiment are described.
後神 利志*; 江端 健悟; 藤田 真奈美; 原田 健志; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一*; Kim, S.; 七村 拓野; et al.
EPJ Web of Conferences, 271, p.11002_1 - 11002_7, 2022/11
In the K1.8 beam-line at Hadron Experimental Facility of J-PARC, a new magnetic spectrometer S-2S is being installed. S-2S was designed to achieve a high momentum resolution of
in FWHM. Several strangeness-physics programs which require the high resolution will be realized by S-2S. The present article introduces J-PARC E70 (missing-mass spectroscopy of
Be) and E94 (missing-mass spectroscopy of
Li,
B, and
C) experiments.
-rays of fuel debris松村 太伊知; 奥村 啓介; 藤田 学*; 坂本 雅洋; 寺島 顕一; Riyana, E. S.
Radiation Physics and Chemistry, 199, p.110298_1 - 110298_8, 2022/10
被引用回数:3 パーセンタイル:30.55(Chemistry, Physical)The characterization of bremsstrahlung and
-rays from fuel debris differs from that of spent fuels evaluated to date, due to factors such as material composition and release of volatile fission products. In this work, in order to clarify the conditions under which the effect of bremsstrahlung compared to the total photons (bremsstrahlung and
-rays) in fuel debris is maximized, the average energies and dose rates from the energy spectra of bremsstrahlung and
-rays on the fuel debris surface were obtained using a Monte Carlo simulation. In the simulation, the average energies and dose rates were evaluated with consideration of the composition, size, fission product release, and retrieval time of the fuel debris. The simulation showed that the composition with the largest amount of change to the average total photons energy caused by bremsstrahlung was the molten fuel debris, and the composition with the maximum fraction of bremsstrahlung in the dose rate was the UO
. The maximum value of the fraction of bremsstrahlung in the dose rate was evaluated to be about 17%. This work is expected to contribute to the prediction of the radiation characteristics of the fuel debris that will be retrieved from the Fukushima Daiichi Nuclear Power Station in the near future.
elastic scattering in the momentum range 0.44-0.80 GeV/c七村 拓野; 藤田 真奈美; 長谷川 勝一; 市川 真也; 市川 裕大; 今井 憲一*; 成木 恵; 佐藤 進; 佐甲 博之; 田村 裕和; et al.
Progress of Theoretical and Experimental Physics (Internet), 2022(9), p.093D01_1 - 093D01_35, 2022/09
被引用回数:23 パーセンタイル:85.14(Physics, Multidisciplinary)We performed a novel
scattering experiment at the J-PARC Hadron Experimental Facility. Approximately 2400
elastic scattering events were identified from
tagged
particles in the
momentum range 0.44 - 0.80 GeV/c. The differential cross sections of the
elastic scattering were derived with much better precision than in previous experiments. The obtained differential cross sections were approximately 2 mb/sr or less, which were not as large as those predicted by the fss2 and FSS models based on the quark cluster model in the short-range region. By performing phase-shift analyses for the obtained differential cross sections, we experimentally derived the phase shifts of the
and
channels for the first time. The phase shift of the 3S1 channel, where a large repulsive core was predicted owing to the Pauli effect between quarks, was evaluated to be
. If the sign of
is assumed to be negative, the interaction in this channel is moderately repulsive, as the Nijmegen extended-sort-core models predicted.
reaction in momentum range 470-650 MeV/
三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 裕大*; 今井 憲一*; 七村 拓野; 佐甲 博之; 佐藤 進; 田村 裕和; et al.
Physical Review Letters, 128(7), p.072501_1 - 072501_6, 2022/02
被引用回数:27 パーセンタイル:87.98(Physics, Multidisciplinary)The differential cross sections of the
reaction were measured accurately for the
momentum
ranging from 470 to 650 MeV/
at the J-PARC Hadron Experimental Facility. Precise angular information about the
reaction was obtained for the first time by detecting approximately 100 reaction events at each angular step of
. The obtained differential cross sections show slightly forward-peaking structure in the measured momentum regions. The cross sections integrated for
were obtained as
mb and
mb for
(MeV/c)
and
(MeV/c)
, respectively. These results show a drastic improvement compared to past measurements of the hyperon-proton scattering experiments. They will play essential roles in updating the theoretical models of the baryon-baryon interactions.
elastic scattering in momentum range 470 to 850 MeV/
三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.
Physical Review C, 104(4), p.045204_1 - 045204_20, 2021/10
被引用回数:27 パーセンタイル:91.43(Physics, Nuclear)A high statistics
scattering experiment is performed at the J-PARC Hadron Experimental Facility. Momentum-tagged
s running in a liquid hydrogen target are accumulated by detecting the reaction with a high intensity
beam of 20 M/spill. The differential cross sections of the
elastic scattering were derived with a drastically improved accuracy by identifying approximately 4,500 events from 1.72
10
. The derived differential cross section shows a clear forward-peaking angular distribution for a
momentum range from 470 to 850 MeV/
. The accurate data will impose a strong constraint on the theoretical models of the baryon-baryon interactions.
-state of a
hypernucleus, 
吉本 雅浩*; 藤田 真奈美; 橋本 直; 早川 修平; 市川 裕大; 市川 真也; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.
Progress of Theoretical and Experimental Physics (Internet), 2021(7), p.073D02_1 - 073D02_19, 2021/07
被引用回数:29 パーセンタイル:84.20(Physics, Multidisciplinary)Bound-systems of
-
are studied via
capture at rest followed by emission of a twin single-
hypernucleus in the emulsion detectors. Two events forming extremely deep
bound states were obtained by analysis of a hybrid method in the E07 experiment at J-PARC and reanalysis of the E373 experiment at KEK-PS. The decay mode of one event was assigned as
+
+
+
. Since there are no excited states for daughter particles, the binding energy of the
hyperon,
, in
nucleus was uniquely determined to be 6.27
0.27 MeV. Another
-
system via the decay
+
+
brings a
value, 8.00
0.77 MeV or 4.96
0.77 MeV, where the two possible values of
correspond to the ground and the excited states of the daughter
nucleus, respectively. Because the
values are larger than those of the previously reported events (KISO and IBUKI), which are both interpreted as the nuclear
state of the
-
system, these new events give the first indication of the nuclear
state of the
hypernucleus,
.
吉田 純也; 赤石 貴也; 藤田 真奈美; 長谷川 勝一; 橋本 直; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; Kim, S.; et al.
JPS Conference Proceedings (Internet), 33, p.011112_1 - 011112_8, 2021/03
J-PARC E07 is the most ambitious and complex emulsion experiment to date investigating double hypernuclei with Hybrid emulsion method. The physics run at the K1.8 beam line in the J-PARC hadron experimental facility have been completed in 2017. The emulsion sheets are presently being analyzed with dedicated optical microscopes. Current statistics are estimated to be more 3 times than that of previous experiments. Quantitative data on the
and
interaction are being accumulated successfully via analysis of double
and
hypernuclei. Multiple
hypernucleus candidates suggests several features about
hypernucleus that the identification efficiency of
C is significantly higher than other mode, many daughters of
C are identified as He or Be, and multiple bound states of
exist in the
N nucleus. An analysis of X-ray spectroscopy of
hyperatoms are ongoing.
identification method by the
reaction for a
scattering experiment at J-PARC坂尾 珠和*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.
JPS Conference Proceedings (Internet), 33, p.011133_1 - 011133_6, 2021/03
The
reaction is an important elementary process to produce
from a proton target and is a key for a
scattering experiment where the momentum of
should be tagged from the missing momentum of the
reaction. However, the
spectroscopy method has not been established yet due to the difficulty of the
detection. Therefore, we have proposed a new
detection method where
and
from the
decay are measured by a forward magnetic spectrometer and a detector cluster surrounding the target, respectively. The feasibility of the
detection method was confirmed by analyzing the J-PARC E40 data taken with such a detector system. In the analysis,
's were successfully identified in the missing mass spectrum of the
reaction.
scattering experiment at J-PARC赤澤 雄也*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.
JPS Conference Proceedings (Internet), 33, p.011134_1 - 011134_6, 2021/03
We are performing a scattering experiment between a
hyperon and a proton (J-PARC E40) at the K1.8 beamline in the J-PARC Hadron Hall. The purpose of this experiment is to investigate the
interaction by measuring the differential cross sections of the
,
elastic scatterings and
inelastic scattering. The experimental data gives a strong constraint on the theoretical models of the
interaction. The identification of
scattering event with a high statistics is important by overcoming the difficulties in the hyperon proton scattering experiment. We have introduced a new identification method of the
scattering event, which does not need to detect
particles directly. We used a new detector system called CATCH and two spectrometer systems installed at the upstream and the downstream of a liquid hydrogen target. A high intensity
beam of 20 M/spill was used to produce
particle. The momenta of
beam and scattered
were measured by the spectrometers to reconstruct the momentum of a
beam produced via the
reactions. The scattering angle and the kinetic energy of recoil protons from the
scattering were measured by CATCH for the identification of the
scattering events by checking the kinematic consistency. A part of the experiment was performed in 2018 and 2019 in J-PARC. As a result of analyzing the collected data, the
production and the
scattering reaction have been identified. It means that our new measurement and analysis method are successfully working well. Analysis for deriving the differential cross section of the
scattering is on going.
-
N system早川 修平; 藤田 真奈美; 長谷川 勝一; 橋本 直; 細見 健二; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.
Physical Review Letters, 126(6), p.062501_1 - 062501_6, 2021/02
被引用回数:55 パーセンタイル:93.50(Physics, Multidisciplinary)In an emulsion-counter hybrid experiment performed at J-PARC, a
absorption event was observed which decayed into twin single-
hypernuclei. Kinematic calculations enabled a unique identification of the reaction process as
N
Be +
He. For the binding energy of the
hyperon in the
-
N system a value of
MeV was deduced. The energy level of
is likely a nuclear
state which indicates a weak
-
coupling.
hypernuclear spectroscopy with the
reaction後神 利志*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 今井 憲一*; 市川 裕大; 七村 拓野; 成木 恵; 佐甲 博之; 佐藤 進; et al.
Journal of Physics; Conference Series, 1643, p.012133_1 - 012133_6, 2020/12
被引用回数:2 パーセンタイル:75.96(Astronomy & Astrophysics)We performed
hypernuclear spectroscopy with the
reaction at J-PARC to investigate the
interaction (J-PARC E05). A new experiment (J-PARC E70) in which a better energy resolution could be achieved is now being prepared. In this article, an analysis status of J-PARC E05 and a preparation status of J-PARC E70 are described.
interaction from the
scattering experiment at J-PARC三輪 浩司*; 藤田 真奈美; 長谷川 勝一; 細見 健二; 市川 真也; 市川 裕大; 今井 憲一*; 七村 拓野; 成木 恵; 佐甲 博之; et al.
Journal of Physics; Conference Series, 1643, p.012174_1 - 012174_6, 2020/12
被引用回数:3 パーセンタイル:83.78(Astronomy & Astrophysics)A high statistics
scattering experiment has been performed at the K1.8 beamline in the J-PARC Hadron Experimental Facility. Data for momentum-tagged
beam running in a liquid hydrogen target were accumulated by detecting the
reaction with a high intensity
beam of 20 M/spill. The number of the
beam was about
in total. The
elastic scattering and the
inelastic scattering events were successfully observed with about 100 times larger statistics than that in past experiments.
O(
He,
)
F reaction; Identification of the low-energy "super" -Gamow-Teller state藤田 浩彦*; 藤田 佳孝*; 宇都野 穣; 吉田 賢市*; 足立 竜也*; Algora, A.*; Csatl
s, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.
Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09
被引用回数:18 パーセンタイル:78.62(Physics, Nuclear)大阪大学のリングサイクロトロンにて
O(
He,
)
F反応実験を行い、その荷電交換反応の断面積から、
のガモフテラー遷移分布
の励起エネルギー分布を測定した。その結果、
Fの基底状態への
が3.1と非常に大きく、その他の励起状態への遷移強度は小さいことがわかった。この実験結果を大規模殻模型計算や乱雑位相近似計算と比較し、基底状態への強い遷移が理論計算によってよく説明されることがわかった。
石丸 恒存; 安江 健一*; 浅森 浩一; 國分 陽子; 丹羽 正和; 渡邊 隆広; 横山 立憲; 藤田 奈津子; 雑賀 敦; 清水 麻由子; et al.
JAEA-Research 2018-008, 83 Pages, 2018/12
本報は、高レベル放射性廃棄物の地層処分技術に関する研究開発のうち、深地層の科学的研究の一環として実施している地質環境の長期安定性に関する研究について、第3期中長期目標期間(平成27年度
平成33年度)における平成28年度に実施した研究開発に係る成果を取りまとめたものである。第3期中長期目標期間における研究の実施にあたっては、最終処分事業の概要調査や安全審査基本指針等の検討・策定に研究成果を適時反映できるよう、(1)調査技術の開発・体系化、(2)長期予測・影響評価モデルの開発、(3)年代測定技術の開発の三つの枠組みで進めている。本報では、それぞれの研究分野に係る科学的・技術的背景を解説するとともに、主な研究成果及び今後の課題等について述べる。