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佐藤 博之; 大橋 弘史
Mechanical Engineering Journal (Internet), 7(3), p.19-00332_1 - 19-00332_11, 2020/06
高温ガス炉コジェネレーションプラントの水素製造施設における有毒ガス漏えい事故に対する確率論的リスク評価手法開発を目的として、コジェネレーション高温ガス炉における有毒ガス漏えい事故時における制御室居住性評価に係る不確かさ評価手法を構築した。また、本開発手法を、HTTRに接続した熱化学法ISプロセスによる水素製造施設に適用した。検討の結果、開発手法により、不確かさの特性把握や定量化が可能であることを明らかにした。また、表面粗度に係る不確かさが制御室の有毒ガス濃度のばらつきに与える影響が大きいことを明らかにした。
佐藤 博之; 青木 健; 大橋 弘史; Yan, X. L.
Nuclear Engineering and Design, 360, p.110493_1 - 110493_8, 2020/04
被引用回数：0 パーセンタイル：100(Nuclear Science & Technology)原子力機構は原子力エネルギーの多様な産業利用に向け、HTTR建設の許認可での経験及び知見を活用し、高温ガス炉固有の特徴を反映した、実用高温ガス炉の安全基準国際標化に向けた活動を実施している。本論文では、高温ガス炉コジェネレーションシステムの許認可に向けた研究開発ロードマップを示した。また、安全要件や設計基準事象選定方針等の検討結果や安全評価手法の確立に向けたHTTR試験計画を示した。加えて、実用高温ガス炉における炉心冷却機能を担う安全設備である自然空冷方式による炉容器冷却設備が安全要件国際標準案に適合することを確認した。
Jung, W.*; Ahn, J. K.*; 長谷川 勝一; Hicks, K.*; Hwang, S.*; 市川 裕大; Kim, S.*; 佐甲 博之; 佐藤 進; 谷田 聖
JPS Conference Proceedings (Internet), 27, p.011007_1 - 011007_6, 2019/11
We have developed HypTPC consists of TPC and the trigger hodoscope for the J-PARC hadron experiments. The TPC Hodoscope has large scintillators of 80 
7 1 cm
to cover the TPC. Especially, we have developed a readout circuit for multiple MPPCs to detect photons generated over a large area of the scintillator. A general methods of applying voltage to multiple MPPCs are parallel and series connections. In the case of parallel connections, a signal has a long tail due to the large sensor capacitance. MEG collaboration used four MPPC segments as a serial connection. However, in the case of a series connection, the requiring bias voltage is very high, and the gain is low. To avoid this problem, we have developed a new individual biasing method with a summing amplifier for stable multiple MPPC readouts. We also made prototype detectors and performed a cosmic-ray test. Brief descriptions of our prototypes and preliminary results of the cosmic-ray test are presented in this article.
scattering experiment at J-PARC and the analysis status中田 祥之*; 長谷川 勝一; 早川 修平*; 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.
JPS Conference Proceedings (Internet), 26, p.023024_1 - 023024_5, 2019/11
J-PARC E40 aims to measure the differential cross sections of the 
elastic scatterings and the 
conversion. A clear peak of 
was observed in a missing mass spectrum of the 
reaction and recoil protons from the 
elastic scattering were successfully observed in the data taken in the summer 2018. The rest of data taking is coming in the spring 2019.
-ray spectroscopy of an 
-shell hypernucleus, 
FYang, S. B.*; 長谷川 勝一; 早川 修平*; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 田村 裕和*; 谷田 聖; et al.
JPS Conference Proceedings (Internet), 26, p.023015_1 - 023015_5, 2019/11
We performed a gamma-ray spectroscopy of 
at J-PARC Hadron Experimental Facility in 2015. It is the first measurement of rays emitted from -shell hypernuclei. In this experiment, we determined the energy spacing between the ground state spin doublet, 
and 
states, as 316 keV. The excitation energies of 
and states are also determined to be 895 and 1266 keV, respectively. The energy spacing is found to be well reproduced by shell-model calculations which describe 
- and 
-shell 
hypernuclei well. The results show that the present theories of the 
interaction describe not only the light hypernuclei but also a heavier hypernucleus.
in nuclei through C
spectrum at 1.8 GeV/
in the J-PARC E05 experiment本多 良太郎*; 長谷川 勝一; 早川 修平; 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.
JPS Conference Proceedings (Internet), 26, p.023014_1 - 023014_4, 2019/11
We measured the 
reaction spectra at 1.8 GeV/ for the graphite and the polyethylene targets in the J-PARC E05 pilot experiment. By comparing the spectra for these two targets, it was found that 
in the 
B nucleus is quite broadened. Furthermore, we also compared broadness of with 
obtained in the 
spectrum. seems to be much more broadened in nuclei than . We gave a possible interpretation, which is related to compositeness of decuplet baryons, for this situation.
hypernucleus in the J-PARC E13 experiment中川 真菜美*; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 田村 裕和; 谷田 聖; et al.
JPS Conference Proceedings (Internet), 26, p.023005_1 - 023005_3, 2019/11
The 
interaction is not much studied than the interaction. To understand the interaction, we study 
hypernuclei. As for the hypernucleus, only the ground state of has been observed. To obtain more information about the interaction, the excited state should be studied. Therefore, we measure the missing-mass of the 
He
reaction at 
GeV/ and 
2-14
at the J-PARC K1.8 beam line. The ground state of is observed whereas a peak of the excited states is not observed. We also observe suppression of the quasi-free process at smaller angles.
Kim, S. H.*; 市川 裕大; 佐甲 博之; 長谷川 勝一; 早川 修平*; 七村 拓野*; 佐藤 進; 谷田 聖; 吉田 純也; 他11名*
Nuclear Instruments and Methods in Physics Research A, 940, p.359 - 370, 2019/10
被引用回数：2 パーセンタイル：43.43(Instruments & Instrumentation)We have developed a gas electron multiplier (GEM)-based time projection chamber (TPC) for the H-dibaryon search experiment at J-PARC. High-rate 
beam particles enter a TPC gas volume of approximately 0.2 m, in a direction perpendicular to the electric field. A long-rectangular hollow section is located inside the TPC volume to accommodate a diamond target. We commissioned the TPC using 230 MeV protons with beam rates of up to 1 MHz. The TPC data acquisition system collected 5768 pad signals in full readout mode, with almost 100% efficiency, at a preset trigger rate of 230 Hz. We operated the TPC in an Ar/CH
gas mixture (90/10) without a magnetic field. The spatial resolutions on the pad plane are measured to be 400-700 
m, which correspond to 230-300 m in a magnetic field of 1 T. We confirmed high tracking capability at beam rates of up to 1 MHz.
, 
Al, and Au collisions at 
GeVAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他296名*
Physical Review Letters, 123(12), p.122001_1 - 122001_9, 2019/09
被引用回数：0 パーセンタイル：100(Physics, Multidisciplinary)We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively-charged hadrons in polarized 
, 
Al and Au collisions at GeV. The measurements have been performed at forward rapidity (
) over the range of 
GeV
and 
. We observed a positive asymmetry 
for positively-charged hadrons in collisions, and a significantly reduced asymmetry in 
+
collisions. These results reveal a nuclear dependence of charged hadron 
in a regime where perturbative techniques are relevant. These results provide new opportunities to use A collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSA as a new handle in studying small-system collisions.
-hypernuclei at J-PARC; Results and perspective小池 武志*; 長谷川 勝一; 早川 修平*; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 田村 裕和; et al.
AIP Conference Proceedings 2130, p.020011_1 - 020011_9, 2019/07
Experimental results from the J-PARC E13 experiments are summarized. A new experimental set up of E13 has established a platform for the future -ray hypernuclear spectroscopy at J-PARC using kaon beams. New rays are identified in 
He and F. The energy of 1.406 MeV for the He
transition confirmed a sizable effect of Charge Symmetry Breaking (CSB) in interaction in the 
hypernuclear system. The identification of four rays in F is made for the first time in shell hypernuclei. Especially, energy spacing of the ground state doublet is found to be 315.5 keV. A good agreement with two theoretical calculations suggests that the theoretical formalism used in shell hypernuclei is also applicable to heavier hypernuclei. Lastly, an overview of the future J-PARC E63 experiment is given.
bound state in the 
C
reaction at 1.8 GeV/永江 知文*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 金原 慎二; 七村 拓野*; 成木 恵; et al.
AIP Conference Proceedings 2130, p.020015_1 - 020015_9, 2019/07
For the full understanding of baryon-baryon interactions in flavor 
, the 
interaction is the last missing piece of information. So far, we have revealed the interaction to be attractive (
MeV), and interaction to be repulsive in the medium to heavy mass-number region. The 
bonding energy is weakly attractive. While we have a few experimental observations suggesting the interaction would be attractive, there still exist large theoretical ambiguities weather it is attractive or not. Experimental determinations on the existence of bound states of hypernuclei by observing bound-state peaks are strongly awaited. In this report, a new preliminary result on the missing-mass spectrum of a C reaction, which strongly suggests the existence of -hypernuclear bound states, is presented.
Adare, A.*; 長谷川 勝一; 今井 憲一; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他666名*
Physical Review Letters, 123(2), p.022301_1 - 022301_10, 2019/07
被引用回数：3 パーセンタイル：20.3(Physics, Multidisciplinary)The PHENIX collaboration presents first measurements of low-momentum (
GeV/) direct-photon yields from Au
Au collisions at 
=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in AuAu collisions at =200. Analyzing the photon yield as a function of the experimental observable 
reveals that the low-momentum (
1,GeV/) direct-photon yield 
is a smooth function of and can be well described as proportional to 
with 
1.25. This new scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and Large Hadron Collider, for centrality selected samples, as well as for different, collision systems. At a given beam energy the scaling also holds for high 
(,GeV/) but when results from different collision energies are compared, an additional -dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
Au collisions at GeVAdare, A.*; 長谷川 勝一; 今井 憲一; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他451名*
Physical Review C, 99(5), p.054903_1 - 054903_29, 2019/05
被引用回数：2 パーセンタイル：48.61(Physics, Nuclear)We present measurements of azimuthal correlations of charged hadron pairs in GeV AuAu collisions after subtracting an underlying event using a model that includes higher-order azimuthal anisotropy 
, 
, and 
. After subtraction, the away-side (
of the highest transverse-momentum trigger (
GeV/) correlations is suppressed compared to that of correlations measured in collisions. At the lowest associated particle , the away-side shape and yield are modified. These observations are consistent with the scenario of radiative-jet energy loss. For the lowest- trigger correlations, an away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-event model. Correlations are also studied differentially versus event-plane angle 
. The angular correlations show an asymmetry when selecting the sign of the trigger-particle azimuthal angle with respect to the 
event plane. This asymmetry and the measured suppression of the pair yield out of plane is consistent with a path-length-dependent energy loss. No 
dependence can be resolved within experimental uncertainties.
collisions at 
GeVAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他296名*
Physical Review D, 99(9), p.092003_1 - 092003_21, 2019/05
被引用回数：0 パーセンタイル：100(Astronomy & Astrophysics)Measurements of the differential production of electrons from open-heavy-flavor hadrons with charm- and bottom-quark content in collisions at GeV are presented. The measurements proceed through displaced-vertex analyses of electron tracks from the semileptonic decay of charm and bottom hadrons using the PHENIX silicon-vertex detector. The relative contribution of electrons from bottom decays to inclusive heavy-flavor-electron production is found to be consistent with fixed-order-plus-next-to-leading-log perturbative-QCD calculations within experimental and theoretical uncertainties. These new measurements in collisions provide a precision baseline for comparable forthcoming measurements in AA collisions.
佐藤 博之; 大橋 弘史
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
高温ガス炉コジェネレーションプラントの水素製造施設における有毒ガス漏えい事故に対する確率論的リスク評価手法開発を目的として、(1)不確実さ因子の摘出、(2)変動パラメータの同定、(3)変動パラメータの不確実さ摘出、(4)感度解析結果や専門家意見を活用した重要因子の選定、(5)不確実さ伝播解析、(6)不確実さ評価結果の分析の6つの手順から構成する制御室居住性に関する不確実さ評価手法を提案した。また、本手法を、HTTRに接続した熱化学法ISプロセスによる水素製造施設に適用し、不確実さの定量化が可能であることを確認した。
GeV proton-nucleus collisionsAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他293名*
Physical Review C, 99(4), p.044912_1 - 044912_10, 2019/04
被引用回数：1 パーセンタイル：48.61(Physics, Nuclear)The PHENIX collaboration has measured high- dihadron correlations in , Al, and Au collisions at GeV. The correlations arise from inter- and intra-jet correlations and thus have sensitivity to nonperturbative effects in both the initial and final states. The distributions of 
, the transverse momentum component of the associated hadron perpendicular to the trigger hadron, are sensitive to initial and final state transverse momenta. These distributions are measured multi-differentially as a function of 
, the longitudinal momentum fraction of the associated hadron with respect to the trigger hadron. The near-side widths, sensitive to fragmentation transverse momentum, show no significant broadening between Au, Al, and . The away-side nonperturbative widths are found to be broadened in Au when compared to ; however, there is no significant broadening in Al compared to collisions. The data also suggest that the away-side broadening is a function of 
, the number of binary nucleon-nucleon collisions, in the interaction. The potential implications of these results with regard to initial and final state transverse momentum broadening and energy loss of partons in a nucleus, among other nuclear effects, are discussed.
pairs from open heavy flavor and Drell-Yan in collisions at GeVAidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他287名*
Physical Review D, 99(7), p.072003_1 - 072003_41, 2019/04
被引用回数：2 パーセンタイル：43.99(Astronomy & Astrophysics)PHENIX reports differential cross sections of pairs from semileptonic heavy-flavor decays and the Drell-Yan production mechanism measured in collisions at GeV at forward and backward rapidity (
). The pairs from 
, 
, and Drell-Yan are separated using a simultaneous fit to unlike- and like-sign muon pair spectra in mass and . The azimuthal opening angle correlation between the muons from and decays and the pair- distributions are compared to distributions generated using 
and 
models, which both include next-to-leading order processes. The measured distributions for pairs from are consistent with calculations. The data presents narrower azimuthal correlations and softer distributions compared to distributions generated from . The data are well described by both models. The extrapolated total cross section for bottom production is 
[b], which is consistent with previous measurements at the Relativistic Heavy Ion Collider in the same system at the same collision energy, and is approximately a factor of two higher than the central value calculated with theoretical models. The measured Drell-Yan cross section is in good agreement with next-to-leading-order quantum-chromodynamics calculations.
Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他312名*
Nature Physics, 15(3), p.214 - 220, 2019/03
被引用回数：39 パーセンタイル：0.33(Physics, Multidisciplinary)Experimental studies of the collisions of heavy nuclei at relativistic energies have established the properties of the quark-gluon plasma (QGP), a state of hot, dense nuclear matter in which quarks and gluons are not bound into hadrons. In this state, matter behaves as a nearly inviscid fluid that efficiently translates initial spatial anisotropies into correlated momentum anisotropies among the particles produced, creating a common velocity field pattern known as collective flow. In recent years, comparable momentum anisotropies have been measured in small-system proton-proton and proton-nucleus (p+A) collisions, despite expectations that the volume and lifetime of the medium produced would be too small to form a QGP. Here we report on the observation of elliptic and triangular flow patterns of charged particles produced in proton-gold (p+Au), deuteron-gold (d+Au) and helium-gold (
He+Au) collisions at a nucleon-nucleon centre-of-mass energy 
= 200 GeV. The unique combination of three distinct initial geometries and two flow patterns provides unprecedented model discrimination. Hydrodynamical models, which include the formation of a short-lived QGP droplet, provide the best simultaneous description of these measurements.
佐藤 博之; Yan, X. L.
Nuclear Engineering and Design, 343, p.178 - 186, 2019/03
被引用回数：1 パーセンタイル：43.43(Nuclear Science & Technology)再生可能エネルギーの出力変動を補完可能な高温ガス炉概念の検討を行った。長周期変動に対しては、既設の圧力制御系を用いて冷却材インベントリを制御しつつ、原子炉入口とタービン入口間にバイパス経路を設置することで、負荷追従時に原子炉流量を一定に制御し、原子炉出力や発電効率の一定運転を可能とした。短周期変動に対しては、炉内黒鉛構造物を蓄熱体として活用し、1次系の温度変動を吸収することで原子炉出力や発電効率の一定運転を可能とした。提案概念について、システム解析を行った結果、既存設備のみの活用により、定格出力に対して20%の負荷変動に対応可能であることを明らかにした。
= 200 GeVAdare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他317名*
Physical Review C, 99(2), p.024903_1 - 024903_16, 2019/02
被引用回数：2 パーセンタイル：26.34(Physics, Nuclear)We present measurements of elliptic and triangular azimuthal anisotropy of charged particles detected at forward rapidity 
in AuAu collisions at GeV, as a function of centrality. The multiparticle cumulant technique is used to obtain the elliptic flow coefficients 
, 
, 
, and 
, and triangular flow coefficients 
and 
. Using the small-variance limit, we estimate the mean and variance of the event-by-event distribution from and . In a complementary analysis, we also use a folding procedure to study the distributions of and directly, extracting both the mean and variance. Implications for initial geometrical fluctuations and their translation into the final state momentum distributions are discussed.
