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論文

Novel approach to explore hydrogen trapping sites in aluminum; Integrating Muon spin relaxation with first-principles calculations

清水 一行*; 西村 克彦*; 松田 健二*; 布村 紀男*; 並木 孝洋*; 土屋 大樹*; 赤丸 悟士*; Lee, S.*; 都留 智仁; 髭本 亘; et al.

International Journal of Hydrogen Energy, 95, p.292 - 299, 2024/12

 被引用回数:0 パーセンタイル:0.00(Chemistry, Physical)

Al-0.06%Mn、Al-0.06%Cr、Al-0.02%Fe、およびAl-0.02%Ni合金(原子%)について、5$$sim$$300Kの温度範囲でゼロ磁場ミューオンスピン緩和実験を行った。双極子場幅($$Delta$$)の温度依存変化から、調製した合金の4つの異なるピークが明らかになった。200K未満で観測された$$Delta$$ピークに対応するミューオン捕捉部位の原子構成は、溶質および溶質空孔対に近接する水素の捕捉エネルギーに対する第一原理計算を用いて詳細に特徴付けられた。この包括的な分析により、ミューオン$$Delta$$ピーク温度と水素捕捉エネルギーの線形相関を確立することができた。しかし、Al-Mn、Al-Cr、Al-Fe、およびAl-Ni合金では、200Kを超えると4番目の$$Delta$$ピークでこの線形関係からの大幅な逸脱が観測された。この矛盾は、4つのAl原子のうち2つが溶質元素と空孔(溶質空孔対)に置換されている四面体サイト内のミューオンと水素の異なる分布関数を考慮することで解釈できる。

論文

Quantitative evaluation of leakage flow rate in the sealing part using graphite gland packing to mount a hydrogen separation membrane tube for HI decomposition membrane reaction

杉本 千紘; Myagmarjav, O.; 田中 伸幸; 野口 弘喜; 竹上 弘彰; 久保 真治

International Journal of Hydrogen Energy, 95, p.98 - 107, 2024/12

 被引用回数:0 パーセンタイル:0.00(Chemistry, Physical)

The thermochemical iodine-sulfur (IS or SI) process can produce hydrogen by decomposing water through chemical reactions and nuclear heat. The hydrogen iodine (HI) decomposition reaction of the IS process thermally decomposes HI at ca. 500$$^{circ}$$C to produce hydrogen. The thermal efficiency of hydrogen production in the thermochemical IS process can be effectively enhanced using a membrane reactor for the HI decomposition reaction; hydrogen separation membrane tubes made of ceramic are attached to a tube plate via sealing parts. The applicability of a sealing method using the expanded graphite grand packing was investigated. During 50 thermal cycles ranging between 25 $$^{circ}$$C-450 $$^{circ}$$C and gas pressure of 0.2-0.8 MPa (gauge), the leakage flow rate was approximately 2$$times$$10$$^{-5}$$ Pa m$$^{3}$$ s$$^{-1}$$. This value is comparable to a detection limit of the standard bubble leak test, indicating that this sealing method works effectively.

論文

Thermal analysis of the hydrogen release behavior of sodium hydride and kinetic analysis using master plot methods

土井 大輔

International Journal of Hydrogen Energy, 91, p.1245 - 1252, 2024/11

 被引用回数:0 パーセンタイル:0.00(Chemistry, Physical)

Hydrogen is a major nonmetallic impurity in the coolant of sodium-cooled fast reactors (SFRs) during normal operation. A higher hydrogen concentration than the gas-liquid equilibrium has been transiently detected in the gas space of actual SFR plants. The presence of several sodium compounds can increase hydrogen generation; however, a thorough understanding of the thermal behavior of candidate reactions is lacking. Herein, thermal analysis reveals the hydrogen release behavior of sodium hydride. Mass spectrometry indicates hydrogen generation with decreasing sample mass, indicating thermal decomposition. Detailed kinetic analysis based on master plot methods indicates that the hydrogen release reaction occurred through a mechanism involving random nucleation and growth of nuclei. Furthermore, the reaction rate was newly formulated based on a kinetic model function representing the above mechanism and the Arrhenius-type reaction rate constant comprising an activation energy of 119.0 $$pm$$ 0.8 kJ mol$$^{-1}$$ and a frequency factor of 1.8 $$times$$ 10$$^{7}$$ s$$^{-1}$$. These findings will enable the numerical simulation of the hydrogen release behavior in SFRs.

論文

Analysis of ex-vessel debris coolability of boiling water reactors

松本 俊慶; 日引 俊*; 丸山 結

International Journal of Energy Research, 2024(1), p.9748588_1 - 9748588_18, 2024/08

 被引用回数:0 パーセンタイル:0.00(Energy & Fuels)

ウェットキャビティ戦略(格納容器内への事前注水方策)の有効性を評価するために、圧力容器から放出される溶融物条件の不確かさを考慮した確率論的な評価手法を構築した。第1段階では、MELCORコードにより溶融物条件を求めた。炉心溶融進展に関係する5つの不確かさパラメータが選択された。インプットパラメータのセットはラテン超方格サンプリングにより発生された。第2段階ではJASMINEコードにより溶融物挙動が解析された。JASMINE解析のパラメータの確率分布はMELCOR解析の結果から決定された。初期水位は0.5、1.0、2.0mに設定された。デブリの高さが冷却性判定のために基準と比較された。一連の計算の結果としてデブリの冷却確率が取得された。さらにMELCOR-JASMINEを組み合わせた解析手法の成立性と技術的な課題について議論された。

論文

CFD applications to pressurized thermal shock-related phenomena

岡垣 百合亜; 日引 俊詞*; 柴本 泰照

International Journal of Energy Research, 2024, p.5114542_1 - 5114542_37, 2024/04

 被引用回数:0 パーセンタイル:0.00(Energy & Fuels)

In pressurized water reactor accident scenarios, the injection of water from the ECCS (ECC injection) might induce a PTS, affecting the RPV integrity. Therefore, PTS is a vital research issue in reactor safety, and its analysis is essential for evaluating the integrity of RPVs, which determines the reactor life. The PTS analysis comprises a coupled analysis between thermal-hydraulic and structural analysis. The thermal-hydraulic approach is particularly crucial, and reliable Computational Fluid Dynamics (CFD) simulations should play a vital role in the future because predicting the temperature gradient of the RPV wall requires data on the transient temperature distribution of the downcomer. Since one-dimensional codes cannot predict the complex three-dimensional flow features during ECC injection, PTS is one reactor safety issue where CFD can benefit from complement evaluations with thermal-hydraulic system analysis codes. This study reviewed the code validation efforts for turbulence models most affecting PTS analysis based on papers published since 2010 on single- and two-phase flow CFD analysis for the experiment on PTS performed in the ROCOM, TOPFLOW, UPTF, and LSTF. The results revealed that in single-phase flow CFD analysis, where knowledge and experience are sufficient, various turbulence models have been considered, and many analyses using LES have been reported. For two-phase flow analysis of air-water conditions, interface capturing/tracking methods were used in addition to two-fluid models. The standard k-$$varepsilon$$ and SST k-$$omega$$ models were still in the validated phase, and various turbulence models have yet to be fully validated. In the two-phase flow analysis of steam-water conditions, many studies have used two-fluid models and RANS, and NEPTUNE_CFD, in particular, has been reported to show excellent prediction performance based on years of accumulated validation.

論文

Opposing mixed convection heat transfer for turbulent single-phase flows

茂木 孝介; 柴本 泰照; 日引 俊詞*; 塚本 直史*; 金子 順一*

International Journal of Energy Research, 2024, p.6029412_1 - 6029412_22, 2024/01

 被引用回数:1 パーセンタイル:0.00(Energy & Fuels)

自然対流熱伝達と強制対流熱伝達が共存する流れを複合対流と呼ぶ。特に強制対流が下降流の場合をopposing flow複合対流と呼ぶ。既往研究において様々な単相opposing flow複合対流の熱伝達相関式が提案されているが、それらは様々な試験装置流路形状、作動流体、熱流動パラメータの範囲で実施された実験結果に基づいている。無次元支配因子の定義や実験的に確認された適用範囲も相関式ごとに異なるため、使用に際してその適用範囲や外挿性を踏まえた上でどの相関式を選択すべきかを整理しておくことは重要である。本稿では既存のopposing flow複合対流の熱伝達相関式と、熱水力システムコードに実装されている単相流壁面熱伝達相関式についてレビューした。また、複数の既往実験データと各相関式との比較を行い、相関式の予測性能を評価した。その結果、Jackson and Fewster相関式、Churchill相関式、Swanson and Catton (IJHMT)相関式は全ての実験データを精度よく予測可能であった。また、乱流複合対流では等温・等熱流束の熱的境界条件による熱伝達率への影響は顕著ではなく、既存の相関式は熱伝達率予測に適用可能であった。さらに、代表長さに水力学相当直径を用いることにより試験装置流路形状の違いに関わらず相関式が適用可能であり、支配パラメータの無次元化により作動流体によらず相関式が適用可能であることを確認した。幅広い無次元数範囲に対して相関式の外挿性を調査した所、Jackson and Fewster相関式、Churchill相関式、Aicher and Martin相関式は自然対流熱伝達、強制対流熱伝達への優れた外挿性を有しており、実験で妥当性が確認されたパラメータ範囲を超えて相関式が適用できることを示した。

論文

Local structural changes in V-Ti-Cr alloy hydrides with hydrogen absorption/desorption cycling

池田 一貴*; 佐次田 頌*; 大友 季哉*; 大下 英敏*; 本田 孝志*; 羽合 孝文*; 齋藤 開*; 伊藤 晋一*; 横尾 哲也*; 榊 浩司*; et al.

International Journal of Hydrogen Energy, 51(Part A), p.79 - 87, 2024/01

 被引用回数:4 パーセンタイル:34.52(Chemistry, Physical)

Low-vanadium-concentration alloys have low durability, and their hydrogen absorption and desorption amounts decrease by 20% after 100 cycles. In this study, we conducted reverse Monte Carlo modeling on X-ray diffraction patterns and neutron pair distribution functions of the hydrogen-absorbed and desorbed samples of a V$$_{0.10}$$Ti$$_{0.36}$$Cr$$_{0.54}$$ alloy to analyze the variations in the local structure. The local structure surrounding the hydrogen atom in the hydrogen-absorbed phase exhibited minimal changes. In contrast, hydrogen occupied both tetrahedral and octahedral sites of the hydrogen-desorbed phase almost equally during the early cycles; however, the amount of hydrogen occupying the tetrahedral sites increased with the number of cycles.

論文

Hydrogen diffusion in cerium oxide thin films fabricated by pulsed laser deposition

Mao, W.*; 福谷 克之; 他8名*

International Journal of Hydrogen Energy, 50(Part D), p.969 - 978, 2024/01

 被引用回数:3 パーセンタイル:22.86(Chemistry, Physical)

Cerium oxide (CeO$$_{2}$$) is well known to be reducible by hydrogen (H$$_{2}$$), yet the diffusion and solution properties of hydrogen in ceria at elevated temperatures have remained challenging to evaluate. We therefore fabricated nanometer-thin ($$sim$$100 nm) cerium oxide films on Si(111) substrates by pulsed laser deposition (PLD) and quantitatively investigated the H depth distributions therein by means of resonant $$^{1}$$H($$^{15}$$N,$$alpha$$$$gamma$$)$$^{12}$$C nuclear reaction analysis (NRA) before and after annealing in H$$_{2}$$ gas at 773-973 K. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) reveal that the as-deposited films exhibit single phase CeO$$_{2}$$ structure and partially reduced stoichiometry (CeO$$_{1.69}$$). H$$_{2}$$ annealing does not largely change the H content of the as-deposited films; in all conditions several atomic percent of hydroxyl (OH) are found to exist in a thin ($$sim$$4 nm) surface layer, whereas stably bound hydrogen in the bulk of the films is almost uniformly distributed and of much smaller quantity ($$sim$$0.2 at.%) than the oxygen vacancy concentration in the partially reduced ceria. Its low concentration and high thermal stability identify this bulk H species as likely being strongly bound to defects in the polycrystalline films rather than as a hydride species that interacts weakly with O-vacancies. The H diffusion coefficient and activation energy in the ceria films are determined as $$>$$ 10$$^{-18}$$ m$$^{2}$$ s$$^{-1}$$ at 773-973 K and $$<$$1.69 eV, respectively. The observed diffusion activation energy is somewhat larger than theoretical predictions for thermal diffusion of H in stoichiometric bulk CeO$$_{2}$$, suggesting that defects and oxygen vacancies in the PLD-fabricated ceria thin films possibly have an impact on the H mobility.

論文

Numerical interpretation of thermal desorption spectra of hydrogen from high-carbon ferrite-austenite dual-phase steel

海老原 健一; 関根 大貴*; 崎山 裕嗣*; 高橋 淳*; 高井 健一*; 大村 朋彦*

International Journal of Hydrogen Energy, 48(79), p.30949 - 30962, 2023/09

 被引用回数:0 パーセンタイル:0.00(Chemistry, Physical)

鉄鋼材料の応力腐食割れの1つである水素脆化を理解するには、鋼材中の水素分布を知る必要があり、それには昇温脱離スペクトルの数値シミュレーションによる解釈が有効である。溶接金属やTRIP鋼において残留オーステナイト(RA)は昇温脱離スペクトルに顕著な影響を与えるが、明確な水素分布についてはこれまでよく知られていない。本研究では、高炭素フェライト-オーステナイト二相鋼の既報の水素昇温脱離スペクトルを、独自にコード化した二次元モデルによって数値シミュレーションし、水素は、その鋼材に含まれる量が少ないときは炭化物表面に、その量が多くなると二相界面に、主にトラップされることを明らかとした。また、界面トラップの水素の脱離ピークの試料厚さ依存性が、従来とは異なる理由で発現することも明らかとなった。

論文

The Investigations of the $$P$$-wave $$B_s$$ states combining quark model and lattice QCD in the coupled channel framework

Yang, Z.*; Wang, G.-J.*; Wu, J.-J.*; 岡 眞; Zhu, S.-L.*

Journal of High Energy Physics (Internet), 2023(1), p.058_1 - 058_19, 2023/01

 被引用回数:6 パーセンタイル:70.34(Physics, Particles & Fields)

ハミルトニアン有効理論にクォーク模型、クォークペア生成、$$B^{(*)}bar K$$相互作用の情報を含むベアな状態と散乱状態の結合を取り入れた形式を用いて、しきい値近傍の$$P$$波の4個の$$B_s$$状態のスペクトルを研究した。

論文

Evidence for the singly Cabibbo-suppressed decay $$Omega^0_ctoXi^-pi^+$$ and search for $$Omega^0_ctoXi^-K^+$$ and $$Omega^-K^+$$ decays at Belle

Han, X.*; 谷田 聖; Belle Collaboration*; 他170名*

Journal of High Energy Physics (Internet), 2023(1), p.55_1 - 55_12, 2023/01

 被引用回数:2 パーセンタイル:38.66(Physics, Particles & Fields)

Using a data sample of 980 fb$$^{-1}$$ collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider, we study for the first time the singly Cabibbo-suppressed decays $$Omega^0_ctoXi^{-}pi^{+}$$ and $$Omega^-K^+$$ and the doubly Cabibbo-suppressed decay $$Omega^0_cto Xi^- K^{+}$$. Evidence for an $$Omega^0_c$$ signal in the $$Omega^0_ctoXi^-pi^+$$ mode is reported with a significance of $$4.5sigma$$ including systematic uncertainties. The ratio of branching fractions to the normalization mode $$Omega_c^0to Omega^-pi^+$$ is measured to be $${cal B}(Omega_{c}^{0} to Xi^{-} pi ^{+} )/{cal B}(Omega_c^0to Omega^-pi^+)=0.253pm 0.053({rm stat.})pm 0.030({rm syst.}).$$ No significant signals of $$Omega^0_ctoXi^-K^+$$ and $$Omega^-K^+$$ modes are found. The upper limits at $$90%$$ confidence level on ratios of branching fractions are determined to be $${cal B}(Omega_{c}^{0} to Xi^{-} K ^{+})/{cal B}(Omega_c^0to Omega^-pi^+) < 0.070$$ and $${cal B}(Omega_{c}^{0} to Omega^{-}K^{+})/{cal B}(Omega_c^0to Omega^-pi^+) < 0.29.$$

論文

Artificial neural network-based path integral simulations of hydrogen isotope diffusion in palladium

君塚 肇*; Thomsen, B.; 志賀 基之

Journal of Physics; Energy (Internet), 4(3), p.034004_1 - 034004_13, 2022/07

 被引用回数:15 パーセンタイル:75.60(Energy & Fuels)

パラジウム-水素系の人工ニューラルネットワークに基づく原子間ポテンシャルを開発するとともに、パラジウム結晶中の水素同位体の量子拡散について、経路積分分子動力学計算を行った。50-1500Kの広い温度範囲で軽水素と重水素の拡散係数を計算し、低温と高温における拡散機構の違いを明らかにした。

論文

Contribution of the Weinberg-type operator to atomic and nuclear electric dipole moments

長村 尚弘*; Gubler, P.; 山中 長閑*

Journal of High Energy Physics (Internet), 2022(6), p.072_1 - 072_30, 2022/06

 被引用回数:6 パーセンタイル:55.39(Physics, Particles & Fields)

The contribution of the CP violating three-gluon Weinberg operator to the atomic and nuclear EDMs is estimated using QCD sum rules. After calculating the transition matrix element between the pion and the vacuum through the Weinberg operator, we obtain the long-range CP-odd nuclear force by determining the isovector CP-odd pion-nucleon vertex, using chiral perturbation theory at NLO. The EDMs of $$^{199}$$Hg, $$^{129}$$Xe, and $$^{225}$$Ra atoms, as well as those of $$^{2}$$H and $$^{3}$$He nuclei are finally given including comprehensive uncertainty analysis. While the leading contribution of the $$^{199}$$Hg EDM is given by the intrinsic nucleon EDM, that of $$^{129}$$Xe atom may be dominated by the one-pion exchange CP-odd nuclear force generated by the Weinberg operator. From current experimental data of the $$^{199}$$Hg atomic EDM, we obtain an upper limit on the Weinberg operator magnitude of $$|omega| < 4times10^{-10}mathrm{GeV}^{-2}$$ if we assume that it is the only source of CP violation at the scale $$mu$$ = 1 TeV.

論文

Search for charged lepton flavor violating decays of $$Upsilon(1S)$$

Patra, S.*; 谷田 聖; Belle Collaboration*; 他216名*

Journal of High Energy Physics (Internet), 2022(5), p.95_1 - 95_17, 2022/05

 被引用回数:7 パーセンタイル:55.39(Physics, Particles & Fields)

We present a search for the charged lepton-flavor-violating decays $$Upsilon(1S)rightarrowellell^prime$$ and radiative charged lepton-flavour-violating decays $$Upsilon(1S)rightarrowgammaellell^prime$$ [$$ell,ell^prime = e, mu, tau$$] using the 158 million $$Upsilon(2S)$$ sample collected by the Belle detector at the KEKB collider. This search uses $$Upsilon(1S)$$ mesons produced in $$pi^+pi^-Upsilon(1S)$$ transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level.

論文

An Improved search for the electric dipole moment of the $$tau$$ lepton

居波 賢二*; 谷田 聖; Belle Collaboration*; 他186名*

Journal of High Energy Physics (Internet), 2022(04), p.110_1 - 110_13, 2022/04

 被引用回数:12 パーセンタイル:75.26(Physics, Particles & Fields)

We report a measurement of the electric dipole moment of the $$tau$$ lepton ($$d_tau$$) using an 833~fb$$^{-1}$$ data sample collected near the $$Upsilon(4S)$$ resonance, with the Belle detector at the KEKB asymmetric-energy $$e^+ e^-$$ collider. Using an optimal observable method, we obtain the real and imaginary parts of $$d_tau$$ as $${rm Re}(d_tau) = (-0.62 pm 0.63) times 10^{-17} ~e{rm cm}$$ and $${rm Im}(d_tau) = (-0.40 pm 0.32) times 10^{-17} ~e{rm cm}$$, respectively. These results are consistent with null electric dipole moment at the present level of experimental sensitivity and improve the sensitivity by about a factor of three.

論文

First Measurement of the $$Lambda_c^+ to p eta'$$ decay

Li, S. X.*; 谷田 聖; Belle Collaboration*; 他197名*

Journal of High Energy Physics (Internet), 2022(3), p.90_1 - 90_11, 2022/03

 被引用回数:8 パーセンタイル:65.00(Physics, Particles & Fields)

We present the first measurement of the branching fraction of the singly Cabibbo-suppressed (SCS) decay $$Lambda_c^+ to p eta'$$ with $$eta' to etapi^+pi^-$$, using a data sample corresponding to an integrated luminosity of 981 $$rm fb^{-1}$$, collected by the Belle detector at the KEKB $$e^{+}$$$$e^{-}$$ asymmetric-energy collider. A significant $$Lambda_c^+$$ signal is observed for the first time with a signal significance of 5.4$$sigma$$. The relative branching fraction with respect to the normalization mode $$Lambda_c^+ to pK^-pi^+$$ is measured to be $$frac{{cal B}(Lambda_c^+ to p eta')}{{cal B}(Lambda_c^+ to p K^-pi^+)} = (7.54 pm 1.32 pm 0.75) times 10^{-3}$$,where the uncertainties are statistical and systematic, respectively. Using the world-average value of $${cal B}(Lambda_c^+ to p K^-pi^+) = (6.28pm0.32)times10^{-2}$$, we obtain $${cal B}(Lambda_c^+ to p eta') = (4.73 pm 0.82 pm 0.47 pm 0.24)times 10^{-4}$$,where the uncertainties are statistical, systematic, and from $${cal B}(Lambda_c^+ to pK^-pi^+)$$, respectively.

論文

Combined analysis of Belle and Belle II data to determine the CKM angle $$ phi_{3} $$ using $$B^+ to D(K_{S}^0 h^+ h^-) h^+$$ decays

Abudin$'e$n, F.*; 谷田 聖; Belle II Collaboration*; 他319名*

Journal of High Energy Physics (Internet), 2022(2), p.63_1 - 63_33, 2022/02

 被引用回数:4 パーセンタイル:42.30(Physics, Particles & Fields)

We present a measurement of the Cabibbo-Kobayashi-Maskawa unitarity triangle angle $$ phi_{3} $$ (also known as~$$gamma$$) using a model-independent Dalitz plot analysis of $$B^+to Dleft(K_{S}^{0}h^{+}h^{-}right)h^+$$, where $$D$$ is either a $$D^0$$ or $$bar{D}{}^0$$ meson and $$h$$ is either a $$pi$$ or $$K$$. This is the first measurement that simultaneously uses Belle and Belle~II data, combining samples corresponding to integrated luminosities of 711 fb$$^{-1}$$ and 128 fb$$^{-1}$$, respectively. All data were accumulated from energy-asymmetric $$e^+e^-$$ collisions at a centre-of-mass energy corresponding to the mass of the $$Upsilon(4S)$$ resonance. We measure $$phi_3 = left(78.4 pm 11.4 pm 0.5 pm 1.0 right)^{circ}$$, where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is from the uncertainties on external measurements of the $$D$$-decay strong-phase parameters.

論文

Search for lepton-flavor-violating tau-lepton decays to $$ellgamma$$ at Belle

宇野 健太*; 谷田 聖; Belle Collaboration*; 他181名*

Journal of High Energy Physics (Internet), 2021(10), p.19_1 - 19_12, 2021/10

 被引用回数:25 パーセンタイル:84.16(Physics, Particles & Fields)

Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays $$tau^{pm}rightarrowell^{pm}gamma$$ ($$ell=e,mu$$) are predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via $$tau^{pm}rightarrowell^{pm}gamma$$ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb$$^{-1}$$, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, $$mathcal{B}(tau^{pm}rightarrow mu^{pm}gamma)$$ $$leq$$ $$4.2times10^{-8}$$ and $$mathcal{B}(tau^{pm}rightarrow e^{pm}gamma)$$ $$leq$$ $$5.6times10^{-8}$$, are set at 90% confidence level.

論文

Measurement of branching fractions and search for $$CP$$ violation in $$D^{0}topi^{+}pi^{-}eta$$, $$D^{0}to K^{+}K^{-}eta$$, and $$D^{0}tophieta$$ at Belle

Li, L. K.*; 谷田 聖; Belle Collaboration*; 他187名*

Journal of High Energy Physics (Internet), 2021(9), p.75_1 - 75_21, 2021/09

 被引用回数:1 パーセンタイル:7.73(Physics, Particles & Fields)

We measure the branching fractions and $$CP$$ asymmetries for the singly Cabibbo-suppressed decays $$D^{0}topi^{+}pi^{-}eta$$, $$D^{0}to K^{+}K^{-}eta$$, and $$D^{0}tophieta$$, using 980 fb$$^{-1}$$ of data from the Belle experiment at the KEKB $$e^+e^-$$ collider. We obtain $$mathcal{B}(D^{0}topi^{+}pi^{-}eta) = [1.22pm 0.02,({rm stat})pm 0.02,({rm syst})pm 0.03,(mathcal{B}_{rm ref})]times 10^{-3},, mathcal{B}(D^{0}to K^{+}K^{-}eta) = [1.80,^{+0.07}_{-0.06},({rm stat})pm 0.04,({rm syst})pm 0.05,(mathcal{B}_{rm ref})]times 10^{-4},, mathcal{B}(D^{0}tophieta) = [1.84pm 0.09,({rm stat})pm 0.06,({rm syst})pm 0.05,(mathcal{B}_{rm ref})]times 10^{-4},, $$ where the third uncertainty ($$mathcal{B}_{rm ref}$$) is from the uncertainty in the branching fraction of the reference mode $$D^{0} to K^{-}pi^{+}eta$$. The color-suppressed decay $$D^{0}tophieta$$ is observed for the first time, with very high significance. The results for the $$CP$$ asymmetries are $$A_{CP}(D^{0}topi^{+}pi^{-}eta) = [0.9pm 1.2,({rm stat})pm 0.5,({rm syst})]%,, A_{CP}(D^{0}to K^{+}K^{-}eta) = [-1.4pm 3.3,({rm stat})pm 1.1,({rm syst})]%,, A_{CP}(D^{0}tophieta) = [-1.9pm 4.4,({rm stat})pm 0.6,({rm syst})]%,. $$ The results for $$D^{0}topi^{+}pi^{-}eta$$ are a significant improvement over previous results. The branching fraction and $$A_{CP}$$ results for $$D^{0}to K^{+}K^{-}eta$$, and the $$A_{CP}$$ result for $$D^{0}tophieta$$, are the first such measurements. No evidence for $$CP$$ violation is found in any of these decays.

論文

Fabrication, permeation, and corrosion stability measurements of silica membranes for HI decomposition in the thermochemical iodine-sulfur process

Myagmarjav, O.; 柴田 愛*; 田中 伸幸; 野口 弘喜; 久保 真治; 野村 幹弘*; 竹上 弘彰

International Journal of Hydrogen Energy, 46(56), p.28435 - 28449, 2021/08

 被引用回数:3 パーセンタイル:10.63(Chemistry, Physical)

In this study, a corrosion-stable silica ceramic membrane was developed to be used in H$$_{2}$$ purification during the hydrogen iodide decomposition (2HI $$rightarrow$$ H$$_{2}$$ + I$$_{2}$$), which is a new application of the silica membranes. From a practical perspective, the membrane separation length was enlarged up to 400 mm and one end of the membrane tubes was closed to avoid any thermal variation along the membrane length and sealing issues. The silica membranes consisted of a three-layer structure comprising a porous $$alpha$$-Al$$_{2}$$O$$_{3}$$ ceramic support, an intermediate layer, and a top silica layer. The intermediate layer was composed of $$gamma$$-Al$$_{2}$$O$$_{3}$$ or silica, and the top silica layer that is H$$_{2}$$ selective was prepared via counter-diffusion chemical vapor deposition of a hexyltrimethoxysilane. A membrane using a silica intermediate layer exhibited a higher H$$_{2}$$/SF$$_{6}$$ selectivity but lower H$$_{2}$$ permeance with compared with the membrane using a $$gamma$$-Al$$_{2}$$O$$_{3}$$ intermediate layer. The membrane using the silica intermediate layer was more stable in corrosive HI gas than a membrane with a $$gamma$$-Al$$_{2}$$O$$_{3}$$ intermediate layer after 300 h of stability tests. To the best of our knowledge, this is the first report of 400-mm-long closed-end silica membranes supported on Si-formed $$alpha$$-Al$$_{2}$$O$$_{3}$$ tubes produced via chemical vapor deposition method. In conclusion, the developed silica membranes seem suitable for membrane reactors that produce H$$_{2}$$ on large scale using HI decomposition in the thermochemical iodine-sulfur process.

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