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Chillery, T.*; Hwang, J.*; 堂園 昌伯*; 今井 伸明*; 道正 新一郎*; 炭竃 聡之*; 千賀 信幸*; 大田 晋輔*; 中山 梓介; 他49名*
Progress of Theoretical and Experimental Physics (Internet), 2023(12), p.121D01_1 - 121D01_11, 2023/12
重陽子は弱束縛系でありクーロン力と核力の下で容易に陽子と中性子に分解する。これまでの実験からは、核子当たり50から200MeVといった高入射エネルギーではこの分解過程が残留核生成に大きな影響を与えることが示されている。しかし、核子当たり50MeV以下のエネルギーでの断面積データはまだ不足している。本研究では、BigRIPSセパレータ、OEDOビームライン、SHARAQスぺクトロメータを用いて、Zr+d反応断面積を核子当たり約28MeVにおいて逆運動学法を用いて測定した。本研究で得られた断面積を過去の測定結果や理論計算と比較した。重陽子の分解の効果を定量的に考慮したDEURACS計算により実験データがよく再現された。本研究で測定された低エネルギー領域におけるデータは、将来の核廃棄物処理施設の検討に役立つと考えられる。
Pedersen, L. G.*; Sahin, E.*; Grgen, A.*; Bello Garrote, F. L.*; 角田 佑介*; 大塚 孝治*; 新倉 潤*; Orlandi, R.; 他59名*
Physical Review C, 107(4), p.044301_1 - 044301_10, 2023/04
被引用回数:0 パーセンタイル:0.02(Physics, Nuclear)Nuclei in the vicinity of Ni (=28, =50) are important benchmarks to study the evolution of shell structure far from stability. Excited states in Cu were observed for the first time following the -decay of Ni, which was produced by in-flight fission of U. Using -ray coincidences, a level scheme comprising eight excited states was built. Using the observed feeding and the -decay properties of the excited states, spin was tentatively assigned to 5 new states. In addition to the -decaying states, an isomeric state with a lifetime of 3.8(4) ms was found to decay by internal conversion. By comparing the results with large scale shell model calculations, quantitative information about the proton-neutron interaction outside the doubly magic Ni core was obtained.
中村 智樹*; 大澤 崇人; 他219名*
Science, 379(6634), p.eabn8671_1 - eabn8671_14, 2023/02
被引用回数:44 パーセンタイル:99.99(Multidisciplinary Sciences)1から8mmのリュウグウ粒子16個の鉱物学的,岩石学的、および物理的特性は、それらがCIコンドライトに最も類似していることを示している。磁硫鉄鉱中のCO含有水の存在は、母天体が太陽系星雲のHOおよびCOのスノーラインを越えた領域で形成したことを示しており、ここでは、リュウグウの鉱物学に基づくと、小さなコンドリュールやCa, Alを含む非常に限られた量の高温物質がある。流体-岩石反応は、低温,高pH、および水/岩石の質量比が1未満の還元条件で発生し、リュウグウのサンプルで最も変化の少ない断片として残っているかんらん石-輝石に富む岩相を、リュウグウサンプルの主要な岩相であるフィロケイ酸塩-炭酸塩に富むものに変えた。リュウグウの母体の流体から磁鉄鉱が結晶化したとき、原始太陽系星雲はまだ存在していた可能性がある。
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:1 パーセンタイル:61.09(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.
Venhart, M.*; Andreyev, A. N.; Cubiss, J. G.*; Wood, J. L.*; Barzakh, A. E.*; Van Beveren, C.*; Cocolios, T. E.*; de Groote, R. P.*; 他19名*
Physical Review C, 105(3), p.034338_1 - 034338_9, 2022/03
被引用回数:1 パーセンタイル:34.54(Physics, Nuclear)The neutron-deficient region of isotopes around =82 is the best studied example of low-energy shape coexistence in nuclei. In this work, the internal transition decay and decay of the 53.3-ms isomeric state in Tl were studied at ISOLDE, CERN. The branching for the internal decay was measured to be 98.5(4)%, while the much weaker decay branching is only about 1.4(4)%. The new results include the first identification of an transition feeding the 3/2 excited state in Tl. Three decays from the Tl isomer were also oserved, and revealed the population of a candidate 9/2 state in Au which has been linked to shape coexistence in the Au nuclei. It is expected that similarly weak decays from isomeric states may be found also in neighbouring Tl isotopes.
外山 健*; 鈴土 知明; 永井 康介*; 他9名*
Journal of Nuclear Materials, 556, p.153176_1 - 153176_7, 2021/12
被引用回数:2 パーセンタイル:32.89(Materials Science, Multidisciplinary)電子照射と3次元アトムプローブ(3D-AP)を使用して、照射促進拡散(RED)の高精度測定を行った。高純度のFeとCuをベース材料としてCu-Fe拡散ペア試料を作成し、2MeVの電子照射を行った。CuのFeマトリックスへの拡散を3D-APを使用して原子レベルで観察し、フィックの法則を使用して拡散係数を直接取得した。その結果、REDが明確に観察され、照射下での拡散と熱拡散の比率が低温で大きくなった。反応速度論モデルを使用してREDを定量的に評価し、実験値は空孔のみを考慮したモデルと良好な一致を示した。これにより、REDが照射誘起空孔によって支配されていることが明らかになった。さらに、FeへのCuの溶解度に対する照射の影響に関する直接的な実験結果が得られ、照射下での溶解度は、熱時効下での溶解度よりも低いことがわかった。
Cao, L.*; 谷田 聖; Belle Collaboration*; 他199名*
Physical Review Letters, 127(26), p.261801_1 - 261801_8, 2021/12
被引用回数:1 パーセンタイル:50.56(Physics, Multidisciplinary)The first measurements of differential branching fractions of inclusive semileptonic decays are performed using the full Belle data set of 711 fb of integrated luminosity at the resonance and for . Differential branching fractions are reported as a function of the lepton momentum, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic decays and other processes, and corrected for resolution and acceptance effects. The measured distributions are compared to predictions from inclusive and hybrid calculations.
Atmacan, H.*; 谷田 聖; Belle Collaboration*; 他219名*
Physical Review D, 104(9), p.L091105_1 - L091105_9, 2021/11
被引用回数:2 パーセンタイル:21.41(Astronomy & Astrophysics)We present a search for the lepton-flavor-violating decays , where , using the full data sample of pairs recorded by the Belle detector at the KEKB asymmetric-energy collider. We use events in which one meson is fully reconstructed in a hadronic decay mode. The lepton is reconstructed indirectly using the momentum of the reconstructed and that of the from the signal decay. We find no evidence for decays and set upper limits on their branching fractions at 90% confidence level of () and ().
Li, S. X.*; 谷田 聖; Belle Collaboration*; 他193名*
Physical Review D, 104(7), p.072008_1 - 072008_8, 2021/10
被引用回数:3 パーセンタイル:30.68(Astronomy & Astrophysics)Using 980.6 of data collected with the Belle detector operating at the KEKB asymmetric-energy collider, we present a measurement of the branching fraction of the singly Cabibbo-suppressed decay . A clear signal is observed for with a statistical significance of 9.1 standard deviations, and we measure the ratio of branching fractions , from which we infer the branching fraction . The first quoted uncertainty is statistical, the second systematic, and the third from the reference mode .
Li, Y.*; 谷田 聖; Belle Collaboration*; 他190名*
Physical Review D, 104(5), p.052005_1 - 052005_9, 2021/09
被引用回数:7 パーセンタイル:62.71(Astronomy & Astrophysics)Using a data sample of 980~fb collected with the Belle detector operating at the KEKB asymmetric-energy collider, we present evidence for the in the resonant substructure of ( = + ) decays. The significance of the signal is 4.2 after considering the systematic uncertainties. The ratio of the branching fraction of relative to that of is calculated to be 0.220 0.059(stat.) 0.035(syst.). The individual ratios of the branching fractions of the two isospin modes are also determined, and found to be =(9.6 3.2(stat.) 1.8(syst.))% and = (5.5 2.8(stat.) 0.7(syst.))%.
Nisar, N. K.*; 谷田 聖; Belle Collaboration*; 他197名*
Physical Review D, 104(3), p.L031101_1 - L031101_8, 2021/08
被引用回数:0 パーセンタイル:10.96(Astronomy & Astrophysics)We report the results of the first search for the decay using of data collected at the resonance with the Belle detector at the KEKB asymmetric-energy collider. We observe no significant signal and set a 90% confidence-level upper limit of on the branching fraction of this decay.
佐藤 健太*; 谷田 聖; 他19名*
Proceedings of Science (Internet), 358, p.413_1 - 413_8, 2021/07
The Relativistic Heavy Ion Collider forward (RHICf) experiment aims at understanding the high-energy hadronic interaction by measuring the cross sections of very forward neutral particles in proton-proton collisions at = 510 GeV. For the analysis of the photon measurement, the trigger efficiency and the particle identification performance are studied by using the Monte Carlo simulation data and the experimental data. In the RHICf operation, two kinds of trigger modes (Shower, HighEM) were implemented. The trigger efficiency of the Shower trigger is 100% for photons with the energies more than 20 GeV. The HighEM trigger is designed to detect high energy photons effectively, and the trigger efficiency of the HighEM trigger is 90% for photons with the energies more than 130 GeV. The correction factor for the photon identification is calculated by using the efficiency and purity. It is found that this correction does not make a sizeable effect on the shape of the energy spectrum because the energy dependency of the factor is small.
McNeil, J. T.*; 谷田 聖; Belle Collaboration*; 他193名*
Physical Review D, 103(11), p.112002_1 - 112002_11, 2021/06
被引用回数:2 パーセンタイル:21.41(Astronomy & Astrophysics)Using the entire data sample of integrated luminosity collected with the Belle detector at the KEKB asymmetric-energy collider, we present an amplitude analysis measuring the branching fractions of the Cabibbo-allowed, -exchange resonant decay with a polarized and the non-resonant decay via a direct process . We present these measurements, relative to the normalization mode , and find branching ratios = and = which suggest that only minor cusping peaks occur in the combinatorial background of due to these decays.
雨森 道紘*; 土屋 晴文; Tibet AS Collaboration*; 他93名*
Nature Astronomy (Internet), 5(5), p.460 - 464, 2021/05
被引用回数:42 パーセンタイル:99.02(Astronomy & Astrophysics)Cosmic rays (protons and other atomic nuclei) are believed to gain energies of petaelectronvolts (PeV) and beyond at astrophysical particle accelerators called "PeVatrons" inside our Galaxy. Although a characteristic feature of a PeVatron is expected to be a hard gamma-ray energy spectrum that extends beyond 100 teraelectronvolts (TeV) without a cut-off, none of the currently known sources exhibit such a spectrum owing to the low maximum energy of accelerated cosmic rays or owing to insufficient detector sensitivity around 100 TeV. Here, we report the observation of gamma-ray emission from the supernova remnant G106.3+2.7 above 10 TeV. This work provides flux data points up to and above 100 TeV and indicates that the very-high-energy gamma-ray emission above 10 TeV is well correlated with a molecular cloud rather than with the pulsar PSR J2229+6114. Regarding the gamma-ray emission mechanism of G106.3+2.7, this morphological feature appears to favour a hadronic origin via the decay caused by accelerated relativistic protons over a leptonic origin via the inverse Compton scattering by relativistic electrons. Furthermore, we point out that an X-ray flux upper limit on the synchrotron spectrum would provide important information to firmly establish the hadronic scenario as the mechanism of particle acceleration at the source.
Wehle, S.*; 谷田 聖; Belle Collaboration*; 他179名*
Physical Review Letters, 126(16), p.161801_1 - 161801_8, 2021/04
被引用回数:13 パーセンタイル:88.21(Physics, Multidisciplinary)We present a measurement of , the branching fraction ratio / , for both charged and neutral mesons. The ratio for the charged case, , is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass, . The analysis is based on a data sample of , containing events, recorded at the resonance with the Belle detector at the KEKB asymmetric-energy collider. The obtained results are consistent with Standard Model expectations.
雨森 道紘*; 土屋 晴文; Tibet AS Collaboration*; 他93名*
Physical Review Letters, 126(14), p.141101_1 - 141101_7, 2021/04
被引用回数:75 パーセンタイル:99.63(Physics, Multidisciplinary)We report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in the Galactic disk. Particularly, all gamma rays above 398 TeV are observed apart from known TeV gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of 's produced through the interaction of protons with the interstellar medium in the Galaxy. This is strong evidence that cosmic rays are accelerated beyond PeV energies in our Galaxy and spread over the Galactic disk.
Acharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他309名*
Physical Review D, 103(5), p.052009_1 - 052009_10, 2021/03
被引用回数:4 パーセンタイル:46.61(Astronomy & Astrophysics)We present a measurement of the transverse single-spin asymmetry for and mesons in collisions in the pseudorapidity range and at a center-of-mass energy of 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. In comparison with previous measurements in this kinematic region, these results have a factor of 3 smaller uncertainties. As hadrons, and mesons are sensitive to both initial- and final-state nonperturbative effects for a mix of parton flavors. Comparisons of the differences in their transverse single-spin asymmetries have the potential to disentangle the possible effects of strangeness, isospin, or mass. These results can constrain the twist-3 trigluon collinear correlation function as well as the gluon Sivers function.
Acharya, U.*; 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397名*
Physical Review C, 102(6), p.064905_1 - 064905_13, 2020/12
被引用回数:5 パーセンタイル:53.56(Physics, Nuclear)The PHENIX experiment at the Relativistic Heavy Ion Collider measured and mesons at midrapidity in UU collisions at GeV in a wide transverse momentum range. Measurements were performed in the decay modes. A strong suppression of and meson production at high transverse momentum was observed in central UU collisions relative to binary scaled results. Yields of and mesons measured in UU collisions show similar suppression pattern to the ones measured in AuAu collisions at GeV for similar numbers of participant nucleons. The / ratios do not show dependence on centrality or transverse momentum, and are consistent with previously measured values in hadron-hadron, hadron-nucleus, nucleus-nucleus, and collisions.
Oskin, P.*; 谷田 聖; Belle Collaboration*; 他198名*
Physical Review D, 102(9), p.092011_1 - 092011_8, 2020/11
被引用回数:0 パーセンタイル:0.01(Astronomy & Astrophysics)Using data collected in the Belle experiment at the KEKB asymmetric-energy collider we search for transitions , and . No significant signals are observed and we set 90% confidence level upper limits on the corresponding visible cross sections: and , respectively.
Cubiss, J. G.*; Andreyev, A. N.; Barzakh, A. E.*; Manea, V.*; Al Monthery, M.*; Althubiti, N. A.*; Andel, B.*; Antalic, S.*; 他39名*
Physical Review C, 102(4), p.044332_1 - 044332_12, 2020/10
被引用回数:5 パーセンタイル:53.56(Physics, Nuclear)A comprehensive study of the isotope Au has been made at the CERN-ISOLDE facility, using resonance laser ionization. Two long-lived states in Au were identified - a low-spin ground state and a high-spin isomer - each of which were produced as pure beams. Using the ISOLTRAP precision Penning trap, the excitation energy of the isomeric state in Au was determined to be 189(14) keV. The -decay fine structure patterns of the two states were studied using the Windmill decay station, providing information on the low-lying states in the daughter nucleus Ir. Nuclear spin assignments of Au and Au are made based on the observed -decay feeding and hyperfine structure intensity patterns.