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Zheng, R.*; Gong, W.; 他6名*
Acta Materialia, 293, p.121098_1 - 121098_12, 2025/07
Hall-Petch law fails when grains smaller than a critical size, due to grain boundary (GB) kinetics-dominated plasticity. To enhance strength, improving GB stability is a consideration. However, this often requires a significant amount of alloying elements, posing resource challenges. Additionally, practical fabrication of extremely fine grains is still an issue. In our study, we firstly demonstrate a remarkable hardening-by-annealing phenomenon in magnesium (Mg) with relatively large grain sizes of 0.2-0.5 
m, even with ultra-low yttrium (Y) addition. We reveal that annealing induces GB segregation/relaxation, effectively limiting the GB kinetics and promoting dislocation-dominated plasticity. Furthermore, the accompanying dislocation annihilation hinders deformation due to dislocation scarcity. As a result, we discovered extraordinary hardening in bulk ultrafine grained Mg-Y ultra-dilute alloy. This work offers a promising avenue for developing energy- and resource-efficient sustainable Mg alloys with superior mechanical properties.
Md produced in the 
He + 
Es reaction西尾 勝久; 廣瀬 健太郎; 牧井 宏之; Orlandi, R.; Kean, K. R.*; 塚田 和明; 豊嶋 厚史*; 浅井 雅人; 佐藤 哲也; Chiera, N. M.*; et al.
Physical Review C, 111(4), p.044609_1 - 044609_12, 2025/04
被引用回数：0In spontaneous fission (SF) it is found that the mass-asymmetric fission of well-known actinides suddenly changes to the symmetric fission when nucleus has a mass number 
larger than 257. We have measured for the first time fission-fragment mass and total-kinetic-energy (TKE) distributions of the excited compound nucleus Md, populated in the reaction He+Es, using the rare isotope Es with a short half-life, 
=276 days. The fission of Md can be interpreted as involving 3 fission modes: an mass-asymmetric mode and two modes of mass-asymmetric fissions, the latter two are manifested by different TKE values. Predominantly symmetric fission was obtained at the excitation energy of 15.0 MeV. By increasing the energy to 18.0 MeV, the asymmetric fission mode dominates. Both such a strong change of fission modes within a small increase of excitation energy and the enhancement of asymmetric split are new phenomena in fission.
Fe
O
Ba, Y.*; 山本 慧; 他6名*
Physical Review B, 111(10), p.104401_1 - 104401_15, 2025/03
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Ferrimagnet insulator yttrium iron garnet (YFeO, YIG) attracts much interest in magnonics and microwave applications due to its relatively low magnetic damping and long magnon relaxation time. The magnetoelastic interaction between YIG magnetization and surface acoustic waves (SAWs) has been the basis in the development of acoustic-surface-wave isolators. However, the investigation of SAW-driven magnetic resonance in YIG is limited by the low compatibility of YIG and SAW devices. In this work, we demonstrate nonreciprocal resonant SAW absorption in an on-chip YIG-SAW device integrated by the focused ion beam technique. We observed two distinct SAW absorption signals attributed to the perpendicular standing spin waves (PSSW). Furthermore, the large observed nonreciprocity is compared to theoretical predictions incorporating the influence of asymmetric surface conditions on PSSW mode profiles and nonreciprocal magnon-SAW coupling. The strongly nonreciprocal SAW attenuation in YIG offers a promising opportunity for highly efficient rf signal processing technologies.
neutron diffractionNaeem, M.*; Ma, Y.*; Knowles, A. J.*; Gong, W.; Harjo, S.; Wang, X.-L.*; Romero Resendiz, L.*; 他6名*
Materials Science & Engineering A, 916, p.147374_1 - 147374_8, 2024/11
被引用回数：2 パーセンタイル：63.37(Nanoscience & Nanotechnology)Heterostructured materials (HSMs) improve the strength-ductility trade-off of alloys, but their cryogenic performance under real-time deformation is unclear. We studied heterostructured CrCoNi medium-entropy alloy via neutron diffraction at 77 K and 293 K. A significant mechanical mismatch between fine and coarse grains led to an exceptional yield strength of 918 MPa at 293 K, increasing to 1244 MPa at 77 K with a uniform elongation of 34%. This strength-ductility synergy at 77 K is attributed to high dislocation pile-up density, increased planar faults, and martensitic transformation. Compared to homogeneous alloys, HSMs show promise for enhancing cryogenic mechanical performance in medium-/high-entropy alloys.
ScZidarova, R.*; 宇都野 穣; 他76名*
Physica Scripta, 99(7), p.075309_1 - 075309_9, 2024/06
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)理化学研究所のRIビームファクトリーにて
Sc(
,
)Sc反応によってScの励起状態を生成し、そこからの脱励起ガンマ線の放出を測定することによってその原子核のエネルギー準位を構築した。1510(30)keVの励起準位など、いくつかの新しい準位を見つけた。その結果を大規模殻模型計算の結果と比較し、ガンマ崩壊様式を考慮した結果、1510(30)keVの準位は
の可能性が高いことがわかった。
experimentLee, D. H.*; 百々 拓; 羽賀 勝洋; 原田 正英; 長谷川 勝一; 春日井 好己; 木下 秀孝; 増田 志歩; 明午 伸一郎; 酒井 健二; et al.
European Physical Journal C, 84, p.409_1 - 409_6, 2024/04
被引用回数：1 パーセンタイル：41.24(Physics, Particles & Fields)JSNS (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that searches for sterile neutrinos via the observation of 
appearance oscillations using muon decay-at-rest neutrinos. The JSNS experiment performed data taking from 2021. In this manuscript, a study of the accidental background is presented. The rate of the accidental background is (9.29
0.39)
10
/ spill with 0.75 MW beam power and comparable to the expected number of signal events.
雨森 道紘*; 土屋 晴文; Tibet AS
Collaboration*; 他116名*
Astrophysical Journal, 954(2), p.200_1 - 200_7, 2023/09
被引用回数：5 パーセンタイル：54.27(Astronomy & Astrophysics)Gamma rays from HESS J1849-000, a middle-aged TeV pulsar wind nebula (PWN), are observed by the Tibet air shower array and the muon detector array. The detection significance of gamma rays reaches 
and 
levels above 25 TeV and 100 TeV, respectively. The energy spectrum measured between 40 TeV 
E 320 TeV for the first time is described with a simple power-law function of dN/dE = 
. The gamma-ray energy spectrum from the sub-TeV to sub-PeV ranges including the results of previous studies can be modeled with the leptonic scenario, Inverse Compton Scattering by high-energy electrons accelerated by the PWN of PSR J1849-0001, but the scenario requires sophisticated theoretical modeling. On the other hand, the gamma-ray energy spectrum can be simply modeled with the hadronic scenario in which gamma rays are generated from the decay of neutral pions produced by collisions between accelerated cosmic-ray protons and the ambient molecular cloud found in the gamma-ray emitting region. The cutoff energy of cosmic-ray protons 
is estimated at 
, suggesting that protons are accelerated up to the PeV energy range. Our study proposes that HESS J1849-000 should be further investigated as a new candidate for a Galactic PeV cosmic-ray accelerator, or "PeVatron".
CuPedersen, L. G.*; Sahin, E.*; G
rgen, A.*; Bello Garrote, F. L.*; Orlandi, R.; 他61名*
Acta Physica Polonica B; Proceedings Supplement, 16(4), p.4-A14_1 - 4-A14_6, 2023/08
被引用回数：0 パーセンタイル：0.00(Physics, Multidisciplinary)Excited states in Cu were observed for the first time following the 
decay of Ni created by in-flight fission of 
U. Based on the coincidences with the observed -ray transitions, a level scheme comprising eight excited states was constructed, with tentative spin assignments for 5 of them. In addition to the -decaying states, an isomeric state with a lifetime of 3.8(4) ms was also found to decay by internal conversion.
Martel, I.*; Acosta, L.*; Aguado, J. L.*; Smallcombe, J.; 他68名*
Nuclear Instruments and Methods in Physics Research B, 541, p.176 - 179, 2023/08
被引用回数：3 パーセンタイル：46.61(Instruments & Instrumentation)The ISOLDE Scientific Infrastructure at CERN offers a unique range of post-accelerated radioactive beams. The scientific program can be improved with the Isolde Superconducting Recoil Separator (ISRS), an innovative spectrometer able to deliver unprecedented (A, Z) resolution. In this paper we present an overview of the physics and ongoing technical developments.
threshold in the 
mass spectrum with 
decaysYang, S.*; 谷田 聖; Belle Collaboration*; 他196名*
Physical Review D, 108(3), p.L031104_1 - L031104_6, 2023/08
被引用回数：5 パーセンタイル：42.62(Astronomy & Astrophysics)We observe a narrow peaking structure in the 
invariant-mass spectrum near the threshold. The peak is clearly seen in 1.5 million events of 
decay using the 
data sample collected by the Belle detector at the KEKB asymmetric-energy 
collider. We try two approaches to explain this structure: as a new resonance and as a cusp at the threshold. The best fit is obtained with a coherent sum of a Flatt
function and a constant background amplitude with the 
(
), while the fits to Breit-Wigner functions are unfavored by more than 7
. The best fit explains the structure as a cusp at the threshold, and the obtained parameters are consistent with the known properties of 
. The observation gives the first identification of a threshold cusp in hadrons from the spectrum shape.
西 隆博*; 橋本 直; 他46名*
Nature Physics, 19(6), p.788 - 793, 2023/06
被引用回数：15 パーセンタイル：88.25(Physics, Multidisciplinary)According to quantum chromodynamics, vacuum is not an empty space, because it is filled with quark-antiquark pairs. The pair has the same quantum numbers as the vacuum and forms a condensate because the strong interaction of the quantum chromodynamics is too strong to leave the vacuum empty. This quark-antiquark condensation, the chiral condensate, breaks the chiral symmetry of the vacuum. The expectation value of the chiral condensate is an order parameter of the chiral symmetry, which is expected to decrease at high temperatures or high matter densities where the chiral symmetry is partially restored. Head-on collisions of nuclei at ultra-relativistic energies have explored the high-temperature regime, but experiments at high densities are rare. Here we measure the spectrum of pionic 
Sn atoms and study the interaction between the pion and the nucleus. We find that the expectation value of the chiral condensate is reduced at finite density compared to the value in vacuum. The reduction is linearly extrapolated to the nuclear saturation density and indicates that the chiral symmetry is partially restored due to the extremely high density of the nucleus.
(980) meson decaying into 
at 
2.4 GeV村松 憲仁*; 土川 雄介; LEPS2 BGOegg Collaboration*; 他61名*
Physical Review C, 107(4), p.L042201_1 - L042201_5, 2023/04
被引用回数：1 パーセンタイル：26.66(Physics, Nuclear)For the first time, differential cross sections and photon beam asymmetries were measured for the reaction 
by using a linearly polarized photon beam up to 2.4 GeV and a liquid hydrogen target. The (980) photoproduction signal was clearly observed owing to the absence of contributions from vector-meson photoproduction. The results indicate the 
-channel exchange of vector mesons as a mechanism of the (980) photoproduction at 
approximate to 2.1 GeV, putting constraints on the nature of (980).
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.
Y
Fe
O films吉川 貴史*; 齊藤 英治; 他6名*
Physical Review Materials (Internet), 6(10), p.104402_1 - 104402_13, 2022/10
被引用回数：7 パーセンタイル：46.06(Materials Science, Multidisciplinary)We have investigated hybridized magnon-phonon excitation (magnon polarons) in spin Seebeck effects (SSEs) in BiYFeO (BixYxIG; x=0, 0.5, and 0.9) films with Pt contact. We observed sharp peak structures in the magnetic field H; dependence of the longitudinal SSE (LSSE) voltages, which appear when the phonon dispersions are tangential to the magnon dispersion curve in BixYIG. By increasing the Bi amount x, the peak fields in the LSSE shift toward lower H values due to the reduction of the sound velocities in BixYIG. We also measured the SSE in a nonlocal configuration and found that magnon-polaron anomalies appear with different signs and intensities. Our result shows composition-tunability of magnon-polaron anomalies and provides a clue to further unravel the physics of magnon-polaron SSEs.
Pang, T.*; 谷田 聖; Belle Collaboration*; 他206名*
Physical Review D, 106(5), p.L051103_1 - L051103_8, 2022/09
被引用回数：0 パーセンタイル：0.00(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 signal and set a 90% confidence-level upper limit of 
on the branching fraction.
decay of the 8
isomer in 
UZhang, M. M.*; Tian, Y. L.*; Wang, Y. S.*; Zhang, Z. Y.*; Gan, Z. G.*; Yang, H. B.*; Huang, M. H.*; Ma, L.*; Yang, C. L.*; Wang, J. G.*; et al.
Physical Review C, 106(2), p.024305_1 - 024305_6, 2022/08
被引用回数：5 パーセンタイル：61.57(Physics, Nuclear)The extremely neutron-deficient even-even uranium isotopes U were produced in the complete-fusion reactions induced by impinging 
Ar and Ca ions on 
W targets. Fusion evaporation residues were separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure) and subsequently identified using the recoil--correlation method. In this paper, we report on new -decay activities with 
keV for 
U and 
keV for 
U, which decay from the 8 isomeric states of U into the 2 states of their daughter nuclei 
Th, respectively. The new results extend the systematics of the -decay fine structure for the 
= 124 and 126 even-even isotones.
meson production in 
Al, Au, 
Au, and 
HeAu collisions at 
GeVAcharya, U. A.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他365名*
Physical Review C, 106(1), p.014908_1 - 014908_13, 2022/07
被引用回数：6 パーセンタイル：67.20(Physics, Nuclear)Small nuclear collisions are mainly sensitive to cold-nuclear-matter effects; however, the collective behavior observed in these collisions shows a hint of hot-nuclear-matter effects. The identified-particle spectra, especially the mesons which contain strange and antistrange quarks and have a relatively small hadronic-interaction cross section, are a good tool to study these effects. The PHENIX experiment has measured mesons in a specific set of small collision systems Al, Au, and HeAu, as well as Au, at GeV. The transverse-momentum spectra and nuclear-modification factors are presented and compared to theoretical-model predictions. The comparisons with different calculations suggest that quark-gluon plasma may be formed in these small collision systems at GeV. However, the volume and the lifetime of the produced medium may be insufficient for observing strangeness-enhancement and jet-quenching effects. Comparison with calculations suggests that the main production mechanisms of mesons at midrapidity may be different in Al versus 
HeAu collisions at GeV. While thermal quark recombination seems to dominate in HeAu collisions, fragmentation seems to be the main production mechanism in Al collisions.
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：55.29(Physics, Particles & Fields)We present a search for the charged lepton-flavor-violating decays 
and radiative charged lepton-flavour-violating decays 
[
] using the 158 million 
sample collected by the Belle detector at the KEKB collider. This search uses mesons produced in 
transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level.
lepton居波 賢二*; 谷田 聖; Belle Collaboration*; 他186名*
Journal of High Energy Physics (Internet), 2022(4), p.110_1 - 110_13, 2022/04
被引用回数：11 パーセンタイル：70.75(Physics, Particles & Fields)We report a measurement of the electric dipole moment of the lepton (
) using an 833~fb
data sample collected near the 
resonance, with the Belle detector at the KEKB asymmetric-energy collider. Using an optimal observable method, we obtain the real and imaginary parts of as 
and 
, 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.
meson decays into and missing energy with a hadronic tagging method at BelleHadjivasiliou, C.*; 谷田 聖; Belle Collaboration*; 他166名*
Physical Review D, 105(5), p.L051101_1 - L051101_8, 2022/03
被引用回数：8 パーセンタイル：55.29(Astronomy & Astrophysics)We present a search for the decays of mesons into a final state containing a baryon and missing energy. These results are obtained from a 711 fb data sample that contains 772 
10
pairs and was collected near the resonance with the Belle detector at the KEKB asymmetric-energy 
collider. We use events in which one meson is fully reconstructed in a hadronic decay mode and require the remainder of the event to consist of only a single . No evidence for these decays is found and we set 90% confidence level upper limits on the branching fractions in the range 2.1-3.8 10
. This measurement provides the world's most restrictive limits, with implications for baryogenesis and dark matter production.
