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Liu, P.-F.*; Li, X.*; Li, J.*; Zhu, J.*; Tong, Z.*; 古府 麻衣子*; 楡井 真実; Xu, J.*; Yin, W.*; Wang, F.*; et al.
National Science Review, 11(12), p.nwae216_1 - nwae216_10, 2024/12
被引用回数:13 パーセンタイル:94.32(Multidisciplinary Sciences)Crystalline solids exhibiting inherently low lattice thermal conductivity () are of great importance in applications such as thermoelectrics and thermal barrier coatings. However,
cannot be arbitrarily low and is limited by the minimum thermal conductivity related to phonon dispersions. In this work, we report the liquid-like thermal transport in a well-ordered crystalline CsAg
Te
, which exhibits an extremely low
value of
0.18 Wm
K
. On the basis of first-principles calculations and inelastic neutron scattering measurements, we find that there are lots of low-lying optical phonon modes at
3.1 meV hosting the avoided-crossing behavior with acoustic phonons. These strongly localized modes are accompanied by weakly bound rattling Ag atoms with thermally induced large amplitudes of vibrations. Using the two-channel model, we demonstrate that coupling of the particle-like phonon modes and the heat-carrying wave-like phonons is essential for understanding the low
, which is heavily deviated from the
temperature dependence of the standard Peierls theory. In addition, our analysis indicates that the soft structural framework with liquid-like motions of the fluctuating Ag atoms is the underlying cause that leads to the suppression of the heat conduction in CsAg
Te
. These factors synergistically account for the ultralow
value. Our results demonstrate that the liquid-like heat transfer could indeed exist in a well-ordered crystal.
Shangguan, Y.*; Bao, S.*; Dong, Z.-Y.*; Xi, N.*; Gao, Y.-P.*; Ma, Z.*; Wang, W.*; Qi, Z.*; Zhang, S.*; Huang, Z.*; et al.
Nature Physics, 19(12), p.1883 - 1889, 2023/09
被引用回数:19 パーセンタイル:93.50(Physics, Multidisciplinary)The magnetization of a quantum magnet can be pinned at a fraction of its saturated value by collective effects. One example of such a plateau phase is found in spin-1/2 triangular-lattice antiferromagnets. They feature strong geometrical frustration and the plateau phase therein is often interpreted as arising from an order-by-disorder mechanism driven by quantum fluctuations. Here we observe a one-third magnetization plateau under an applied magnetic field in the spin-1 antiferromagnet NaNi
BiO
with a honeycomb lattice, which, with conventional magnetic interactions, would not be geometrically frustrated. Based on our elastic neutron scattering measurements, we propose the spin structure of the plateau phase to be an unusual partial spin-flop ferrimagnetic order. Our theoretical calculations indicate that bond-anisotropic Kitaev interactions are the source of frustration that produces the plateau. These results suggest that Kitaev interactions provide a different route to frustration and phases driven by quantum fluctuations in high-spin magnets.
Wang, Q.*; Hu, Q.*; Zhao, C.*; Yang, X.*; Zhang, T.*; Ilavsky, J.*; Kuzmenko, I.*; Ma, B.*; 舘 幸男
International Journal of Coal Geology, 261, p.104093_1 - 104093_15, 2022/09
被引用回数:12 パーセンタイル:69.82(Energy & Fuels)To understanding the spatial heterogeneity of mineral and pore structure variations in fine-grained shale, microscale X-ray fluorescence (micro-XRF) mapping, (ultra-) small-angle X-ray scattering [(U)SAXS] and wide-angle X-ray scattering were applied for two samples from a piece of Eagle Ford Shale in South Texas. Thin section petrography and field emission-scanning electron microscopy, X-ray diffraction (XRD), total organic carbon, and pyrolysis were also utilized to investigate the potential spatial heterogeneity of pore types, mineral and organic matter compositions for both samples. Overall, the siliceous-carbonate mineral contents in these carbonate-rich Eagle Ford Shale vary between laminations at mm scales. By analyzing six selected sub-samples on each of two samples with X-ray scattering and XRD techniques, nm-sized pores are mainly interparticle ones in the higher calcite regions, where the porosity is also relatively lower, while the lower calcite regions consist of both interparticle and intraparticle pore types with higher porosity. Finally, the micro-XRF and (U)SAXS are combined to generate porosity distribution maps to provide more insights about its heterogeneity related to the laminations and fractures at our observational scales.
Zhang, 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:60.14(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.
Yan, S. Q.*; Li, X. Y.*; 西尾 勝久; Lugaro, M.*; Li, Z. H.*; 牧井 宏之; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; 廣瀬 健太郎; et al.
Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10
被引用回数:5 パーセンタイル:33.27(Astronomy & Astrophysics)The long-lived Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction
Fe(n,
)
Fe on
Fe (half-life=44.5 days) is the key reaction for the production of
Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1
-ray strength function but a negligible constraint on the M1 and E2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the
Fe(n,
)
Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5
3.5 mb at
= 30 keV and 13.4
1.7 mb at
= 90 keV, roughly 10%-20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of
Fe from the
Fe(n,
)
Fe rate are at most 25
. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of
Fe.
奥村 拓馬*; 東 俊行*; Bennet, D. A.*; Caradonna, P.*; Chiu, I.-H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; 橋本 直; et al.
IEEE Transactions on Applied Superconductivity, 31(5), p.2101704_1 - 2101704_4, 2021/08
被引用回数:3 パーセンタイル:13.80(Engineering, Electrical & Electronic)超伝導転移端センサー(TES)マイクロ熱量計は、優れたエネルギー分解能と高い効率を持った、加速器施設での実験に理想的なX線検出器である。高強度パルス荷電粒子ビームを用いたTES検出器の性能を研究するために、日本の陽子加速器研究施設(J-PARC)でパルスミュオンビームを用いてX線スペクトルを測定した。X線エネルギーの実質的な時間的シフトがパルスミュオンビームの到着時間と相関していることを発見した。これは、最初のパルスビームからのエネルギー粒子の入射によるパルスパイルアップによって合理的に説明された。
奥村 拓馬*; 東 俊行*; Bennet, D. A.*; Caradonna, P.*; Chiu, I. H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; 橋本 直; et al.
Physical Review Letters, 127(5), p.053001_1 - 053001_7, 2021/07
被引用回数:18 パーセンタイル:76.09(Physics, Multidisciplinary)超伝導遷移エッジ型センサーマイクロカロリメーターを用いて、鉄のミュー原子から放出される電子X線を観測した。FWHMでの5.2eVのエネルギー分解能により、電子特性
および
X線の非対称の広いプロファイルを約6keVの超衛星線
線とともに観察することができた。このスペクトルは、電子のサイドフィードを伴う、負ミュオンと
殻電子による核電荷の時間依存スクリーニングを反映している。シミュレーションによると、このデータは電子
殻および
殻の正孔生成と、ミュオンカスケードプロセス中のそれらの時間発展を明確に示している。
Benu, D. P.*; Earnshaw, J.*; Ashok, A.*; 土谷 邦彦; Saptiama, I.*; Yuliarto, B.*; Suendo, V.*; Mukti, R. R.*; 福光 延吉*; 有賀 克彦*; et al.
Bulletin of the Chemical Society of Japan, 94(2), p.502 - 507, 2021/02
被引用回数:12 パーセンタイル:54.62(Chemistry, Multidisciplinary)本研究は、TiO含有量を変化させたメソポーラスAl
O
-TiO
複合材料の製造開発及び医療用放射性同位元素の製造のためのMo吸着剤の性能向上のために行った。TiO
の含有量の増加は、元の形態を変えることなく、Al
O
表面へのより多くのTiO
ナノ粒子の形成を促進する。開発したAl
O
-2.5%Ti及びAl
O
-5%Tiのアルミナ試料はアモルファスであったが、Al
O
-10%Tiでは、TiO
がAl
O
表面に被覆されていた。一方、TiO
の添加により、比表面積はAl
O
の177m
/gからAl
O
-5%Ti試料では982m
/gまで大幅に増加した。これにより、Mo吸着量は、Al
O
で37.1mg/g、Al
O
-2.5%Tiで39.0mg/g、Al
O
-10%Tiで40.5mg/gであったが、Al
O
-5%Tiはよりも高い44.5mg/gを示した。これにより、従来のAl
O
の吸着能力と比較して、Al
O
-TiO
複合材料の吸着能力の向上に見通しを得た。
Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.
Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01
被引用回数:14 パーセンタイル:75.82(Astronomy & Astrophysics)Fine structure in the decay of
U was observed in the fusion-evaporation reaction
Re(
Ar,p3n) by using fast digital pulse processing technique. Two
-decay branches of
U feeding the ground state and 244 keV excited state of
Th were identified by establishing the decay chain
U
Th
Ra
Rn. The
-particle energy for the ground-state to ground-state transition of
U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62
s. Evolution of nuclear structure for
=131 even-
isotones from Po to U was discussed in the frameworks of nuclear mass and reduced
-decay width, a weakening octupole deformation in the ground state of
U relative to its lighter isotones
Ra and
Th was suggested.
小野 章*; Xu, J.*; Colonna, M.*; Danielewicz, P.*; Ko, C. M.*; Tsang, M. B.*; Wang, Y,-J.*; Wolter, H.*; Zhang, Y.-X.*; Chen, L.-W.*; et al.
Physical Review C, 100(4), p.044617_1 - 044617_35, 2019/10
被引用回数:75 パーセンタイル:98.53(Physics, Nuclear)2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究では、辺の長さが20fmの直方体に320個の中性子と陽子をランダム配置し、それらが70fm/cの間に起こす散乱の回数やエネルギーを計算した。ここでは、特にパイオンやその前駆体であるデルタ共鳴の生成に注目して比較を行った。参加コードは、個々の粒子の時間発展を追うQMD型コードと、粒子の位置や運動量の確率分布を決めておき、散乱や崩壊が発生したときそれらを乱数サンプリングするBUU型コードがあり、発表者が用いたJQMDは前者に属する。本研究により、計算における時間刻みが各コードによる結果の差の主な原因であることが分かった。さらに、今後のJQMDの改良方針の策定に有益な知見を得ることができた。
阿部 充志*; Bae, S.*; Beer, G.*; Bunce, G.*; Choi, H.*; Choi, S.*; Chung, M.*; da Silva, W.*; Eidelman, S.*; Finger, M.*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2019(5), p.053C02_1 - 053C02_22, 2019/05
被引用回数:161 パーセンタイル:99.30(Physics, Multidisciplinary)この論文はJ-PARCにおける、ミューオン異常磁気モーメントと電気双極子モーメント(EDM)
を測定する新しいアプローチを紹介する。我々の実験のゴールは、これまでと独立の、1/10の運動量と1/20のストレージリングを用いて、
と
をこれまでにない精密な磁場で測定することである。さらに過去の実験との顕著な違いは、1/1000の横エミッタンスミューオンビーム(サーマルミューオンビーム)を用い、効率的なソレノイドへ縦入射し、ミューオンからの崩壊陽電子をトラッキングし、その小さな運動量ベクトルを求める点である。
は統計精度450ppb、系統誤差70ppb、EDMについては
e
cmの精度で測定することを目標とする。
Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; 小野 章*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.
Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03
被引用回数:117 パーセンタイル:98.99(Physics, Nuclear)2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究はモデル間の共通点と差異を明らかにし、各モデルの問題点を明らかにした。比較において、辺の長さが20fmの直方体に320個の中性子と320個の陽子をランダム配置し、それらが時間発展に伴って起こす散乱の回数や散乱時のエネルギーなどを計算する条件が設定された。また、結果以外にも、理論モデルを構成するアルゴリズムについても比較を行った。発表者は重イオン核反応モデルJQMD(JAERI Quantum Molecular Dynamics)を用いて計算を行い、世界で開発されている15の計算コードによる計算結果と比較した。コードアルゴリズムの比較では、JQMDは必ず陽子から 優先的に衝突確率を計算し、その後に中性子の衝突を計算するため、物理描像の妥当性が指摘された。一方、JQMDは他のモデルとほぼ同じ計算結果を出すことも判明した。衝突回数や運動量の計算値が平均から2倍以上乖離するモデルもある中で、JQMDは本計算条件で安定した性能を発揮することが確認された。
Shand, C. M.*; Podolyk, Zs.*; G
rska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.
Physics Letters B, 773, p.492 - 497, 2017/10
被引用回数:28 パーセンタイル:87.55(Astronomy & Astrophysics)Low-lying states in neutron-rich Zn nuclei were measured for the first time via in-beam
-ray spectroscopy at RIKEN. These include the 4
to 2
in
Zn and the 2
to 0
and 4
to 2
in
Zn. The reduced E(
) energies and increased E(4
)/E(2
) ratios at
=52,54 compared to
Zn attest that the magicity is confined just on the neutron number
=50 only. The levels observed in
Zn suggest the onset of deformation towards heavier Zn isotopes. The data were compared to state-of-the-art shell model calculations.
Flavigny, F.*; Doornenbal, P.*; Obertelli, A.*; Delaroche, J.-P.*; Girod, M.*; Libert, J.*; Rodriguez, T. R.*; Authelet, G.*; 馬場 秀忠*; Calvet, D.*; et al.
Physical Review Letters, 118(24), p.242501_1 - 242501_6, 2017/06
被引用回数:40 パーセンタイル:86.04(Physics, Multidisciplinary)The first -ray spectroscopy of very neutron rich
Kr isotopes was carried out at the RIBF at RIKEN Nishina center. Excited states in these isotopes were populated via (p,2p) reactions using radioactive
Rb beams accelerated to 220 MeV/nucleon. The new data show a significant increase in deformation beyond N=60, as well as competing configurations (shape-coexistence) at low energy. The data were compared with beyond-mean-field calculations which predict level energies in good agreement with observation, and suggest oblate-prolate shape coexistence.
Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Rodriguez, T. R.*; Authelet, G.*; 馬場 秀忠*; Calvet, D.*; Chteau, F.*; Corsi, A.*; Delbart, A.*; et al.
Physical Review C, 95(4), p.041302_1 - 041302_6, 2017/04
被引用回数:31 パーセンタイル:89.26(Physics, Nuclear)Neutron-rich isotopes of selenium, Se, where studied via in beam
-ray spectroscopy after nucleon removal reactions at RIBF in RIKEN. The low-energy excitations of these nuclei were investigated using
-
coincidences, and the first and second excited 2
states were found at remarkably low energies. The analysis and comparison with self-consistent beyond-mean field calculations suggest that both shape coexistence and triaxiality are needed to describe these isotopes.
Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 角田 佑介*; Otsuka, T.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.
Physics Letters B, 765, p.328 - 333, 2017/02
被引用回数:38 パーセンタイル:92.29(Astronomy & Astrophysics)The level schemes of neutron-rich isotopes Co and
Ni were populated in the
decay of
Fe and studied using
-delayed
-ray spectroscopy of the
decay, at the RIBF in RIKEN, Japan. The experimental results were compared to state-of-the-art shell-model calculations, and indicate a dominance of prolate deformation in the low-lying states, coexisting with spherical states. The
decay of the
isobars is shown to progress in accordance to a new type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.
Paul, N.*; Corsi, A.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; 馬場 秀忠*; Bally, B.*; Bender, M.*; Calvet, D.*; Chteau, F.*; et al.
Physical Review Letters, 118(3), p.032501_1 - 032501_7, 2017/01
被引用回数:46 パーセンタイル:88.07(Physics, Multidisciplinary)The first measurement of rays emitted by the very neutron rich nuclei
Mo (Z=42) and
Zr (Z=40) was carried out at the RIBF facility at RIKEN. These data shine light on the postulated N=70 harmonic oscillator shell. If the spin-orbit splitting which gives rise to the N=82 shell gap is reduced in very neutron-rich nuclei, the harmonic oscillator gap at N=70 should open instead. However, both the measured energy of the first excited state
Mo and
Zr, respectively 235(7) keV and 185(11) keV, and their E(4
)/E(2
) ratio, indicate that these nuclei are good rotors, and exclude the shell stabilization scenario at Z=40 and N=70. These results were compared to state-of-the-art density functional theoretical calculations using Gogny and Skyrme effective interactions.
Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; Lorusso, G.*; Patel, Z.*; et al.
Physical Review C, 93(3), p.034328_1 - 034328_14, 2016/03
被引用回数:26 パーセンタイル:83.29(Physics, Nuclear)Low-lying excited states in Ni have been investigated at RIKEN by studying the
decay of
Co to
Ni.
Co was separated with BigRIPS, implanted into the WaS3ABi Silicon array, and the
ray measured using the EURICA
spectrometer. From the analysis, 60 new
-ray transitions and 21 new levels in
Ni were observed. The new experimental information is compared to shell-model calculations which include neutron excitation across the
shell. The calculations reproduce rather well the observed states, implying that a clear understanding of these low-lying excitations has been achieved.
Benzoni, G.*; Morales, A. I.*; Watanabe, H.*; 西村 俊二*; Coraggio, L.*; Itaco, N.*; Gargano, A.*; Browne, F.*; Daido, R.*; Doornenbal, P.*; et al.
Physics Letters B, 751, p.107 - 112, 2015/12
被引用回数:20 パーセンタイル:75.16(Astronomy & Astrophysics)The decays of
Mn have been measured at the RIBF facility at RIKEN using the EURICA
spectrometer combined with an active stopper consisting of a stack of Si detectors. Half-lives and
-delayed neutron emission probabilities have been extracted for these decays, together with first experimental information on excited states populated in
Fe. The data indicate a continuously increasing deformation for Fe isotopes up to A=70, and interpreted to be due to the interplay between quadrupole correlation of specific neutron orbitals and the monopole component of the proton-neutron interaction.
Bottoni, S.*; Leoni, S.*; Fornal, B.*; Raabe, R.*; Rusek, K.*; Benzoni, G.*; Bracco, A.*; Crespi, F. C. L.*; Morales, A. I.*; Bednarczyk, P.*; et al.
Physical Review C, 92(2), p.024322_1 - 024322_8, 2015/08
被引用回数:24 パーセンタイル:78.91(Physics, Nuclear)An exploratory experiment was performed at REX-ISOLDE CERN to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The transfer of triton and alpha particles in a reaction of a beam of Rb onto a
Li target were studied through particle-
coincidence measurements. The results indicate that such cluster transfer reactions can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.