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論文

The $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross section from the surrogate ratio method and its effect on the $$^{60}$$Fe nucleosynthesis

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

The long-lived $$^{60}$$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 $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe on $$^{59}$$Fe (half-life=44.5 days) is the key reaction for the production of $$^{60}$$Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1 $$gamma$$-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 $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5$$pm$$3.5 mb at $$kT$$ = 30 keV and 13.4$$pm$$1.7 mb at $$kT$$ = 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 $$^{60}$$Fe from the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$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 $$^{60}$$Fe.

論文

Implications of the $$Z_{cs}$$(3985) and $$Z_{cs}$$(4000) as two different states

Meng, L.*; Wang, B.*; Wang, G.-J.*; Zhu, S.-L.*

Science Bulletin, 66(20), p.2065 - 2071, 2021/10

最近発見された2つのテトラクォーク状態$$Z_{cs}$$(3985)と$$Z_{cs}$$(4000)の崩壊を有効理論を用いて調べた結果、崩壊の分岐比からこれらが同じ状態か異なる状態かを判断できることがわかった。

論文

Martensitic transformation in CrCoNi medium-entropy alloy at cryogenic temperature

Naeem, M.*; Zhou, H.*; He, H.*; Harjo, S.; 川崎 卓郎; Lan, S.*; Wu, Z.*; Zhu, Y.*; Wang, X.-L.*

Applied Physics Letters, 119(13), p.131901_1 - 131901_7, 2021/09

We investigated the in situ deformation behavior of the CrCoNi medium-entropy alloy at a cryogenic temperature of 140 K and compared it with deformation at room temperature. The sample exhibited higher strength and larger ductility at the cryogenic temperature. The CrCoNi alloy remained single-phase face-centered cubic at room temperature, while deformation at 140 K resulted in a martensitic transformation to the hexagonal close-packed structure. The phase transformation, an additional deformation mechanism to stacking faults, twinning, and dis- location slip, resulted in a higher work hardening at cryogenic temperature. The study addresses the structure metastability in the CrCoNi alloy, which led to the formation of epsilon-martensite from the intrinsic stacking faults.

論文

Probing the long-range structure of the $$T^{+}_{cc}$$ with the strong and electromagnetic decays

Meng, L.*; Wang, G.-J.*; Wang, B.*; Zhu, S.-L.*

Physical Review D, 104(5), p.L051502_1 - L051502_8, 2021/09

最近発見された$$T^+_{cc}$$状態の長距離構造をその強い相互作用と電磁相互作用による崩壊の分岐の様子から推定することが可能であることを示した。その結果、$$T_{cc}$$の主成分は$$D^{*+}D^0$$であることがわかった。

論文

Higher fully charmed tetraquarks; Radial excitations and $$P$$-wave states

Wang, G.-J.*; Meng, L.*; 岡 眞; Zhu, S.-L.*

Physical Review D, 104(3), p.036016_1 - 036016_15, 2021/08

 被引用回数:0

チャームクォーク2個と反クォーク2個の束縛状態であるテトラクォークの動径励起状態と$$P$$波励起状態のスペクトルを、クォーク模型を用いて解析した。クォーク模型は標準的なカラークーロン力と線形閉じ込め力を持つもので、チャーモニウム状態でパラメータを決めた。ダイクォークの基底状態を用いて、カラーが$$bar 3_c 3_c$$$$6_c bar 6_c$$の状態を取り入れた計算の結果、$$6_c bar 6_c$$状態が低いエネルギーとなることがわかった。$$rho$$モードと$$lambda$$モードの励起状態を調べた結果、最近発見されたX(6900)に相当するエネルギー領域には$$0^{++}$$状態,$$2^{++}$$状態,$$1^{+-}$$状態、および$$2^{-+}$$$$P$$波状態が対応していることが明らかになった。また、エキゾチックな量子数を持つ$$0^{--}$$$$1^{-+}$$状態は主に$$P$$波の$$eta_c J/psi$$, $$J/psi J/psi$$にそれぞれ崩壊することがわかった。

論文

Suppressed lattice disorder for large emission enhancement and structural robustness in hybrid lead iodide perovskite discovered by high-pressure isotope effect

Kong, L.*; Gong, J.*; Hu, Q.*; Capitani, F.*; Celeste, A.*; 服部 高典; 佐野 亜沙美; Li, N.*; Yang, W.*; Liu, G.*; et al.

Advanced Functional Materials, 31(9), p.2009131_1 - 2009131_12, 2021/02

 被引用回数:1 パーセンタイル:27.27(Chemistry, Multidisciplinary)

有機-無機ハロゲン化物ペロブスカイトは非常に柔らかいために、圧力などの外部刺激により格子定数を容易に変化させることができ、有用な光電特性を引き出すのに有効である。一方でこの特性は、多少の加圧でも、格子を歪ませてしまい、光と物質の相互作用を弱め、それによる性能の低下を引き起こす。そこで本研究では、代表的な物質であるヨウ化メチルアンモニウム鉛に対して圧力効果および同位体効果を調べ、それらが格子歪を抑制することが分かった。このことは、それらが、これまで得られなかったような光学的,機械的特性を持つ物質を得る手段として有効であることを示している。

論文

Mass spectrum and strong decays of tetraquark $$bar c bar s qq$$ states

Wang, G.-J.*; Meng, L.*; Xiao, L.-Y.*; 岡 眞; Zhu, S.-L.*

European Physical Journal C, 81(2), p.188_1 - 188_12, 2021/02

 被引用回数:4 パーセンタイル:90.39(Physics, Particles & Fields)

クォーク模型を用いて、S波の$$bar c bar s qq$$テトラクォーク状態の質量を計算し、さらに$$D^{-(*)}K^{(*)}$$チャネルへの崩壊幅の計算を行った。これらは、最近LHCbで報告されている$$X^0(2900)$$状態の理解につながる。また、対応する$$I=0$$の状態として、$$X(2649)$$を予言した。この状態が実験的に見つかることで、この模型が実証されてインパクトが大きい。

論文

Ultra-fine CeO$$_{2}$$ particles triggered strong interaction with LaFeO$$_{3}$$ framework for total and preferential CO oxidation

Zheng, Y.*; Xiao, H.*; Li, K.*; Wang, Y.*; Li, Y.*; Wei, Y.*; Zhu, X.*; Li, H.-W.*; 松村 大樹; Guo, B.*; et al.

ACS Applied Materials & Interfaces, 12(37), p.42274 - 42284, 2020/09

 被引用回数:3 パーセンタイル:55.29(Nanoscience & Nanotechnology)

Interactions between the active components with the support are one of the fundamentally factors in determining the catalytic performance of a catalyst. In this study, we investigated the interaction between CeO$$_{2}$$ and LaFeO$$_{3}$$, the two important oxygen storage materials in catalysis area, by tuning the sizes of CeO$$_{2}$$ particles and highlight a two-fold effect of the strong oxide-oxide interaction in determining the catalytic activity and selectivity for preferential CO oxidation in hydrogen feeds. It is found that the anchoring of ultra-fine CeO$$_{2}$$ particles at the framework of three-dimensional-ordered macroporous LaFeO$$_{3}$$ surface results in a strong interaction between the two oxides that induces the formation of abundant uncoordinated cations and oxygen vacancy at the interface. This discovery demonstrates that in hybrid oxide-based catalysts, tuning the interaction among different components is essential for balancing the catalytic activity and selectivity.

論文

Nature of structural instabilities in superconducting Sr$$_3$$Ir$$_4$$Sn$$_{13}$$

金子 耕士; Cheung, Y. W.*; Hu, Y.*; 今井 正樹*; 谷奥 泰明*; 金川 響*; 村川 譲一*; 森山 広大*; Zhang, W.*; Lai, K. T.*; et al.

JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03

A quantum critical point appears as a second-order phase transition which takes place at zero temperature. In contrast to heavy-fermion systems in which magnetism often plays a vital role, recent studies revealed that structural instabilities can drive a system to a quantum critical point as well. In quasi-skutterudite (Ca,Sr)$$_3T_4$$Sn$$_{13}$$ ($$T$$=Rh, Ir), Sr$$_3$$Ir$$_4$$Sn$$_{13}$$ exhibits superconductivity around $$T_{rm sc}$$$${sim}$$5 K and a structural transition at $$T^*{simeq}$$147 K. Applying physical or chemical pressure on Sr$$_3$$Ir$$_4$$Sn$$_{13}$$ suppresses $$T^*$$ rapidly, and a quasi-linear $$T$$ dependence of electrical resistivity, signature of non-Fermi liquid behavior, was observed where $$T^*$$ extrapolates to 0 K. The isomorphs (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ exhibits similar behavior, where the criticality can be reached by $$x{sim}$$0.9 without external pressure. Neutron scattering experiments in Sr$$_3$$Ir$$_4$$Sn$$_{13}$$ evidences the second order nature of the structural transition at $$T^*$$ by the observation of a continuous evolution of superlattice peak below $$T^*$$ and a gradual increase of critical scattering upon approaching to $$T^*$$ by cooling. Increase of $$x$$ in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ toward the quantum critical point leads to the systematic variation of the critical exponents of the order parameter. In addition, this substitution induces the phonon softening around the M point towards zero energy revealed by inelastic X-ray scattering experiment. We will present systematic variations in both elastic and inelastic channels upon approaching to the quantum critical point.

論文

$$alpha$$-decay properties of $$^{200,202}$$Fr

Ghys, L.*; Andreyev, A. N.; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; Cocolios, T. E.*; Cubiss, J.*; Derkx, X.*; et al.

Physical Review C, 100(5), p.054310_1 - 054310_13, 2019/11

 被引用回数:9 パーセンタイル:84.91(Physics, Nuclear)

The aim of this work was to investigate the $$alpha$$-decay properties of $$^{200,202}$$Fr and daughter products. Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Due to the very high statistics and the high beam purity, improved decay data for $$^{202}$$Fr and its daughters were obtained. The observation of crossover transitions positioned the isomeric high-spin level of $$^{198}$$At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of $$^{198}$$At and 52(3) ms for the ground-state decay of $$^{200}$$Fr.

論文

Inverse odd-even staggering in nuclear charge radii and possible octupole collectivity in $$^{217,218,219}$$At revealed by in-source laser spectroscopy

Barzakh, A. E.*; Cubiss, J. G.*; Andreyev, A. N.; Seliverstov, M. D.*; Andel, B.*; Antalic, S.*; Ascher, P.*; Atanasov, D.*; Beck, D.*; Biero$'n$, J.*; et al.

Physical Review C, 99(5), p.054317_1 - 054317_9, 2019/05

 被引用回数:5 パーセンタイル:71.02(Physics, Nuclear)

Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in $$^{217,218,219}$$At have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope $$^{218}$$At has been found to be larger than the average.

論文

Evidence of a structural quantum critical point in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ from a lattice dynamics study

Cheung, Y. W.*; Hu, Y. J.*; 今井 正樹*; 谷奥 泰明*; 金川 響*; 村川 譲一*; 森山 広大*; Zhang, W.*; Lai, K. T.*; 吉村 一良*; et al.

Physical Review B, 98(16), p.161103_1 - 161103_5, 2018/10

 被引用回数:6 パーセンタイル:46.5(Materials Science, Multidisciplinary)

Approaching a quantum critical point has been an effective route to stabilize superconductivity. While the role of magnetic QCPs has been extensively discussed, similar exploration of a structural QCP is scarce. Using inelastic X-ray scattering, we examine the phonon spectrum of the nonmagnetic quasi-skutterudite (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$, which represents a precious system to explore the interplay between structural instabilities and superconductivity by tuning the Ca concentration x. We unambiguously detect the softening of phonon modes around the M point on cooling towards the structural transition. Intriguingly, at x = 0:85, the soft mode energy squared at the M point extrapolates to zero at -5.7 K, providing the first compelling microscopic evidence of a structural QCP in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$. The enhanced phonon density-of-states at low energy provides the essential ingredient for realizing strong-coupling superconductivity near the structural QCP.

論文

Investigation of the electronic structure and lattice dynamics of the thermoelectric material Na-doped SnSe

Wu, P.*; Zhang, B.*; Peng, K. L.*; 萩原 雅之*; 石川 喜久*; 古府 麻衣子; Lee, S. H.*; 組頭 広志*; Hu, C. S.*; Qi, Z. M.*; et al.

Physical Review B, 98(9), p.094305_1 - 094305_7, 2018/09

 被引用回数:5 パーセンタイル:40.47(Materials Science, Multidisciplinary)

熱電材料であるNaドープしたSnSeについて、ARPES, 中性子回折, 中性子非弾性散乱でその電子構造と格子ダイナミクスを測定した結果を報告する。

論文

Odd and even modes of neutron spin resonance in the bilayer iron-based superconductor CaKFe$$_{4}$$As$$_{4}$$

Xie, T.*; Wei, Y.*; Gong, D.*; Fennell, T.*; Stuhr, U.*; 梶本 亮一; 池内 和彦*; Li, S.*; Hu, J.*; Luo, H.*

Physical Review Letters, 120(26), p.267003_1 - 267003_7, 2018/06

 被引用回数:18 パーセンタイル:83.86(Physics, Multidisciplinary)

We report an inelastic neutron scattering study on the spin resonance in the bilayer iron-based superconductor CaKFe$$_4$$As$$_4$$. In contrast to its quasi-two-dimensional electron structure, three strongly $$L$$-dependent modes of spin resonance are found below $$T_c$$ = 35 K. The mode energies are below and linearly scale with the total superconducting gaps summed on the nesting hole and electron pockets, essentially in agreement with the results in cuprate and heavy fermion superconductors. This observation supports the sign-reversed Cooper-pairing mechanism under multiple pairing channels and resolves the long-standing puzzles concerning the broadening and dispersive spin resonance peak in iron pnictides. More importantly, the triple resonant modes can be classified into odd and even symmetries with respect to the distance of Fe-Fe planes within the Fe-As bilayer unit. Thus, our results closely resemble those in the bilayer cuprates with nondegenerate spin excitations, suggesting that these two high-$$T_c$$ superconducting families share a common nature.

論文

Observation of magnetoelastic effects in a quasi-one-dimensional spiral magnet

Wang, C.*; Daiwei, Y.*; Liu, X.*; Chen, R.*; Du, X.*; Hu, B.*; Wang, L.*; 飯田 一樹*; 蒲沢 和也*; 脇本 秀一; et al.

Physical Review B, 96(8), p.085111_1 - 085111_5, 2017/08

AA2017-0274.pdf:1.02MB

 被引用回数:4 パーセンタイル:30.24(Materials Science, Multidisciplinary)

This paper presents a systematic study of spin and lattice dynamics in the quasi-one-dimensional spiral magnet CuBr$$_2$$, using Raman scattering in conjunction with infrared and neutron spectroscopy. Along with the development of spin correlations upon cooling, we observe a rich set of broad Raman bands at energies that correspond to phonon-dispersion energies near the one-dimensional magnetic wave vector. The low-energy bands further exhibit a distinct intensity maximum at the spiral magnetic ordering temperature.

論文

Local moments in the heterogeneous electronic state of Cd-substituted CeCoIn$$_5$$; NQR relaxation rates

酒井 宏典; Ronning, F.*; 服部 高典; 徳永 陽; 神戸 振作; Zhu, J.-X.*; Wakeham, N.*; 安岡 弘志; Bauer, E. D.*; Thompson, J. D.*

Journal of Physics; Conference Series, 807(3), p.032001_1 - 032001_6, 2017/04

 被引用回数:1 パーセンタイル:42.46

量子臨界金属CeCoIn$$_5$$のInを少量のCdで置換した時の電子状態を核四重極共鳴(NQR)を用いて調べた。およそ半分のCd置換子周りで局所的にCeの局在モーメントが発生することを、縦緩和率$$1/T_1$$のサイト依存性から明らかにした。横緩和率$$T_{rm 2G}$$の測定も行い、局在スピン周りでは、$$T_1T/T_{rm 2G}^2$$が温度$$T$$に比例し、一方、置換子から離れたところでは、$$T_1T/T_{rm 2G}^2propto T^{0.7}$$となっており、純CeCoIn$$_5$$$$T^{0.75}$$に近く、バルクの電子状態は量子臨界状態のままである。

論文

Second-order structural transition in (Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$

Cheung, Y. W.*; Hu, Y. J.*; Goh, S. K.*; 金子 耕士; 筒井 智嗣; Logg, P. W.*; Grosche, F. M.*; 金川 響*; 谷奥 泰明*; 今井 正樹*; et al.

Journal of Physics; Conference Series, 807(3), p.032002_1 - 032002_4, 2017/04

BB2016-0329.pdf:0.86MB

 被引用回数:3 パーセンタイル:78.73

(Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ is a member of the substitution series (Ca$$_{x}$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ which has recently been argued to feature a structural quantum critical point at $$x_c$$ = 0.9. In the stoichiometric compound Sr$$_{3}$$Rh$$_{4}$$Sn$$_{13}$$, the structural transition at $$T^*$$ $$approx$$ 138 K has been shown to be a second-order phase transition. Moving towards xc, we examine the character of the structural transition in (Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ (i.e. $$x$$ = 0.5, $$T^*$$ $$approx$$ 55 K) using electrical resistivity, heat capacity and X-ray scattering. The absence of the thermal hysteresis in specific heat around $$T^*$$, and the continuous evolution of the superlattice reflection detected by X-ray diffraction are consistent with the scenario that the structural transition associated with a modulation vector $$q$$ = (0.5, 0.5, 0) in (Ca$$_{0.5}$$Sr$$_{0.5}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ remains second-order on approaching the quantum critical point.

論文

Stability and synthesis of superheavy elements; Fighting the battle against fission - Example of $$^{254}$$No

Lopez-Martens, A.*; Henning, G.*; Khoo, T. L.*; Seweryniak, D.*; Alcorta, M.*; 浅井 雅人; Back, B. B.*; Bertone, P. F.*; Boilley, D.*; Carpenter, M. P.*; et al.

EPJ Web of Conferences, 131, p.03001_1 - 03001_6, 2016/12

 被引用回数:1 パーセンタイル:48.81

原子番号が100を超える原子核の核分裂障壁の高さとその角運動量依存性を初めて測定した。核分裂による崩壊が優勢となり始める励起エネルギーを決定できる初期分布法という方法を$$^{254}$$Noの測定に適用した。$$^{254}$$Noの核分裂障壁はスピンゼロにおいて6.6MeVと決定された。このことは、$$^{254}$$Noが原子核の殻効果によって強く安定化されていることを示している。

論文

Spin excitations in optimally P-doped BaFe$$_2$$(As$$_{0.7}$$P$$_{0.3}$$)$$_2$$ superconductor

Hu, D.*; Yin, Z.*; Zhang, W.*; Ewings, R. A.*; 池内 和彦*; 中村 充孝; Roessli, B.*; Wei, Y.*; Zhao, L.*; Chen, G.*; et al.

Physical Review B, 94(9), p.094504_1 - 094504_7, 2016/09

AA2016-0252.pdf:2.18MB

 被引用回数:14 パーセンタイル:65.12(Materials Science, Multidisciplinary)

最適Pドープされた超伝導体BaFe$$_2$$(As$$_{0.7}$$P$$_{0.3}$$)$$_2$$ (T$$_c$$=30K)におけるスピン励起の温度及びエネルギー依存性が非弾性中性子散乱実験を使って調べられた。我々の実験結果は密度汎関数理論や動的平均場理論で予想される計算結果と矛盾しておらず、BaFe$$_2$$(As$$_{0.7}$$P$$_{0.3}$$)$$_2$$における平均プニクトゲン高さの減少が、電子相関の強さを弱め、磁気励起の有効バンド幅の増加に寄与することを示唆している。

論文

$$beta$$-delayed fission and $$alpha$$ decay of $$^{196}$$At

Truesdale, V. L.*; Andreyev, A.; Ghys, L.*; Huyse, M.*; Van Duppen, P.*; Sels, S.*; Andel, B.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; et al.

Physical Review C, 94(3), p.034308_1 - 034308_11, 2016/09

 被引用回数:9 パーセンタイル:65.59(Physics, Nuclear)

A nuclear-decay spectroscopy study of the neutron-deficient isotope $$^{196}$$At is reported where an isotopically pure beam was produced using the selective Resonance Ionization Laser Ion Source and On-Line Isotope Mass Separator (CERN). The fine-structure $$alpha$$ decay of $$^{196}$$At allowed the low-energy excited states in the daughter nucleus $$^{192}$$Bi to be investigated. A $$beta$$-delayed fission study of $$^{196}$$At was also performed. A mixture of symmetric and asymmetric fission-fragment mass distributions of the daughter isotope $$^{196}$$Po (populated by $$beta$$ decay of $$^{196}$$At) was deduced based on the measured fission-fragment energies. A $$beta$$DF probability $$P_{rm beta DF}$$($$^{196}$$At) = 9(1)$$times$$10$$^{-5}$$ was determined.

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