池部 友理恵*; 大島 真澄*; 伴場 滋*; 浅井 雅人; 塚田 和明; 佐藤 哲也; 豊嶋 厚史*; Bi, C.*; 瀬戸 博文*; 天野 光*; et al.
Applied Radiation and Isotopes, 164, p.109106_1 - 109106_7, 2020/10
長澤 真*; Qin, H.-B.*; 山口 瑛子; 高橋 嘉夫*
Chemistry Letters, 49(8), p.909 - 911, 2020/08
Speciation of rare earth elements (REE) in marine ferromanganese oxides (MFMO) was conducted by extended X-ray absorption fine structure (EXAFS) and sequential extraction to compare the enrichment mechanisms and extraction rates between MFMO and ion-adsorption type deposits, which can be reasonably explained by the formation of inner- and outer-sphere complexes in the two materials for yttrium and other REE.
岡安 悟; 針井 一哉*; 小畠 雅明; 吉井 賢資; 福田 竜生; 石田 真彦*; 家田 淳一; 齊藤 英治
Journal of Applied Physics, 128(8), p.083902_1 - 083902_7, 2020/08
The ion-irradiation tolerance of thermoelectric devices based on the spin Seebeck effect (SSE) was investigated by using 320 MeV gold ion (Au) beams modeling cumulative damages due to fission products emitted from the surface of spent nuclear fuels. For this purpose, prototypical Pt/YFeO/GdGaO SSE elements were irradiated with varying the dose level at room temperature and measured the SSE voltage of them. We confirmed that the thermoelectric and magnetic properties of the SSE elements are not affected by the ion-irradiation up to ions/cm fluence and that the SSE signal is extinguished around ions/cm, in which the ion tracks almost fully cover the sample surface. We also performed the hard X-ray photoemission spectroscopy (HAXPES) measurements to understand the effects at the interface of Pt/YFeO. The HAXPES measurements suggest that the chemical reaction that diminishes the SSE signals is enhanced with the increase of the irradiation dose. The present study demonstrates that SSE-based devices are applicable to thermoelectric generation even in harsh environments for a long time period.
Grund, J.*; 浅井 雅人; Blaum, K.*; Block, M.*; Chenmarev, S.*; Dllmann, Ch. E.*; Eberhardt, K.*; Lohse, S.*; 永目 諭一郎*; Nagy, Sz.*; et al.
Nuclear Instruments and Methods in Physics Research A, 972, p.164013_1 - 164013_8, 2020/08
田屋 英俊*; Park, A.*; Cho, S.*; Gubler, P.; 服部 恒一*; Hong, J.*; Huang, X.-G.*; Lee, S. H.*; 門内 明彦*; 大西 明*; et al.
Physical Review C, 102(2), p.021901_1 - 021901_6, 2020/08
We investigate the hadron production from the vortical quark-gluon plasma created in heavy-ion collisions. Based on the quark-coalescence and statistical hadronization models, we show that total hadron yields summed over the spin components are enhanced by the local vorticity with quadratic dependence. The enhancement factor amounts to be a few percent and may be detectable within current experimental sensitivities. We also show that the effect is stronger for hadrons with larger spin, and thus propose a new signature of the local vorticity, which may be detected by the yield ratio of distinct hadron species having different spins such as and . The vorticity dependence of hadron yields seems robust, with consistent predictions in both of the hadron production mechanisms for reasonable values of the vorticity strength estimated for heavy-ion collisions.
Stryjczyk, M.*; Andel, B.*; Andreyev, A. N.; Cubiss, J.*; Pakarinen, J.*; 他43名*
Physical Review C, 102(2), p.024322_1 - 024322_9, 2020/08
Decay spectroscopy of the long-lived states in Tl has been performed at ISOLDE, CERN. The decay from the low-spin (2) state in Tl was observed for the first time and a half-life was determined. Based on the -decay energy, the relative positions of the long-lived states were fixed, with the (2) state as the ground state, the 7 state at 77(56) keV, and the 10 state at 451(56) keV. The level scheme of the internal decay of the Tl(10) state, which was known to decay solely through emission of 374-keV -ray transition, was extended and a lower limit for the -decay branching b 5.9(3)% was determined. The extracted retardation factors for the decay of the 10 state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the d shell in the isomeric decay and significant structure differences between Tl and Tl.
Xu, M.*; 山本 慧; Puebla, J.*; Baumgaertl, K.*; Rana, B.*; 三浦 勝哉*; 高橋 宏昌*; Grundler, D.*; 前川 禎通*; 大谷 義近*
Science Advances (Internet), 6(32), p.eabb1724_1 - eabb1724_4, 2020/08
One of the most fundamental forms of magnon-phonon-interaction is an intrinsic property of magnetic materials, the "magnetoelastic coupling." This particular form of interaction has been the basis for describing magnetic materials and their strain related applications, where strain induces changes of internal magnetic fields. Different from the magnetoelastic coupling, more than 40 years ago, it was proposed that surface acoustic waves may induce surface magnons via rotational motion of the lattice in anisotropic magnets. However, a signature of this magnon-phonon coupling mechanism, termed magneto-rotation coupling, has been elusive. Here, we report the first observation and theoretical framework of the magneto-rotation coupling in a perpendicular anisotropic ultra-thin lim Ta/CoFeB/MgO, which consequently induces nonreciprocal acoustic wave attenuation with an unprecedented ratio up to 100% rectification at a theoretically predicted optimized condition. Our work not only experimentally demonstrates a fundamentally new path for investigating magnon-phonon coupling, but also justifies the feasibility of the magneto-rotation coupling based application.
AIP Conference Proceedings 2249, p.030002_1 - 030002_7, 2020/07
山内 宏樹; Sari, D. P.*; 渡邊 功雄*; 安井 幸夫*; Chang, L.-J.*; 近藤 啓悦; 伊藤 孝; 石角 元志*; 萩原 雅人*; Frontzek, M. D.*; et al.
Communications Materials (Internet), 1, p.43_1 - 43_6, 2020/07
今井 正樹; 中堂 博之; 松尾 衛; 前川 禎通; 齊藤 英治
Physical Review B, 102(1), p.014407_1 - 014407_5, 2020/07
The angular momentum compensation temperature of ferrimagnets has attracted much attention because of high-speed magnetic dynamics near . We show that NMR can be used to investigate domain wall dynamics near in ferrimagnets. We performed Fe-NMR measurements on the ferrimagnet HoFeO with = 245 K. In a multi-domain state, the NMR signal is enhanced by domain wall motion. We found that the NMR signal enhancement shows a maximum at in the multi-domain state. The NMR signal enhancement occurs due to increasing domain-wall mobility toward . We develop the NMR signal enhancement model involves domain-wall mobility. Our study shows that NMR in multi-domain state is a powerful tool to determine , even from a powder sample and it expands the possibility of searching for angular momentum-compensated materials.
Acharya, U.*; 長谷川 勝一; 今井 憲一*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他358名*
Physical Review C, 102(1), p.014902_1 - 014902_23, 2020/07
Charmonium is a valuable probe in heavy-ion collisions to study the properties of the quark gluon plasma, and is also an interesting probe in small collision systems to study cold nuclear matter effects, which are also present in large collision systems. With the recent observations of collective behavior of produced particles in small system collisions, measurements of the modification of harmonium in small systems have become increasingly relevant. We present the results of measurements at forward and backward rapidity in various small collision systems, , Al, Au and HeAu, at =200 GeV. The results are presented in the form of the observable , the nuclear modification factor, a measure of the ratio of the invariant yield compared to the scaled yield in collisions. We examine the rapidity, transverse momentum, and collision centrality dependence of nuclear effects on production with different projectile sizes and He, and different target sizes Al and Au. The modification is found to be strongly dependent on the target size, but to be very similar for Au and HeAu. However, for 0% - 20% central collisions at backward rapidity, the modification for HeAu is found to be smaller than that for Au, with a mean fit to the ratio of (stat)(syst), possibly indicating final state effects due to the larger projectile size.
Gottardo, A.*; de Angelis, G.*; Doornenbal, P.*; Coraggio, L.*; Gargano, A.*; Itaco, N.*; Orlandi, R.; 他52名*
Physical Review C, 102(1), p.014323_1 - 014323_8, 2020/07
Reduced transition probabilities have been measured for the neutron-rich Ni nuclei with relativistic Coulomb excitation performed at the RIKEN Nishina Center. Excitation energies compare well with the result of large-scale shell-model calculations, while values are larger than predicted. This could indicate an increasing contribution of proton excitations across the shell closure when approaching Ni.
Andel, B.*; Andreyev, A. N.; Antalic, S.*; Al Monthery, M.*; Barzakh, A.*; Bissell, M. L.*; Chrysalidis, K.*; 他29名*
Physical Review C, 102(1), p.014319_1 - 014319_12, 2020/07
-delayed fission (DF) decay of a low-spin (ls) and a high-spin (hs) isomer in Bi was studied at the ISOLDE facility at CERN. Their DF partial half-lives were determined: , DF(Bi)= 5.6(8) 10 s and , DF(Bi)=1.7(6) 10 s. This work is the first DF study of two states in one isotope and allowsthe spin dependence of low-energy fission to be explored. The fission fragment mass distribution of a daughter nuclide Pb, following the decay of the high-spin isomer, was deduced and indicates a mixture of symmetric and asymmetric fission modes.
Benito, J.*; Fraile, L. M.*; Korgul, A.*; Piersa, M.*; Adamska, E.*; Andreyev, A. N.; lvarez-Rodrguez, R.*; 他81名*
Physical Review C, 102(1), p.014328_1 - 014328_18, 2020/07
The structure of the doubly magic Sn has been investigated at the ISOLDE facility at CERN, populated both by the -decay of In and --delayed neutron emission of In. The level scheme of Sn is greatly expanded with the addition of 68 -ray transitions and 17 levels. The identification of particle-hole multiplets both for protons and neutrons and the transition rates connecting different particle-hole configurations may provide input on the two-body matrix elements and single-particle states for state-of-the-art calculations.
Kim, Y.*; 肥山 詠美子*; 岡 眞; 鈴木 渓
Physical Review D, 102(1), p.014004_1 - 014004_9, 2020/07
Ku, Y.*; 谷田 聖; Belle Collaboration*; 他153名*
Physical Review D, 102(1), p.012003_1 - 012003_9, 2020/07
We report searches for and decays, where the energy of the photon is required to be larger than 0.5 GeV. These results are obtained from a data sample that contains pairs and was collected near the resonance with the Belle detector at the KEKB collider. We observe no significant signal for either decay and set upper limits on their branching fractions at confidence level of and .
Chen, Y. Q.*; 谷田 聖; Belle Collaboration*; 他181名*
Physical Review D, 102(1), p.012002_1 - 012002_12, 2020/07
We present the results of the first Dalitz plot analysis of the decay . The analysis is performed on a data set corresponding to an integrated luminosity of 953 collected by the Belle detector at the asymmetric-energy KEKB collider. The Dalitz plot is well described by a combination of the six resonant decay channels , , , , and , together with and S-wave components. The decays and are observed for the first time. We measure ratio of the branching fractions, . Using the Dalitz fit result, the ratio is measured to be ; this is much lower than the theoretical expectations () made under the assumption that is a pure state. The product branching fraction is determined. In addition, the contribution to the resonance shape is confirmed with 10.1 statistical significance using the three-channel Flatte model. We also measure . This is consistent with, and more precise than, the current world average , deviates with a significance of more than from the theoretical predictions of (0.51-0.92)%.
Frotscher, A.*; Gmez-Ramos, M.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; 馬場 秀忠*; Orlandi, R.; 他86名*
Physical Review Letters, 125(1), p.012501_1 - 012501_7, 2020/07
Twenty-one two-proton () knock-out cross sections of neutron-rich radioactive isotopes were measured in inverse kinematics using the MINOS time-projection chamber at RIBF, RIKEN. The proton angular distributions, measured for the first time, reveal that the reaction kinematics of the () reaction is consistent with sequential proton collisions within the projectile nucleus.
Puebla, J.*; Xu, M.*; Rana, B.*; 山本 慧; 前川 禎通*; 大谷 義近*
Journal of Physics D; Applied Physics, 53(26), p.264002_1 - 264002_7, 2020/06
Voltage induced magnetization dynamics of magnetic thin films is a valuable tool to study anisotropic fields, exchange couplings, magnetization damping and spin pumping mechanism. A particularly well established technique is the ferromagnetic resonance (FMR) generated by the coupling of microwave photons and magneti- zation eigenmodes in the GHz range. Here we review the basic concepts of the so-called acoustic ferromagnetic resonance technique (a-FMR) induced by the coupling of surface acoustic waves (SAW) and magnetization of thin films. Interestingly, additional to the benefits of the microwave excited FMR technique, the coupling be- tween SAW and magnetization also offers fertile ground to study magnon-phonon and spin rotation couplings. We describe the in-plane magnetic field angle dependence of the a-FMR by measuring the absorption / trans- mission of SAW and the attenuation of SAW in the presence of rotational motion of the lattice, and show the consequent generation of spin current by acoustic spin pumping.
黒田 健太*; 新井 陽介*; Rezaei, N.*; 國定 聡*; 櫻木 俊輔*; Alaei, M.*; 木下 雄斗*; Bareille, C.*; 野口 亮*; 中山 充大*; et al.
Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06
Solids with competing interactions often undergo complex phase transitions. Among them, CeSb is the most famous material where a number of the distinct magnetic phases called devil's staircase appear. We observed the electronic structure evolution across the devil's staircase transitions using bulk-sensitive angle-resolved photoemission spectroscopy.