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Moon, J. Y.*; 伊藤 由太; 他13名*
Journal of the Korean Physical Society, 87(5), p.640 - 648, 2025/09
被引用回数：2 パーセンタイル：47.86(Physics, Multidisciplinary)A new large-scale heavy-ion accelerator complex, RAON (Rare isotope Accelerator complex for ON-line experiments), in Korea has implemented the state-of-art device, multi-reflection time-of-flight mass spectrometer (MRTOF-MS) for the mass spectrometry of the exotic nuclei. Using the multi-reflections of ions between a pair of grid-free mirror electrodes and therefore extending the fly length, it can achieve the incredibly high mass resolving power of within a short measurement time of 
10 ms, providing the nuclear mass of the exotic nuclei with a high-precision level of sub-ppm. The device is coupled to one of the beamlines in the ISOL experimental hall, ready for participating in the longstanding topics of nuclear structure in the outskirts of the nuclear chart and nucleosynthesis of heavy elements in explosive astrophysical environments. The exclusively high mass resolving power is also advantageous for reducing the isobaric contaminants that rare isotope ion beam facilities suffer from. In this paper, we present a summary of the construction and current performance of the RAON MRTOF-MS.
-ray spectroscopy toward the proton dripline; The Curious case of 
ArBeck, T.*; 宇都野 穣; 他13名*
Physical Review C, 111(4), p.044306_1 - 044306_7, 2025/04
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)米国超伝導サイクロトロン研究所にて陽子過剰な不安定核Arのインビームガンマ線分光実験を行い、新たに1900keVの脱励起ガンマ線を見つけた。これは3767(5)keVの励起準位が存在することを表す。この原子核の鏡像核であるSiで最も近い励起準位は4231(1)keVであり、この2つの原子核のペアにおける鏡像対称性が著しく破れていることがわかった。殻模型計算を行った結果、
殻から
殻に2粒子2空孔励起した状態が多く含まれた状態ではないかと考えられる。
with 
= 2.1 K revealed by 
Te NMR松村 拓輝*; 徳永 陽; 酒井 宏典; 神戸 振作; 他13名*
Physical Review B, 111(9), p.094507_1 - 094507_9, 2025/03
被引用回数：2 パーセンタイル：80.70(Materials Science, Multidisciplinary)To investigate the intrinsic magnetic properties of UTe, we performed Te-NMR measurements on the ultra-clean single-crystalline UTe with superconducting transition temperature = 2.1 K and compared the results with those of the = 1.6 K sample. The broadening of the linewidth of the NMR spectrum in the a-axis magnetic field and the low-temperature magnetic fluctuations observed in the 1.6 K sample are suppressed in the ultra-clean sample, indicating that such magnetic properties originate from a tiny amount of U deficiency. The present results suggest that the magnetic properties in UTe are sensitive to the U deficiency. We also observed a peculiar angular dependence of the NMR quantities due to large magnetic anisotropy with the a-axis as the magnetic easy axis.
GeTe homojunctions小幡 玲二*; 齊藤 英治; 吉川 貴史; 他13名*
Advanced Materials, 37(8), p.2411459_1 - 2411459_11, 2025/02
被引用回数：4 パーセンタイル：96.28(Chemistry, Multidisciplinary)Twistronics, a novel engineering approach involving the alignment of van der Waals (vdW) integrated two-dimensional materials at specific angles, has recently attracted significant attention. Novel nontrivial phenomena have been demonstrated in twisted vdW junctions (the so-called magic angle), such as unconventional superconductivity, topological phases, and magnetism. However, there have been only few reports on integrated vdW layers with large twist angles 
, such as twisted interfacial Josephson junctions using high-temperature superconductors. Herein, vdW homojunctions of the thin-magnetic flakes, Fe
GeTe
(FGT), with large ranging from 0 to 90 deg, without inserting any tunnel barriers are assembled. Nevertheless, these vdW homojunctions exhibit tunnel-magnetoresistance (TMR) like behavior (pseudo-TMR (PTMR) effect) with the ratios highly sensitive to the values, revealing that the vdW gap at the junction interface between the twisted FGT layers behaves like a tunnel barrier and the serves a control parameter for PTMR by drastically varying magnitudes of the lattice-mismatch and the subsequent appearance of antiferromagnetic (AFM) spin alignment. First-principles calculations considering vacuum gaps indicate strong dependence of TMR on the driven by the sixfold screw rotational symmetry of bulk FGT. The present homojunctions hold promise as a platform for novel AFM spin-dependent phenomena and spintronic applications.
Balibrea-Correa, J.*; 木村 敦; 他133名*
Nuclear Instruments and Methods in Physics Research A, 1064, p.169385_1 - 169385_13, 2024/07
被引用回数：3 パーセンタイル：72.26(Instruments & Instrumentation)A Monte Carlo method for detectors using the Total Energy Deposition principle (which is obtained via application of the PHWT) was proposed. In this method, both dead-time and pile-up effects are considered simultaneously in a consistent manner. To validate this method in harsh count rate conditions, we have applied it to two different types of C
D liquid scintillators at different count rate conditions and demonstrated the capability to account for these effects in neutron-capture cross-section measurements at the CERN n_TOF facility. The method brings very good results under the count rates up to 
8 c/
s.
Pb, the heaviest 
-process; Only isotope in the solar systemCasanovas-Hoste, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 133(5), p.052702_1 - 052702_8, 2024/07
被引用回数：3 パーセンタイル：69.02(Physics, Multidisciplinary)Tl(n, ) cross section was measured at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of Tl produced at the Institute Laue Langevin high flux reactor. At the -process temperatures of kT 
8 keV and kT 30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new Tl MACS, the uncertainty arising from the Tl(n, ) cross section on the -process abundance of Pb has been reduced from 30% down to +8%/-6%, and the -process calculations are in agreement with the latest solar system abundance of Pb reported by K. Lodders in 2021.
) cross-section measurements at n_TOF EAR2Alcayne, V.*; 木村 敦; 他134名*
Radiation Physics and Chemistry, 217, p.111525_1 - 111525_11, 2024/04
被引用回数：6 パーセンタイル：93.43(Chemistry, Physical)The neutron time-of-flight facility n_TOF at CERN is a spallation source dedicated to measurements of neutron induced reaction cross-sections of interest in nuclear technologies, astrophysics, and other applications. Since 2014, Experimental ARea 2 (EAR2) is operational and delivers a neutron fluence of 
neutrons per nominal proton pulse, which is 50 times higher than the one of the other experimental area. The high neutron flux at EAR2 results in high counting rates in the detectors that challenged the previously existing capture detection systems. For this reason, a Segmented Total Energy Detector (sTED) has been developed to overcome the limitations in the detector's response, by reducing the active volume and by using a photo-multiplier (PMT) optimized for high counting rates. This paper presents the main characteristics of the sTED, including energy and time resolution, response to -rays, and provides details for the Pulse Height Weighting Technique (PHWT). The sTED has been validated to perform neutron-capture cross-section measurements in EAR2 in the neutron energy range from thermal up to at least 400 keV.
Ce(n, ) cross section at n_TOF and its astrophysical implications for the chemical evolution of the universeAmaducci, S.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 132(12), p.122701_1 - 122701_8, 2024/03
被引用回数：5 パーセンタイル：79.96(Physics, Multidisciplinary)Ce(n,) is a key reaction for slow neutron-capture (-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty 5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
condensed state in 
Mg using the 
C+C scatteringFujikawa, Y.*; Kawabata, T.*; Adachi, S.*; 廣瀬 健太郎; 牧井 宏之; 西尾 勝久; Orlandi, R.; 洲嵜 ふみ; 他13名*
Physics Letters B, 848, p.138384_1 - 138384_6, 2024/01
被引用回数：8 パーセンタイル：80.89(Astronomy & Astrophysics)We searched for the 6-condensed state in Mg by measuring the C+C scattering with the SAKRA Si detector array. By using the invariant-mass method for the detected 3 particles, the inclusive cross sections for the C+C 
C(0
) + X and C(3
) + X reactions were determined. In both the inclusive C(0) + X channel and the exclusive C(0) + C(0
) channel, the cross section peaked at E
= 19.4 MeV, which correspond to the excitation energy of E
= 33.3 MeV in Mg. This 19.4-MeV state is a candidate for the 6-condensed state
Nb isotopes; Evidence for shape coexistence in 
=58 
NbKumar, V.*; Chapman, R.*; O'Donnell, D.*; Ollier, J.*; Orlandi, R.; Smith, J. F.*; Spohr, K.-M.*; Torres, D. A.*; 他13名*
Physical Review C, 108(4), p.044313_1 - 044313_19, 2023/10
被引用回数：1 パーセンタイル：19.80(Physics, Nuclear)The nuclear structure of neutron-rich niobium isotopes 
Nb were studied at the Legnaro National Laboratories using -ray spectroscopy. The isotopes were produced in two different experiments, either using multi-nucleon transfer reactions of 
Zr 530-MeV beam onto a 
Sn target, or via fusion-fission of 
S on 
Yb. The level schemes of these isotopes were extended respectively up to excitation energies of 4545, 5409, and 3814 keV. The structure of the low-lying states in these isotopes was interpreted and discussed in the context of shell-model calculations. In particular, for the Nb isotope (
=41, =58), the results indicate the presence of shape-coexistence at low-energies, which was observed for the first time in this isotope.
Th at the CERN n_TOF facilityMichalopoulou, V.*; 原田 秀郎; 木村 敦; 他134名*
Physical Review C, 108(1), p.014616_1 - 014616_15, 2023/07
被引用回数：2 パーセンタイル：59.08(Physics, Nuclear)The neutron-induced fission cross section of Th has been measured at the neutron time-of-flight facility n_TOF located at CERN. The experiment was performed at the experimental area EAR-1 with a neutron flight path of 185 m, using Micromegas detectors for the detection of the fission fragments. The Th(n,f) cross section was determined relative to the 
U(n, f) one, covering the energy range from the fission threshold up to 400 MeV. The results from the present work are compared with existing cross-section datasets and the observed discrepancies are discussed and analyzed.
Patronis, N.*; 木村 敦; 他130名*
EPJ Techniques and Instrumentation (Internet), 10, p.13_1 - 13_10, 2023/05
During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the n_TOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the n_TOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported.
decays with the Belle II experimentAbudin
n, F.*; 谷田 聖; Belle II Collaboration*; 他413名*
Physical Review D, 107(7), p.072002_1 - 072002_24, 2023/04
被引用回数：12 パーセンタイル：77.58(Astronomy & Astrophysics)We present measurements of the first to fourth moments of the lepton mass squared 
of 
decays for 
and with 
a hadronic system containing a charm quark. These results use a sample of electron-positron collisions at the 
resonance corresponding to 
of integrated luminosity and collected by the Belle II experiment in 2019 and 2020. To identify the system and reconstruct , one of the 
mesons from an 
decay is fully reconstructed in a hadronic decay mode using a multivariate tagging algorithm. We report raw and central moments for 
up to 
, probing up to 77% of the accessible phase space. This is the first measurement of moments in the experimentally challenging range of ![$$[ 1.5, 2.5 ] , mathrm{GeV^2/c^4}$$](/search/images/ERNSAMJOGUWCAMROGUQF0IC2FQQFY1LBORUHE1L1I3SVMXRSF3RV2ND3EQ.gif)
.
Domingo-Pardo, C.*; 木村 敦; 他135名*
European Physical Journal A, 59(1), p.8_1 - 8_11, 2023/01
被引用回数：13 パーセンタイル：91.21(Physics, Nuclear)This article presents a few selected developments and future ideas related to the measurement of (n, ) data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with -ray imaging capability for background suppression, and the development of an array of small-volume organic scintilla tors aimed at exploiting the high instantaneous neutron-flux of EAR2.
investigated by 
SR, neutron and X-ray diffractionNocerino, E.*; 杉山 純; 他13名*
Scientific Reports (Internet), 12, p.21657_1 - 21657_11, 2022/12
Two-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing properties, due to the strong interplay between lattice geometry and electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe, being a 2D-TLA, enriched the range of materials which can present such properties. In this work, the true magnetic nature and ground state of LiCrTe have been revealed. From high-resolution NPD the magnetic spin order at base temperature is not, as previously suggested, helical, but rather collinear antiferromagnetic (AFM) with ferromagnetic (FM) spin coupling within the ab-plane and AFM coupling along the c-axis. From detailed SR measurements we observe an AFM ordering temperature 
125 K. Finally, by combining our magnetic studies with high-resolution synchrotron X-ray diffraction (XRD), we find a clear coupling between the nuclear and magnetic spin lattices.
NiOCl and SrNiOF辻本 吉廣*; 杉山 純; 他13名*
Physical Review Materials (Internet), 6(11), p.114404_1 - 114404_12, 2022/11
The magnetic properties of the S = 1/2 two-dimensional square-lattice antiferromagnets SrNiOX (X = Cl, F) with the trivalent nickel ions in a low-spin state were studied by magnetic susceptibility, heat capacity, neutron powder diffraction, high-field electron spin resonance (ESR), muon spin rotation and relaxation (SR)measurements, and density functional theory (DFT) calculations. Both oxyhalides are isostructural to an ideal quantum square-lattice antiferromagnet SrCuOCl, but the chlorine/fluorine anion exclusively occupies an apical site in an ordered/disordered manner with an oxygen anion, resulting in the formation of highly distortedNiO
X octahedra with an off-center nickel ion. The mechanism of ferromagnetic superexchange interactions and the reason for the difference between the magnetic ground states in these nickel oxyhalides are discussed.
Moreno-Soto, J.*; 木村 敦; 他130名*
Physical Review C, 105(2), p.024618_1 - 024618_14, 2022/02
被引用回数：2 パーセンタイル：28.06(Physics, Nuclear)The -ray spectra from neutron-capture reactions on the 
U, 
U, and 
U nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions (PSFs) and nuclear level density (NLD). No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths.
, 
, and 
decays at BelleLi, Y.*; 谷田 聖; Belle Collaboration*; 他213名*
Physical Review D, 105(1), p.L011102_1 - L011102_10, 2022/01
被引用回数：7 パーセンタイル：49.19(Astronomy & Astrophysics)Using the entire data sample of 
collected with the Belle detector at the KEKB asymmetric-energy 
collider, we present measurements of the branching fractions of the Cabibbo-favored decays , , and . Taking the decay 
as the normalization mode, we measure the branching fraction ratio 
with improved precision, and measure the branching fraction ratios 
and 
for the first time. Taking into account the branching fraction of the normalization mode, the absolute branching fractions are determined to be 
, 
, and 
. The first and second uncertainties above are statistical and systematic, respectively, while the third ones arise from the uncertainty of the branching fraction of .
studied by angle-resolved photoemission spectroscopyHagiwara, K.*; 社本 真一; 他13名*
Physical Review Research (Internet), 3(4), p.043151_1 - 043151_5, 2021/12
In order to study the possible superconductivity at the polar surfaces of 1111-type iron-based superconductors, which is doped with a large amount of holes in spite of the electron doping in bulk materials, we have performed angle-resolved photoemission spectroscopy (ARPES) studies on superconducting PrFeAsO crystals. We have indeed observed the opening of a superconducting gap on surface-derived hole pockets as well as on a bulk-derived hole pocket. The superconducting gap is found to open on the surface-derived hole pockets below the bulk 
, which suggests that the surface superconductivity is possibly induced by proximity effect from the bulk. We have also observed the opening of a large pseudogap on the surface-derived hole pockets, which is similar to the pseudogap in 122-type bulk superconductors doped with a smaller amount of holes. This suggests that the opening of a large pseudogap is a characteristic property of hole-doped iron-based superconductors.
Ge(n,) cross section at the n_TOF facility at CERNGawlik, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review C, 104(4), p.044610_1 - 044610_7, 2021/10
被引用回数：5 パーセンタイル：54.03(Physics, Nuclear)The Ge(n,) reaction has been measured at the n_TOF facility at CERN via the time-of-flight technique. Neutron capture cross sections on Ge are of interest to a variety of low-background experiments, such as neutrinoless double 
decay searches, and to nuclear astrophysics. We have determined resonance capture kernels up to 52 keV neutron energy and used the new data to calculate Maxwellian-averaged neutron capture cross sections for k
T values of 5 to 100 keV.
