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Tang, T. L.*; 上坂 友洋*; 川瀬 頌一郎; Beaumel, D.*; 堂園 昌伯*; 藤井 俊彦*; 福田 直樹*; 福永 拓*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.
Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05
被引用回数:9 パーセンタイル:88.96(Physics, Multidisciplinary)中性子過剰核Fの構造が(
)反応で調査した。
軌道の分光学的因子は1.0
0.3と大きいが、一方で残留核である
Oが基底状態である割合は約35%,励起状態は約0.65%であることが明らかになった。この結果は、
Fのコア核
Oは基底状態とは大きく異なり、
Oの
軌道に陽子がひとつ加わることで
Oと
Fの中性子軌道が相当に変化していると推測される。これは酸素同位体ドリップライン異常のメカニズムである可能性がある。
山本 剛史*; 長谷川 勝一; 早川 修平; 細見 健二; Hwang, S.; 市川 裕大; 今井 憲一; 金原 慎二; 中田 祥之; 佐甲 博之; et al.
Physical Review Letters, 115(22), p.222501_1 - 222501_5, 2015/11
被引用回数:54 パーセンタイル:92.84(Physics, Multidisciplinary)The energy spacing between the spin-doublet bound state of He
was determined to be
keV, by measuring
rays for the
transition with a high efficiency germanium detector array in coincidence with the
He reaction at J-PARC. In comparison to the corresponding energy spacing in the mirror hypernucleus
H, the present result clearly indicates the existence of charge symmetry breaking (CSB) in
interaction. By combining the energy spacings with the known ground-state binding energies, it is also found that the CSB effect is large in the
ground state but is vanishingly small in the
excited state, demonstrating that the
CSB interaction has spin dependence.
Kim, S. H.*; Hwang, S.; Ahn, J. K.*; 江川 弘行; 早川 修平; Hong, B.*; 細見 健二; 今井 憲一; Kim, M. H.*; Lee, J. Y.*; et al.
Nuclear Instruments and Methods in Physics Research A, 795, p.39 - 44, 2015/09
被引用回数:3 パーセンタイル:32.14(Instruments & Instrumentation)We have developed a time-of-flight (ToF) array consisting of 24 plastic scintillators for triggering and timing measurements in a series of planned experiments to study double-strangeness hadronic and nuclear systems at the K1.8 beamline of J-PARC. Each ToF scintillator is 180 cm long with a cross-section of 83 cm
and is read out by H1949-50 photomultiplier tubes at both ends. The timing and attenuation properties of the scintillators are measured using cosmic-ray muons and
rays from
. The cosmic-ray muon events are triggered by three pairs of 120-cm-long plastic scintillators, sandwiching the ToF array. The intrinsic time resolutions of the scintillators are estimated to be in the range 60-100 ps, which is adequate for reliable separation between
and
at 1.2 GeV/
. The attenuation length is measured to be approximately 210 cm, which is half that for a bulk scintillator.
佐甲 博之; Ahn, J. K.*; Baek, K. H.*; Bassalleck, B.*; Fujioka, H.*; Guo, L.*; 長谷川 勝一; Hicks, K.*; Honda, R.*; Hwang, S. H.*; et al.
Journal of Instrumentation (Internet), 9(4), p.C04009_1 - C04009_10, 2014/04
被引用回数:3 パーセンタイル:18.85(Instruments & Instrumentation)(,
)反応によるHダイバリオン探索実験(J-PARC E42)のためのTPCの開発を行っている。TPCにおいてHが2個の
と2個の
に崩壊する事象を測定する。TPCのドリフト体積は50cm直径、55cmドリフト長を持つ8角柱構造をしておりAr-CH
ガスを使用する。増幅部には3層のGEMを使用する。荷電粒子の運動量測定のためTPCにはドリフト電場と平行に鉛直方向の1Tの双極磁場を超伝導ヘルムホルツ型磁石によりかける。H崩壊のアクセプタンスを最大にするためダイアモンド標的がTPC内部の筒状の穴に設置される。さらに、超高レートの
ビームをTPCに直接照射するため陽イオンフィードバックを極力抑制必要がある。このためTPCにGEMとgating gridを採用した。
小林 正起*; 石田 行章*; Hwang, J. I.*; Song, G. S.*; 滝沢 優*; 藤森 淳; 竹田 幸治; 大河内 拓雄*; 岡根 哲夫; 斎藤 祐児; et al.
Physical Review B, 79(20), p.205203_1 - 205203_5, 2009/05
被引用回数:7 パーセンタイル:35.36(Materials Science, Multidisciplinary)The electronic structure of InV
O
(
) has been investigated by photoemission spectroscopy and X-ray absorption spectroscopy (XAS). The V
core-level photoemission and XAS spectra revealed that the V ion is in the trivalent state, which is the same valence state as that of In in In
O
. The V
partial density of states obtained by the resonant photoemission technique showed a sharp peak above the O
band. While the O
XAS spectrum of In
V
O
was similar to that of In
O
, there were differences in the In
and
XAS spectra between the V-doped and pure In
O
. The observations give clear evidence for hybridization between the In-derived conduction band and the V
orbitals in In
V
O
.
Song, G.*; 小林 正起*; Hwang, J. I.*; 片岡 隆*; 滝沢 優*; 藤森 淳; 大河内 拓雄; 竹田 幸治; 岡根 哲夫; 斎藤 祐児; et al.
Physical Review B, 78(3), p.033304_1 - 033304_4, 2008/07
被引用回数:8 パーセンタイル:39.26(Materials Science, Multidisciplinary)The electronic structure of the magnetic semiconductor GaCr
N, and the effect of Si doping on it have been investigated by photoemission and soft X-ray absorption spectroscopy. We have confirmed that Cr in GaN is predominantly trivalent when substituting for Ga and that Cr 3
states appear within the band gap of GaN just above the N 2
-derived valence-band maximum. As a result of Si doping, downward shifts of the core levels (except for Cr 2
) and the formation of new states near the Fermi level were observed, which we attribute to the upward chemical-potential shift and the formation of a small amount of Cr
species caused by electron doping. Possibility of Cr-rich cluster growth by Si doping are discussed based on the spectroscopic and magnetization data.
小林 正起*; 石田 行章*; Hwang, J. I.*; Song, G. S.*; 藤森 淳; Yang, C. S.*; Lee, L.*; Lin, H.-J.*; Huang, D.-J.*; Chen, C. T.*; et al.
New Journal of Physics (Internet), 10, p.055011_1 - 055011_15, 2008/05
被引用回数:13 パーセンタイル:62.96(Physics, Multidisciplinary)The electronic structure of the Cr ions in the diluted ferromagnetic semiconductor ZnCr
Te (
=0.03 and 0.15) thin films has been investigated using X-ray magnetic circular dichroism (XMCD) and photoemission spectroscopy (PES). The line shape of the Cr
XMCD spectra is independent of
,
, and
, indicating that the ferromagnetism is originated from the same electronic states of the Cr ion. Cluster-model analysis indicates that the ferromagnetic XMCD signal is originated from Cr ions substituted for the Zn site. The Cr
partial density of states extracted using Cr
resonant PES shows a broad feature near the top of the valence band, suggesting strong
,
-
hybridization. Based on these findings, we conclude that double exchange mechanism cannot explain the ferromagnetism in Zn
Cr
Te.
Hwang, T.; 長谷川 晃*; 戸村 恵子*; 海老澤 直樹*; 外山 健*; 永井 康介*; 福田 誠*; 宮澤 健*; 田中 照也*; 野上 修平*
no journal, ,
To clarify the irradiation hardening behavior of neutron-irradiated tungsten(W), the formation behavior of rhenium(Re)-enriched cluster and W-Re precipitation with displacement damage in fission reactors environment was investigated by the atom probe tomography (APT) technique, and the results obtained by APT and microstructural observation by transmission electron microscopy (TEM) were compared. The samples were irradiated to 0.96 dpa at 538C in a fast experimental reactor Joyo, and irradiated to 0.90 dpa at 500
C in a mixed spectrum reactor HFIR. The chemical compositions of the matrix, Re clusters, and precipitates were determined by the AP analysis. The Joyo-irradiated samples contained lower levels of transmuted Re and Os, while the HFIR-irradiated samples contained higher levels of Re and Os. The Re-enriched clusters demonstrated characteristic spatial distribution related to defect cluster distribution in each irradiated specimen.