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Journal Articles

Multiple mechanisms in proton-induced nucleon removal at $$sim$$100 MeV/nucleon

Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; G$'o$mez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.

Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04

 Times Cited Count:2 Percentile:90.46(Physics, Multidisciplinary)

We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient $$^{14}$$O nucleus with large Fermi-surface asymmetry at $$sim$$100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.

Journal Articles

Fine structure in the $$alpha$$ decay of the 8$$^{+}$$ isomer in $$^{216,218}$$U

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

 Times Cited Count:1 Percentile:34.54(Physics, Nuclear)

Journal Articles

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

AA2020-0819.pdf:1.29MB

 Times Cited Count:31 Percentile:96.65(Physics, Multidisciplinary)

A quasifree ($$p$$,$$pn$$) experiment was performed to study the structure of the Borromean nucleus $$^{17}$$B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for $$1s_{1/2}$$ and $$0d_{5/2}$$ orbitals, and a surprisingly small percentage of 9(2)% was determined for $$1s_{1/2}$$. Our finding of such a small $$1s_{1/2}$$ component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in $$^{17}$$B. The present work gives the smallest $$s$$- or $$p$$-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of $$s$$ or $$p$$ orbitals is not a prerequisite for the occurrence of a neutron halo.

Journal Articles

Proton shell evolution below $$^{132}$$Sn; First measurement of low-lying $$beta$$-emitting isomers in $$^{123,125}$$Ag

Chen, Z. Q.*; Li, Z. H.*; Hua, H.*; Watanabe, Hiroshi*; Yuan, C. X.*; Zhang, S. Q.*; Lorusso, G.*; Orlandi, R.; 60 of others*

Physical Review Letters, 122(21), p.212502_1 - 212502_6, 2019/05

 Times Cited Count:17 Percentile:77.81(Physics, Multidisciplinary)

Journal Articles

Interstitial hydrogen atoms in face-centered cubic iron in the Earth's core

Ikuta, Daijo*; Otani, Eiji*; Sano, Asami; Shibazaki, Yuki*; Terasaki, Hidenori*; Yuan, L.*; Hattori, Takanori

Scientific Reports (Internet), 9, p.7108_1 - 7108_8, 2019/05

 Times Cited Count:32 Percentile:92.34(Multidisciplinary Sciences)

Hydrogen is likely one of the light elements in the Earth's core. Despite its importance, no direct observation has been made of hydrogen in an iron lattice at high pressure. We made the first direct determination of site occupancy and volume of interstitial hydrogen in a face-centered cubic (fcc) iron lattice up to 12 GPa and 1200 K using the in situ neutron diffraction method. At pressures $$<$$ 5 GPa, the hydrogen content in the fcc iron hydride lattice (x) was small at x $$<$$ 0.3, but increased to x $$>$$ 0.8 with increasing pressure. Hydrogen atoms occupy both octahedral (O) and tetrahedral (T) sites; typically 0.870 in O-sites and 0.057 in T-sites at 12 GPa and 1200 K. The fcc lattice expanded approximately linearly at a rate of 2.22 $AA $^{3}$$ per hydrogen atom, which is higher than previously estimated (1.9 $AA $^{3}$$/H). The lattice expansion by hydrogen dissolution was negligibly dependent on pressure. The large lattice expansion by interstitial hydrogen reduced the estimated hydrogen content in the Earth's core that accounted for the density deficit of the core. The revised analyses indicate that whole core may contain hydrogen of 80 times of the ocean mass with 79 and 0.8 ocean mass for the outer and inner cores, respectively.

Journal Articles

Dirac surface state-modulated spin dynamics in a ferrimagnetic insulator at room temperature

Tang, C.*; Song, Q.*; Chang, C.-Z.*; Xu, Y.*; Onuma, Yuichi; Matsuo, Mamoru*; Liu, Y.*; Yuan, W.*; Yao, Y.*; Moodera, J. S.*; et al.

Science Advances (Internet), 4(6), p.eaas8660_1 - eaas8660_6, 2018/06

AA2018-0166.pdf:0.7MB

 Times Cited Count:27 Percentile:84.7(Multidisciplinary Sciences)

Journal Articles

Resonant inelastic X-ray scattering study of electronic excitations in insulating K$$_{0.83}$$Fe$$_{1.53}$$Se$$_2$$

Gretarsson, H.*; Nomura, Takuji; Jarrige, I.*; Lupascu, A.*; Upton, M. H.*; Kim, J.*; Casa, D.*; Gog, T.*; Yuan, R. H.*; Chen, Z. G.*; et al.

Physical Review B, 91(24), p.245118_1 - 245118_8, 2015/06

 Times Cited Count:6 Percentile:28.15(Materials Science, Multidisciplinary)

Journal Articles

Energetic ion transport by microturbulence is insignificant in tokamaks

Pace, D. C.*; Austin, M. E.*; Bass, E. M.*; Budny, R.*; Heidbrink, W. W.*; Hillesheim, J. C.*; Holcomb, C. T.*; Gorelenkova, M.*; Grierson, B. A.*; McCune, D. C.*; et al.

Physics of Plasmas, 20(5), p.056108_1 - 056108_18, 2013/05

 Times Cited Count:32 Percentile:82.46(Physics, Fluids & Plasmas)

Energetic ion transport due to microturbulence is investigated in MHD-quiescent plasmas by way of neutral beam injection in the DIII-D tokamak. A range of on-axis and off-axis beam injection scenarios are employed to vary relevant parameters such as the character of the background microturbulence and the value of Eb/Te, where Eb is the energetic ion energy and Te the electron temperature. In all cases it is found that any transport enhancement due to microturbulence is too small to observe experimentally. These transport effects are modeled using numerical and analytic expectations that calculate the energetic ion diffusivity due to microturbulence. It is determined that energetic ion transport due to coherent modes, including possible reductions in neutral beam current drive, is a considerably larger effect and should therefore be considered more important for ITER.

Journal Articles

The Spectra of the multicharged argon hollow ions; Observation, modeling and using for diagnostics of the early stage of the heating of clusters by a supper high contrast femtosecond laser pulses

Pikuz, T.; Faenov, A.*; Skobelev, I.*; Fortov, V. E.*; Boldarev, A.*; Gasilov, V.*; Chen, L. M.*; Zhang, L.*; Yan, W.*; Yuan, D.*; et al.

AIP Conference Proceedings 1465, p.181 - 201, 2012/07

 Times Cited Count:0 Percentile:0.13

Journal Articles

Study of X-ray emission enhancement via a high-contrast femtosecond laser interacting with a solid foil

Chen, L.-M.; Kando, Masaki; Xu, M. H.*; Li, Y.-T.*; Koga, J. K.; Chen, M.*; Xu, H.*; Yuan, X.-H.*; Dong, Q. L.*; Sheng, Z. M.*; et al.

Physical Review Letters, 100(4), p.045004_1 - 045004_4, 2008/02

 Times Cited Count:90 Percentile:92.62(Physics, Multidisciplinary)

We observed the increase of the K-$$alpha$$ X-ray conversion efficiency (hK) produced by a 60 fs frequency doubled high contrast laser pulse focused on Cu foil, compared to the case of the fundamental laser pulse. hK shows a strong dependence on the nonlinearly skewed shape of the laser pulse. It reaches a maximum for a 100 fs negatively skewed pulse. The electron spectrum shaping contributes to the enhancement of hK. Simulations demonstrate that high contrast lasers are an effective tool for optimizing the X-ray emission, via the enhanced Vacuum Heating mechanism.

Journal Articles

Microvoid formation in hydrogen-implanted ZnO probed by a slow positron beam

Chen, Z. Q.; Kawasuso, Atsuo; Xu, Y.; Naramoto, Hiroshi*; Yuan, X. L.*; Sekiguchi, Takashi*; Suzuki, Ryoichi*; Odaira, Toshiyuki*

Physical Review B, 71(11), p.115213_1 - 115213_8, 2005/03

 Times Cited Count:104 Percentile:93.73(Materials Science, Multidisciplinary)

ZnO crystals were implanted with 20-80 keV hydrogen ions up to a total dose of 4.4$$times$$10$$^{15}$$ cm$$^{-2}$$. Positron annihilation measurements show introduction of zinc vacancies, which are filled with hydrogen atoms. After isochronal annealing at 200-500 $$^{circ}$$C, the vacancies agglomerate into hydrogen bubbles. Further annealing at 600-700 $$^{circ}$$C causes release of hydrogen out of the bubbles, leaving large amount of microvoids. These microvoids are annealed out at high temperature of 1000 $$^{circ}$$C. Cathodoluminescence measurements reveal that hydrogen ions also passivate deep level emission centers before their release from the sample, and lead to the improvement of the UV emission.

Journal Articles

Production and recovery of defects in phosphorus-implanted ZnO

Chen, Z. Q.; Kawasuso, Atsuo; Xu, Y.; Naramoto, Hiroshi; Yuan, X. L.*; Sekiguchi, Takashi*; Suzuki, Ryoichi*; Odaira, Toshiyuki*

Journal of Applied Physics, 97(1), p.013528_1 - 013528_6, 2005/01

 Times Cited Count:147 Percentile:96.39(Physics, Applied)

Phosphorus ions were implanted into ZnO crystals with energies of 50-380 keV to a dose of 10$$^{13}$$-10$$^{15}$$ cm$$^{-2}$$. Positron annihilation measurements show the introduction of vacancy clusters after implantation. These vacancy clusters evolve to microvoids after annealing at a temperature of 600$$^{circ}$$C, and disappear gradually up to 1100$$^{circ}$$C. Raman scattering measurements show the production of oxygen vacancies (V$$_{O}$$). They are annealed up to 700$$^{circ}$$C accompanying the agglomeration of vacancy clusters. The light emissions of ZnO are suppressed due to the competing nonradiative recombination centers introduced by implantation. Recovery of the light emission occurs above 600$$^{circ}$$C. The vacancy-type defects detected by positrons might be part of the nonradiative recombination centers. Hall measurement shows n-type conductivity for the P$$^+$$-implanted ZnO layer, which suggests that phosphorus is an amphoteric dopant.

Journal Articles

Hydrogen bubble formation in H-implanted ZnO studied using a slow positron beam

Chen, Z. Q.; Maekawa, Masaki; Kawasuso, Atsuo; Yamamoto, Shunya; Yuan, X. L.*; Sekiguchi, Takashi*; Suzuki, Ryoichi*; Odaira, Toshiyuki*

JAERI-Review 2004-025, TIARA Annual Report 2003, p.193 - 195, 2004/11

20-80 keV hydrogen ions were implanted into ZnO single crystals up to a total dose of 4.4$$times$$10$$^{15}$$ cm$$^{-2}$$. Positron annihilation measurements using a slow positron beam revealed introduction of vacancies after implantation, which are filled with hydrogen impurities. After annealing, these hydrogen filled vacancies grow into large hydrogen bubbles. At annealing temperature of 500-700$$^{circ}$$C, these hydrogen impurities are released from the bubbles, and remain open microvoids. These microvoids are finally annealed out at about 1100$$^{circ}$$C. The effects of hydrogen implantation on the light luminescence in ZnO will also be discussed.

Journal Articles

Evolution of voids in Al$$^+$$-implanted ZnO probed by a slow positron beam

Chen, Z. Q.; Maekawa, Masaki; Yamamoto, Shunya; Kawasuso, Atsuo; Yuan, X. L.*; Sekiguchi, Takashi*; Suzuki, Ryoichi*; Odaira, Toshiyuki*

Physical Review B, 69(3), p.035210_1 - 035210_10, 2004/01

 Times Cited Count:91 Percentile:93.48(Materials Science, Multidisciplinary)

Introduction and annealing behavior of defects in Al$$^+$$-implanted ZnO have been studied using energy variable slow positron beam. Vacancy clusters are produced after Al$$^+$$-implantation. With increasing ion dose above 10$$^{14}$$ Al$$^+$$/cm$$^2$$ the implanted layer is amorphized. Heat treatment up to 600 $$^{circ}$$C enhances the creation of large voids that allow the positronium formation. The large voids disappear accompanying the recrystallization process by the further heat treatment above 600 $$^{circ}$$C. Afterwards, implanted Al impurities are completely activated to contribute the n-type conduction. The ZnO crystal quality is also improved after recrystallization.

Journal Articles

Present status of the negative ion based neutral beam injector for JT-60U

Oga, Tokumichi; Umeda, Naotaka; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; et al.

Review of Scientific Instruments, 73(2), p.1058 - 1060, 2002/02

 Times Cited Count:12 Percentile:55.36(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Study of increasing the beam power on the negative ion based neutral beam injector for JT-60U

Kuriyama, Masaaki; Akino, Noboru; Ebisawa, Noboru; Grisham, L. R.*; Hikida, Shigenori*; Honda, Atsushi; Ito, Takao; Kawai, Mikito; Kazawa, Minoru; Kusaka, Makoto*; et al.

Fusion Engineering and Design, 56-57(Part.A), p.523 - 527, 2001/10

 Times Cited Count:5 Percentile:39.04(Nuclear Science & Technology)

no abstracts in English

Journal Articles

The Arabidopsis dwarf1 mutant is defective in the conversion of 24-methylenecholesterol to campesterol in brassinosteroid biosynthesis

Choe, S.*; Dilkes, B. P.*; Gregory, B. D.*; Ross, A. S.*; Yuan, H.*; Noguchi, Takahiro*; Fujioka, Shozo*; Takatsuto, Suguru*; Tanaka, Atsushi; Yoshida, Shigeo*; et al.

Plant Physiology, 119(3), p.897 - 907, 1999/03

 Times Cited Count:184 Percentile:97.2(Plant Sciences)

no abstracts in English

17 (Records 1-17 displayed on this page)
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