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Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri. A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:1 Percentile:100(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Shell evolution of $$N$$ = 40 isotones towards $$^{60}$$Ca; First spectroscopy of $$^{62}$$Ti

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Men$'e$ndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

 Times Cited Count:2 Percentile:11.68(Astronomy & Astrophysics)

Excited states in the $$N$$ = 40 isotone $$^{62}$$Ti were populated via the $$^{63}$$V($$p$$,$$2p$$)$$^{62}$$Ti reaction at $$sim$$200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using $$gamma$$-ray spectroscopy. The energies of the $$2_1^+ rightarrow 0_{rm gs}^+$$ and $$4_1^+ rightarrow 2_1^+$$ transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring $$^{64}$$Cr and $$^{66}$$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Journal Articles

Quasifree neutron knockout from $$^{54}$$Ca corroborates arising $$N=34$$ neutron magic number

Chen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.

Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10

 Times Cited Count:6 Percentile:18.18(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Fusion reaction $$^{48}$$Ca+$$^{249}$$Bk leading to formation of the element Ts (Z=117)

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review C, 99(5), p.054306_1 - 054306_16, 2019/05

 Times Cited Count:5 Percentile:16.29(Physics, Nuclear)

We have performed an experiment to synthesize the element 117 (Ts) with the $$^{48}$$Ca+$$^{249}$$Bk fusion reaction. Four $$alpha$$-decay chains attributed to the element 117 were observed. Two of them were long decay chains which can be assigned to the one originating from the $$alpha$$ decay of $$^{294}$$Ts. The other two were short decay chains which are consistent with the one originating from the $$alpha$$ decay of $$^{293}$$Ts. We have compared the present results with the literature data, and found that our present results mostly confirmed the literature data, leading to the firm confirmation of the synthesis of the element 117.

Journal Articles

Neutron-hole states in $$^{131}$$Sn and spin-orbit splitting in neutron-rich nuclei

Orlandi, R.; Pain, S. D.*; Ahn, S.*; Jungclaus, A.*; Schmitt, K. T.*; Bardayan, D. W.*; Catford, W. N.*; Chapman, R.*; Chipps, K. A.*; Cizewski, J. A.*; et al.

Physics Letters B, 785, p.615 - 620, 2018/10

 Times Cited Count:4 Percentile:37.52(Astronomy & Astrophysics)

Journal Articles

RELAP5 modeling of the HTTR-GT/H$$_{2}$$ secondary system and turbomachinery

Humrickhouse, P. W.*; Sato, Hiroyuki; Imai, Yoshiyuki; Sumita, Junya; Yan, X. L.

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 9 Pages, 2018/10

This work describes the development of a RELAP5-3D model of the HTTR-GT/H$$_{2}$$ plant secondary system. The RELAP5-3D model presently includes detailed models of several of the heat exchangers in the secondary system as well as the turbomachinery, which includes two compressors and two gas turbines connected to a common shaft and motor. The predictions of the model agreed well to design parameters in both sole power generation and hydrogen co-generation modes in most instances. Both the turbomachinery and heat exchanger models rely on extensive customization via RELAP5-3D control variables, and these implementations are outlined in detail. Potential improvements to the RELAP5-3D turbine model are discussed.

Journal Articles

In situ observations reveal how spectral reflectance responds to growing season phenology of an open evergreen forest in Alaska

Kobayashi, Hideki*; Nagai, Shin*; Kim, Y.*; Yan, W.*; Ikeda, Kyoko*; Ikawa, Hiroki*; Nagano, Hirohiko; Suzuki, Rikie*

Remote Sensing, 10(7), p.1071_1 - 1071_19, 2018/07

 Times Cited Count:4 Percentile:57.65(Remote Sensing)

Plant phenology timings, such as spring green-up and autumn senescence, are essential state information characterizing biological responses and terrestrial carbon cycles. Current efforts for the in situ reflectance measurements are not enough to obtain the exact interpretation of how seasonal spectral signature responds to phenological stages in boreal evergreen needleleaf forests. This study shows the first in situ continuous measurements of canopy scale (overstory + understory) and understory spectral reflectance and vegetation index in an open boreal forest in interior Alaska. Two visible and near infrared spectroradiometer systems were installed at the top of the observation tower and the forest understory, and spectral reflectance measurements were performed in 10 min intervals from early spring to late autumn. We found that canopy scale normalized difference vegetation index (NDVI) varied with the solar zenith angle. On the other hand, NDVI of understory plants was less sensitive to the solar zenith angle. Due to the influence of the solar geometry, the annual maximum canopy NDVI observed in the morning satellite overpass time (10-11 am) shifted to the spring direction compared with the standardized NDVI by the fixed solar zenith angle range (60-70 degree). We also found that the in situ NDVI time-series had a month-long high NDVI plateau in autumn, which was completely out of photosynthetically active periods when compared with eddy covariance net ecosystem exchange measurements. The result suggests that the onset of an autumn high NDVI plateau is likely to be the end of the growing season. In this way, our spectral measurements can serve as baseline information for the development and validation of satellite-based phenology algorithms in the northern high latitudes.

Journal Articles

The $$^{95}$$Zr($$n, gamma$$)$$^{96}$$Zr cross section from the surrogate ratio method and its effect on $$s$$-process nucleosynthesis

Yan, S. Q.*; Li, Z. H.*; Wang, Y. B.*; Nishio, Katsuhisa; Lugaro, M.*; Karakas, A. I.*; Makii, Hiroyuki; Mohr, P.*; Su, J.*; Li, Y. J.*; et al.

Astrophysical Journal, 848(2), p.98_1 - 98_8, 2017/10

 Times Cited Count:0 Percentile:100(Astronomy & Astrophysics)

Journal Articles

Examination of the surrogate ratio method for the determination of the $$^{93}$$Zr(n,$$gamma$$)$$^{94}$$Zr cross section with $$^{90,92}$$Zr($$^{18}$$O,$$^{16}$$O)$$^{92,94}$$Zr reactions

Yan, S. Q.*; Li, Z. H.*; Wang, Y. B.*; Nishio, Katsuhisa; Makii, Hiroyuki; Su, J.*; Li, Y. J.*; Nishinaka, Ichiro; Hirose, Kentaro; Han, Y. L.*; et al.

Physical Review C, 94(1), p.015804_1 - 015804_5, 2016/07

 Times Cited Count:3 Percentile:62.53(Physics, Nuclear)

Journal Articles

Energy neutral phosphate fertilizer production using high temperature reactors; A Philippine case study

Haneklaus, N.*; Reyes, R.*; Lim, W. G.*; Tabora, E. U.*; Palattao, B. L.*; Petrache, C.*; Vargas, E. P.*; Kunitomi, Kazuhiko; Ohashi, Hirofumi; Sakaba, Nariaki; et al.

Philippine Journal of Science, 144(1), p.69 - 79, 2015/06

The Philippines may profit from extracting uranium (U) from phosphoric acid during fertilizer production in a way that the recovered U can be beneficiated and taken as raw material for nuclear reactor fuel. Used in a high temperature reactor (HTR) that provides electricity and/or process heat for fertilizer processing and U extraction, energy-neutral fertilizer production, an idea first proposed by Haneklaus et al., is possible. This paper presents a first case study of the concept regarding a representative phosphate fertilizer plant in the Philippines and exemplary HTR designs (HTR50S and GTHTR300C) developed by the Japan Atomic Energy Agency (JAEA). Three different arrangements (version I-III), ranging from basic electricity supply to overall power supply including on site hydrogen production for ammonia conversion, are introduced and discussed.

Journal Articles

Overview of plasma-material interaction experiments on EAST employing MAPES

Ding, F.*; Luo, G.-N.*; Pitts, R.*; Litnovsky, A.*; Gong, X.*; Ding, R.*; Mao, H.*; Zhou, H.*; Wampler, W. R.*; Stangeby, P. C.*; et al.

Journal of Nuclear Materials, 455(1-3), p.710 - 716, 2014/12

 Times Cited Count:21 Percentile:7.65(Materials Science, Multidisciplinary)

Journal Articles

$$^{48}$$Ca + $$^{249}$$Bk fusion reaction leading to element Z = 117; Long-lived $$alpha$$-decaying $$^{270}$$Db and discovery of $$^{266}$$Lr

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review Letters, 112(17), p.172501_1 - 172501_5, 2014/05

 Times Cited Count:162 Percentile:1.18(Physics, Multidisciplinary)

The superheavy element with atomic number 117 was produced in the $$^{48}$$Ca + $$^{249}$$Bk fusion reaction using the gas-filled recoil separator TASCA at GSI in Germany. This result verified the previous result of the discovery of new element 117 reported by Flerov Laboratory of Nuclear Reactions in Russia, which makes certain the synthesis and discovery of element 117 in human history. On the other hand, the last nucleus in the $$alpha$$ decay chain from the element 117 was assigned to be the unknown nucleus $$^{266}$$Lr instead of the previously reported $$^{270}$$Db, and $$^{270}$$Db was found to be the $$alpha$$-decaying nucleus with very long half-life.

Journal Articles

An International initiative on long-term behavior of high-level nuclear waste glass

Gin, S.*; Abdelouas, A.*; Criscenti, L.*; Ebert, W.*; Ferrand, K.*; Geisler, T.*; Harrison, M.*; Inagaki, Yaohiro*; Mitsui, Seiichiro; Mueller, K. T.*; et al.

Materials Today, 16(6), p.243 - 248, 2013/06

 Times Cited Count:202 Percentile:1.35(Materials Science, Multidisciplinary)

The nations producing borosilicate glass as a confinement material for high-level waste resulting from spent fuel reprocessing have decided to reinforce scientific collaboration in order to obtain consensus on the mechanisms controlling the long-term dissolution rate of glass. This goal is the most important issue for developing reliable predictive models usable for performance assessment and safety demonstration of geological storage of such materials. This collaboration involves numerous laboratories working either in fundamental or applied research and using all the modern tools available in material science. We present first the situation of the six countries involved in the project regarding their history in nuclear waste vitrification, current policy, and geological disposal project development. This provides an understanding of the common and country specific needs regarding the issue of long-term behavior of glass. Then main proposals and first results are briefly presented.

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:28 Percentile:13.33(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:100

Journal Articles

Local thermal expansion and the C-C stretch vibration of the dicarbon antisite in 4H SiC

Devaty, R. P.*; Yan, F.*; Choyke, W. J.*; Gali, A.*; Kimoto, Tsunenobu*; Oshima, Takeshi

Materials Science Forum, 717-720, p.263 - 266, 2012/05

 Times Cited Count:1 Percentile:36.05

Journal Articles

Anharmonic vibrations of the dicarbon antisite defect in 4H-SiC

Yan, F.*; Devaty, R. P.*; Choyke, W. J.*; Gali, A.*; Kimoto, Tsunenobu*; Oshima, Takeshi; Pensl, G.*

Applied Physics Letters, 100(13), p.132107_1 - 132107_3, 2012/03

 Times Cited Count:2 Percentile:89.21(Physics, Applied)

Journal Articles

On maximizing the ICRF antenna loading for ITER plasmas

Mayoral, M.-L.*; Bobkov, V.*; Colas, L.*; Goniche, M.*; Hosea, J.*; Kwak, J. G.*; Pinsker, R.*; Moriyama, Shinichi; Wukitch, S.*; Baity, F. W.*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 11 Pages, 2011/03

For any given ICRF antenna design for ITER, the maximum achievable power strongly depends on the density profiles in the SOL. It has been suggested that gas injection can be used to modify the SOL profiles and thus minimize the sensitivity of the ICRF coupling to variations in the density at the edge of the confined plasma. Recently joint experiments coordinated by the ITPA were performed to characterize further this method. An increase in SOL density during gas injection led to improved coupling for all tokamaks in this multi-machine comparison. The effectiveness of using gas injection over a wide range of conditions, as a tool to tailor the edge density in front of the ICRF antennas, is documented for different gas inlet location and plasma configurations. In addition, any deleterious effects on the confinement and interaction with the antenna near-field are not investigated.

Journal Articles

From a single-band metal to a high-temperature superconductor via two thermal phase transitions

He, R.-H.*; Hashimoto, Makoto*; Karapetyan, H.*; Koralek, J. D.*; Hinton, J. P.*; Testaud, J. P.*; Nathan, V.*; Yoshida, Yoshiyuki*; Yao, H.*; Tanaka, Kiyohisa*; et al.

Science, 331(6024), p.1579 - 1583, 2011/03

 Times Cited Count:230 Percentile:1.15(Multidisciplinary Sciences)

The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature $$T^*$$ using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at $$T^*$$ of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature ($$T_c$$), entangled in an energy-momentum dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.

Journal Articles

Tomography of an ultrafast laser driven proton source

Ter-Avetisyan, S.*; Schn$"u$rer, M.*; Nickles, P. V.*; Sandner, W.*; Borghesi, M.*; Nakamura, Tatsufumi; Mima, Kunioki*

Physics of Plasmas, 17(6), p.063101_1 - 063101_6, 2010/06

 Times Cited Count:7 Percentile:68.17(Physics, Fluids & Plasmas)

Using a multichannel Thomson spectrometer we have implemented a tomographic approach allowing the reconstruction of the emission characteristics of a laser driven proton source with high energy and spatial resolution. The results demonstrate the complexity of the temporal and spatial characteristics of such a source. The emitted proton beam, which is laminar and divergent ant high energies, becomes convergent at low energies. This implies that a fraction of the proton beam having this kinetic energy is emitted in a collimated way from the target at the turning point between these tow behaviors. Only a finite fraction of the target surface is contributing to the ion spectrum, which is measured at a specific angle within the beam cone. Therefore the momentum distribution of the protons in the emitted beam at any point in space can be controlled by determining the proton source area.

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