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Structural and compositional characteristics of Fukushima release particulate material from Units 1 and 3 elucidates release mechanisms, accident chronology and future decommissioning strategy

Martin, P. G.*; Jones, C. P.*; Bartlett, S.*; Ignatyev, K.*; Megson-Smith, D.*; 佐藤 志彦; Cipiccia, S.*; Batey, D. J.*; Rau, C.*; 末木 啓介*; et al.

Scientific Reports (Internet), 10, p.22056_1 - 22056_17, 2020/12

 被引用回数:0 パーセンタイル:0.01(Multidisciplinary Sciences)

The structural form and elemental distribution of material originating from different Fukushima Daiichi Nuclear Power Plant reactors (Units 1 and 3) is hereby examined to elucidate their contrasting release dynamics and the current in-reactor conditions to influence future decommissioning challenges. Complimentary computed X-ray absorption tomography and X-ray fluorescence data show that the two suites of Si-based material sourced from the different reactor Units have contrasting internal structure and compositional distribution. The known event and condition chronology correlate with the observed internal and external structures of the particulates examined, which suggest that Unit 1 ejecta material sustained a greater degree of melting than that likely derived from reactor Unit 3. In particular, we attribute the near-spherical shape of Unit 1 ejecta and their internal voids to there being sufficient time for surface tension to round these objects before the hot (and so relatively low viscosity) silicate melt cooled to form glass. In contrast, a more complex internal form associated with the sub-mm particulates invoked to originate from Unit 3 suggest a lower peak temperature, over a longer duration. Using volcanic analogues, we consider the structural form of this material and how it relates to its environmental particulate stability and the bulk removal of residual materials from the damaged reactors. We conclude that the brittle and angular Unit 3 particulate are more susceptible to further fragmentation and particulate generation hazard than the round, higher-strength, more homogenous Unit 1 material.


International network of nuclear structure and decay data evaluators

Dimitriou, P.*; Basunia, S*; Bernstein, L.*; Chen, J.*; Elekes, Z.*; Huang, X.*; Hurst, A.*; 飯村 秀紀; Jain, A. K.*; Kelley, J.*; et al.

EPJ Web of Conferences, 239, p.15004_1 - 15004_4, 2020/09

 被引用回数:0 パーセンタイル:0.19

評価済み核構造データファイル(Evaluated Nuclear Structure Data File: ENSDF)は、原子核構造と崩壊に関する様々な実験データを全ての核種について集めて、それらの実験データの評価値を与えてある世界唯一のデータファイルである。ENSDFは定期的に更新されており、そのための評価作業は各国の評価者で分担している。評価作業を速やかに行うために、IAEAの援助の下に評価者の国際的なネットワークが組織されている。この発表では、ネットワークの最近の活動のうち、ENSDFの処理コードの開発、測定が必要とされているデータのリストの作成、インターネット版核図表の利用の拡充などについて報告する。また、核構造・崩壊データの需要が増大しているにもかかわらず、評価者が減っている問題についても述べる。


$$alpha$$-decay branching ratio of $$^{180}$$Pt

Cubiss, J. G.*; Harding, R. D.*; Andreyev, A. N.; Althubiti, N.*; Andel, B.*; Antalic, S.*; Barzakh, A. E.*; Cocolios, T. E.*; Day Goodacre, T.*; Farooq-Smith, G. J.*; et al.

Physical Review C, 101(1), p.014314_1 - 014314_4, 2020/01

 被引用回数:5 パーセンタイル:84.86(Physics, Nuclear)



Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes; Coulomb excitation of $$^{182}$$Hg, $$^{184}$$Hg, $$^{186}$$Hg and $$^{188}$$Hg

Wrzosek-Lipska, K.*; Rezynkina, K.*; Bree, N.*; Zieli$'n$ska, M.*; Gaffney, L. P.*; Petts, A.*; Andreyev, A. N.; Bastin, B.*; Bender, M.*; Blazhev, A.*; et al.

European Physical Journal A, 55(8), p.130_1 - 130_23, 2019/08

 被引用回数:7 パーセンタイル:80.58(Physics, Nuclear)

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass $$^{182-188}$$Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0$$^{+}_{1,2}$$, 2$$^{+}_{1,2}$$, and 4$$^{+}_{1}$$ states was observed in all nuclei under study. Reduced $$E2$$ matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.


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

 被引用回数:5 パーセンタイル:56.63(Astronomy & Astrophysics)

Low-lying neutron-hole states in $$^{131}$$Sn were populated via the $$^{132}$$Sn(d,t) reaction at Oak Ridge National Laboratory. The triton angular distributions were compared to DWBA calculations and revealed spectroscopic factors compatible with a single-hole nature of the states populated. The data permit to determine the spin-orbit splitting of the strongly bound $$d_{3/2}$$ and $$d_{5/2}$$ neutron orbits below the shell gap, which was compared to the splitting of the weakly bound 3$$p$$ and 2$$f$$ orbits above the gap. The comparison revealed a smaller energy splitting of the 3$$p$$ orbits. All splittings were reproduced using Woods-Saxon calculations, and the lower splitting of the 3$$p$$ orbits was explained to arise from the large radial extent of the wavefunction and small value of the amplitude at the surface. This result is important to understand at a fundamental level the spin-orbit interaction, and its effects on neutron-rich nuclei.


EXILL; A High-efficiency, high-resolution setup for $$gamma$$-spectroscopy at an intense cold neutron beam facility

Jentschel, M.*; Blanc, A.*; de France, G.*; K$"o$ster, U.*; Leoni, S.*; Mutti, P.*; Simpson, G.*; Soldner, T.*; Ur, C.*; Urban, W.*; et al.

Journal of Instrumentation (Internet), 12(11), p.P11003_1 - P11003_33, 2017/11

 被引用回数:27 パーセンタイル:86.8(Instruments & Instrumentation)

A highly efficient array of high-purity germanium (HPGe) detectors was developed and operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of $$gamma$$-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 10$$^8$$ns$$^{-1}$$cm$$^{-2}$$ at the target position and negligible neutron halo. The target was surrounded by an array of eight to ten anti-Compton shielded EXOGAM Clover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr$$_{3}$$:(Ce) detectors from the FATIMA collaboration.


Collectivity in the light radon nuclei measured directly via Coulomb excitation

Gaffney, L. P.*; Robinson, A. P.*; Jenkins, D. G.*; Andreyev, A.; Bender, M.*; Blazhev, A.*; Bree, N.*; Bruyneel, B.*; Butler, P.*; Cocolios, T. E.*; et al.

Physical Review C, 91(6), p.064313_1 - 064313_11, 2015/06

 被引用回数:8 パーセンタイル:57.47(Physics, Nuclear)

Radioactive ion beams of $$^{202,204}$$Rn were studied by means of low-energy Coulomb excitation at REX-ISOLDE, CERN. The electric-quadrupole (E2) matrix elements connecting the first excited 2$$^+$$ to the ground state of these nuclei was extracted, which permits to determine the collectivity of these isotopes, which in both cases is deduced to be weak, as expected from the low-lying level-energy scheme. Comparisons were also made with beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced.


Single-neutron orbits near $$^{78}$$Ni; Spectroscopy of the N=49 isotope $$^{79}$$Zn

Orlandi, R.; M$"u$cher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.

Physics Letters B, 740, p.298 - 302, 2015/01

 被引用回数:20 パーセンタイル:82.78(Astronomy & Astrophysics)

Single-neutron states in $$^{79}$$Zn have been populated using the reaction $$^{78}$$Zn(d,p) at REX-Isolde, CERN. The analysis reveals that the lowest excited states in $$^{79}$$Zn lie at approximately 1 MeV, and involve neutron orbits above the N=50 shell gap. A 5/2$$^{+}$$ configuration was assigned to the 983-keV state. Comparison with large-scale shell model calculations supports a robust neutron N=50 shell closure for $$^{78}$$Ni. These data constitute an important step towards the understanding the magicity of $$^{78}$$Ni and the structure of nuclei in the region.


$$B(E2;2^+_1rightarrow 0^+_1)$$ value in $$^{90}$$Kr

R$'e$gis, J.-M.*; Jolie, J.*; Saed-Samii, N.*; Warr, N.*; Pfeiffer, M.*; Blanc, A.*; Jentschel, M.*; K$"o$ster, U.*; Mutti, P.*; Soldner, T.*; et al.

Physical Review C, 90(6), p.067301_1 - 067301_4, 2014/12

 被引用回数:21 パーセンタイル:82.71(Physics, Nuclear)

A smooth onset of collectivity in $$^{88,92,94,96}$$Kr has been determined from reported $$B(E2;2^+_1rightarrow 0^+_1)$$ and E(2$$^+_1$$) values. This is in contrast to the sudden onset in even-even Zr, Mo, and Sr isotopes. Our objective was to complete the systematics by determining the $$B(E2;2^+_1rightarrow 0^+_1)$$ value in $$^{90}$$Kr, which was produced by cold-neutron-induced fission of $$^{235}$$U. The lifetime of the 2$$^+_1$$ state in $$^{90}$$Kr was measured via the electronic $$gamma - gamma$$ timing technique using the EXILL and FATIMA spectrometers. Based on the measured mean lifetime of $$tau$$ = 15(10) ps, the $$B(E2;2^+_1rightarrow 0^+_1)$$ value of 13$$^{+26}_{-5}$$ W.u. in $$^{90}$$Kr is determined for the first time and the smooth onset of deformation in the even-even Kr isotopes beyond neutron number N=50 is confirmed.


Observation of $$^{239}$$Pu nuclear magnetic resonance

安岡 弘志; Koutroulakis, G.*; 中堂 博之; Richmond, S.*; Veirs, D. K.*; Smith, A. I.*; Bauer, E. D.*; Thompson, J. D.*; Jarvinen, G. D.*; Clark, D. L.*

Science, 336(6083), p.901 - 904, 2012/05

 被引用回数:42 パーセンタイル:86.45(Multidisciplinary Sciences)

The spin-1/2 plutonium-239 ($$^{239}$$Pu) nucleus should in principle be active in nuclear magnetic resonance spectroscopy. However, its signal has eluded detection for the past fifty years. Here, we report observation of a $$^{239}$$Pu resonance from a solid sample of plutonium dioxide, PuO$$_2$$, subjected to a wide scan of external magnetic field values ($$B_0=3$$ to 8T) at a temperature of 4 Kelvin. By mapping the external field dependence of the measured resonance frequency, we determined the nuclear gyromagnetic ratio $$^{239}$$$$gamma$$$$_{rm n}$$(PuO$$_2$$)/2$$pi$$ to be 2.856 $$pm$$ 0.001 MHz/T. Assuming a free-ion value for the Pu$$^{4+}$$ hyperfine coupling constant, we estimated a bare $$^{239}$$$$gamma$$$$_{rm n}$$/2$$pi$$ value of approximately 2.29 MHz/T, corresponding to a nuclear magnetic moment of $$mu$$$$_{rm n}$$ $${approx}$$ 0.15 $$mu$$$$_{rm N}$$ (where $$mu$$$$_{rm N}$$ is the nuclear magneton).


Structural analysis and superconductivity of CeFeAsO$$_{1-x}$$H$$_{x}$$

松石 聡*; 半那 拓*; 村場 善行*; Kim, S. W.*; Kim, J. E.*; 高田 昌樹*; 社本 真一; Smith, R. I.*; 細野 秀雄*

Physical Review B, 85(1), p.014514_1 - 014514_6, 2012/01

 被引用回数:41 パーセンタイル:85.51(Materials Science, Multidisciplinary)

LnFeAsO$$_{1-x}$$H$$_{x}$$($$Ln$$=lanthanoid)の1111型鉄系超伝導体を代表して、CeFeAsO$$_{1-x}$$(D,H)$$_{x}$$ ($$x$$=0.0-0.48)で粉末中性子回折と放射光X線回折測定を行った。これらの結果は、出発物質の水素の種類に関係なく両方の試料でH$$^{-}$$イオンが酸素サイトを占めていることを強く示唆している。


ENDF/B-VII.1 nuclear data for science and technology; Cross sections, covariances, fission product yields and decay data

Chadwick, M. B.*; Herman, M.*; Oblo$v{z}$insk$'y$, P.*; Dunn, M. E.*; Danon, Y.*; Kahler, A. C.*; Smith, D. L.*; Pritychenko, B.*; Arbanas, G.*; Arcilla, R.*; et al.

Nuclear Data Sheets, 112(12), p.2887 - 2996, 2011/12

 被引用回数:1623 パーセンタイル:100(Physics, Nuclear)



Cross-shell excitations near the "island of inversion"; Structure of $$^{30}$$Mg

Daecon, A. N.*; Smith, J. F.*; Freeman, S. J.*; Janssens, R. V. F.*; Carpenter, M. P.*; Hadinia, B.*; Hoffman, C. R.*; Kay, B. P.*; Lauritsen, T.*; Lister, C. J.*; et al.

Physical Review C, 82(3), p.034305_1 - 034305_7, 2010/09

 被引用回数:19 パーセンタイル:75.27(Physics, Nuclear)



$$^{235}$$U nuclear relaxation rates in an itinerant antiferromagnet USb$$_2$$

Baek, S.-H.*; Curro, N. J.*; 酒井 宏典; Bauer, E. D.*; Cooley, J. C.*; Smith, J. L.*

Physical Review B, 81(5), p.054435_1 - 054435_5, 2010/02

 被引用回数:5 パーセンタイル:28.15(Materials Science, Multidisciplinary)

$$^{235}$$U nuclear spin-lattice ($$T_1^{-1}$$) and spin-spin ($$T_2^{-1}$$) relaxation rates in the itinerant antiferromagnet USb$$_2$$ are reported as a function of temperature in zero field. The heating effect from the intense rf pulses that are necessary for the $$^{235}$$U NMR results in unusual complex thermal recovery of the nuclear magnetization which does not allow measuring $$T_1^{-1}$$ directly. By implementing an indirect method, however, we successfully extracted $$T_1^{-1}$$ of the $$^{235}$$U. We find that the temperature dependence of $$T_1^{-1}$$ for both $$^{235}$$U and $$^{121}$$Sb follows the power law ($$propto T^{n}$$) with the small exponent $$n$$ = 0.3 suggesting that the same relaxation mechanism dominates the on-site and the ligand nuclei, but an anomaly at 5 K was observed, possibly due to the change in the transferred hyperfine coupling on the Sb site.


Computational infrastructure for nuclear astrophysics

Smith, M. S.*; Lingerfelt, E. J.*; Scott, J. P.*; Nesaraja, C. D.*; Hix, W. R.*; Chae, K.*; 小浦 寛之; Meyer, R. A.*; Bardayan, D. W.*; Blackmon, J. C.*; et al.

AIP Conference Proceedings 847, p.470 - 472, 2006/07

インターネット上で利用可能な天体核物理に関するコンピュータシステムのサイトを再構築した。これは、天体物理のシミュレーションを最新の原子核物理の結果を用いて行うように作成されたシステムで、URL: nucastrodata.orgから無料で利用可能である。Java言語を用いて作成されたシステムであり、Windows, Macintosh, Unixといったプラットホームに依存せず、数回のマウス操作で中性子捕獲反応率、原子核質量等といった核データの可視化や、p過程やr過程といった元素合成計算の結果をアニメーション動画として表示することを平易に行うことが可能である。今回の再構築で特に原子核質量の可視化及びr過程元素合成の動画化のシステムを新たに開発した。


Multipass beam breakup in energy recovery linacs

Pozdeyev, E.*; Tennant, C.*; Bisognano, J. J.*; 沢村 勝; 羽島 良一; Smith, T. I.*

Nuclear Instruments and Methods in Physics Research A, 557(1), p.176 - 188, 2006/02

 被引用回数:12 パーセンタイル:65.95(Instruments & Instrumentation)



New features in the computational infrastructure for nuclear astrophysics

Smith, M. S.*; Lingerfelt, E. J.*; Scott, J. P.*; Nesaraja, C. D.*; Chae, K.*; 小浦 寛之; Roberts, L. F.*; Hix, W. R.*; Bardayan, D. W.*; Blackmon, J. C.*

Proceedings of Science (Internet), 5 Pages, 2006/00



Nuclear masses; Theoretical models, experimental evaluations, & web disseminations

Smith, M. S.*; Kondev, F.*; 小浦 寛之; Lingerfelt, E. J.*; Buckner, K.*; Nesaraja, C. D.*

no journal, , 



Visualization, analyis, and management of nuclear mass information at nucearmasses.org

Smith, M. S.*; Lingerfelt, E. J.*; Buckner, K.*; Nesaraja, C. D.*; 小浦 寛之; Kondev, F.*

no journal, , 

原子核質量データを効率的に利用するためのインターネットツール"nuclearmasses.org"を開発した。このWebツールはPC, Macといったプラットホームに依存しないクライアント/サーバアプリケーションで、原子核質量の多量の測定値,原子核質量の理論モデル、及び原子核の評価済み質量データを自由に利用することが可能である。このツールの用途としては以下のものが挙げられる。(1)基礎・応用科学における原子核質量の広範囲の利用、(2)大規模測定能力、施設、及び新しい結果における物凄い成長、及び、(3)原子核の質量情報を広める既存のシステムの不適当のために。本システムを用いることで、研究者自身による大規模データセットのアップロード、格納、共有、カスタマイズし、これらを平易に可視化することが可能である。


Masses of unstable nuclei; Visualization and analysis at nuclearmassess.org

Smith, M. S.*; Lingerfelt, E. J.*; Buckner, K.*; Nesaraja, C. D.*; 小浦 寛之; Kondev, F.*

no journal, , 


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