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Journal Articles

A First glimpse at the shell structure beyond $$^{54}$$Ca; Spectroscopy of $$^{55}$$K, $$^{55}$$Ca, and $$^{57}$$Ca

Koiwai, Takuma*; Wimmer, K.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Duguet, T.*; Holt, J. D.*; Miyagi, Takayuki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; et al.

Physics Letters B, 827, p.136953_1 - 136953_7, 2022/04

no abstracts in English

Journal Articles

Pairing forces govern population of doubly magic $$^{54}$$Ca from direct reactions

Browne, F.*; Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Ogata, Kazuyuki*; Utsuno, Yutaka; Yoshida, Kazuki; Achouri, N. L.*; Baba, Hidetada*; Calvet, D.*; et al.

Physical Review Letters, 126(25), p.252501_1 - 252501_7, 2021/06

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Direct proton-knockout reactions of $$^{55}$$Sc were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of $$^{54}$$Ca were investigated through $$gamma$$-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological inter-nucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of $$^{55}$$Sc, valence proton removals populated predominantly the ground-state of $$^{54}$$Ca. This counter-intuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

Journal Articles

High-spin states in $$^{35}$$S

Go, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.

Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03

 Times Cited Count:0 Percentile:0.03(Physics, Nuclear)

Journal Articles

First spectroscopic study of $$^{51}$$Ar by the ($$p$$,2$$p$$) reaction

Juh$'a$sz, M. M.*; Elekes, Z.*; Sohler, D.*; Utsuno, Yutaka; Yoshida, Kazuki; Otsuka, Takaharu*; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Baba, Hidetada*; et al.

Physics Letters B, 814, p.136108_1 - 136108_8, 2021/03

 Times Cited Count:1 Percentile:74.98(Astronomy & Astrophysics)

The nuclear structure of $$^{51}$$Ar was studied by the ($$p$$,2$$p$$) reaction using $$gamma$$-ray spectroscopy for the bound and unbound states. Comparing the results to our shell-model calculations, two bound and six unbound states were established. The low cross sections populating the two bound states of $$^{51}$$Ar could be interpreted as a clear signature for the presence of significant sub-shell closures at neutron numbers 32 and 34 in argon isotopes.

Journal Articles

Oxygen potential measurement of (U,Pu,Am)O$$_{2 pm x}$$ and (U,Pu,Am,Np)O$$_{2 pm x}$$

Hiroka, Shun; Matsumoto, Taku; Kato, Masato; Sunaoshi, Takeo*; Uno, Hiroki*; Yamada, Tadahisa*

Journal of Nuclear Materials, 542, p.152424_1 - 152424_9, 2020/12

 Times Cited Count:1 Percentile:39.17(Materials Science, Multidisciplinary)

The measurement of oxygen potential was conducted at 1,673, 1,773, and 1,873 K for (U$$_{0.623}$$Pu$$_{0.350}$$Am$$_{0.027}$$)O$$_{2}$$ and at 1,873 and 1,923 K for (U$$_{0.553}$$Pu$$_{0.285}$$Am$$_{0.015}$$Np$$_{0.147}$$)O$$_{2}$$ by using a thermo-gravimeter and an oxygen sensor. Am inclusion in terms of substituting the U significantly increased the oxygen potential. Similarly, the inclusion of Np as a substitute for U increased the oxygen potential; however, the effect was not as large as that with the Pu or Am addition at the same rate. The results were analyzed via defect chemistry and certain defect formations were suggested in the reducing region and the near-stoichiometric region by plotting the relationship between PO$$_{2}$$ and the deviation from the stoichiometry. The equilibrium constants of the defect reactions were arranged to reproduce the experiment such that Am/Np contents were included in the entropy with coefficients fitting the experimental data.

Journal Articles

$$N$$ = 32 shell closure below calcium; Low-lying structure of $$^{50}$$Ar

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Men$'e$ndez, J.*; Ogata, Kazuyuki*; Schwenk, A.*; Shimizu, Noritaka*; Simonis, J.*; et al.

Physical Review C, 102(6), p.064320_1 - 064320_9, 2020/12

 Times Cited Count:1 Percentile:35.83(Physics, Nuclear)

Low-lying excited states in the $$N$$ = 32 isotope $$^{50}$$Ar were investigated by in-beam $$gamma$$-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a 3$$^{-}$$ state. The level scheme built using $$gamma$$ $$gamma$$ coincidences was compared to shell-model calculations in the $$sd-pf$$ model space and to ${it ab initio}$ predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to 2$$^{+}$$ states, while the previously proposed 4$$^{+}_{1}$$ state could also correspond to a 2$$^{+}$$ state.

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:21 Percentile:92.26(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Research and development on membrane IS process for hydrogen production using solar heat

Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.

International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07

 Times Cited Count:12 Percentile:67.04(Chemistry, Physical)

Journal Articles

Thermal and mechanical properties of CeO$$_{2}$$

Suzuki, Kiichi; Kato, Masato; Sunaoshi, Takeo*; Uno, Hiroki*; Carvajal-Nunez, U.*; Nelson, A. T.*; McClellan, K. J.*

Journal of the American Ceramic Society, 102(4), p.1994 - 2008, 2019/04

The fundamental properties of CeO$$_{2}$$ were assessed using a range of experimental techniques. The oxygen potential of CeO$$_{2}$$ was measured by the thermogravimetric technique, and a numerical fit for the oxygen potential of CeO$$_{2}$$ is derived based on defect chemistry. Mechanical properties of CeO$$_{2}$$ were obtained using sound velocity measurement, resonant ultrasound spectroscopy and nanoindentation. The obtained mechanical properties of CeO$$_{2}$$ are then used to evaluate the Debye temperature and Gruneisen constant. The heat capacity and thermal conductivity of CeO$$_{2}$$ were also calculated using the Debye temperature and the Gruneisen constant. Finally, the thermal conductivity was calculated based upon laser flash analysis measurements. This result demonstrates that the thermal conductivity has strong dependence upon material purity.

Journal Articles

Nuclear moments of the low-lying isomeric $$1^+$$ state of $$^{34}$$Al; Investigation on the neutron $$1p1h$$ excitation across $$N=20$$ in the island of inversion

Xu, Z. Y.*; Heylen, H.*; Asahi, Koichiro*; Boulay, F.*; Daugas, J. M.*; de Groote, R. P.*; Gins, W.*; Kamalou, O.*; Koszor$'u$s, $'A$.*; Lykiardopoupou, M.*; et al.

Physics Letters B, 782, p.619 - 626, 2018/07


 Times Cited Count:5 Percentile:56.63(Astronomy & Astrophysics)

no abstracts in English

Journal Articles

Seismic evaluation for a large-sized reactor vessel targeting SFRs in Japan

Uchita, Masato*; Miyagawa, Takayuki*; Dozaki, Koji*; Chikazawa, Yoshitaka; Kubo, Shigenobu; Hayafune, Hiroki; Suzuno, Tetsuji*; Fukasawa, Tsuyoshi*; Kamishima, Yoshio*; Fujita, Satoshi*

Proceedings of 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) (CD-ROM), p.380 - 386, 2018/04

It is well-known that pool-type SFRs are the main streams recently in a field of Generation IV reactors. The pool-type encloses primary pumps and IHXs located around the core barrel in a main vessel. Consequently, the main vessel diameter trends to be larger than that of loop-types. From the viewpoint of commercialization in the future, a target of the vessel diameter and its weight including Sodium coolant will increase further. In this paper, the prospects are described in terms of seismic design and structural integrity for the thermal loadings to prevent buckling of the reactor vessel based on parameter studies with diameters of the vessel. In addition, the seismic isolation device which will be effective as a countermeasure is proposed in order to secure a margin against buckling of a large reactor vessel.

Journal Articles

Interaction of rare earth elements and components of the Horonobe deep groundwater

Kirishima, Akira*; Kuno, Atsushi*; Amamiya, Hiroki; Kubota, Takumi*; Kimuro, Shingo*; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki*; et al.

Chemosphere, 168, p.798 - 806, 2017/02

 Times Cited Count:1 Percentile:5.42(Environmental Sciences)

For better understanding of the migration behavior of minor actinides (MA) in deep groundwater, the interaction of doped rare earth elements (REEs) and components in Horonobe deep groundwater was studied. Appx. 10 ppb of rare earth elements, i.e., Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm and Yb were doped to the sample groundwater collected from a packed sections in borehole drilled from 140 m depth experiment drift of Horonobe underground research laboratory (URL), Hokkaido, Japan. Then, that groundwater was sequentially filtrated by 0.2 micron pore filter, 10 kDa, 3 kDa and 1 kDa of nominal molecular weight limit (NMWL) ultrafilters by keeping inert condition. After that, the filtrate solutions were analyzed by ICP-MS to determine the concentrations of retained REEs at each filtration steps, while the used filters were analyzed by the neutron activation analysis (NAA) and TOF-SIMS element mapping to know the amount and chemical speciation of trapped fraction of the REEs on each filter. A remarkable relation between the retention ratios of REEs in the filtrate solutions and the ionic radius was observed, i.e., smaller rare earth element solves more in liquid phase under the Horonobe groundwater condition. NAA and TOF-SIMS analyses revealed that certain portions of REEs were trapped by 0.2 micron pore filters as rare earth phosphates which corresponded with the predicted predominant species by a chemical equilibrium calculation for the Horonobe groundwater condition, while small portions of colloidal REEs were trapped by 10 kDa and 3 kDa NMWL ultrafilters. The result suggested that phosphate anion plays an important role in the chemical behavior of REEs in saline (seawater based) groundwater, which could be referred for the prediction of migration behavior of trivalent actinide released from the repository of radioactive waste in far future.

Journal Articles

Engineering a spin-orbital magnetic insulator by tailoring superlattices

Matsuno, Jobu*; Ihara, Kota*; Yamamura, Shugen*; Wadachi, Hiroki*; Ishii, Kenji; Shankar, V.*; Kee, H.-Y.*; Takagi, Hidenori*

Physical Review Letters, 114(24), p.247209_1 - 247209_5, 2015/06

 Times Cited Count:113 Percentile:97.77(Physics, Multidisciplinary)

Journal Articles

Biogeochemical signals from deep microbial life in terrestrial crust

Suzuki, Yohei*; Konno, Yuta*; Fukuda, Akari*; Komatsu, Daisuke*; Hirota, Akinari*; Watanabe, Katsuaki*; Togo, Yoko*; Morikawa, Noritoshi*; Hagiwara, Hiroki; Aosai, Daisuke*; et al.

PLOS ONE (Internet), 9(12), p.e113063_1 - e113063_20, 2014/12

 Times Cited Count:9 Percentile:36.08(Multidisciplinary Sciences)

We present multi-isotopic evidence of microbially mediated sulfate reduction in a granitic aquifer, a representative of the terrestrial crust habitat. Deep groundwater of meteoric origin was collected from underground boreholes drilled into the Cretaceous Toki granite, central Japan. A large sulfur isotopic fractionation of 20-60 permil diagnostic to microbial sulfate reduction is associated with the investigated groundwater containing sulfate below 0.2 mM. In contrast, a small carbon isotopic fractionation ($$<$$ 30 permil) is not indicative of methanogenesis. Our results demonstrate that the deep biosphere in the terrestrial crust is metabolically active and playing a crucial role in the formation of reducing groundwater even under low energy fluxes.

Journal Articles

Hydrochemical changes associated with construction of Mizunami Underground Research Laboratory

Mizuno, Takashi; Aosai, Daisuke; Shingu, Shinya; Hagiwara, Hiroki; Yamamoto, Yuhei; Fukuda, Akari

Nihon Genshiryoku Gakkai Wabun Rombunshi, 12(1), p.89 - 102, 2013/03

no abstracts in English

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2010

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Ueno, Takashi; Tokuyasu, Shingo; Daimaru, Shuji; Takeuchi, Ryuji; et al.

JAEA-Review 2012-020, 178 Pages, 2012/06


Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II. And Phase III started in 2010 fiscal year. This report shows the results of the investigation, construction and collaboration studies in fiscal year 2010, as a part of the Phase II based on the MIU Master Plan updated in 2002.

JAEA Reports

Monitoring of pore water pressure and groundwater chemistry at MSB-2 and MSB-4 boreholes in the MIU construction site; April, 2010 - March, 2011

Hagiwara, Hiroki; Shingu, Shinya; Kurita, Kazuaki*; Eguchi, Keita*; Horita, Masakuni*; Mizuno, Takashi

JAEA-Data/Code 2012-005, 67 Pages, 2012/06


Japan Atomic Energy Agency has been carried out investigations to understand the fluctuation of groundwater chemistry related to the shafts excavation at the Mizunami Underground Research Laboratory in Mizunami City, Gifu prefecture, Japan. The data for pore water pressure, water temperature and groundwater chemistry have been provided from two surface-based boreholes, MSB-2 and MSB-4 boreholes, installed a modular multilevel groundwater monitoring system (MP system). The monitoring has been conducted once in a month since April 2003. According to the results, the shaft excavation has caused drawdown of the hydraulic head and change in the groundwater chemistry in the MIU construction site. In this report, the data of monitoring at the MSB-2 and the MSB-4 boreholes from April 2010 to March 2011 were compiled. In addition, the monitoring results at the DH-2 borehole as part of Regional Hydrogeological Study project, are summarized as an appendix.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry in the Mizunami group and Toki granite (fiscal year 2010)

Shingu, Shinya; Hagiwara, Hiroki; Masuda, Kaoru*; Iizuka, Masatoshi*; Inui, Michiharu*; Mizuno, Takashi

JAEA-Data/Code 2012-003, 50 Pages, 2012/06


Japan Atomic Energy Agency has been investigated the groundwater chemistry on excavating the underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project at Mizunami City, Gifu Prefecture, Japan. This report compiles data set of the groundwater chemistry obtained at MIU in the fiscal year 2010. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling date, sampling method, analytical method) and methodology for quality control is described.

Journal Articles

Magnons and electromagnons in a spin-lattice-coupled frustrated magnet CuFeO$$2$$ as seen via inelastic neutron scattering

Nakajima, Taro*; Suno, Azusa*; Mitsuda, Setsuo*; Terada, Noriki*; Kimura, Shojiro*; Kaneko, Koji; Yamauchi, Hiroki

Physical Review B, 84(18), p.184401_1 - 184401_7, 2011/11

 Times Cited Count:32 Percentile:79.37(Materials Science, Multidisciplinary)

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry in the Mizunami group and Toki granite (fiscal year 2009)

Shingu, Shinya; Sai, Masataka*; Hagiwara, Hiroki; Mizuno, Takashi

JAEA-Data/Code 2011-004, 49 Pages, 2011/06


This report compiles data set of the groundwater chemistry obtained at Mizunami Underground Research Laboratory (MIU) in the fiscal year 2009. These data include groundwater chemistry of inflow in the shafts and sampled groundwater in the boreholes, which drilled from sub-stages of MIU and from surface (MSB-2, MSB-4, and MIZ-1). Basic information (e.g. sampling location, sampling date, sampling method, analytical method) is also described in terms of ensuring traceability of data.

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