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Journal Articles

$$alpha$$-clustering in atomic nuclei from first principles with statistical learning and the Hoyle state character

Otsuka, Takaharu; Abe, Takashi*; Yoshida, Toru*; Tsunoda, Yusuke*; Shimizu, Noritaka*; Itagaki, Naoyuki*; Utsuno, Yutaka; Vary, J. P.*; Maris, P.*; Ueno, Hideki*

Nature Communications (Internet), 13(1), p.2234_1 - 2234_10, 2022/04

 Times Cited Count:0 Percentile:0.01(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Development of dose estimation method using wild animal teeth for low dose exposure

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.

KEK Proceedings 2021-2, p.91 - 96, 2021/12

We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.

Journal Articles

Modelling concrete degradation by coupled non-linear processes

Oda, Chie; Kawama, Daisuke*; Shimizu, Hiroyuki*; Benbow, S. J.*; Hirano, Fumio; Takayama, Yusuke; Takase, Hiroyasu*; Mihara, Morihiro; Honda, Akira

Journal of Advanced Concrete Technology, 19(10), p.1075 - 1087, 2021/10

 Times Cited Count:0 Percentile:0(Construction & Building Technology)

Concrete in a transuranic (TRU) waste repository is considered a suitable material to ensure safety, provide structural integrity and retard radionuclide migration after the waste containers fail. In the current study, coupling between chemical, mass-transport and mechanical, so-called non-linear processes that control concrete degradation and crack development were investigated by coupled numerical models. Application of such coupled numerical models allows identification of the dominant non-linear processes that will control long-term concrete degradation and crack development in a TRU waste repository.

Journal Articles

Lifetime measurements of excited states in $$^{55}$$Cr

Kleis, H.*; Seidlitz, M.*; Blazhev, A.*; Kaya, L.*; Reiter, P.*; Arnswald, K.*; Dewald, A.*; Droste, M.*; Fransen, C.*; M$"o$ller, O.*; et al.

Physical Review C, 104(3), p.034310_1 - 034310_9, 2021/09

 Times Cited Count:0 Percentile:0.02(Physics, Nuclear)

no abstracts in English

Journal Articles

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950$$^{circ}$$C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

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

 Times Cited Count:19 Percentile:98.17(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

Variational approach with the superposition of the symmetry-restored quasiparticle vacua for nuclear shell-model calculations

Shimizu, Noritaka*; Tsunoda, Yusuke*; Utsuno, Yutaka; Otsuka, Takaharu*

Physical Review C, 103(1), p.014312_1 - 014312_11, 2021/01

 Times Cited Count:5 Percentile:87.74(Physics, Nuclear)

no abstracts in English

Journal Articles

A Coupled modeling simulator for near-field processes in cement engineered barrier systems for radioactive waste disposal

Benbow, S. J.*; Kawama, Daisuke*; Takase, Hiroyasu*; Shimizu, Hiroyuki*; Oda, Chie; Hirano, Fumio; Takayama, Yusuke; Mihara, Morihiro; Honda, Akira

Crystals (Internet), 10(9), p.767_1 - 767_33, 2020/09

 Times Cited Count:2 Percentile:41.44(Crystallography)

Details are presented of the development of a coupled modeling simulator for assessing the evolution in the near-field of a geological repository for radioactive waste disposal where concrete is used as a backfill. The simulator uses OpenMI, a standard for exchanging data between simulation software programs at run-time, to form a coupled chemical-mechanical-hydrogeological model of the system. The approach combines a tunnel scale stress analysis finite element model, a discrete element model for accurately modeling the patterns of emerging cracks in the concrete, and a finite element and finite volume model of the chemical processes and alteration in the porous matrix and cracks in the concrete, to produce a fully coupled model of the system. Combining existing detailed simulation software in this way with OpenMI has the benefit of not relying on simplifications that might be necessary to combine all of the modeled processes in a single piece of software.

Journal Articles

External exposure dose estimation by electron spin resonance technique for wild Japanese macaque captured in Fukushima Prefecture

Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Mitsuyasu, Yusuke*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; et al.

Radiation Measurements, 134, p.106315_1 - 106315_4, 2020/06

 Times Cited Count:2 Percentile:23.17(Nuclear Science & Technology)

The relationship between the CO$$_{2}$$ radical intensity and the absorbed dose (dose response curve) of tooth enamel of Japanese macaque was observed by electron spin resonance and the detection limit of our system was estimated to be 33.5 mGy, which is comparable to the detection limit for human molar teeth. Using the dose response curve, external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined. The results suggest that the external exposure dose for the wild Japanese macaques were ranged between 45 mGy to 300 mGy.

Journal Articles

Thick-restart block Lanczos method for large-scale shell-model calculations

Shimizu, Noritaka*; Mizusaki, Takahiro*; Utsuno, Yutaka; Tsunoda, Yusuke*

Computer Physics Communications, 244, p.372 - 384, 2019/11

 Times Cited Count:80 Percentile:99.62(Computer Science, Interdisciplinary Applications)

no abstracts in English

JAEA Reports

Quick examination of heavy mineral composition based on chemical analysis using electron probe microanalyzer in the Tono Geoscience Center

Yonaga, Yusuke; Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Yoshikawa, Kiyotaka*; Niwa, Masakazu

JAEA-Testing 2018-001, 29 Pages, 2018/07

JAEA-Testing-2018-001.pdf:3.82MB
JAEA-Testing-2018-001-appendix(CD-ROM).zip:1.64MB

Study on the formation process of mountains provides important clues for evaluating the uplift and erosion related to long-term changes of geological environment for geological disposal. Provenance analysis of detrital sediments is often be effective to understand the process. In the Tono Geoscience Center, quick and efficient mineralogical and chemical analyses for heavy minerals in basement rocks and sediments have been developed using the electron probe microanalyzer (JEOL JXA-8530F EPMA), as one of the promising tool for provenance analysis. To contribute evaluation of the analyses, sample preparation and EPMA analyses of heavy minerals were shown in this paper.

Journal Articles

Inventory analysis of suspended radiocesium derived from Niida River during a typhoon-induced flood event

Uchiyama, Yusuke*; Azuma, Kohei*; Odani, Sachika*; Iwasaki, Toshiki*; Tsumune, Daisuke*; Kamidaira, Yuki; Shimizu, Yasuyuki*; Onda, Yuichi*

Doboku Gakkai Rombunshu, B2 (Kaigan Kogaku) (Internet), 73(2), p.I_685 - I_690, 2017/10

no abstracts in English

Journal Articles

Monte Carlo shell model studies with massively parallel supercomputers

Shimizu, Noritaka*; Abe, Takashi*; Homma, Michio*; Otsuka, Takaharu*; Togashi, Tomoaki*; Tsunoda, Yusuke*; Utsuno, Yutaka; Yoshida, Toru*

Physica Scripta, 92(6), p.063001_1 - 063001_19, 2017/06

 Times Cited Count:20 Percentile:79.92(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Are there signatures of harmonic oscillator shells far from stability?; First spectroscopy of $$^{110}$$Zr

Paul, N.*; Corsi, A.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; Baba, Hidetada*; Bally, B.*; Bender, M.*; Calvet, D.*; Ch$^a$teau, F.*; et al.

Physical Review Letters, 118(3), p.032501_1 - 032501_7, 2017/01

 Times Cited Count:30 Percentile:87.73(Physics, Multidisciplinary)

Journal Articles

Large-scale shell-model studies for exotic nuclei; Probing shell evolution

Utsuno, Yutaka; Otsuka, Takaharu*; Shimizu, Noritaka*; Tsunoda, Yusuke*; Homma, Michio*; Abe, Takashi*; Mizusaki, Takahiro*; Togashi, Tomoaki*; Brown, B. A.*

Proceedings of International Conference on Nuclear Theory in the Supercomputing Era 2014 (NTSE 2014), p.29 - 34, 2016/00

no abstracts in English

Journal Articles

Analysis of tungsten transport in JT-60U plasmas

Shimizu, Yusuke*; Fujita, Takaaki*; Arimoto, Hideki*; Nakano, Tomohide; Hoshino, Kazuo; Hayashi, Nobuhiko

Plasma and Fusion Research (Internet), 10(Sp.2), p.3403062_1 - 3403062_4, 2015/07

Journal Articles

Recent advances in shell evolution with shell-model calculations

Utsuno, Yutaka; Otsuka, Takaharu*; Tsunoda, Yusuke*; Shimizu, Noritaka*; Homma, Michio*; Togashi, Tomoaki*; Mizusaki, Takahiro*

JPS Conference Proceedings (Internet), 6, p.010007_1 - 010007_8, 2015/06

no abstracts in English

Journal Articles

Identification of deformed intruder states in semi-magic $$^{70}$$Ni

Chiara, C. J.*; Weisshaar, D.*; Janssens, R. V. F.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Harker, J. L.*; Walters, W. B.*; Recchia, F.*; Albers, M.*; Alcorta, M.*; et al.

Physical Review C, 91(4), p.044309_1 - 044309_10, 2015/04

 Times Cited Count:33 Percentile:91.67(Physics, Nuclear)

The neutron-rich isotope $$^{70}$$Ni was produced by multi-nucleon transfer reactions of $$^{70}$$Zn in the Argonne National Laboratory, and an in-beam $$gamma$$-ray experiment were performed using the GRETINA array. The $$2^+_2$$ and $$4^+_2$$ levels of $$^{70}$$Ni were observed for the first time. Those levels are regarded as large deformed states associated with proton excitation from the $$f_{7/2}$$ orbit because they cannot be reproduced by a shell-model calculation assuming a small valence space without $$f_{7/2}$$. A theoretical analysis based on the Monte Carlo shell model published in 2014 indicates that those levels corresponds to a prolate deformed band. The present result demonstrates the occurrence of shape coexistence in neutron-rich Ni isotopes other than a known case of $$^{68}$$Ni, and confirms the predictive power of the Monte Carlo shell-model calculation.

Journal Articles

Nature of isomerism in exotic sulfur isotopes

Utsuno, Yutaka; Shimizu, Noritaka*; Otsuka, Takaharu*; Yoshida, Toru*; Tsunoda, Yusuke*

Physical Review Letters, 114(3), p.032501_1 - 032501_5, 2015/01

AA2014-0621.pdf:0.23MB

 Times Cited Count:33 Percentile:85.76(Physics, Multidisciplinary)

In usual even-even nuclei, $$0^+_1$$, $$2^+_1$$, $$4^+_1cdots$$ states are known to be connected via strong $$E2$$ transitions. The recently observed $$4^+_1$$ state in the neutron-rich nucleus $$^{44}$$S has a strongly hindered $$E2$$ transition to the $$4^+_1$$ state. We report the origin of this strong hindrance in this paper. While shell-model calculations reproduce the hindrance, their many-body wave functions are too complicated for one to understand the nature. In this study, we introduce a novel method to obtain wave functions in the intrinsic frame by performing the variation after angular-momentum projection. The $$0^+_1$$, $$2^+_1$$ states are dominated by the usual $$K=0$$ state, whereas for the $$4+$$ level the $$K=4$$ state is lower than $$K=0$$ state, which causes the $$E2$$ hindrance. We also account for similar $$E2$$ hindrance in $$^{43}$$S in this framework. The $$4^+$$ level is the lightest-mass high-$$K$$ isomer ever found.

Journal Articles

Recent shell-model results for exotic nuclei

Utsuno, Yutaka; Otsuka, Takaharu*; Shimizu, Noritaka*; Homma, Michio*; Mizusaki, Takahiro*; Tsunoda, Yusuke*; Abe, Takashi*

EPJ Web of Conferences, 66, p.02106_1 - 02106_8, 2014/03

 Times Cited Count:13 Percentile:96.93

no abstracts in English

57 (Records 1-20 displayed on this page)