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Journal Articles

Level structures of $$^{56,58}$$Ca cast doubt on a doubly magic $$^{60}$$Ca

Chen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Chazono, Yoshiki*; Hagen, G.*; Holt, J. D.*; et al.

Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08

Gamma decays were observed in $$^{56}$$Ca and $$^{58}$$Ca following quasi-free one-proton knockout reactions from $$^{57,59}$$Sc. For $$^{56}$$Ca, a $$gamma$$ ray transition was measured to be 1456(12) keV, while for $$^{58}$$Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the $$2^{+}_{1} rightarrow 0^{+}_{gs}$$ decays. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for $$2^{+}_{1}$$ level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the $$0_{f5/2}$$ and $$0_{g9/2}$$ orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic $$^{60}$$Ca and potentially drives the dripline of Ca isotopes to $$^{70}$$Ca or even beyond.

Journal Articles

First spectroscopic study of odd-odd $$^{78}$$Cu

Pedersen, L. G.*; Sahin, E.*; G$"o$rgen, A.*; Bello Garrote, F. L.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Niikura, Megumi*; Orlandi, R.; 59 of others*

Physical Review C, 107(4), p.044301_1 - 044301_10, 2023/04

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

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, p.2234_1 - 2234_10, 2022/04

 Times Cited Count:9 Percentile:95.34(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Moments and radii of exotic Na and Mg isotopes

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

Physical Review C, 105(1), p.014319_1 - 014319_8, 2022/01

no abstracts in English

Journal Articles

PSTEP: Project for solar-terrestrial environment prediction

Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.

Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12

 Times Cited Count:6 Percentile:52.8(Geosciences, Multidisciplinary)

The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.

Journal Articles

Emergence of spin-orbit coupled ferromagnetic surface state derived from Zak phase in a nonmagnetic insulator FeSi

Otsuka, Yusuke*; Kanazawa, Naoya*; Hirayama, Motoaki*; Matsui, Akira*; Nomoto, Takuya*; Arita, Ryotaro*; Nakajima, Taro*; Hanashima, Takayasu*; Ukleev, V.*; Aoki, Hiroyuki; et al.

Science Advances (Internet), 7(47), p.eabj0498_1 - eabj0498_9, 2021/11

 Times Cited Count:3 Percentile:42.29(Multidisciplinary Sciences)

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

AA2020-0764.pdf:0.89MB

 Times Cited Count:11 Percentile:94.39(Physics, Nuclear)

no abstracts in English

Journal Articles

$$beta$$ decay of $$^{75}$$Ni and the systematics of the low-lying level structure of neutron-rich odd-$$A$$ Cu isotopes

Bello Garrote, F. L.*; Sahin, E.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; G$"o$rgen, A.*; Orlandi, R.; 61 of others*

Physical Review C, 102(3), p.034314_1 - 034314_13, 2020/09

 Times Cited Count:3 Percentile:46.04(Physics, Nuclear)

Journal Articles

Recontamination prevention technologies to prevent radioactive cesium from its runoff from not decontaminated forests to living areas

Nagasu, Ryosuke*; Tanabe, Daijiro*; Yokotsuka, Satoshi*; Kumazawa, Noriyuki*; Ajiki, Takaya*; Aizawa, Yusuke*; Naganawa, Hirochika; Nagano, Tetsushi; Yanase, Nobuyuki*; Mitamura, Hisayoshi*; et al.

Kankyo Joka Gijutsu, 17(2), p.58 - 61, 2018/03

A new technology to suppress cesium migration from forests has been developed collaboratively by Ibaraki University, Kumagai-gumi Co., Ltd. and its group company, Technos, and JAEA. The new technology utilizes polyelectrolytes (polymers with electric charges) and clay minerals to control Cs migration with the aid of natural forces such as rainfall and rainwater runoff. In Imitate-mura, Fukushima, verification tests of the new technology have been performed and its effect on controlling Cs migration from forests to grass farm adjoining the forests has been proven.

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:24 Percentile:81.66(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Type II shell evolution in $$A=70$$ isobars from the $$N geq 40$$ island of inversion

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; Tsunoda, Yusuke*; Otsuka, T.*; Nishimura, Shunji*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.

Physics Letters B, 765, p.328 - 333, 2017/02

 Times Cited Count:31 Percentile:92.19(Astronomy & Astrophysics)

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:36 Percentile:88.46(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

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:36 Percentile:91.68(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:34 Percentile:84.73(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:14 Percentile:96.87

no abstracts in English

Journal Articles

Novel shape evolution in exotic Ni isotopes and configuration-dependent shell structure

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

Physical Review C, 89(3), p.031301_1 - 031301_5, 2014/03

AA2013-0908.pdf:2.19MB

 Times Cited Count:148 Percentile:99.37(Physics, Nuclear)

no abstracts in English

Journal Articles

Shape coexistence in $$^{68}$$Ni

Suchyta, S.*; Liddick, S. N.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Bennett, M. B.*; Chemey, A.*; Homma, Michio*; Larson, N.*; Prokop, C. J.*; Quinn, S. J.*; et al.

Physical Review C, 89(2), p.021301_1 - 021301_5, 2014/02

 Times Cited Count:76 Percentile:97.51(Physics, Nuclear)

no abstracts in English

Journal Articles

Variational procedure for nuclear shell-model calculations and energy-variance extrapolation

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

Physical Review C, 85(5), p.054301_1 - 054301_6, 2012/05

AA2012-0118.pdf:1.01MB

 Times Cited Count:21 Percentile:74.08(Physics, Nuclear)

no abstracts in English

33 (Records 1-20 displayed on this page)