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Journal Articles

First observation of $$^{28}$$O

Kondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.

Nature, 620(7976), p.965 - 970, 2023/08

 Times Cited Count:5 Percentile:92.64(Multidisciplinary Sciences)

no abstracts in English

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

 Times Cited Count:1 Percentile:0.02(Astronomy & Astrophysics)

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

Study of the $$N=32$$ and $$N=34$$ shell gap for Ti and V by the first high-precision multireflection time-of-flight mass measurements at BigRIPS-SLOWRI

Iimura, Shun*; Rosenbusch, M.*; Takamine, Aiko*; Tsunoda, Yusuke*; Wada, Michiharu*; Chen, S.*; Hou, D. S.*; Xian, W.*; Ishiyama, Hironobu*; Yan, S.*; et al.

Physical Review Letters, 130(1), p.012501_1 - 012501_6, 2023/01

 Times Cited Count:5 Percentile:94.66(Physics, Multidisciplinary)

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:17 Percentile:95.19(Multidisciplinary Sciences)

no abstracts in English

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

AA2021-0426.pdf:0.73MB

 Times Cited Count:2 Percentile:34.88(Physics, Nuclear)

no abstracts in English

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:17 Percentile:93.85(Physics, Nuclear)

no abstracts in English

Journal Articles

The Impact of nuclear shape on the emergence of the neutron dripline

Tsunoda, Naofumi*; Otsuka, Takaharu; Takayanagi, Kazuo*; Shimizu, Noritaka*; Suzuki, Toshio*; Utsuno, Yutaka; Yoshida, Sota*; Ueno, Hideki*

Nature, 587, p.66 - 71, 2020/11

 Times Cited Count:40 Percentile:92.47(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Structure of $$^{30}$$Mg explored via in-beam $$gamma$$-ray spectroscopy

Kitamura, Noritaka*; Wimmer, K.*; Shimizu, Noritaka*; Bader, V. M.*; Bancroft, C.*; Barofsky, D.*; Baugher, T.*; Bazin, D.*; Berryman, J. S.*; Bildstein, V.*; et al.

Physical Review C, 102(5), p.054318_1 - 054318_13, 2020/11

AA2020-0765.pdf:4.4MB

 Times Cited Count:4 Percentile:45.12(Physics, Nuclear)

no abstracts in English

Journal Articles

Preparation, characterization, and dilute solution properties of four-branched cage-shaped poly(ethylene oxide)

Noda, Takashi*; Doi, Yuya*; Ota, Yutaka*; Takata, Shinichi; Takano, Atsushi*; Matsushita, Yushu*

Journal of Polymer Science, 58(15), p.2098 - 2107, 2020/08

 Times Cited Count:8 Percentile:37.53(Polymer Science)

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:167 Percentile:99.87(Computer Science, Interdisciplinary Applications)

no abstracts in English

Journal Articles

Spectroscopy of strongly deformed $$^{32}$$Ne by proton knockout reactions

Murray, I.*; MacCormick, M.*; Bazin, D.*; Doornenbal, P.*; Aoi, Nori*; Baba, Hidetada*; Crawford, H. L.*; Fallon, P.*; Li, K.*; Lee, J.*; et al.

Physical Review C, 99(1), p.011302_1 - 011302_7, 2019/01

AA2018-0517.pdf:0.8MB

 Times Cited Count:17 Percentile:85.66(Physics, Nuclear)

no abstracts in English

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

AA2018-0159.pdf:0.5MB

 Times Cited Count:7 Percentile:53.6(Astronomy & Astrophysics)

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:27 Percentile:81.43(Physics, Multidisciplinary)

no abstracts in English

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

Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples

Furuta, Takuya; Maeyama, Takuya*; Ishikawa, Kenichi*; Fukunishi, Nobuhisa*; Fukasaku, Kazuaki*; Takagi, Shu*; Noda, Shigeho*; Himeno, Ryutaro*; Hayashi, Shinichiro*

Physics in Medicine & Biology, 60(16), p.6531 - 6546, 2015/08

 Times Cited Count:18 Percentile:62.62(Engineering, Biomedical)

Low reproducibility of dose distribution in inhomogeneous regions such as soft matter near bones is known with the simple dose analysis currently adopted in treatment planning of particle cancer therapy. Therefore a treatment planning system based on Monte Carlo simulation having better accuracy is highly desired. In order to assess the simulation accuracy of a Monte Carlo simulation code in situations closely related to medical application, we performed a comparison of dose distribution in a biological sample obtained by experiment and that by simulation. In particular, we irradiate a carbon beam on a biological sample composed of fresh chicken meat and bones, with a PAGAT gel dosimeter placed behind it, and compare the complex dose distribution in the gel dosimeter created by the beam passing through the inhomogeneous sample. Monte Carlo simulation using PHITS code was conducted by reconstructing the biological sample from its computed tomography images. The simulation accurately reproduced the experimental distal edge structure of the dose distribution with an accuracy under about 2 mm.

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:39 Percentile:91.59(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

Parallel computing with Particle and Heavy Ion Transport code System (PHITS)

Furuta, Takuya; Sato, Tatsuhiko; Ogawa, Tatsuhiko; Niita, Koji*; Ishikawa, Kenichi*; Noda, Shigeho*; Takagi, Shu*; Maeyama, Takuya*; Fukunishi, Nobuhisa*; Fukasaku, Kazuaki*; et al.

Proceedings of Joint International Conference on Mathematics and Computation, Supercomputing in Nuclear Applications and the Monte Carlo Method (M&C + SNA + MC 2015) (CD-ROM), 9 Pages, 2015/04

In Particle and Heavy Ion Transport code System PHITS, two parallel computing functions are prepared to reduce the computational time. One is the distributed-memory parallelization using message passing interface (MPI) and the other is the shared-memory parallelization using OpenMP directives. Each function has advantages and disadvantages, and thus, by adopting both functions in PHITS, it is possible to conduct parallel computing suited for needs of users. It is also possible to conduct the hybrid parallelization by the intra-node OpenMP parallelization and the inter-node MPI parallelization in supercomputer systems. Each parallelization functions were explained together with some application results obtained using a workstation and a supercomputer system, K computer at RIKEN.

Journal Articles

Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

Maeyama, Takuya*; Fukunishi, Nobuhisa*; Ishikawa, Kenichi*; Furuta, Takuya; Fukasaku, Kazuaki*; Takagi, Shu*; Noda, Shigeho*; Himeno, Ryutaro*; Fukuda, Shigekazu*

Radiation Physics and Chemistry, 107, p.7 - 11, 2015/02

 Times Cited Count:12 Percentile:70.51(Chemistry, Physical)

We study the radiological characteristics of VIP polymer gel dosimeters under carbon beam irradiation with energy of 135 and 290 AMeV. To evaluate dose response of VIP polymer gels, the transverse relaxation rate R2 of the dosimeters measured by magnetic resonance imaging (MRI) as a function of linear energy transfer (LET), rather than penetration depth, as is usually done in previous reports. LET is evaluated by use of the particle transport simulation code PHITS. Our results reveal that the dose response decreases with increasing dose-averaged LET and that the response-LET relation also varies with incident carbon beam energy. The latter can be explained by taking into account the contribution from fragmentation products. Furthermore, as an application of the evaluated response-LET relation, we compare the measured and simulated R2 distribution in a VIP gel formed by heterogeneous irradiation and obtain agreement in overall distribution and range within an accuracy of 5% and 1-2 mm, respectively.

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:37 Percentile:85.46(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.

112 (Records 1-20 displayed on this page)