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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

 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

"Southwestern" boundary of the $$N = 40$$ island of inversion; First study of low-lying bound excited states in $$^{59}$$V and $$^{61}$$V

Elekes, Z.*; Juh$'a$sz, M. M.*; Sohler, D.*; Sieja, K.*; Yoshida, Kazuki; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Achouri, N. L.*; Baba, Hidetada*; et al.

Physical Review C, 106(6), p.064321_1 - 064321_10, 2022/12

 Times Cited Count:2 Percentile:0.02(Physics, Nuclear)

The low-lying level structure of $$^{59}$$V and $$^{61}$$V was investigated for the first time. The neutron knockout reaction and inelastic proton scattering were applied for $$^{61}$$V while the neutron knock-out reaction provided the data for $$^{59}$$V. Four and five new transitions were determined for $$^{59}$$V and $$^{61}$$V, respectively. Based on the comparison to our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja (LNPS) interaction, three of the observed $$gamma$$ rays for each isotope could be placed in the level scheme and assigned to the decay of the first 11/2$$^{-}$$ and 9/2$$^{-}$$ levels. The ($$p$$,$$p'$$) excitation cross sections for $$^{61}$$V were analyzed by the coupled-channels formalism assuming quadrupole plus hexadecapole deformations. Due to the role of the hexadecapole deformation, $$^{61}$$V could not be unambiguously placed on the island of inversion.

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

 Times Cited Count:4 Percentile:52.69(Astronomy & Astrophysics)

no abstracts in English

Journal Articles

Investigation of the ground-state spin inversion in the neutron-rich $$^{47,49}$$Cl isotopes

Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; G$'o$mez-Ramos, M.*; et al.

Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10

AA2021-0468.pdf:1.29MB

 Times Cited Count:5 Percentile:46.8(Physics, Nuclear)

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:10 Percentile:69.3(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

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

AA2020-0747.pdf:0.83MB

 Times Cited Count:5 Percentile:46.8(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

$$N$$ = 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

AA2020-0748.pdf:0.75MB

 Times Cited Count:11 Percentile:73.66(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

IAEA Photonuclear Data Library 2019

Kawano, Toshihiko*; Cho, Y. S.*; Dimitriou, P.*; Filipescu, D.*; Iwamoto, Nobuyuki; Plujko, V.*; Tao, X.*; Utsunomiya, Hiroaki*; Varlamov, V.*; Xu, R.*; et al.

Nuclear Data Sheets, 163, p.109 - 162, 2020/01

 Times Cited Count:80 Percentile:99.62(Physics, Nuclear)

Journal Articles

Shell evolution of $$N$$ = 40 isotones towards $$^{60}$$Ca; First spectroscopy of $$^{62}$$Ti

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Men$'e$ndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

 Times Cited Count:31 Percentile:96.23(Astronomy & Astrophysics)

Excited states in the $$N$$ = 40 isotone $$^{62}$$Ti were populated via the $$^{63}$$V($$p$$,$$2p$$)$$^{62}$$Ti reaction at $$sim$$200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using $$gamma$$-ray spectroscopy. The energies of the $$2_1^+ rightarrow 0_{rm gs}^+$$ and $$4_1^+ rightarrow 2_1^+$$ transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring $$^{64}$$Cr and $$^{66}$$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Journal Articles

Reference database for photon strength functions

Goriely, S.*; Dimitriou, P.*; Wiedeking, M.*; Belgya, T.*; Firestone, R.*; Kopecky, J.*; Krti$v{c}$ka, M.*; Plujko, V.*; Schwengner, R.*; Siem, S.*; et al.

European Physical Journal A, 55(10), p.172_1 - 172_52, 2019/10

 Times Cited Count:64 Percentile:92.18(Physics, Nuclear)

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

AA2019-0306.pdf:0.57MB

 Times Cited Count:47 Percentile:92.65(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

A New simultaneous measurement system of wide Q-range small angle neutron scattering combined with polarized Fourier transform infrared spectroscopy

Kaneko, Fumitoshi*; Kawaguchi, Tatsuya*; Radulescu, A.*; Iwase, Hiroki*; Morikawa, Toshiaki*; Takata, Shinichi; Nishiura, Masayoshi*; Hou, Z.*

Review of Scientific Instruments, 90(9), p.093906_1 - 093906_6, 2019/09

 Times Cited Count:3 Percentile:17.94(Instruments & Instrumentation)

Journal Articles

Complexation of syndiotactic polystyrene with branched molecules

Kaneko, Fumitoshi*; Radulescu, A.*; Iwase, Hiroki*; Takata, Shinichi; Nishiura, Masayoshi*; Hou, Z.*

Macromolecular Symposia, 386(1), p.1900008_1 - 1900008_5, 2019/08

 Times Cited Count:0 Percentile:0.14(Polymer Science)

Journal Articles

Gamma-ray spectrum from thermal neutron capture on gadolinium-157

Hagiwara, Kaito*; Yano, Takatomi*; Das, P. K.*; Lorenz, S.*; Ou, Iwa*; Sakuda, Makoto*; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Harada, Hideo; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(2), p.023D01_1 - 023D01_26, 2019/02

 Times Cited Count:32 Percentile:87.41(Physics, Multidisciplinary)

Journal Articles

A New Standard DNA Damage (SDD) data format

Schuemann, J.*; McNamara, A. L.*; Warmenhoven, J. W.*; Henthorn, N. T.*; Kirkby, K.*; Merchant, M. J.*; Ingram, S.*; Paganetti, H.*; Held, K. D.*; Ramos-Mendez, J.*; et al.

Radiation Research, 191(1), p.76 - 93, 2019/01

 Times Cited Count:47 Percentile:94.65(Biology)

We propose a new Standard DNA Damage (SDD) data format to unify the interface between the simulation of damage induction in DNA and the biological modelling of DNA repair processes, and introduce the effect of the environment (molecular oxygen or other compounds) as a flexible parameter. Such a standard greatly facilitates inter-model comparisons, providing an ideal environment to tease out model assumptions and identify persistent, underlying mechanisms. Through inter-model comparisons, this unified standard has the potential to greatly advance our understanding of the underlying mechanisms of radiation-induced DNA damage and the resulting observable biological effects when radiation parameters and/or environmental conditions change.

Journal Articles

Developing reliable reaction gamma-ray data

Dimitriou, P.*; Belgya, T.*; Cho, Y.-S.*; Filipescu, D.*; Firestone, R.*; Goriely, S.*; Iwamoto, Nobuyuki; Kawano, Toshihiko*; Kopecky, J.*; Krticka, M.*; et al.

EPJ Web of Conferences, 178, p.06005_1 - 06005_3, 2018/05

 Times Cited Count:2 Percentile:74.98(Optics)

no abstracts in English

Journal Articles

CIELO collaboration summary results; International evaluations of neutron reactions on uranium, plutonium, iron, oxygen and hydrogen

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Kahler, A. C.*; Talou, P.*; Plompen, A. J.*; Schillebeeckx, P.*; et al.

Nuclear Data Sheets, 148, p.189 - 213, 2018/02

 Times Cited Count:66 Percentile:98.06(Physics, Nuclear)

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - $$^{235}$$U, $$^{238}$$U, $$^{239}$$Pu, $$^{56}$$Fe, $$^{16}$$O and $$^{1}$$H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality. This report summarizes our results and outlines plans for the next phase of this collaboration.

Journal Articles

The CIELO collaboration; Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Kahler, A. C.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Pigni, M.*; Dunn, M.*; Leal, L.*; et al.

EPJ Web of Conferences, 146, p.02001_1 - 02001_9, 2017/09

 Times Cited Count:6 Percentile:95.25(Nuclear Science & Technology)

The CIELO collaboration has studied neutron cross sections on nuclides ($$^{16}$$O, $$^{56}$$Fe, $$^{235,238}$$U and $$^{239}$$Pu) that significantly impact criticality in nuclear technologies with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

Journal Articles

Precise determination of $$^{12}_{Lambda}$$C level structure by $$gamma$$-ray spectroscopy

Hosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

 Times Cited Count:14 Percentile:66.59(Physics, Multidisciplinary)

Level structure of the $$^{12}_{Lambda}$$C hypernucleus was precisely determined by means of $$gamma$$-ray spectroscopy. We identified four $$gamma$$-ray transitions via the $$^{12}$$C$$(pi^{+},K^{+}gamma)$$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $$(2^{-}, 1^{-}_{1})$$ was measured to be $$161.5pm0.3$$(stat)$$pm0.3$$ (syst)keV from the direct $$M1$$ transition. Excitation energies of the $$1^{-}_{2}$$ and $$1^{-}_{3}$$ states were measured to be $$2832pm3pm4$$, keV and $$6050pm8pm7$$, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $$Lambda$$ hypernuclei.

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