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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

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

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

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:10 Percentile:98.7(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

Formation of $$alpha$$ clusters in dilute neutron-rich matter

Tanaka, Junki*; Yang, Z.*; Typel, S.*; Adachi, Satoshi*; Bai, S.*; Van Beek, P.*; Beaumel, D.*; Fujikawa, Yuki*; Han, J.*; Heil, S.*; et al.

Science, 371(6526), p.260 - 264, 2021/01

 Times Cited Count:8 Percentile:99.26(Multidisciplinary Sciences)

By employing quasi-free $$alpha$$-cluster-knockout reactions, we obtained direct experimental evidence for the formation of $$alpha$$ clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between $$alpha$$-cluster formation and the neutron skin.

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

International network of nuclear structure and decay data evaluators

Dimitriou, P.*; Basunia, S*; Bernstein, L.*; Chen, J.*; Elekes, Z.*; Huang, X.*; Hurst, A.*; Iimura, Hideki; Jain, A. K.*; Kelley, J.*; et al.

EPJ Web of Conferences, 239, p.15004_1 - 15004_4, 2020/09

 Times Cited Count:0 Percentile:0.19

The Evaluated Nuclear Structure Data File (ENSDF) includes the most extensive and comprehensive set of nuclear structure and decay data evaluations performed by the international network of Nuclear Structure and Decay Data evaluators (NSDD) under the auspices of the IAEA. In this report we describe some of the recent NSDD activities and provide future perspectives.

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:13 Percentile:97.21(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

Fine structure in the $$alpha$$ decay of $$^{223}$$U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

 Times Cited Count:6 Percentile:89.19(Astronomy & Astrophysics)

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:21 Percentile:92.26(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Provenance of uranium particulate contained within Fukushima Daiichi Nuclear Power Plant Unit 1 ejecta material

Martin, P. G.*; Louvel, M.*; Cipiccia, S.*; Jones, C. P.*; Batey, D. J.*; Hallam, K. R.*; Yang, I. A. X.*; Satou, Yukihiko; Rau, C.*; Mosselmans, J. F. W.*; et al.

Nature Communications (Internet), 10(1), p.2801_1 - 2801_7, 2019/06

 Times Cited Count:15 Percentile:84.77(Multidisciplinary Sciences)

Synchrotron radiation (SR) analysis techniques alongside secondary ion mass spectrometry (SIMS) measurements have been made on sub-mm particulate material derived from reactor Unit 1 of the Fukushima Daiichi Nuclear Power Plant (FDNPP). Using these methods, it has been possible to investigate the distribution, state and isotopic composition of micron-scale U particulate contained within the larger Si-based ejecta material. Through combined SR micro-focused X-ray fluorescence (SR-micro-XRF) and absorption contrast SR micro-focused X-ray tomography (SR-micro-XRT), the U particulate was found to be located around the exterior circumference of the highly-porous particle. Synchrotron radiation micro-focused X-ray absorption near edge structure (SR-micro-XANES) analysis of a number of these entrapped particles revealed them to exist within the U(IV) oxidation state, as UO$$_{2}$$, and identical in structure to reactor fuel. Confirmation that this U was of nuclear origin ($$^{235}$$U-enriched) was provided through secondary ion mass spectrometry (SIMS) analysis with an isotopic enrichment ratio characteristic of a provenance from reactor Unit 1 at the FDNPP. These results provide clear evidence of the event scenario (that a degree of core fragmentation and release occurred from reactor Unit 1), with such spent fuel ejecta existing; (i) within the stable U(IV) oxidation state; and (ii) contained within a bulk Si-based particle. While this U is unlikely to represent an environmental or health hazard, such assertions would likely change, however, should break-up of the Si-containing bulk particle occur. However, more important to the long-term decommissioning of the reactors (and clean-up) on the FDNPP, is the knowledge that core integrity of reactor Unit 1 was compromised with nuclear material existing outside of the reactors primary containment.

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

Sorption behavior of Np(V) on illite, shale and MX-80 in high ionic strength solutions

Nagasaki, Shinya*; Saito, Takumi; Yang, T.*

Journal of Radioanalytical and Nuclear Chemistry, 308(1), p.143 - 153, 2016/04

 Times Cited Count:8 Percentile:66.89(Chemistry, Analytical)

Sorption of Np(V) on illite, shale and MX-80 under oxidizing conditions were first studied in two types of high ionic strength solutions: (1) a reference brine solution (SR-270-PW) with an ionic strength (I) of 6.0 M, and (2) Na-Ca-Cl solutions (with different Na/Ca molar ratios and different ionic strengths, up to a maximum of 4.6 M). The effects of pHc, Na/Ca ratio, and ionic strength on sorption in Na-Ca-Cl solutions were investigated. The Kd values increased with increasing pHc and Na/Ca ratio for all sorbents studied. The Kd values on illite and shale were independent of the ionic strength over the range 0.10-4.6 M, and the Kd value on MX-80 was independent of ionic strength greater than 1.0 M. The Kd values and the sorption isotherms in both SR-270-PW and Na-Ca-Cl solutions were also studied.

Journal Articles

Measurement of neutron production cross sections from heavy ion induced reaction

Shigyo, Nobuhiro*; Uozumi, Yusuke*; Imabayashi, Yoichi*; Itashiki, Yutaro*; Satoh, Daiki; Kajimoto, Tsuyoshi*; Sanami, Toshiya*; Koba, Yusuke*; Takada, Masashi*; Matsufuji, Naruhiro*; et al.

JAEA-Conf 2014-002, p.81 - 87, 2015/02

Cancer therapy using heavy ion beam has been adopted as highly advanced medical treatment by reason of its clinical advantages. It has become more important to estimate the risk of secondary cancer from recent survey. During treatment, secondary particles such as neutrons and -rays are producedby heavy ion induced nuclear reactions in a patient body as well as beam delivery apparatuses. For the risk assessment of secondary cancer, it is essential to know contribution of secondary neutrons by extra dose to organs in the vicinity of the irradiated tumor because the secondary neutron has a long flight path length and gives undesired dose to normal tissues in a wide volume. The experimental data of neutron energy spectra are required for dose estimations with high accuracy. Especially, precise data around neutron energy of 1 MeV is required because neutron of the energy region has a large relative biological eectiveness. Estimation of the secondary neutron yield data is important for estimation of radiation safety on both of workers and public in treatment facilities.

Journal Articles

Measurement of proton, deuteron, and triton production double differential cross sections on carbon by 290 MeV/nucleon Ar ions

Kajimoto, Tsuyoshi*; Hashiguchi, Taro*; Shigyo, Nobuhiro*; Satoh, Daiki; Uozumi, Yusuke*; Song, T. Y.*; Lee, C. W.*; Kim, J. W.*; Yang, S. C.*; Koba, Yusuke*; et al.

JAEA-Conf 2014-002, p.127 - 132, 2015/02

Particle transport Monte Carlo codes such as PHITS, FLUKA and so on are used for radiation safety design of high energy accelerators. The validity of code is con rmed by comparison with many experimental data. In this study, we report proton, deuteron, and triton production double differential cross sections (DDXs) from a graphite target by 290 MeV/nucleon Ar ions. The measured spectra are compared with those calculated by PHITS and FLUKA codes.

Journal Articles

Coherent control of single spins in silicon carbide at room temperature

Widmann, M.*; Lee, S.-Y.*; Rendler, T.*; Son, N. T.*; Fedder, H.*; Paik, S.*; Yang, L.-P.*; Zhao, N.*; Yang, S.*; Booker, I.*; et al.

Nature Materials, 14(2), p.164 - 168, 2015/02

 Times Cited Count:309 Percentile:99.49(Chemistry, Physical)

Journal Articles

Actuator and diagnostic requirements of the ITER plasma control system

Snipes, J. A.*; Beltran, D.*; Casper, T.*; Gribov, Y.*; Isayama, Akihiko; Lister, J.*; Simrock, S.*; Vayakis, G.*; Winter, A.*; Yang, Y.*; et al.

Fusion Engineering and Design, 87(12), p.1900 - 1906, 2012/12

 Times Cited Count:21 Percentile:86.21(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutron scattering studies of the spin-5/2 antiferromagnetic linear trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

Hase, Masashi*; D$"o$nni, A.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*; Sakai, Osamu*; Pomjakushin, V. Y.*; Keller, L.*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; et al.

Journal of Physics; Conference Series, 340, p.012066_1 - 012066_7, 2012/00

 Times Cited Count:1 Percentile:46.98

We determined the magnetic structure below $$T_{rm N1}=2.2(1)$$ K of the spin-5/2 antiferromagnetic (AF) trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$ using neutron powder diffraction experiments. The incommensurate propagation vector is expressed as [0, $$k_y$$, 0], due to competition between the nearest-neighbor and next-nearest-neighbor interactions in trimerized chains. The value of $$k_y$$ is 0.316 to 0.331, changing rapidly at $$T_{rm N2}= 1.75(5)$$ K. We confirmed that the intra-trimer $$J_1$$ interaction is AF. The magnetic excitation peaks were obsereved at 0.46, 0.68, and 1.02 meV. The weak Q dependence indicates the discrete energy levels, which do not contradict the AF trimer model with the intra-trimer interaction value of 0.29 meV (3.4 K).

Journal Articles

Magnetic excitations in the spin-5/2 antiferromagnetic trimer substance SrMn$$_3$$P$$_4$$O$$_{14}$$

Hase, Masashi*; Matsuda, Masaaki*; Kaneko, Koji; Metoki, Naoto; Kakurai, Kazuhisa; Yang, T.*; Cong, R.*; Lin, J.*; Ozawa, Kiyoshi*; Kitazawa, Hideaki*

Physical Review B, 84(21), p.214402_1 - 214402_6, 2011/12

 Times Cited Count:9 Percentile:42.37(Materials Science, Multidisciplinary)

Journal Articles

Arc discharge characteristics of a long pulse ion source for the KSTAR neutral beam injector

Chang, D. H.*; Jeong, S. H.*; Jin, J. T.*; Chang, D. S.*; Kim, T. S.*; Lee, K. W.*; In, S. R.*; Oh, B. H.*; Bae, Y. S.*; Kim, J. S.*; et al.

Journal of the Korean Physical Society, 59(2), p.275 - 280, 2011/08

 Times Cited Count:3 Percentile:29.52(Physics, Multidisciplinary)

A long pulse ion source (LPIS) for the neutral beam injector (NBI) has been developed for the Korea Superconducting Tokamak Advanced Research (KSTAR) superconducting tokamak. The arc discharge characteristics of the ion source were investigated on the first KSTAR neutral beam injector (NBI-1). The ion source consists of a magnetic bucket plasma generator with multi-pole cusp fields and a set of prototype tetrode accelerators with circular apertures. Stable and efficient arc plasmas up to an arc power of 70 kW have been produced by using a constant power-mode operation of the arc power supply. The reliable operation region of the arc discharges has been investigated for various filament heating voltages, arc powers, and amounts of injected deuterium gas.

31 (Records 1-20 displayed on this page)