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Journal Articles

Production of $$^{266}$$Bh in the $$^{248}$$Cm($$^{23}$$Na,5$$n$$)$$^{266}$$Bh reaction and its decay properties

Haba, Hiromitsu*; Fan, F.*; Kaji, Daiya*; Kasamatsu, Yoshitaka*; Kikunaga, Hidetoshi*; Komori, Yukiko*; Kondo, Narumi*; Kudo, Hisaaki*; Morimoto, Koji*; Morita, Kosuke*; et al.

Physical Review C, 102(2), p.024625_1 - 024625_12, 2020/08

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri. A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:1 Percentile:30.13(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Study on formation mechanism of {332}$$<$$113$$>$$ deformation twinning in metastable $$beta$$-type Ti alloy focusing on stress-induced $$alpha"$$ martensite phase

Cho, K.*; Morioka, Ryota*; Harjo, S.; Kawasaki, Takuro; Yasuda, Hiroyuki*

Scripta Materialia, 177, p.106 - 111, 2020/03

 Times Cited Count:3 Percentile:8.3(Nanoscience & Nanotechnology)

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:3 Percentile:13.44(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

Development of inter-digital H-mode drift-tube linac prototype with alternative phase focusing for a muon linac in the J-PARC muon g-2/EDM experiment

Nakazawa, Yuga*; Iinuma, Hiromi*; Iwata, Yoshiyuki*; Iwashita, Yoshihisa*; Otani, Masashi*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Yamazaki, Takayuki*; Yoshida, Mitsuhiro*; Kitamura, Ryo; et al.

Journal of Physics; Conference Series, 1350, p.012054_1 - 012054_7, 2019/12

 Times Cited Count:0 Percentile:100

An inter-digital H-mode drift-tube linac (IH-DTL) is developed in a muon linac at the J-PARC E34 experiment. IH-DTL will accelerate muons from 0.34 MeV to 4.5 MeV at a drive frequency of 324 MHz. Since IH-DTL adopts an APF method, with which the beam is focused in the transverse direction using the rf field only, the proper beam matching of the phase-space distribution is required before the injection into the IH-DTL. Thus, an IH-DTL prototype was fabricated to evaluate the performance of the cavity and beam transmission. As a preparation of the high-power test, tuners and coupler are designed and fabricated. In this paper, the development of the tuner and the coupler and the result of the low-power measurement will be presented.

Journal Articles

Negative muonium ion production with a C12A7 electride film

Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Matoba, Shiro*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Hasegawa, Kazuo; et al.

Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12

 Times Cited Count:0 Percentile:100

Negative muonium atom ($$mu^+$$e$$^-$$e$$^-$$, Mu$$^-$$) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented. Measured production rate of the Mu$$^-$$ were 10$$^{-3}$$/s for all the Al, electride, and SUS target. Significant enhancement on electride target was not observed, thus it is presumed that the surface condition should be more carefully treated. There was no material dependence of the Mu$$^-$$ averaged energy: it was 0.2$$pm$$0.1keV.

Journal Articles

Development of fabrication and inspection technologies for oxidation-resistant fuel element for high-temperature gas-cooled reactors

Aihara, Jun; Yasuda, Atsushi*; Ueta, Shohei; Ogawa, Hiroaki; Honda, Masaki*; Ohira, Koichi*; Tachibana, Yukio

Nippon Genshiryoku Gakkai Wabun Rombunshi, 18(4), p.237 - 245, 2019/12

Development of fabrication and inspection technologies of oxidation resistant fuel element for improvement of safety of high temperature gas-cooled reactors (HTGRs) in severe oxidation accident was carried out. Simulated coated fuel particles (CFPs), alumina particles, were over-coated with mixed powder of Si, C and small amount of resin to form over-coated particles, and over-coated particles were molded and hot-pressed to sinter simulated oxidation resistant fuel elements with SiC/C mixed matrix. Simulated oxidation resistant fuel elements with matrix whose Si/C mole ratio is 1.00 were fabricated. Failure fraction of CFPs in fuel elements is one of very important inspection subjects of HTGR fuel. It is essential that CFPs are extracted from fuel elements without additional failure. Development of method for extraction of CFPs was carried out. Desolation of SiC by KOH method or pressurized acidolysis method should be applied to extraction of CFPs.

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

 Times Cited Count:8 Percentile:16.18(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Beam commissioning of muon beamline using negative hydrogen ions generated by ultraviolet light

Nakazawa, Yuga*; Bae, S.*; Choi, H.*; Choi, S.*; Iijima, Toru*; Iinuma, Hiromi*; Kawamura, Naritoshi*; Kitamura, Ryo; Kim, B.*; Ko, H. S.*; et al.

Nuclear Instruments and Methods in Physics Research A, 937, p.164 - 167, 2019/09

 Times Cited Count:1 Percentile:58.8(Instruments & Instrumentation)

A muon linac is under development for the precise measurement of the muon anomalous magnetic moment ($$g$$-2) and electric dipole moment (EDM) with a reaccelerated thermal muon beam. An H$$^-$$ source driven by an ultraviolet light has been developed for the muon acceleration experiment. Prior to the acceleration experiment, a beamline commissioning was performed using this H$$^-$$ beam, since the accelerated muon intensity is very low. We successfully measured the magnetic rigidity, which is essential for identifying the accelerated muons. This H$$^-$$ source is capable of utilizing as a general-purpose beam source for other beamline.

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 Times Cited Count:4 Percentile:25.43(Physics, Multidisciplinary)

Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for $$^{107}$$Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.

Journal Articles

Nowcast and forecast of galactic cosmic ray (GCR) and solar energetic particle (SEP) fluxes in magnetosphere and ionosphere; Extension of WASAVIES to earth orbit

Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Miyoshi, Yoshizumi*; Ueno, Haruka*; Nagamatsu, Aiko*

Journal of Space Weather and Space Climate (Internet), 9, p.A9_1 - A9_11, 2019/03

 Times Cited Count:2 Percentile:49.6(Astronomy & Astrophysics)

Real-time estimation of astronaut doses during solar particle events (SPE) is one of the most challenging tasks in cosmic-ray dosimetry. We therefore develop a new computational method that can nowcast the solar energetic particle (SEP) as well as galactic cosmic-ray (GCR) fluxes on any Earth orbit during a large SPE associating with ground level enhancement. It is an extended version of WArning System for AVIation Exposure to Solar Energetic Particle, WASAVIES. The extended version, called WASAVIES-EO, can calculate the GCR and SEP fluxes outside a satellite based on its two-line element data. Moreover, organ dose and dose-equivalent rates of astronauts in the International Space Station (ISS) can be estimated using the system, considering its shielding effect. The accuracy of WASAVIES-EO was validated based on the dose rates measured in ISS, as well as based on high-energy proton fluxes observed by POES satellites.

Journal Articles

Prototype of an Inter-digital H-mode Drift-Tube Linac for muon linac

Nakazawa, Yuga*; Iinuma, Hiromi*; Iwata, Yoshiyuki*; Iwashita, Yoshihisa*; Otani, Masashi*; Kawamura, Naritoshi*; Mibe, Tsutomu*; Yamazaki, Takayuki*; Yoshida, Mitsuhiro*; Kitamura, Ryo*; et al.

Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.180 - 183, 2019/01

We have developed an Interdigital H-mode (IH) Drift-Tube Linac (DTL) design with an alternative phase focusing (APF) scheme for a muon linac, in order to measure the anomalous magnetic moment and electric dipole moment (EDM) of muons at the Japan Proton Accelerator Research Complex (J-PARC). The IH-DTL accelerates muons from beta 0.08 to 0.28 at an operational frequency of 324 MHz. The output beam emittances are calculated as 0.315 $$pi$$ and 0.195 $$pi$$ mm mrad in the horizontal and vertical directions, respectively, which satisfies the experimental requirement.

Journal Articles

Enhancement of Fe-N-C carbon catalyst activity for the oxygen reduction reaction; Effective increment of active sites by a short and repeated heating process

Yasuda, Satoshi; Uchibori, Yosuke*; Wakeshima, Makoto*; Hinatsu, Yukio*; Ogawa, Hiroaki; Yano, Masahiro; Asaoka, Hidehito

RSC Advances (Internet), 8(66), p.37600 - 37605, 2018/11

 Times Cited Count:3 Percentile:70.3(Chemistry, Multidisciplinary)

We present a quantitative study on the effect of a newly obtained thermal history on the formation of Fe-N-C catalytic sites. A short and repeated heating process is employed as the new thermal history, where short heating (1 min) followed by quenching is applied to a sample with arbitrary repetition. Through electrochemical quantitative analysis, it is found that the new process effectively increases the Fe-N-C mass-based site density (MSD) to almost twice that achieved using a conventional continuous heating process, while the turn-over frequency (TOF) is independent of the process. Elemental analysis shows that the new process effectively suppresses the thermal desorption of Fe and N atoms during the initial formation stage and consequently contributes to an increase in the Fe-N-C site density. The resultant catalytic activity (gravimetric kinetic current density (0.8 V vs. RHE)) is 1.8 times higher than that achieved with the continuous heating process.

Journal Articles

STM-induced SiO$$_{2}$$ decomposition on Si(110)

Yano, Masahiro; Uozumi, Yuki*; Yasuda, Satoshi; Asaoka, Hidehito; Tsukada, Chie*; Yoshida, Hikaru*; Yoshigoe, Akitaka

e-Journal of Surface Science and Nanotechnology (Internet), 16, p.370 - 374, 2018/08

Journal Articles

Characterization of SiO$$_{2}$$ reduction reaction region at void periphery on Si(110)

Yano, Masahiro; Uozumi, Yuki*; Yasuda, Satoshi; Tsukada, Chie*; Yoshida, Hikaru*; Yoshigoe, Akitaka; Asaoka, Hidehito

Japanese Journal of Applied Physics, 57(8S1), p.08NB13_1 - 08NB13_4, 2018/07

 Times Cited Count:1 Percentile:88.11(Physics, Applied)

Journal Articles

Variation of half-life and internal-conversion electron energy spectrum between $$^{235m}$$U oxide and fluoride

Shigekawa, Yudai*; Kasamatsu, Yoshitaka*; Yasuda, Yuki*; Kaneko, Masashi; Watanabe, Masayuki; Shinohara, Atsushi*

Physical Review C, 98(1), p.014306_1 - 014306_5, 2018/07

 Times Cited Count:1 Percentile:78.75(Physics, Nuclear)

The nuclear half-life of $$^{235m}$$U has been reported to vary depending on the chemical environment. In this study, both the half-life and the internal-conversion (IC) electron energy spectrum were measured for $$^{235m}$$U with identical chemical environments for the first time. $$^{235m}$$U oxide and fluoride samples were subjected to these measurements, and clear differences in the half-life and the energy spectrum between these samples were observed. The peaks in the energy spectra were identified with the relativistic density functional theory calculation, and the molecular orbital states of the $$^{235m}$$U oxide and fluoride estimated from the energy spectra and the calculation qualitatively explained the difference in the half-lives between the samples.

Journal Articles

Real time and automatic analysis program for WASAVIES; Warning system for aviation exposure to solar energetic particles

Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*

Space Weather, 16(7), p.924 - 936, 2018/07

 Times Cited Count:7 Percentile:28.73(Astronomy & Astrophysics)

A physics-based warning system of aviation exposure to solar energetic particles, WASAVIES, is improved to be capable of real-time and automatic analysis. In the improved system, the count rates of several neutron monitors (NM) at the ground level, as well as the proton fluxes measured by the GOES satellite are continuously downloaded at intervals of 5 min and used for determining the model parameters. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. A web-interface of WASAVIES is also developed and will be released in the near future through the public server of NICT.

Journal Articles

Uniform Si nano-dot fabrication using reconstructed structure of Si(110)

Yano, Masahiro; Uozumi, Yuki*; Yasuda, Satoshi; Asaoka, Hidehito

Japanese Journal of Applied Physics, 57(6S1), p.06HD04_1 - 06HD04_4, 2018/06

 Times Cited Count:3 Percentile:60.22(Physics, Applied)

Journal Articles

Effect of deflected inflow on flows in a strongly-curved 90 degree elbow

Iwamoto, Yukiharu*; Kusuzaki, Ryo*; Sogo, Motosuke*; Yasuda, Kazunori*; Yamano, Hidemasa; Tanaka, Masaaki

Proceedings of ASME-JSME-KSME Joint Fluids Engineering Conference 2015 (AJK 2015-FED) (USB Flash Drive), p.1767 - 1773, 2015/07

Wall pressure measurements and flow visualization were conducted for a 90 degree elbow of which the axis curvature radius became the same as its inner diameter (125 mm). A deflected inflow, having an almost constant velocity slope, was introduced. Ensemble averaged pressure distributions showed no normalized pressure difference in cases of Reynolds numbers of 320,000 and 500,000. Comparisons with uniform inlet flow case proved; low-pressure region at the intrados of the elbow was weakened whereas a high pressure region outside strengthened in the deflected inflow case. Pressure distribution downstream of the elbow increased at the inside until two diameters downstream from the elbow exit. Flow visualization showed the pressure increase from collision of a strengthened secondary flow of extrados convection. The unsteady pressure distribution showed a circumferential extent of a strongly fluctuating region in and downstream the elbow decreased, comparing with the uniform inlet flow case.

JAEA Reports

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JPDR facilities, 4

Omori, Hiroyuki; Nebashi, Koji; Shimada, Asako; Tanaka, Kiwamu; Yasuda, Mari; Hoshi, Akiko; Tsuji, Tomoyuki; Ishimori, Kenichiro; Kameo, Yutaka

JAEA-Data/Code 2014-029, 31 Pages, 2015/03


Simple and rapid methods to evaluate the radioactivity concentrations are required for the radioactive waste generated from research facilities in the Japan Atomic Energy Agency to dispose of in a near-surface repository. In order to establish the methods to evaluate the radioactivity concentrations of miscellaneous solid waste generated from research and testing reactors, we collected and analyzed samples from miscellaneous solid waste generated by the decommissioning of JPDR (Japan Power Demonstration Reactor). In this report, we reported the analytical data determined in fiscal 2014 ($$^{137}$$Cs and $$^{93}$$Mo) and summarized them with the radioactivity concentrations obtained in the past as basic data to consider the evaluation method of radioactivity concentrations in the stored waste taken from JPDR.

154 (Records 1-20 displayed on this page)