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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
Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.
Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08
Times Cited Count:2 Percentile:68.16(Astronomy & Astrophysics)Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
Thiessen, K. M.*; Boznar, M. Z.*; Charnock, T. W.*; Chouhan, S. L.*; Federspiel, L.; Grai, B.*; Grsic, Z.*; Helebrant, J.*; Hettrich, S.*; Hulka, J.*; et al.
Journal of Radiological Protection, 42(2), p.020502_1 - 020502_8, 2022/06
Times Cited Count:5 Percentile:78.52(Environmental Sciences)Kumagai, Tomohisa*; Miura, Yasufumi*; Miura, Naoki*; Marie, S.*; Almahdi, R.*; Mano, Akihiro; Li, Y.; Katsuyama, Jinya; Wada, Yoshitaka*; Hwang, J.-H.*; et al.
Journal of Pressure Vessel Technology, 144(1), p.011509_1 - 011509_18, 2022/02
Times Cited Count:1 Percentile:20.34(Engineering, Mechanical)To predict fracture behavior for ductile materials, some ductile fracture simulation methods different from classical approaches have been investigated based on appropriate models of ductile fracture. For the future use of the methods to overcome restrictions of classical approaches, the applicability to the actual components is of concern. In this study, two benchmark problems on the fracture tests supposing actual components were provided to investigate prediction ability of simulation methods containing parameter decisions. One was the circumferentially through-wall and surface cracked pipes subjected to monotonic bending, and the other was the circumferentially through-wall cracked pipes subjected to cyclic bending. Participants predicted the ductile crack propagation behavior by their own approaches, including FEM employed GTN yielding function with void ratio criterion, are FEM employed GTN yielding function, FEM with fracture strain or energy criterion modified by stress triaxiality, XFEM with J or delta J criterion, FEM with stress triaxiality and plastic strain based ductile crack propagation using FEM, and elastic-plastic peridynamics. Both the deformation and the crack propagation behaviors for monotonic bending were well reproduced, while few participants reproduced those for cyclic bending. To reproduce pipe deformation and fracture behaviors, most of groups needed parameters which were determined toreproduce pipe deformation and fracture behaviors in benchmark problems themselves and it is still difficult to reproduce them by using parameters only from basic materials tests.
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:14 Percentile:74.18(Physics, Multidisciplinary)The structure of a neutron-rich F nucleus is investigated by a quasifree () knockout reaction. The sum of spectroscopic factors of orbital is found to be 1.0 0.3. The result shows that the O core of F nucleus significantly differs from a free O nucleus, and the core consists of 35% O, and 65% excited O. The result shows that the O core of F nucleus significantly differs from a free O nucleus. The result may infer that the addition of the proton considerably changes the neutron structure in F from that in O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
Sako, Hiroyuki; Hasegawa, Shoichi; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Hicks, K.*; Ahn, J. K.*; Kim, S. H.*; Lee, J. W.*; Hwang, S. H.*
Proceedings of Science (Internet), 281, p.266_1 - 266_5, 2017/05
Although baryon resonances have been studied for a long time, our knowledge on their properties are still limited. Recently a Dynamical-Couple Channel (DCC) model shows there are significant contributions of reactions to these baryon resonances. However, there are only 240 thousand events of reaction data measured in 1970's. Thus, we proposed an experiment E45 to study baryon resonances in reaction utilizing Hz beams at J-PARC. We aim at clarifying most of baryon mass levels. We measure these reactions in a large acceptance Time Projection Chamber inside a Helmholtz dipole magnet. We will measure these reactions in small momentum steps over a large beam momentum range and perform partial wave analysis to extract properties of each resonance. In this presentation, we will show the experimental design, expected results in simulations, and the status of the detectors.
Kim, S. H.*; Hwang, S.; Ahn, J. K.*; Ekawa, Hiroyuki; Hayakawa, Shuhei; Hong, B.*; Hosomi, Kenji; Imai, Kenichi; Kim, M. H.*; Lee, J. Y.*; et al.
Nuclear Instruments and Methods in Physics Research A, 795, p.39 - 44, 2015/09
Times Cited Count:4 Percentile:33.25(Instruments & Instrumentation)Sako, Hiroyuki; Sugimura, Hitoshi; Ahn, J. K.*; Han, Y.*; Hasegawa, Shoichi; Hwang, S. H.*; Ichikawa, Yudai; Imai, Kenichi; Kiuchi, Ryuta*; Ozawa, Kyoichiro; et al.
Nuclear Instruments and Methods in Physics Research A, 763, p.65 - 81, 2014/11
Times Cited Count:5 Percentile:38.03(Instruments & Instrumentation)We developed a prototype TPC for an H-dibaryon search experiment at J-PARC. To investigate its performance, we conducted tests with Ar-CH (90:10) and Ar-CF (95:5), where the former is mainly used. The detection efficiency was measured to be 98% at the beam rate up to cps/cm, and 90% at the rate of cps/cm. Based on the measured horizontal resolution of 0.19-0.46 mm at the drift length of 5-20 cm, the position resolution of better than 0.3 mm is estimated in 1 T magnetic field. The ion backflow fraction was measured to be 5% and reduced up to 3% at the gain of . The horizontal position distortion due to ion backflow in the gate operation was suppressed within mm at the beam rates up to cps/cm. On the other hand, the distortion with the gate open was measured to be mm. The distortion in the final experiment is estimated to be mm.
Sako, Hiroyuki; Ahn, J. K.*; Baek, K. H.*; Bassalleck, B.*; Fujioka, H.*; Guo, L.*; Hasegawa, Shoichi; Hicks, K.*; Honda, R.*; Hwang, S. H.*; et al.
Journal of Instrumentation (Internet), 9(4), p.C04009_1 - C04009_10, 2014/04
Times Cited Count:3 Percentile:16.04(Instruments & Instrumentation)A TPC has been developed for J-PARC E42 experiment to search for H-dibaryon in (, ) reaction. An event with 2 and 2 protons decaying from H-dibaryon is searched for inside the TPC. The TPC has octagonal prism shape drift volume with about 50 cm diameter with 55 cm drift length filled with Ar-CH (90:10) gas. At the end of the drift volume, 3-layer GEMs are equipped. In order to analyze momenta of produced particles, the TPC is applied with 1 T dipole magnetic field parallel to the drift electric field with a superconducting Helmholz magnet. In order to maximize the acceptance of H-dibaryon events, a diamond target is installed inside the TPC drift volume, in a cylindrical hole opened from the top to the middle of the drift volume. Since extremely high-rate beam is directly injected into the TPC drift volume to the target, a gating grid and GEMs are adopted to suppress positive-ion feedback.
Sugimura, Hitoshi; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Kiuchi, Ryuta; Ichikawa, Yudai; Hwang, S. H.*; Hasegawa, Shoichi; Tanida, Kiyoshi; J-PARC E10 Collaboration*
Physics Letters B, 729, p.39 - 44, 2014/02
Times Cited Count:31 Percentile:86.77(Astronomy & Astrophysics)We have carried out an experiment to search for a neutron-rich hypernucleus, H, by the Li(,K) reaction at p = 1.2 GeV/c. The obtained missing-mass spectrum with an estimated energy resolution of 3.2 MeV (FWHM) showed no peak structure corresponding to the H hypernucleus neither below nor above the H+2n particle decay threshold. An upper limit of the production cross section for the bound H hypernucleus was estimated to be 1.2 nb/sr at 90% confidence level.
Tokiyasu, Atsushi*; Imai, Kenichi; Hwang, S. H.*; LEPS Collaboration*
Physics Letters B, 728, p.616 - 621, 2014/01
Times Cited Count:61 Percentile:95.9(Astronomy & Astrophysics)Hwang, S. H.*; Hicks, K.*; Ahn, J. K.*; Nakano, Takashi*
Few-Body Systems, 54(7-10), p.1037 - 1041, 2013/08
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)Imai, Kenichi; Hwang, S. H.*; Hicks, K.*; LEPS Collaboration*
Physical Review Letters, 108(9), p.092001_1 - 092001_5, 2012/03
Times Cited Count:21 Percentile:71.66(Physics, Multidisciplinary)The exclusive reaction was measured using lineraly polarized photon at GeV. Angular distributions of the system were fitted to extract spin-density matrix elements of the decay. The measured parity asymmetry shows that natural parity exchange is dominant in this reaction. This result clearly indicates the need for -channel exchange of the scalar exchange.
Kwak, J. G.*; Wang, S. J.*; Bae, Y. D.*; Kim, S. H.*; Hwang, C. K.*; Moriyama, Shinichi
Fusion Engineering and Design, 86(6-8), p.938 - 941, 2011/10
Times Cited Count:1 Percentile:10.73(Nuclear Science & Technology)KAERI have been developing the transmitters for ICRF heating for KSTAR and the cyclotron accelerator since 1996. The toroidal magnetic field of KSTAR is nominally 3 T so that 25-60 MHz transmitter is required to cover ICRF heating scenarios of the KSTAR. The first transmitter is operating up to 60 MHz and it succeeded in achieving 2 MW for 300 s in 2008. Up to 300 kW RF power was successfully injected to KSTAR plasmas. The second one is 70 kW/CW transmitter used for the cyclotron accelerator and their frequency range is from 25 to 50 MHz. Its engineering design was finished. The third one is 1 MW/VHF transmitter which was loaned from JAEA. As the operating ICRF frequency of KSTAR is lower, its cavity structure will be modified from 110 MHz to 60 MHz. The test results of 60 MHz and lessons from the high power test of 2 MW transmitter will be introduced and the circuit analysis and engineering design work for the second and third amplifiers will be shown.
Kobayashi, Masaki*; Ishida, Yukiaki*; Hwang, J. I.*; Song, G. S.*; Takizawa, Masaru*; Fujimori, Atsushi; Takeda, Yukiharu; Okochi, Takuo*; Okane, Tetsuo; Saito, Yuji; et al.
Physical Review B, 79(20), p.205203_1 - 205203_5, 2009/05
Times Cited Count:7 Percentile:33.2(Materials Science, Multidisciplinary)Kobayashi, Masaki*; Ishida, Yukiaki*; Hwang, J. I.*; Song, G. S.*; Fujimori, Atsushi; Yang, C. S.*; Lee, L.*; Lin, H.-J.*; Huang, D.-J.*; Chen, C. T.*; et al.
New Journal of Physics (Internet), 10, p.055011_1 - 055011_15, 2008/05
Times Cited Count:15 Percentile:64.38(Physics, Multidisciplinary)Kang, J.-S.*; Kim, J. H.*; Sekiyama, Akira*; Kasai, Shuichi*; Suga, Shigemasa*; Han, S. W.*; Kim, K. H.*; Muro, Takayuki*; Saito, Yuji; Hwang, C.*; et al.
Physical Review B, 66(11), p.113105_1 - 113105_4, 2002/09
Times Cited Count:65 Percentile:90.19(Materials Science, Multidisciplinary)The electronic structures of SrFeMoO (SFMO) and BaFeMoO (BFMO) double perovskites have been investigated using Fe 2p-3d resonant photoemission spectroscopy (PES) and the Cooper minimum in the Mo 4d photoionization cross section. The states close to the Fermi level are found to have a strongly mixed Mo–Fe t character, indicating that the Fe valence is far from pure 3+. The Fe 2p x-ray absorption spectroscopy spectra reveal the mixed-valent Fe –Fe configurations, and a larger Fe component for BFMO than for SFMO, suggesting an operative double exchange interaction. The valence-band PES spectra reveal good agreement with the local-spin-density-approximation (LSDA+U) calculation.
Sato, Susumu; Sako, Hiroyuki; Hasegawa, Shoichi; Sugimura, Hitoshi; Ichikawa, Yudai; Ozawa, Kyoichiro; Kiuchi, Ryuta*; Hwang, S. H.*; Imai, Kenichi
no journal, ,
no abstracts in English
Sako, Hiroyuki; Imai, Kenichi; Sato, Susumu; Hasegawa, Shoichi; Hwang, S. H.*; Sugimura, Hitoshi; Ichikawa, Yudai; Tanida, Kiyoshi; Kiuchi, Ryuta*; Ahn, J. K.*; et al.
no journal, ,
The H-dibaryon has been proposed as a stable 6-quark sate, and various experiments have been performed to search for it, but never been successful. KEK-PS E224 and E522 experiments observed peaks near the threshold in the invariant mass spectra although statistics is not enough. On the other hand, recent lattice QCD calculations predict the H is a shallow bound state or a resonance state. We proposed J-PARC E42 experiment to search for the H-dibaryon in (,) reaction with two-order higher statistics and higher mass resolutions.
Imai, Kenichi; Hwang, S. H.*
no journal, ,