Metoki, Naoto; Shibata, Kaoru; Matsuura, Masato*; Kitazawa, Hideaki*; Suzuki, Hiroyuki*; Yamauchi, Hiroki; Hagihara, Masato; Frontzek, M. D.*; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 91(5), p.054710_1 - 054710_6, 2022/05
Hyperfine splitting of Nd nuclei in NdPdAl has been studied by means of high-resolution neutron spectroscopy. We observed inelastic peaks at eV coming from the hyperfine splitting in the magnetically ordered phase due to the hyperfine interactions between Nd nuclei (=7/2) and the 4 electrons with ground state composed of mainly . At very low temperatures, nuclear spin of Nd is polarized with increasing occupation probability of low energy levels and contributes to the enhancement of the antiferromagnetic Bragg intensities: the elastic non-spin-flip channel is dominant. As an application of this phenomenon, we determined the Nd moment and hyperfine splitting from the temperature dependence of an antiferromagnetic Bragg intensities for NdPdGe.
Arai, Yosuke*; Kuroda, Kenta*; Nomoto, Takuya*; Tin, Z. H.*; Sakuragi, Shunsuke*; Bareille, C.*; Akebi, Shuntaro*; Kurokawa, Kifu*; Kinoshita, Yuto*; Zhang, W.-L.*; et al.
Nature Materials, 21(4), p.410 - 415, 2022/04
Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.
Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03
We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.
Suzuki, Hideaki*; Takayama, Yusuke
JAEA-Research 2020-015, 52 Pages, 2020/12
It is anticipated that the coupled thermal hydraulic and mechanical (THM) processes will occur, involving an interactive process with radioactive decay heat arising from the vitrified waste, infiltration of groundwater from the host rock into the buffer material, swelling pressure of buffer material due to its saturation in the near-field of a geological disposal system for high-level radioactive waste repository. In order to evaluate these phenomena in the near-field, the THM model has been developed. In this report, the density dependence of thermal, hydraulic and mechanical properties of the buffer material was investigated to evaluate the near-field environment. These density dependence schemes were added to the coupled THM model. The THM analysis of the in-situ experiment of engineered barrier system (EBS) experiment at the Horonobe Underground Research Laboratory was carried out. As a result, the effect of the density change of the buffer material on the temperature and infiltration behavior of buffer material was found. A case analysis on the long-term behavior of the near field was also carried out. Then, the behavior that the buffer material swelled out toward the backfill material and the density of the buffer material decreasing was shown.
Kuroda, Kenta*; Arai, Yosuke*; Rezaei, N.*; Kunisada, So*; Sakuragi, Shunsuke*; Alaei, M.*; Kinoshita, Yuto*; Bareille, C.*; Noguchi, Ryo*; Nakayama, Mitsuhiro*; et al.
Nature Communications (Internet), 11, p.2888_1 - 2888_9, 2020/06
Sun, X. H.*; Wang, H.*; Otsu, Hideaki*; Sakurai, Hiroyoshi*; Ahn, D. S.*; Aikawa, Masayuki*; Fukuda, Naoki*; Isobe, Tadaaki*; Kawakami, Shunsuke*; Koyama, Shumpei*; et al.
Physical Review C, 101(6), p.064623_1 - 064623_12, 2020/06
The spallation and fragmentation reactions of Xe induced by proton, deuteron and carbon at 168 MeV/nucleon were studied at RIKEN Radioactive Isotope Beam Factory via the inverse kinematics technique. The cross sections of the lighter products are larger in the carbon-induced reactions due to the higher total kinetic energy of carbon. The energy dependence was investigated by comparing the newly obtained data with previous results obtained at higher reaction energies. The experimental data were compared with the results of SPACS, EPAX, PHITS and DEURACS calculations. These data serve as benchmarks for the model calculations.
Metoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagihara, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.
JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03
Rare earths (4) and actinides (5) provide variety of interesting states realized with competing interactions between the increasing number of electrons. Since crystal field splitting of many-body electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the electron states of heavy electron compounds NpPdAl and actinide and rare earth based iso-structural family.
Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Authelet, G.*; et al.
Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03
The structures of the neutron-rich Co isotopes were investigated via () knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Level schemes were reconstructed using the coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations suggests coexistence of spherical and deformed shapes at low excitation energies in the Co isotopes.
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
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 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.
Marufuji, Takato; Sato, Takumi; Ito, Hideaki; Suzuki, Hisashi; Fujishima, Tadatsune; Nakano, Tomoyuki
JAEA-Technology 2019-006, 22 Pages, 2019/05
Radioactive contamination incident occurred at Plutonium Fuel Research Facility (PFRF) in Oarai Research and Development Institute, Japan Atomic Energy Agency on June 6, 2017. During inspection work of storage container containing nuclear fuel materials, the PVC bag packaging in the storage container ruptured when a worker opened the lid in the hood, and a part of contents was spattered over the room. The cause of the increase of internal pressure of the storage container was gas generation by alpha radiolysis of the epoxy resin mixed with nuclear fuel materials. Opening inspection of about 70 similar containers stored in PFRF has been planned to confirm the condition of the contents and to stabilize the stored materials containing organic compounds. For safe and reliable open inspection of the storage containers with high internal pressure in the glove box, it is necessary to develop a pressure-resistant chamber in which the storage containers are opened and the contents are inspected under gastight condition. This report summarizes the concerns and countermeasures of the chamber design and the design results of the chamber.
Kobayashi, Toru; Akutsu, Kazuhiro*; Nakase, Masahiko*; Suzuki, Shinichi; Shiwaku, Hideaki; Yaita, Tsuyoshi
Separation Science and Technology, 54(13), p.2077 - 2083, 2019/02
Development of separation reagent, which can efficiently separate lanthanides, is of increasing importance because it concerns establishment of purification and recycle techniques rare-earth elements. In our research group, several hetero donor type ligands, which have both oxygen and heterocyclic nitrogen atoms as donor atoms, were developed and revealed that this type of ligands show the selective complexation with specific lanthanide. In this paper, we will discuss the lanthaides complexation properties of the hetero donor type ligand containing benzimidazole group as nitrogen donor (-methyl--phenyl-2-(1-benzimidazol-2-yl)-pyridine-6-carboxamide) based on structural investigation by crystallography.
Elekes, Z.*; Kripk, *; Sohler, D.*; Sieja, K.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; Baba, Hidetada*; et al.
Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01
The nuclear structure of the Ni nucleus was investigated by (,) reaction using a NaI(Tl) array to detect the deexciting prompt rays. A new transition with an energy of 2227 keV was identified by and coincidences. Our shell-model calculations using the Lenzi, Nowacki, Poves, and Sieja interaction produced good candidates for the experimental proton hole states in the observed energy region, and the theoretical cross sections showed good agreement with the experimental values. Although we could not assign all the experimental states to the theoretical ones unambiguously, the results are consistent with a reasonably large Z = 28 shell gap for nickel isotopes in accordance with previous studies.
Kofuji, Hirohide; Watanabe, So; Takeuchi, Masayuki; Suzuki, Hideya; Matsumura, Tatsuro; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.61 - 65, 2018/11
Kobayashi, Toru; Suzuki, Shinichi; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.74 - 77, 2018/11
Development of extractant, which can efficiently separate actinides, is of increasing importance because it concerns establishment and simplification of separation techniques in nuclear fuel cycle and decontamination of radioactive wastes. In this study, the complexation properties of N-alkyl-N-phenyl-1,10-phenanthroline-2-carboxamide (PTA) with trivalent lanthanides (Ln) were investigated based on structural analysis by using X-ray crystallography and extended X-ray absorption fine structure (EXAFS) methods. As a result, it is revealed that two PTA molecules coordinate with Ln as tridentate ligand via two nitrogen in phenanthroline moiety and one oxygen in amide moiety in both crystal and solution states. The slight difference in coordination bond distances are observed between Eu and Nd complexes, this difference corresponds to the difference in ionic radius between Nd and Eu. This result indicates slight difference in ionic radii of Ln hardly affects coordination properties of PTA.
Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Hagihara, Masato*; Masuda, Takatsugu*; Aczel, A. A.*; Chi, S.*; Hong, T.*; Matsuda, Masaaki*; et al.
Journal of the Physical Society of Japan, 87(9), p.094704_1 - 094704_8, 2018/09
The -electron states of PrPdAl were revealed by neutron inelastic scattering. The flat -orbitals with large become stable under the two-dimensional CEF potential of unique crystal structure, which is the origin of the Ising anisotropy. A systematic understanding is possible in RPdAl based on this CEF potential. Especially the -type anisotropy in NpPdAl can be qualitatively understood with the positive Stevens factors. It mean that the local property is important for the physical properties of RPdAl including the heavy fermion superconductivity in NpPdAl.
Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro
Journal of the Physical Society of Japan, 87(8), p.084708_1 - 084708_7, 2018/08
Inelastic neutron scattering experiments were carried out in order to study the -electron states of NdPdAlThe CEF levels at 0K, 35.4K, 88.3K, 101.5K, and 198.8K were clarified from the excitation spectra. The ground state contains the orbital with as a main component due to a large negative BK, which is the origin of the strong uniaxial anisotropy. The estimated magnetic moment, the calculated susceptibility, magnetization curve, and specific heat are in good agreement with the experimental data. The existence of a common charge distribution with CePdAl and PrPdAl. Indicates that a localized character is important even in actinide-based iso-structural compounds as actually observed in UPdAl and also NpPdAl, in which the valence crossover plays important role for the heavy fermion superconductivity.
Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*
Metals, 8(7), p.558_1 - 558_10, 2018/07
The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO. Replacement of distillation byextraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with UV-Vis and EXAFS spectroscopies, and we examined the properties of Ru extracted with N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide) amine (EHBAA). EXAFS and UV-Vis spectra of Ru in HCl solutions revealed that the predominant Ru species in 0.5-10 M HCl solutions changed from [RuCl(HO)] to [RuCl] with the HCl concentration. The extraction percentages of Ru in the EHBAA system increased with increasing HCl concentration, reached 80% at [HCl] = 5 M, and decreased athigher HCl concentrations. EXAFS analysis of the extracted complex indicated that the Ru had 5 Cl and 1 HO in its inner coordination sphere. The similarity of the dependence on HCl concentrations of the extraction in the EHBAA system and the distribution profile of [RuCl(HO)] on [RuCl(HO)] suggested that the EHBAA extracted the pentachlorido species.
Kuroda, Kenta*; Ochi, Masayuki*; Suzuki, Hiroyuki*; Hirayama, Motoaki*; Nakayama, Mitsuhiro*; Noguchi, Ryo*; Bareille, C.*; Akebi, Shuntaro*; Kunisada, So*; Muro, Takayuki*; et al.
Physical Review Letters, 120(8), p.086402_1 - 086402_6, 2018/02
Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
Shand, C. M.*; Podolyk, Zs.*; Grska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.
Physics Letters B, 773, p.492 - 497, 2017/10