Development of analytical techniques for isotopic composition determination of uranium particles in environmental sample for safeguards with Secondary Ion Mass Spectrometry

Tomita, Ryohei; Tomita, Jumpei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

Hosha Kagaku, (48), p.1 - 15, 2023/09

Secondary Ion Mass Spectrometry (SIMS) is the method to detect secondary ions produced by the sputtering of primary ions. SIMS is one of effective method to measure isotopic composition of particles containing nuclear material in environmental sample for safeguards. We are a group member of the International Atomic Energy Agency (IAEA)'s network of analytical laboratories and have developed analytical techniques using SIMS and other mass spectrometers for nuclear safeguards. We will introduce the principle of SIMS and analytical techniques developed by our group to measure isotopic composition of uranium particles which having a particle diameter of micron order in environmental sample for safeguards.

Band gap formation in graphene by hybridization with Hex-Au(001) reconstructed surface

Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Vacuum and Surface Science, 66(9), p.525 - 530, 2023/09

https://doi.org/10.1380/vss.66.525

As Au (001) surfaces exhibit a quasi-one-dimensional corrugated structure, Hex-Au(001), its periodicity was predicted to change the electronic structure of graphene when graphene was grown on this surface. Furthermore, the hybridization between graphene and Au is known to introduce bandgap and spin polarization into graphene. Here, we report angle-resolved photoemission spectroscopy and density functional theory calculation of graphene on a Hex-Au(001) surface. A bandgap of 0.2 eV in the graphene Dirac cone was observed at the crossing point of the graphene Dirac cone and Au 6sp bands, indicating that the origin of the bandgap formation was the hybridization between the graphene Dirac cone and Au 6sp band. We discussed the hybridization mechanism and anticipated spin injection into the graphene Dirac cone.

Level structures of Ca cast doubt on a doubly magic 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

https://doi.org/10.1016/j.physletb.2023.138025

Gamma decays were observed in Ca and Ca following quasi-free one-proton knockout reactions from Sc. For Ca, a ray transition was measured to be 1456(12) keV, while for Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the decays. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for 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 and orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic Ca and potentially drives the dripline of Ca isotopes to Ca or even beyond.

Development plan for coupling technology between high temperature gas-cooled reactor HTTR and hydrogen production facility, 1; Overview of the HTTR heat application test plan to establish high safety coupling technology

Nomoto, Yasunobu; Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

Analytical technique for isotope composition of nuclear micro particles

Miyamoto, Yutaka; Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Yasuda, Kenichiro

Isotope News, (786), p.22 - 25, 2023/04

https://www.jrias.or.jp/books/cat3/2023/786.html

no abstracts in English

Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito

Physical Review Materials (Internet), 7(1), p.014002_1 - 014002_10, 2023/01

https://doi.org/10.1103/PhysRevMaterials.7.014002

Au(001) surfaces exhibit a complex reconstructed structure [Hex-Au(001)] comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene-Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a Hex-Au(001) surface. The crossing point of the original and replica graphene bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene and Au bands, indicating that the bandgap is generated using hybridization of the graphene and Au bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene and Au would result in spin injection into graphene.

Extended neutron orbital and the shell closure in Ca

Enciu, M.*; Liu, H. N.*; Obertelli, A.*; Doornenbal, P.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; Yoshida, Kazuki; Achouri, N. L.*; Baba, Hidetada*; et al.

Physical Review Letters, 129(26), p.262501_1 - 262501_7, 2022/12

https://doi.org/10.1103/PhysRevLett.129.262501

The one-neutron knockout from Ca was performed at 230 MeV/nucleon combined with prompt spectroscopy. The momentum distributions corresponding to the removal of and neutrons were measured. The cross sections are consistent with a shell closure at the neutron number , found as strong as at and in Ca isotopes from the same observables. The analysis of the momentum distributions leads to a difference of the root-mean-square radii of the neutron and orbitals of 0.61(23) fm, in agreement with the modified-shell-model prediction of 0.7 fm suggesting that the large root-mean-square radius of the orbital in neutron-rich Ca isotopes is responsible for the unexpected linear increase of the charge radius with the neutron number.

Preparation of the particles containing isotope reference uranium for the determination of the low abundant U isotope ratios

Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka

KEK Proceedings 2022-2, p.154 - 158, 2022/11

Precise determination of minor U isotopes (U and U) of particles from the safeguard environmental samples is powerful method for detecting the undeclared nuclear activities. In this study, preparation method of U particle was examined to utilize for the minor U isotope determination. The porous silica particles were used as the particle matrix and lutetium was mixed to the impregnation solution as U impregnation indicator for the particle picking. The result of the Scanning Electron Microscope indicated that the contacting the solution with Si particles overnight gently could produce the impregnated particles effectively rather than the mixing them with PFA stick.

Optimization of SIMS-APM for high enrichment uranium particles including higher uranium hydride

Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Yasuda, Kenichiro; Esaka, Fumitaka; Miyamoto, Yutaka

KEK Proceedings 2021-2, p.146 - 150, 2021/12

no abstracts in English

Design for detecting recycling muon after muon-catalyzed fusion reaction in solid hydrogen isotope target

Okutsu, Kenichi*; Yamashita, Takuma*; Kino, Yasushi*; Nakashima, Ryota*; Miyashita, Konan*; Yasuda, Kazuhiro*; Okada, Shinji*; Sato, Motoyasu*; Oka, Toshitaka; Kawamura, Naritoshi*; et al.

Fusion Engineering and Design, 170, p.112712_1 - 112712_4, 2021/09

https://doi.org/10.1016/j.fusengdes.2021.112712

A muonic molecule which consists of two hydrogen isotope nuclei (deuteron (d) or tritium (t)) and a muon decays immediately via nuclear fusion and the muon will be released as a recycling muon, and start to find another hydrogen isotope nucleus. The reaction cycle continues until the muon ends up its lifetime of 2.2 s. Since the muon does not participate in the nuclear reaction, the reaction is so called a muon catalyzed fusion (CF). The recycling muon has a particular kinetic energy (KE) of the muon molecular orbital when the nuclear reaction occurs. Since the KE is based on the unified atom limit where distance between two nuclei is zero. A precise few-body calculation estimating KE distribution (KED) is also in progress, which could be compared with the experimental results. In the present work, we observed recycling muons after CF reaction.