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Tomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
Journal of Nuclear Science and Technology, 63(4), p.443 - 454, 2026/04
Times Cited Count：1 Percentile：0.00(Nuclear Science & Technology)Maki, Daisuke*; Inukai, Yuji*; Sekiguchi, Hiroshi*; Shinozaki, Wakako*; Shimizu, Hideo*; Suzuki, Tomokazu*; Takemura, Takashi*; Hagiwara, Masayuki*; Higaki, Shogo*; Yoshitomi, Hiroshi; et al.
Hoken Butsuri (Internet), 61(1), p.16 - 22, 2026/03
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
Physical Review D, 113(3), p.036002_1 - 036002_12, 2026/02
Times Cited Count：0 Percentile：0.00(Astronomy & Astrophysics)We present a theoretical study on how the anomalous magnetic moment (AMM) of Dirac fermions influences the fermionic Casimir effect in the presence of magnetic fields. The analysis is carried out by generalizing the standard Lifshitz formula to incorporate the AMM. Our extended formulation reveals that the presence of the AMM leads to an increase in the fermionic Casimir energy. Notably, when the AMM becomes sufficiently large, this enhancement is markedly amplified due to the gapless nature of the lowest Landau level. We further provide quantitative estimates of the Casimir energy contributions from various fermions, such as electrons, muons, and constituent quarks, subjected to magnetic fields.
Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Takamiya, Koichi*; Igarashi, Yasuhito*; Yamasaki, Shinya*; Sakaguchi, Aya*; Yasuda, Kenichiro
Analytical Methods, 12 Pages, 2026/00
Times Cited Count：0Tomita, Ryohei; Tomita, Jumpei; Yomogida, Takumi; Suzuki, Daisuke; Miyamoto, Yutaka; Yasuda, Kenichiro
Analytical Methods, 17(44), p.9017 - 9025, 2025/10
Times Cited Count：2 Percentile：34.87(Chemistry, Analytical)Tomita, Ryohei; Tomita, Jumpei; Suzuki, Daisuke; Miyamoto, Yutaka; Yasuda, Kenichiro
Journal of Nuclear Science and Technology, 62(10), p.939 - 948, 2025/10
Times Cited Count：1 Percentile：41.98(Nuclear Science & Technology)A new automated particle measurement (APM) combined with micromanipulation using large geometry secondary ion mass spectrometry instrument was proposed and demonstrated to remove the particle mixing effect, which indicated that the aggregation of uranium particles was detected as a single uranium particle, from APM results. The results showed that the new APM method was more effective than the traditional APM method in removing the particle mixing effect from the APM results and determining the existence of minor uranium isotopes in the samples.
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
Physics Letters B, 868, p.139758_1 - 139758_6, 2025/09
Times Cited Count：1 Percentile：43.93(Astronomy & Astrophysics)The Lifshitz formula has long served as a foundational framework for analyzing the Casimir effect under finite-temperature conditions. In this work, we extend its applicability to situations involving finite chemical potential, thereby incorporating quantum field contributions beyond thermal effects. We illustrate the broad utility of the resulting generalized formula by exploring characteristic features of the Casimir effect across a variety of setups, including different boundary conditions, temperature regimes, spatial dimensionalities, and chemical potential imbalances. This extended framework is particularly relevant to systems such as dense quark matter and Dirac/Weyl semimetals, where the chemical potential functions as a tunable parameter that influences the Casimir force.
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
Physical Review D, 112(3), p.034020_1 - 034020_17, 2025/08
Times Cited Count：1 Percentile：28.22(Astronomy & Astrophysics)We conduct a theoretical analysis of the Casimir effect arising from Dirac fermions in magnetized, finite-density matter. Our primary focus is on quark fields in the magnetic dual chiral density wave (MDCDW) phase, a candidate for an inhomogeneous ground state in strongly interacting Dirac systems. In this phase, the Casimir energy exhibits intricate oscillatory behavior as a function of separation distance, stemming from the combined effects of the chemical potential, external magnetic field, and spatial modulation of the ground state. To gain a deeper understanding, we decompose the Casimir energy into individual Landau level contributions, revealing distinct types of Casimir effects depending on whether the contribution originates from the lowest or higher Landau levels. We also highlight unique features that emerge due to energy level splitting between quark flavors, such as up and down quarks.
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
International Journal of Modern Physics A, 40(10-11), p.2543022_1 - 2543022_9, 2025/04
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)In this talk, we discuss the discovery of a new Casimir effect that emerges from the quark field in dense, thin quark matter when the magnetic field is zero or non-zero. Surprisingly, in the dual chiral density wave (DCDW) phase, a candidate ground state of dense quark matter, the Casimir energy oscillates as a function of thickness. This finding highlights a novel oscillating Casimir phenomenon driven by QCD dynamics in extreme conditions.
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
International Journal of Modern Physics A, 40(10-11), p.2543020_1 - 2543020_8, 2025/04
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)In this talk, I discuss the general features of the Casimir effect induced from quantum fields at finite chemical potential, particularly at finite density. Historically, the thermal Casimir effect has been well-established by the cooperation between theory and experiment, whereas its counterpart at finite chemical potential is still not. This is because it is usually difficult to control the chemical potential of photons in equilibrium experimentally. On the other hand, if one focuses on fermionic systems, their chemical potentials may be a tunable parameter for the Casimir effect. In addition, various quantum many-body phenomena realized at finite fermion density can modify the typical property of the Casimir effect. Within some theoretical frameworks, we evaluate the Casimir energy for Dirac fields at finite density and particularly show an oscillatory behavior as a function of the separation of boundary conditions or the chemical potential. As physical and realistic examples of the Casimir effect at finite chemical potential, I discuss applications to fermion fields inside thin dense quark matter in hadron physics and to Dirac/Weyl semimetal thin films in solid-state physics. Such materials will be platforms to examine the fermionic Casimir effect at finite chemical potential.
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
International Journal of Modern Physics A, 40(10-11), p.2543017_1 - 2543017_8, 2025/01
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)We investigate the characteristics of Casimir energy within a lattice-regularized spacetime framework. Typically, Casimir energy requires a regularization procedure to remove divergences originating from vacuum fluctuations of quantum fields. In this work, we adopt lattice regularization, wherein discretization effects persist as long as the lattice spacing remains finite. We first detail how the Casimir energy is computed using both naive and Wilson fermion formulations. When discretization artifacts are limited to only a few lattice points, it becomes possible to recover the continuum Casimir energy by taking the continuum limit. To illustrate physical applications, we evaluate the Casimir energy for electron fields in Dirac/Weyl semimetals, where lattice effects are meaningfully retained, and for photon fields in axion electrodynamics, where the continuum limit is accurately reproduced.
Fujii, Daisuke; Nakayama, Katsumasa*; Suzuki, Kei
Physical Review D, 110(1), p.014039_1 - 014039_15, 2024/07
Times Cited Count：7 Percentile：58.29(Astronomy & Astrophysics)The Casimir effect is known to be induced from photon fields confined by a small volume, and also its fermionic counterpart has been predicted in a wide range of quantum systems. Here, we investigate what types of Casimir effects can occur from quark fields in dense and thin quark matter. In particular, in the dual chiral density wave, which is a possible ground state of dense quark matter, we find that the Casimir energy oscillates as a function of the thickness of matter. This oscillating Casimir effect is regarded as an analog of that in Weyl semimetals and is attributed to the Weyl points in the momentum space of quark fields. In addition, we show that an oscillation is also induced from the quark Fermi sea, and the total Casimir energy is composed of multiple oscillations.
U/
U isotopic analysis of trace uranium in safeguards environmental samples using multicollector inductively coupled plasma mass spectrometryTomita, Jumpei; Tomita, Ryohei; Suzuki, Daisuke; Yasuda, Kenichiro; Miyamoto, Yutaka
Journal of the American Society for Mass Spectrometry, 35(6), p.1178 - 1183, 2024/05
Times Cited Count：1 Percentile：14.20(Biochemical Research Methods)A sensitive analytical technique was investigated in order to determine 10
order of U/U ratio in the sub-ng of uranium using a multi-collector ICP-MS. First, the solution volume was concentrated to one tenth to obtain higher intensities. Next, data acquisition was started from the beginning of the solution uptake and continued until all solution was exhausted. Taking advantage of multi-collector measurement, all data were used with excepting the portion affected by air mixing at the beginning and end of sample introduction. The isotope ratios were calculated from the total counts of each isotope. This technique was applied to U isotope standard (IRMM-184) to measure the 10 order of U/U ratio in the sub-ng of uranium. Measured values were in good agreement with the certified value within the uncertainity (
=2). The uncertainties obtained with this new technique (32% on average) were revised to be 10 times smaller than those obtained with the conventionalmethod.
FKatsumata, Tetsuhiro*; Suzuki, Ryo*; Sato, Naoto*; Oda, Ryoya*; Motoyama, Shingo*; Suzuki, Shumpei*; Nakashima, Mamoru*; Inaguma, Yoshiyuki*; Mori, Daisuke*; Aimi, Akihisa*; et al.
Chemistry of Materials, 36(8), p.3697 - 3704, 2024/04
Times Cited Count：2 Percentile：6.26(Chemistry, Physical)A perovskite-type oxynitride BaFeOF was prepared by high-pressure synthesis. Since the SHG signal was observed in the obtained material, suggesting the existence of spontaneous polarization, the mechanism of polarization was investigated by synchrotron high-energy X-ray diffraction. The obtained pair distribution functions were fitted, and a local polarization mechanism with different orientations was found. Since BaFeOF is also a magnetic material, a magnetic domain and a ferroelectric domain are considered to coexist.
Fukasawa, Tetsuo*; Suzuki, Akihiro*; Endo, Yoichi*; Inagaki, Yaohiro*; Arima, Tatsumi*; Muroya, Yusa*; Endo, Keita*; Watanabe, Daisuke*; Matsumura, Tatsuro; Ishii, Katsunori; et al.
Journal of Nuclear Science and Technology, 61(3), p.307 - 317, 2024/03
Times Cited Count：5 Percentile：48.90(Nuclear Science & Technology)A flexible waste management system (FWM) is being developed to apply future MA partitioning and transmutation (P&T) technology to current HLLW. This FWM system will store high-level waste (HLLW) in granular form until MA partitioning and transmutation technology is realized. The feasibility of the main process was essentially confirmed by basic experiments and preliminary thermal analysis for granule production by rotary kiln from simulated HLLW and for temporary storage (50 years) of HLW granules at the HLW storage facility, respectively. The granule production experiments revealed that relatively large particles can be produced by the rotary kiln. The results of the thermal analysis showed that the small diameter canisters could be used to safely store the granules at a higher storage density than vitrified HLW. The effectiveness of the FWM system in terms of potential radiotoxicity and repository area was also evaluated, and it was shown that FWM can reduce these factors and has significant advantages in the disposal of HLW generated in current reprocessing plants. Since LWR fuel is stored for a long period of time in Japan and the operation of a reprocessing plant is expected to start soon, the FWM system is considered to be an effective system for reducing the environmental burden of HLW disposal.
Be ground-state molecular structure using Be(
)
He triple differential reaction cross-section measurementsLi, P. J.*; Beaumel, D.*; Lee, J.*; Assi
, M.*; Chen, S.*; Franchoo, S.*; Gibelin, J.*; Hammache, F.*; Harada, T.*; Kanada-En'yo, Yoshiko*; et al.
Physical Review Letters, 131(21), p.212501_1 - 212501_7, 2023/11
Times Cited Count：38 Percentile：94.71(Physics, Multidisciplinary)The cluster structure of the neutron-rich isotope Be has been probed via the () reaction. The triple differential cross-section was extracted and compared to distorted-wave impulse approximation reaction calculations performed in a microscopic framework using the Tohsaki-Horiuchi-Schuck-R
pke wave function and the wave function deduced from Antisymmetrized Molecular Dynamics calculations. The remarkable agreement between calculated and measured cross-sections in both shape and magnitude validates the description of the Be ground-state as a rather compact nuclear molecule.
Sato, Hisashi*; Takayama, Yusuke; Suzuki, Hideaki*; Sato, Daisuke*
JAEA-Data/Code 2023-010, 47 Pages, 2023/09
JAEA-Data-Code-2023-010.pdf:1.45MB
When a high-level radioactive waste repository is constructed in a coastal area, it is necessary to fully evaluate the impact of seawater-based groundwater on engineered barriers, including buffer materials. In this report, one-dimensional saltwater infiltration tests were conducted to obtain data to understand the impact of seawater-based groundwater on the migration phenomena of water and solutes in the buffer material during the transient period. As a result, it was confirmed that the infiltration rate increased as the NaCl concentration in the infiltration solution increased. And it was confirmed that the water content ratio distribution changed as the NaCl concentration in the infiltration solution increased. As a result of analysis of the chloride ion concentration of the post-test specimens confirmed that chloride ion enrichment was occurred with infiltration. As a result of verifying the mechanism by which chloride ion enrichment occurs, it was confirmed that the phenomenon of chloride ion enrichment due to infiltration depends on the initial water content ratio.
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.
Takagi, Hirotaka*; Takagi, Rina*; Minami, Susumu*; Nomoto, Takuya*; Oishi, Kazuki*; Suzuki, Michito*; Yanagi, Yuki*; Hirayama, Motoaki*; Khanh, N.*; Karube, Kosuke*; et al.
Nature Physics, 19(7), p.961 - 968, 2023/07
Times Cited Count：124 Percentile：99.55(Physics, Multidisciplinary)Miyamoto, Yutaka; Suzuki, Daisuke; Tomita, Ryohei; Tomita, Jumpei; Yasuda, Kenichiro
Isotope News, (786), p.22 - 25, 2023/04
no abstracts in English
