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Batsaikhan, M.; Oba, Hironori*; Karino, Takahiro; Akaoka, Katsuaki; Wakaida, Ikuo*; Iwata, Yoshihiro; Sakamoto, Kan*
Journal of Analytical Atomic Spectrometry, 41(4), p.1324 - 1335, 2026/04
Times Cited Count：0 Percentile：0.00(Chemistry, Analytical)
100 m fiber-coupled microchip laser-induced breakdown spectroscopy for remote elemental analysis applicationsBatsaikhan, M.; Oba, Hironori; Wakaida, Ikuo
Optics Express (Internet), 32(25), p.45158 - 45170, 2024/12
Times Cited Count：2 Percentile：28.05(Optics)Batsaikhan, M.; Oba, Hironori; Karino, Takahiro; Akaoka, Katsuaki; Wakaida, Ikuo
Optics Express (Internet), 32(24), p.42624 - 42638, 2024/11
Times Cited Count：0 Percentile：0.00(Optics)Karino, Takahiro; Akaoka, Katsuaki; Wakaida, Ikuo
Proceedings of International Topical Workshop on Fukushima Decommissioning Research 2024 (FDR2024) (Internet), 3 Pages, 2024/10
Tamura, Koji; Nakanishi, Ryuzo; Oba, Hironori; Karino, Takahiro; Shibata, Takuya; Taira, Takunori*; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 61(8), p.1109 - 1116, 2024/08
Times Cited Count：3 Percentile：39.40(Nuclear Science & Technology)Almaviva, S.*; Karino, Takahiro; Akaoka, Katsuaki; Wakaida, Ikuo
Spectrochimica Acta, Part B, 218, p.106960_1 - 106960_7, 2024/08
Times Cited Count：2 Percentile：30.17(Spectroscopy)Batsaikhan, M.; Akaoka, Katsuaki; Saeki, Morihisa*; Karino, Takahiro; Oba, Hironori; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 61(5), p.658 - 670, 2024/05
Times Cited Count：2 Percentile：26.62(Nuclear Science & Technology)no abstracts in English
Oba, Hironori; Wakaida, Ikuo; Taira, Takunori*
Sumato Purosesu Gakkai-Shi, 13(2), p.51 - 58, 2024/03
no abstracts in English
Batsaikhan, M.; Oba, Hironori; Karino, Takahiro; Akaoka, Katsuaki; Wakaida, Ikuo
Journal of Analytical Atomic Spectrometry, 39(2), p.423 - 432, 2024/02
Times Cited Count：5 Percentile：49.88(Chemistry, Analytical)Iwata, Yoshihiro; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo; Hasegawa, Shuichi*
Journal of the Optical Society of America B, 41(1), p.119 - 126, 2024/01
Times Cited Count：4 Percentile：40.99(Optics)Calcium Rydberg levels are of significant interest for efficient and isotope-selective resonance ionization of trace radionuclides such as calcium-41 (
Ca). In this study, we report novel measurement data on the energy level shifts of calcium-43 (
Ca) for 4sns 
S
and 4s(n-1)d D
(n=40, 45, 50, 55, 60) Rydberg levels due to hyperfine-induced singlet-triplet mixing specific to isotopes with an odd mass number.
Koyama, Shinichi; Ikeuchi, Hirotomo; Mitsugi, Takeshi; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Tsai, T.-H.; Takano, Masahide; Fukaya, Hiroyuki; Nakamura, Satoshi; et al.
Hairo, Osensui, Shorisui Taisaku Jigyo Jimukyoku Homu Peji (Internet), 216 Pages, 2023/11
In FY 2021 and 2022, JAEA perfomed the subsidy program for "the Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy, Thermal Behavior Estimation, and Abbreviated Analysis))" started in FY 2021. This presentation material summarized the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning, Contaminated Water and Treated Water Management.
Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo
Applied Optics, 62(31), p.8434 - 8441, 2023/10
Times Cited Count：6 Percentile：51.93(Optics)Utilizing micro-lasers and microwaves, the impact of microwaves on the expansion of air plasma was examined. Microwaves was applied to the air plasma generated by a micro-laser, the plasma growth image was visualized and emissions spectra using by a high-resolution spectrometer was observed, and temperature changes and electron density was analyzed. A 400-fold increase in plasma volume due to microwave enhancement, even though the micro-laser operated at a modest energy level of 1 mJ was observed. Although a slight change in electron temperature was observed during microwave irradiation, it was pointed towards the ability of microwaves to sustain plasma characteristics over time. These will be suggested that the microwave application potentially improves the analytical performance of laser-induced breakdown spectroscopy (LIBS).
Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo
Scientific Reports (Internet), 13, p.13901_1 - 13901 _11, 2023/08
Times Cited Count：17 Percentile：89.21(Multidisciplinary Sciences)This study explores the potential of utilizing microwaves to sustain the expansion of transient laser ablation plasma of Zr target. By application of microwaves on the plasma, significant enhancement with a two to three order of magnitude increase in the plasma emission intensity was observed. It was investigated that the electron temperature decreased from 10,000 K to 3000 K with volume expansion owing to increased surrounding air interaction, while the plasma can be sustained in air by using microwaves. These results emphasize the contribution of microwaves in promoting enhanced emission and plasma formation at controlled, low temperature, thereby demonstrating the potential of microwaves to enhance the accuracy and performance of laser-induced breakdown spectroscopy. These also mitigate the generation of toxic fumes and dust during ablation, a critical benefit when handling hazardous materials such as radioactive nuclear fuel debris in the decommissioning of accident nuclear power station.
Ikeda, Yuji*; Soriano, J. K.*; Oba, Hironori; Wakaida, Ikuo
Scientific Reports (Internet), 13, p.4828_1 - 4828_9, 2023/03
Times Cited Count：16 Percentile：89.21(Multidisciplinary Sciences)Tamura, Koji; Nakanishi, Ryuzo; Oba, Hironori; Taira, Takunori*; Wakaida, Ikuo
Japanese Journal of Applied Physics, 61(3), p.032003_1 - 032003_5, 2022/03
Times Cited Count：2 Percentile：10.14(Physics, Applied)Oba, Hironori; Wakaida, Ikuo; Taira, Takunori*
Denki Gakkai-Shi, 142(2), p.77 - 80, 2022/02
no abstracts in English
Iwata, Yoshihiro; Miyabe, Masabumi; Akaoka, Katsuaki; Wakaida, Ikuo
Journal of Quantitative Spectroscopy & Radiative Transfer, 275, p.107882_1 - 107882_9, 2021/11
Times Cited Count：6 Percentile：33.42(Optics)Following the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, an isotope-selective analysis method using laser resonance ionization has been developed for strontium-90. In this study, the isotope shifts and hyperfine structure constants of stable isotopes were measured for two schemes expected to have high isotopic selectivity, and the isotope shifts of strontium-90 were evaluated using the King plot analysis. The measured strontium-90 optical isotopic selectivities ranged from 
to 
, which are sufficient for analysis of real samples.
Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*; Yamazaki, Atsushi*; Sato, Yuki; Torii, Tatsuo; Wakaida, Ikuo
Journal of Nuclear Engineering and Radiation Science, 7(4), p.042002_1 - 042002_7, 2021/10
For the application in the measurement of the high dose rate hot spots inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, we propose a novel one-dimensional radiation distribution sensing method using an optical fiber sensor based on wavelength spectrum unfolding. The proposed method estimates the incident position of radiation to the fiber by the unfolding of the wavelength spectrum output from the fiber edge using the fact that the attenuation length of light along the fiber depends on the wavelength. Because this method measures the integrated light intensity, this method can avoid the problem of counting loss and signal pile-up, which occurs in the radiation detector with pulse counting mode under high dose rate field. Through basic experiments using the ultraviolet light source and 
Sr/Y radioactive point source, basic properties of source position detection were confirmed.
Miyabe, Masabumi; Satou, Yukihiko; Wakaida, Ikuo; Terabayashi, Ryohei*; Sonnenschein, V.*; Tomita, Hideki*; Zhao, Y.*; Sakamoto, Tetsuo*
Journal of Physics B; Atomic, Molecular and Optical Physics, 54(14), p.145003_1 - 145003_8, 2021/07
Times Cited Count：2 Percentile：12.94(Optics)Two-color two-step photoionization optogalvanic spectroscopy was performed using high-repetition-rate titanium sapphire lasers and a uranium hollow cathode lamp to find the two-step resonance ionization schemes of uranium. Many ionization transitions were observed by exciting uranium atoms in a ground state into five, even parity, excited levels with the first-step laser and by scanning the second-step laser wavelengths. By blocking the first-step laser, single-color, two-photon ionization transitions were also identified. From these results, we have found more than 50 odd-parity autoionizing levels of uranium in the energy, ranging from the ionization potential (49958.4 cm
) to 51150 cm. The determined energy levels are within 1 cm of previously reported values.
Tamura, Koji; Oba, Hironori; Saeki, Morihisa; Taguchi, Tomitsugu*; Lim, H. H.*; Taira, Takunori*; Wakaida, Ikuo
Journal of Nuclear Science and Technology, 58(4), p.405 - 415, 2021/04
Times Cited Count：16 Percentile：77.81(Nuclear Science & Technology)Radiation dose rate effects on the properties of a compact fiber-optic laser-induced breakdown spectroscopy (LIBS) system with a monolithic Nd:YAG/Cr:YAG composite ceramics were investigated for remote analysis in hazardous environment. To investigate radiation effects on the LIBS signal, properties related to the Nd:YAG laser operation such as oscillation threshold, output energy, oscillation timing, temporal pulse shape, and beam profile were measured as a function of the radiation dose rate from 0 to 10 kGy/hr in view of their influences to the signal. LIBS spectra of zirconium metal were measured under irradiation. Although signal intensity decreased considerably by irradiation, informative spectra were well obtained even at the maximum radiation dose rate. From the comparison of the LIBS-related parameters among the laser properties, signal reduction was mainly ascribed to the pulse energy reduction. Scintillation emission spectra were also measured from the ceramics during the irradiation, where the signal intensity increased linearly with the dose rate. The results show that the developed system.
