Improved multicomponent analysis method for electron spin resonance spectra of gamma-irradiated tooth enamel

Yamashita, Takuma*; Iwami, Satone*; Mitsuyasu, Yusuke*; Ono, Kenta*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.

KEK Proceedings 2024-6, p.85 - 90, 2024/12

To clarify the radiation effects of the accident at the TEPCO's Fukushima Daiichi NPP on living organisms, it is important to accurately estimate the dose to each individual. We have developed a multi-component analysis program using random number optimization to extract only the components derived from carbonate radicals from the ESR spectra.

Development of a nondestructive assay technique using a laser-driven neutron source

Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Wei, T.*; Yogo, Akifumi*; et al.

Dai-45-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2024/11

Demonstration of shape analysis of neutron resonance transmission spectrum measured with a laser-driven neutron source

Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Lan, Z.*; Wei, T.*; et al.

Scientific Reports (Internet), 14, p.21916_1 - 21916_9, 2024/09

https://doi.org/10.1038/s41598-024-72836-8

Preliminary status and results of the JAEA/ISCN fission signature assay instrument for delayed gamma-ray spectrometry nuclear safeguards

Rodriguez, D.; Akamatsu, Shunsuke*; Rossi, F.; Suzuki, Satoshi*; Takahashi, Tone

Proceedings of 65th Annual Meeting of the Institute of Nuclear Materials Management (Internet), 9 Pages, 2024/07

Production rates of long-lived radionuclides Be and Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxes

Sakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.

Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05

https://doi.org/10.1103/PhysRevD.109.102005

Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as Be and Al have been accumulating in these rocks, concentrations of Be and Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced Be and Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.

Petrography and geochronology of the Kuki granite, Kitakami mountains, northeastern Japan; Shallow crustal intrusion and emplacement processes of granitic magma

Suzuki, Satoshi*; Yuguchi, Takashi*; Ishiguro, Keito*; Endo, Kyoka*; Kato, Asuka*; Yokoyama, Kosuke*; Ogita, Yasuhiro; Yokoyama, Tatsunori; Sakata, Shuhei*; Ono, Takeshi*; et al.

Journal of Mineralogical and Petrological Sciences (Internet), 119(1), p.230807_1 - 230807_18, 2024/02

https://doi.org/10.2465/jmps.230807

Understanding the crustal evolutionary dynamics of island arc-trench systems requires a thorough evaluation of magma chamber processes, and especially of shallow crustal granitic magma intrusion and emplacement processes. To address this, we studied the petrography and geochronology of the Kuki granite, Kitakami Mountains, northeast Japan, as an example of a non-adakitic granite at the magmatic flare-up stage. Granitic borehole samples reflect vertical variation within a magma chamber. Whole-rock chemical composition and mode data reveal a vertical transition from felsic to mafic composition with increasing depth, potentially due to gravitational fractionation of crystals in the magma chamber. The pressure and temperature history of the Kuki granite indicates no change in the magma depth with cooling from 800 to 730C, and geobarometric calculations indicate the emplacement of magma at a depth of approximately10 km. Simultaneous determination of the zircon U Pb age, Ti concentration, and Th/U yields 1) the time temperature history of granitic magma before its solidification, and 2) the correlation between temperature and Th/U in the magma. The magma chamber cooled from ca. 900 to 700C at approximately 125 Ma. The change in Th/U with temperature indicates greater fractional crystallization in the magma chamber at temperatures above 800C than below 800C. Samples from different depth exhibit common tendencies in terms of the relationship between Th/U and temperature, indicating the same system of fractional crystallization throughout the cooling magma chamber.

Estimation of external dose for wild Japanese macaques captured in Fukushima prefecture; Decomposition of electron spin resonance spectrum

Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.

Radiation Protection Dosimetry, 199(14), p.1620 - 1625, 2023/09

https://doi.org/10.1093/rpd/ncad146

We have been conducting dose assessments for Japanese macaques captured in Fukushima to reveal radiobiological effects on the low-dose expose animals. To accurately determine the external exposure dose, it is desirable to examine the analysis of the CO radical intensity. We examined ESR spectra of teeth of 10 macaques captured in Fukushima by two spectrum-decomposition algorithms.

Multiple mechanisms in proton-induced nucleon removal at 100 MeV/nucleon

Pohl, T.*; Sun, Y. L.*; Obertelli, A.*; Lee, J.*; Gmez-Ramos, M.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Cai, B. S.*; Yuan, C. X.*; Brown, B. A.*; et al.

Physical Review Letters, 130(17), p.172501_1 - 172501_8, 2023/04

https://doi.org/10.1103/PhysRevLett.130.172501

We report on the first proton-induced single proton- and neutron-removal reactions from the neutron deficient O nucleus with large Fermi-surface asymmetry at 100 MeV/nucleon. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively.

Outlining zircon growth in a granitic pluton using 3D cathodoluminescence patterns, U-Pb age, titanium concentration, and Th/U; Implications for the magma chamber process of Okueyama granite, Kyushu, Japan

Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*

Lithos, 440-441, p.107026_1 - 107026_14, 2023/03

https://doi.org/10.1016/j.lithos.2023.107026

We propose a new method for elucidating zircon growth in granitic plutons, based on variations in three-dimensional 3D cathodoluminescence (CL) patterns, U-Pb ages, titanium concentration, and Th/U ratios. We focused on the zircon growth processes in the Okueyama granite (OKG) in central Kyushu, Japan, to obtain interpretations of magma chamber processes that result in the formation of granitic plutons. The OKG consists of three lithofacies: biotite granite (BG), hornblende granite (HG), and hornblende granodiorite (HGD). To determine the 3D internal structure and growth pattern of a zircon crystal, we performed CL observations for multi-sections of the samples. Simultaneously, we also determined the zircon U-Pb age and titanium concentration of the center sections of the samples. The 3D distribution of the oscillatory zoning can be used to determine the crystal nucleus. The simultaneous determination of zircon U-Pb ages and Ti concentrations of the granite samples indicates the time-temperature (t-T) history of granitic magma before its solidification. The t-T histories of the BG, HG, and HGD represented similar cooling behaviors within the magma chamber: rapid cooling from the zircon crystallization temperature to the closure temperature of the biotite K-Ar system between 16 Ma and 10 Ma. The variations in the Th/U ratios against temperature also demonstrate a different trend at the boundary of approximately 670 C. Fractional crystallization in the magma chamber progressed significantly at temperatures above 670 C; below 670 C, crystallization progressed slowly, indicating only minimal changes in the magma composition. The variations in the Th/U ratio against temperature in the BG, HG, and HGD portrayed common tendencies, indicating the same behavior in the progression of fractional crystallization among the three lithofacies, which in turn, represented the same behavior within the entire magma chamber.

Optimization of mercury flow with microbubbles in the target-vessel design by means of machine learning

Kogawa, Hiroyuki; Futakawa, Masatoshi; Haga, Katsuhiro; Tsuzuki, Takayuki*; Murai, Tetsuro*

JAEA-Technology 2022-023, 128 Pages, 2022/11

JAEA-Technology-2022-023.pdf:9.0MB

In a mercury target of the J-PARC (Japan Proton Accelerator Research Complex), pulsed proton beams repeatedly bombard the flowing mercury which is confined in a stainless-steel vessel (target vessel). Cavitation damage caused by the propagation of the pressure waves is a factor of the life of the target vessel. As a measure to reduce damages, we developed a bubbler to inject the gas microbubbles into the flowing mercury, which can reduce the pressure waves. To operate the mercury target vessel stably with the 1 MW high-intensity proton beams, further reduction of the damage is required. The bubbler setting position should be closer to the beam window to increase the bubble population, which could enhance the reduction effect on the pressure waves and damage. However, the space at the beam window of the target vessel is restricted. The bubbler design and setting position as well as the vane design for the mercury flowing pattern are optimized by means of a machine learning technique to get more suitable bubble distribution, increasing in bubble population and optimizing bubble size nearby the beam window of the target vessel. The results of CFD analyses performed with 1000 cases were used for machine learning. Since the flow rate of mercury affects the temperature of the target vessel, this was used for the constraint condition. As a result, we found a design of mercury target vessel that can increase the bubble population by ca. 20% higher than the current design.