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Ebihara, Kenichi; Sekine, Daiki*; Sakiyama, Yuji*; Takahashi, Jun*; Takai, Kenichi*; Omura, Tomohiko*
International Journal of Hydrogen Energy, 48(79), p.30949 - 30962, 2023/09
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)To understand hydrogen embrittlement (HE), which is one of the stress corrosion cracking of steel materials, it is necessary to know the H distribution in steel, which can be effectively interpreted by numerical simulation of thermal desorption spectra. In weld metals and TRIP steels, residual austenite significantly influences the spectra, but a clear H distribution is not well known. In this study, an originally coded two-dimensional model was used to numerically simulate the previously reported spectra of high-carbon ferritic-austenitic duplex stainless steels, and it was found that H is mainly trapped at the carbide surface when the amount of H in the steel is low and at the duplex interface when the amount of H is high. It was also found that the thickness dependence of the H desorption peak for the interface trap site is caused by a different reason than the conventional one.
Kimura, Yoshiki; Tsuchiya, Kenichi*
Radioisotopes, 72(2), p.121 - 139, 2023/07
Rapid and precise radioisotope identification in the scene of nuclear detection and nuclear security incidents is one of the challenging issues for the prompt response on the detection alarm or the incidents. A radioisotope identification algorithm using a deep artificial neural network model applicable to handheld gamma-ray detectors has been proposed in the present paper. The proposed algorithm automatically identifies gamma-emitting radioisotopes based on the count contribution ratio (CCR) from each of them estimated by the deep artificial neural network model trained by simulated gamma-ray spectra. The automated radioisotope identification algorithm can support first responders of nuclear detection and nuclear security incidents without sufficient experience and knowledge in radiation measurement. The authors tested the performance of the proposed algorithm using two different types of deep artificial neural network models in application to handheld detectors having high or low energy resolution. The proposed algorithm showed high performance in identifying artificial radioisotopes for actually measured gamma-ray spectra. It was also confirmed that the algorithm is applicable to identifying 
U and automated uranium categorization by analyzing estimated CCRs by the deep artificial neural network models. The authors also com-pared the performance of the proposed algorithm with a conventional radioisotope identification method and discussed promising ways to improve the performance of the algorithm using the deep artificial neural network.
Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.
EPJ Web of Conferences, 284, p.01023_1 - 01023_4, 2023/05
Times Cited Count：0 Percentile：0.21(Nuclear Science & Technology)For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron, lead, and bismuth have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics. The measured TTNYs and DDXs were compared with calculations by the Monte Carlo transport code PHITS with its default physics model of INCL version 4.6 combined with GEM and those with the JENDL-4.0/HE nuclear data library.
Matsuyama, Tsugufumi*; Nakae, Masanori*; Murakami, Masashi; Yoshida, Yukihiko; Machida, Masahiko; Tsuji, Koichi*
Spectrochimica Acta, Part B, 199, p.106593_1 - 106593_6, 2023/01
Times Cited Count：2 Percentile：45.92(Spectroscopy)Sasaki, Yuji; Nakase, Masahiko*; Kaneko, Masashi; Kobayashi, Toru; Takeshita, Kenji*; Matsumiya, Masahiko*
Analytical Sciences, 5 Pages, 2023/00
Times Cited Count：0 Percentile：0(Chemistry, Analytical)We conducted three field researches on Ru-extraction, XANES, and DFT-calculation. The order of the distribution ratio, D(Ru), from acid, HCl 
H
SO
HNO
HClO, by MIDOA is studied by XANES spectra, which indicates the valency change of Ru in HCl media and supports the ion pairing extraction of anionic Ru ion and cationic MIDOA. The same extractant trend, NTAamide MIDOA IDOA, due to D values as the energy gap of HOMO and LUMO could be found by DFT calculation, which suggests that the reaction heat has a positive correlation with extractability for extractant.
Okamoto, Yoshihiro; Shiwaku, Hideaki; Shimamura, Keisuke*; Kobayashi, Hidekazu; Nagai, Takayuki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*
Journal of Nuclear Materials, 570, p.153962_1 - 153962_13, 2022/11
Simulated nuclear waste glass samples containing phosphorus, which increase the solubility of molybdenum, were prepared and analyzed using synchrotron X-ray Absorption Fine Structure (XAFS) analysis for some constituent elements and Raman spectroscopic analysis of their complex structure. Changes in local structure and chemical state due to different phosphorus additions and waste loading rates were systematically studied. Consequently, no crystalline phase due to the molybdate compound was observed even at a maximum waste content of 30 wt% (corresponding to 1.87 mol% MoO). Oxidation proceeded when the waste-loading rate was increased, whereas the reduction proceeded when phosphorus was added. In some cases, the effects of oxidation and reduction were offset. The local structure around specific elements can be classified as follows; Zn that is affected mainly by the waste-loading rate, Ce that is affected by both the waste-loading rate and phosphorus addition, and Zr element that is not affected by either of them. From the comparison between the analytical results of Mo and other elements, it was considered that the added phosphorus exists as a free PO structural unit and may deprive the alkali metal coordinated to the molybdate ion.
Terasaka, Yuta; Watanabe, Kenichi*; Uritani, Akira*
Hoshasen (Internet), 47(3), p.89 - 96, 2022/10
lattice QCD with chiral fermionsAoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kanamori, Issaku*; Kaneko, Takashi*; Nakamura, Yoshifumi*; Rohrhofer, C.*; Suzuki, Kei
Proceedings of Science (Internet), 396, p.332_1 - 332_7, 2022/07
The axial U(1) anomaly in high-temperature QCD plays an important role to understand the phase diagram of QCD. The previous works by JLQCD Collaboration studied high-temperature QCD using 2-flavor dynamical chiral fermions such as the domain-wall fermion and reweighted overlap fermion. We extend our simulations to QCD with 2+1-flavor dynamical quarks, where the masses of the up, down, and strange quarks are near the physical point, and the temperatures are close to or higher than the pseudocritical temperature. In this talk, we will present the results for the Dirac spectrum, topological susceptibility, axial U(1) susceptibility, and hadronic collelators.
Aoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*; Suzuki, Kei
Proceedings of Science (Internet), 396, p.050_1 - 050_9, 2022/07
In the early days of QCD, the axial 
anomaly was considered as a trigger for the breaking of the 
symmetry through topological excitations of gluon fields. However, it has been a challenge for lattice QCD to quantify the effect. In this work, we simulate QCD at high temperatures with chiral fermions. The exact chiral symmetry enables us to separate the contribution from the axial breaking from others among the susceptibilities in the scalar and pseudoscalar channels. Our result in two-flavor QCD indicates that the chiral susceptibility, which is conventionally used as a probe for breaking, is actually dominated by the axial breaking at temperatures 
MeV.
Matsumura, Taichi; Okumura, Keisuke; Fujita, Manabu*
JAEA-Conf 2021-001, p.144 - 149, 2022/03
We require reliable nuclear data that can appropriately evaluate the radiation characteristics of fuel debris for the purpose such as development of new sensors, non-destructive assay technologies and optimization of radiation shielding. In the past, even if different results were obtained depending on calculation codes, it was difficult to clarify what caused the differences. To overcome it, we have developed a new reliable code to calculate radiation decay and radioactive source spectra that can accurately treat with large amounts of nuclides and all decay modes in the decay data file. As the first step, we compared the photon spectra of fuel debris by using the recent decay data files: JENDL/DDF-2015, decay sub-libraries of ENDF/B-VIII.0 and JEFF-3.3. In the presentation, we will report requests for the modifications on the decay scheme and branching ratio of decay mode for the next JENDL decay data file.
Ueki, Taro
Progress in Nuclear Energy, 144, p.104099_1 - 104099_7, 2022/02
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Randomized Weierstrass function (RWF) has been under development for evaluating the uncertainty of random media criticality due to the material mixture under disorder. In this work, the modelling capability of RWF is refined so that the spectrum range can be controlled by specifying its lower and upper ends of the frequency domain variable. As a result, it becomes possible to make fair criticality comparison among replicas of random media under inverse power law power spectra. Technically, the infinite sum of trigonometric terms in RWF is extended to cover the arbitrarily low frequency domain and then truncated to finite terms for the sole purpose of spectrum range control. This means that the refinement is free of the convergence issue towards a fractal characteristic of Weierstrass function and thus termed Incomplete Randomized Weierstrass function (IRWF). As a demonstration, a three-dimensional version of IRWF is applied to the mixture of three fuels with different burnups in a water-moderated environment. Monte Carlo criticality calculations are carried out to evaluate the uncertainty of neutron effective multiplication factor due to the indeterminacy of the fuel mixture formation.
anomaly in the chiral susceptibility of QCD at high temperatureAoki, Shinya*; Aoki, Yasumichi*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*; Suzuki, Kei
Progress of Theoretical and Experimental Physics (Internet), 2022(2), p.023B05_1 - 023B05_12, 2022/02
Times Cited Count：8 Percentile：81.66(Physics, Multidisciplinary)The chiral susceptibility, or the first derivative of the chiral condensate with respect to the quark mass, is often used as a probe for the QCD phase transition since the chiral condensate is an order parameter of 
symmetry breaking. However, the chiral condensate also breaks the axial symmetry, which is usually not studied as it is already broken by the anomaly and apparently has little impact on the transition. We investigate the susceptibilities in the scalar and pseudoscalar channels in order to quantify how much the axial breaking contributes to the chiral phase transition. Employing a chirally symmetric lattice Dirac operator and its eigenmode decomposition, we separate the axial breaking effects from others. Our result in two-flavor QCD indicates that both of the connected and disconnected chiral susceptibilities are dominated by axial breaking at temperatures 
MeV after the quadratically divergent constant is subtracted.
anomaly at high temperature with lattice chiral fermionsAoki, Shinya*; Aoki, Yasumichi*; Cossu, G.*; Fukaya, Hidenori*; Hashimoto, Shoji*; Kaneko, Takashi*; Rohrhofer, C.*; Suzuki, Kei
Physical Review D, 103(7), p.074506_1 - 074506_18, 2021/04
Times Cited Count：12 Percentile：72(Astronomy & Astrophysics)We investigate the axial anomaly of two-flavor QCD at temperatures 190-330 MeV. In order to preserve precise chiral symmetry on the lattice, we employ the M
bius domain-wall fermion action as well as overlap fermion action implemented with a stochastic reweighting technique. Compared to our previous studies, we reduce the lattice spacing to 0.07 fm, simulate larger multiple volumes to estimate finite size effect, and take more than four quark mass points, including one below physical point to investigate the chiral limit. We measure the topological susceptibility, axial susceptibility, and examine the degeneracy of partners in meson/baryon correlators. All the data above the critical temperature indicate that the axial violation is consistent with zero within statistical errors. The quark mass dependence suggests disappearance of the anomaly at a rate comparable to that of the symmetry breaking.
Ebihara, Kenichi; Sugiyama, Yuri*; Matsumoto, Ryosuke*; Takai, Kenichi*; Suzudo, Tomoaki
Metallurgical and Materials Transactions A, 52(1), p.257 - 269, 2021/01
Times Cited Count：9 Percentile：51.51(Materials Science, Multidisciplinary)We simulated the thermal desorption spectra of a small-size iron specimen to which was applied during charging with hydrogen atoms using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy clusters 
, which is composed of nine vacancies and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduced the experimental spectra except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of 
and 
is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.
Nakamura, Satoshi; Kimura, Takahiro; Ban, Yasutoshi; Tsubata, Yasuhiro; Matsumura, Tatsuro
JAEA-Technology 2020-009, 22 Pages, 2020/08
JAEA-Technology-2020-009.pdf:2.92MB
Partitioning and transmutation technology division is planning to measure fission rate ratios that contribute to validate nuclear data of minor actinides (MA). For this purpose, MA sources for fission chambers were prepared using electrodeposition method. The radioactivity of each MA source was quantified, and its uncertainty was evaluated. Seven types of MA sources with different radioactivity were prepared using four nuclides of 
Np, 
Am, 
Am, and 
Cm. A Cm source solution of which radioactivity was quantified by isotope dilution method was used to prepare working standard sources of Cm. The radioactivities were quantified as 1461 Bq, 2179 Bq, and 2938 Bq for Np sources, 1.428 MBq for Am source, 370.5 kBq and 89.57 kBq for Am sources, and 2.327 MBq for Cm source with, the uncertainty of 0.35% (1
). This report summarizes the method for preparation and quantification of MA sources, and uncertainty evaluation.
lattice QCDSuzuki, Kei; Aoki, Shinya*; Aoki, Yasumichi*; Cossu, G.*; Fukaya, Hidenori*; Hashimoto, Shoji*; Rohrhofer, C.*
Proceedings of Science (Internet), 363, p.178_1 - 178_7, 2020/08
We investigate the high-temperature phase of QCD using lattice QCD simulations with dynamical Mbius domain-wall fermions. On generated configurations, we study the axial symmetry, overlap-Dirac spectra, screening masses from mesonic correlators, and topological susceptibility. We find that some of the observables are quite sensitive to lattice artifacts due to a small violation of the chiral symmetry. For those observables, we reweight the Mbius domain-wall fermion determinant by that of the overlap fermion. We also check the volume dependence of observables. Our data near the chiral limit indicates a strong suppression of the axial anomaly at temperatures 
220 MeV.
Rohrhofer, C.*; Aoki, Yasumichi*; Cossu, G.*; Fukaya, Hidenori*; Gattringer, C.*; Glozman, L. Ya.*; Hashimoto, Shoji*; Lang, C. B.*; Suzuki, Kei
Proceedings of Science (Internet), 363, p.227_1 - 227_7, 2020/08
Properties of QCD matter change significantly around the chiral crossover temperature, and the effects on 
and topological susceptibilities, as well as the meson spectrum have been studied with much care. Baryons and the effect of parity doubling in this temperature range have been analyzed previously by various other groups employing different setups. Here we construct suitable operators to investigate chiral and axial symmetries in the baryon spectrum. Measurements for different volumes and quark-masses are done with two flavors of chirally symmetric domain-wall fermions at temperatures above the critical one. The possibility of emergent 
and 
symmetries is discussed.
Kirihara, Yoichi; Nakashima, Hiroshi; Sanami, Toshiya*; Namito, Yoshihito*; Itoga, Toshiro*; Miyamoto, Shuji*; Takemoto, Akinori*; Yamaguchi, Masashi*; Asano, Yoshihiro*
Journal of Nuclear Science and Technology, 57(4), p.444 - 456, 2020/04
Times Cited Count：7 Percentile：61.94(Nuclear Science & Technology)no abstracts in English
Meigo, Shinichiro; Takei, Hayanori; Matsuda, Hiroki; Yuri, Yosuke*; Yuyama, Takahiro*
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.515 - 519, 2019/07
no abstracts in English
Riyana, E. S.*; Suda, Shoya*; Ishibashi, Kenji*; Matsuura, Hideaki*; Katakura, Junichi*; Sun, G. M.*; Katano, Yoshiaki
Journal of Nuclear Science and Technology, 56(5), p.369 - 375, 2019/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Nuclear reactors produce a great number of electron antineutrinos mainly from beta-decay chains of fission products. Such neutrinos have energies mostly in MeV range. We are interested in neutrinos in a region of keV, since they may have information on fuel burn-up and may be detected in future with advanced measurement technology. We calculate reactor antineutrino spectra especially in the low energy region. In this work we present neutrino spectra from various reactors such as typical PWR reactor and others types of reactors for comparison. Our result shows the electron antineutrino flux in the low energy region increases with burn-up of nuclear fuel by accumulated nuclides with low Q values in beta decay.
