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Kikuchi, Tatsuya*; Mashita, Ryo*; Masui, Tomomi*; Kanaya, Toshiji*; Kishimoto, Hiroyuki*; Nakajima, Kenji
Physical Review E, 113(6), p.065418_1 - 064518_10, 2026/06
Times Cited Count：1 Percentile：80.20(Physics, Fluids & Plasmas)We investigated the local dynamics of polybutadiene over a wide temperature range, using quasielastic neutron scattering combined in the modified mode distribution analysis. Among these processes, the subpicosecond fast process was analyzed using a local diffusion model, which characterizes the dynamics via two physically meaningful parameters: the local diffusion coefficient and the harmonic potential stiffness. Temperature-dependent analysis revealed a distinct dynamic transition near the glass transition, which is interpreted as the disappearance of cooperative diffusion involving multiple segments. Furthermore, an additional relaxation mode, termed the extra-fast process, was identified and interpreted as a higher-order mode within the local diffusion model. These findings suggest a unified physical framework for the evolution of local motions across the glass transition and establish a robust methodology for quantifying polymer dynamics at subnanometer and subpicosecond scales.
Ishibashi, Atsushi; Masui, Kenji; Goto, Yuichi; Yamamoto, Masahiko; Taguchi, Shigeo; Ishikawa, Satoshi*; Ishikawa, Tomoya*
Nihon Hozen Gakkai Dai-19-Kai Gakujutsu Koenkai Yoshishu, p.18 - 21, 2023/08
An inner-box typed hot cell for analysis of highly radioactive samples has been operated for about 40 years in Tokai Reprocessing Plant since its installation in 1980. During the operation of analytical hot cell, improvement and upgrades including auxiliary equipment have been performed, in addition to keep the equipment in proper condition through periodic inspections and maintenance. This paper describes about these efforts for analytical hot cell and its results.
Masui, Kenji; Yamamoto, Masahiko; Kuno, Takehiko; Surugaya, Naoki
Nihon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.25 - 30, 2016/07
no abstracts in English
Matsuki, Takuya; Masui, Kenji; Sekine, Megumi; Tanigawa, Masafumi; Yasuda, Takeshi; Tsutagi, Koichi; Ishiyama, Koichi; Nishida, Naoki; Horigome, Kazushi; Mukai, Yasunobu; et al.
Proceedings of INMM 57th Annual Meeting (Internet), 9 Pages, 2016/07
The International Atomic Energy Agency (IAEA) has proposed in its long-term research and development (R&D) plan, development of a real-time measurement technology to monitor and verify nuclear material movement continuously as part of an advanced approach to effectively and efficiently conduct safeguards for reprocessing facilities. Since the Tokai Reprocessing Plant (TRP) has solutions containing both Pu and fission products (FP), a new detector development project to monitor Pu with FP is being carried out from 2015 to 2017. This project is mainly conducted in the High Active Liquid Waste Storage (HALWS) in the TRP. For the first step of this project, as the confirmation of composition of high active liquid waste (HALW) to evaluate neutron/
-ray emitted from solution in the selected HALW tank which has the most amount of Pu in HALW tanks at the TRP, we took HALW sample and conducted -ray spectrum measurement for HALW. As a study of detector setting location, to survey the available neutron/-ray (i.e. intensity) at the outside surface of the cell where HALW tank is located, we implemented continuous measurement by neutron/-ray detector. In this paper, we report three -ray peaks related with 
Pu and 
Pu measured in the composition research of HALW, which is needed to identify Pu amount by the new detector that we are developing and the result of radiation measurement on the surface of the cell.
Masui, Tomomi*; Kishimoto, Hiroyuki*; Kikuchi, Tatsuya; Kawamura, Seiko; Inamura, Yasuhiro; Koga, Tadanori*; Nakajima, Kenji
Journal of Physics; Conference Series, 502(1), p.012057_1 - 012057_4, 2014/04
Times Cited Count：4 Percentile：84.30(Materials Science, Multidisciplinary)By using a quasielastic neutron scattering technique (disk-chopper-type spectrometer AMATERAS at J-PARC), we have investigated the microscopic dynamics of polybutadiene (PB) in which silica particles were embedded. The experimental results gave us both a damped vibration mode of PB and jumped diffusion motion of the segments. It was found that these dynamical features remain unaffected by the presence of the silica particle, while the residence time of the jumped diffusion motion becomes longer at the high filler loading.
collisions at 
= 200 and 62.4 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06
Times Cited Count：200 Percentile：99.33(Physics, Nuclear)Transverse momentum distributions and yields for 
, and 
in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as 
and 
scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
and Au+Au collisions at 
= 200 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.
Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04
Times Cited Count：10 Percentile：53.41(Physics, Nuclear)Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.
cuprates studied by resonant inelastic X-ray scatteringIshii, Kenji; Hoesch, M.*; Inami, Toshiya; Kuzushita, Kaori*; Owada, Kenji; Tsubota, Masami; Murakami, Yoichi; Mizuki, Junichiro; Endo, Yasuo; Tsutsui, Kenji*; et al.
Journal of Physics and Chemistry of Solids, 69(12), p.3118 - 3124, 2008/12
Times Cited Count：3 Percentile：17.31(Chemistry, Multidisciplinary)
Cu
O
studied by resonant inelastic X-ray scatteringIshii, Kenji; Tsutsui, Kenji*; Endo, Yasuo*; Toyama, Takami*; Kuzushita, Kaori; Inami, Toshiya; Owada, Kenji; Maekawa, Sadamichi*; Masui, Takahiko*; Tajima, Setsuko*; et al.
AIP Conference Proceedings 850, p.445 - 446, 2006/09
Mott gap excitations in the optimally doped high-
superconductor YBaCuO ( = 93 K) have been studied by the resonant inelastic X-ray scattering method. Anisotropic spectra in the 
-plane are observed in a twin-free crystal. The excitation from the one-dimensional CuO chain is enhanced at 2 eV near the zone boundary of the 
direction, while the excitation from the CuO plane is broad at 1.5-4 eV and almost independent of the momentum transfer. Theoretical calculation based on the one-dimensional and two-dimensional Hubbard model reproduces the observed spectra when different values of the on-site Coulomb energy are assumed. The Mott gap of the CuO chain site is found to be much smaller than that of the CuO plane site.
CuO ( = 93 K) studied by resonant inelastic X-ray scatteringIshii, Kenji; Tsutsui, Kenji*; Endo, Yasuo*; Toyama, Takami*; Kuzushita, Kaori; Inami, Toshiya; Owada, Kenji; Maekawa, Sadamichi*; Masui, Takahiko*; Tajima, Setsuko*; et al.
Physical Review Letters, 94(18), p.187002_1 - 187002_4, 2005/05
Times Cited Count：40 Percentile：79.80(Physics, Multidisciplinary)Mott gap excitations in the optimally doped high- superconductor YBaCuO ( = 93 K) have been studied by the resonant inelastic X-ray scattering method. Anisotropic spectra in the -plane are observed in a twin-free crystal. The excitation from the one-dimensional CuO chain is enhanced at 2 eV near the zone boundary of the direction, while the excitation from the CuO plane is broad at 1.5-4 eV and almost independent of the momentum transfer. Theoretical calculation based on the one-dimensional and two-dimensional Hubbard model reproduces the observed spectra when different values of the on-site Coulomb energy are assumed. The Mott gap of the CuO chain site is found to be much smaller than that of the CuO plane site.
Asakura, Yoshiro*; Miyahara, Kenji; ; Masui, J.*; Kondo, Isao*; ; ; Kamata, Masayuki
PNC TN852 81-18, 266 Pages, 1981/05
None
Miyahara, Kenji; Asakura, Yoshiro*; ; Masui, J.*; Kondo, Isao*; ; Kamata, Masayuki;
PNC TN852 81-15, 46 Pages, 1981/04
None
Aoya, Juri; Masui, Kenji; Horigome, Kazushi; Yamamoto, Masahiko; Taguchi, Shigeo
no journal, ,
Determination of alpha nuclides is essential for transfer and storage of fuel debris. A flow injection analysis system combining solvent extraction and liquid scintillation detector has been developed for rapid determination of plutonium in the debris with high processing capability. Liquid sample containing plutonium has been fed into a static mixer by flowing carrier solution and contacted with an extractant Aliquat 336 dissolved in xylene. Then, the mixture has been separated into an aqueous phase and an organic phase by membrane separator to extract plutonium. The organic phase has been fed into a flow cell for liquid scintillation counting after mixed with liquid scintillator. The performance of the analysis system has been evaluated by measuring plutonium standard solution.
Ishii, Kenji; Tsutsui, Kenji*; Endo, Yasuo*; Toyama, Takami*; Inami, Toshiya; Owada, Kenji; Kuzushita, Kaori*; Hoesch, M.; Tsubota, Masami; Mizuki, Junichiro; et al.
no journal, ,
Resonant inelastic X-ray scattering studies on high-
superconductors Nd
Ce
CuO
and YBaCuO
are presented. In NdCuO and YBaCuO
, which are Mott insulators, an excitation across the Mott gap is observed around 2 eV. The spectral weight of this excitation shifts to higher energy with increasing the momentum transfer and the dispersion of the excitation is larger along the ![$$[pi,pi]$$](/search/images/ERNVY2DJFROHA0K3EQ.gif)
direction than the ![$$[pi,0]$$](/search/images/ERNVY2DJFQYF0JA.gif)
direction. An intraband excitation in the upper Hubbard band emerges in the spectra of electron-doped Nd
Ce
CuO. As a function of the momentum transfer in the CuO plane, the excitation shifts to higher energy up to 2-2.5 eV at the zone boundary, accompanied by an increase of the spectral width. On the other hand, excitations from two inequivalent Cu sites in hole-doped YBaCuO
are distinguished by the momentum dependence and the Mott gap of the CuO chain site is found to be much smaller than that of the CuO plane site.
Masui, Kenji; Suzuki, Yasaka*; Kitao, Takahiko; Inada, Satoshi; Yamada, Keiji; Watahiki, Masaru
no journal, ,
no abstracts in English
Namatame, Toshihiro; Masui, Kenji; Takahashi, Masatomi; Sato, Takehiko; Fujimoto, Ikuo; Tanaka, Yukiyoshi
no journal, ,
no abstracts in English
Masui, Kenji; Kitao, Takahiko; Inada, Satoshi; Yamada, Keiji; Watahiki, Masaru
no journal, ,
no abstracts in English
Kuno, Takehiko; Okano, Masanori; Masui, Kenji; Suzuki, Yutaka; Yamada, Keiji; Watahiki, Masaru; Hiyama, Toshiaki
no journal, ,
no abstracts in English
