The Influence of structural dynamics in two-dimensional hybrid organic-inorganic perovskites on their photoluminescence efficiency; Neutron scattering analysis

Rajeev, H. S.*; Hu, X.*; Chen, W.-L.*; Zhang, D.*; Chen, T.*; 古府 麻衣子*; 梶本 亮一; 中村 充孝; Chen, A. Z.*; Johnson, G. C.*; et al.

Journal of the Physical Society of Japan, 94(3), p.034602_1 - 034602_14, 2025/03

https://doi.org/10.7566/JPSJ.94.034602

Two-dimensional hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for light-emitting diode applications. In this study, by using time-of-flight neutron spectroscopy we identified and quantitatively separated the lattice vibrational and molecular rotational dynamics of two perovskites, butylammonium lead iodide (BA)PbI and phenethyl-ammonium lead iodide (PEA)PbI. By examining the corresponding temperature dependence, we found that the lattice vibrations, as evidenced by neutron spectra, are consistent with the lattice dynamics obtained from Raman scattering. We revealed that the rotational dynamics of organic molecules in these materials tend to suppress their photoluminescence quantum yield (PLQY) while the vibrational dynamics did not show predominant correlations with the same. Additionally, we observed photoluminescence emission peak splitting for both systems, which becomes prominent above certain critical temperatures where the suppression of PLQY begins. This study suggests that the rotational motions of polarized molecules may lead to a reduction in exciton binding energy or the breaking of degeneracy in exciton binding energy levels, enhancing non-radiative recombination rates, and consequently reducing photoluminescence yield. These findings offer a deeper understanding of fundamental interactions in 2D HOIPs and could guide the design of more efficient light-emitting materials for advanced technological applications.

Evaluation report for sludge measurement by nondestructive assay (Plutonium Scrap Multiplicity Counter)(Joint research)

谷川 聖史; 瀬谷 和仁*; 浅川 直也*; 林 宏幸*; 堀籠 和志; 向 泰宣; 北尾 貴彦; 中村 仁宣; Henzlova, D.*; Swinhoe, M. T.*; et al.

JAEA-Technology 2024-014, 63 Pages, 2025/02

JAEA-Technology-2024-014.pdf:3.02MB

プルトニウム転換技術開発施設の廃液処理工程で発生したスラッジ中のPu量を評価する上で、スラッジは生成上、多くの不純物(Na, Fe, Ni等)を含み不均質であるため、従来の破壊分析ではサンプリングによる代表性が乏しく、Pu量測定に係る測定不確かさが大きかった(約24%)。この測定不確かさを低減させるために、日本原子力研究開発機構と米国ロスアラモス国立研究所は共同で中性子を利用した非破壊測定装置のPlutonium Scrap Multiplicity Counter (PSMC)を用いた測定技術の開発を進めた。MOX粉末を用いた模擬スラッジやモンテカルロ法により検証等を行いPSMC検出器パラメーター(predelay, doubles gatefraction等)を最適化し、高分解能ガンマ線分光分析を組み合わせて測定した結果、含有不純物の影響はないことが確認でき、従来法と比べ新たに設定した非破壊測定方法における測定不確かさは約6.5%まで低減できた。さらに、PSMC測定値の妥当性を評価するため、IAEA立ち合いの下、ガンマ線を測定しPu量を評価するIn Situ Object Counting System (ISOCS)を用いた比較測定した結果、ISOCSとPSMCの測定値は両方の測定不確かさの範囲内で一致したため、PSMCによる測定値の妥当性が確認された。これらの結果より、本非破壊測定技術はスラッジのように不純物を多く含み、サンプリングの代表性が乏しいアイテムに有効であり、スラッジの計量管理に適用することが認められた。

Sm synchrotron-radiation-based Mssbauer and SR studies of SmRuGe

筒井 智嗣; 伊藤 孝; 中村 仁*; 吉田 実生*; 小林 義男*; 依田 芳卓*; 中村 惇平*; 幸田 章宏*; 東中 隆二*; 青木 大*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

https://doi.org/10.1007/s10751-024-01900-6

Sm SR-based Mssbauer and muon spin relaxation (SR) spectroscopies have been applied to SmRuGe. The temperature dependence of the Sm SR-based Mssbauer spectra in the paramagnetic state implies the presence of dynamical nuclear Zeeman and/or quadrupole interactions. The time differential SR spectra also exhibit a marked temperature dependence in the paramagnetic state, indicating the presence of magnetic fluctuation in SmRuGe at least. These results in the present work infer that the dynamical hyperfine interactions observed using the mutually complementary spectroscopic methods are connected with the mechanism of the heavy fermion behavior in SmRuGe.

Large spontaneous Hall effect with flexible domain control in the antiferromagnetic material TaMnP

小手川 恒*; 中村 彰良*; Huyen, V. T. N.*; 新井 祐樹*; 藤 秀樹*; 菅原 仁*; 林 純一*; 武田 圭生*; 田端 千紘; 金子 耕士; et al.

Physical Review B, 110(21), p.214417_1 - 214417_8, 2024/12

https://doi.org/10.1103/PhysRevB.110.214417

In this study, we show that the orthorhombic system TaMnP exhibits a large anomalous Hall conductivity (AHC) in spite of the small net magnetization. Neutron scattering experiment and the observation of the AH effect comprehensively suggest a dominant AF structure in TaMnP is represented by . The AHC is one of the largest among those observed in AF materials at zero fields. First-principles calculations suggest that the spin-orbit interaction originating in nonmagnetic Ta-5 electrons significantly contributes to the enhancement of Berry curvatures in the momentum space. We found that the AF domain switching is triggered by the magnetic fields along all the crystal axes. This indicates that the AF domain determining the sign of the Hall response can be controlled even through the small net magnetization symmetrically different.

Effect of neutron beam properties on dose distributions in a water phantom for boron neutron capture therapy

石川 諒尚; 田中 浩基*; 中村 哲志*; 熊田 博明*; 櫻井 良憲*; 渡辺 賢一*; 吉橋 幸子*; 棚上 裕生*; 瓜谷 章*; 鬼柳 善明*

Journal of Radiation Research (Internet), 65(6), p.765 - 775, 2024/11

https://doi.org/10.1093/jrr/rrae076

From the viewpoints of the advantage depths (ADs), peak tumor dose, and skin dose, we evaluated the effect of neutron beam properties, namely, the ratio between thermal and epithermal neutron fluxes (thermal/epithermal ratio), fast neutron component, and -ray component on the dose distribution. Several parameter surveys were conducted with respect to the beam properties of neutron sources for boron neutron capture therapy assuming boronophenylalanine as the boron agent using our dose calculation tool, called SiDE. The ADs decreased by 3% at a thermal/epithermal ratio of 20% - 30% compared with the current recommendation of . The skin dose increased with the increasing thermal/epithermal ratio, reaching a restricted value of 14 Gy-eq at a thermal/epithermal ratio of . The fast neutron component was modified using two different models, namely, the "linear model," in which the fast neutron intensity decreases log-linearly with the increasing neutron energy, and the "moderator thickness (MT) model," in which the fast neutron component is varied by adjusting the moderator thickness in a virtual beam shaping assembly. Although a higher fast neutron component indicated a higher skin dose, the increment was at a fast neutron component of Gy cm for both models. Furthermore, in the MT model, the epithermal neutron intensity was higher at a fast neutron component of Gy cm compared with the current recommendation of Gy cm. The -ray component also caused no significant disadvantages up to several times larger compared with the current recommendation.

France-Japan collaboration on severe accident studies in sodium-cooled fast reactors, 2; Methodologies and calculations of severe accident phases

曽我部 丞司; 石田 真也; 田上 浩孝; 岡野 靖; 神山 健司; 小野田 雄一; 松場 賢一; 山野 秀将; 久保 重信; 久保田 龍三郎*; et al.

Proceedings of International Conference on Nuclear Fuel Cycle (GLOBAL2024) (Internet), 4 Pages, 2024/10

日仏協力の枠組みにおいて、タンク型ナトリウム冷却高速を対象とした過酷事故の評価手法を定義し、解析評価を実施した。

Circular polarization measurement for individual gamma rays in capture reactions with intense pulsed neutrons

遠藤 駿典; 安部 亮太*; 藤岡 宏之*; 猪野 隆*; 岩本 修; 岩本 信之; 河村 しほり*; 木村 敦; 北口 雅暁*; 小林 龍珠*; et al.

European Physical Journal A, 60(8), p.166_1 - 166_10, 2024/08

https://doi.org/10.1140/epja/s10050-024-01392-6

Measurements of -ray circular polarization emitted from neutron capture reactions provide valuable information for nuclear physics studies. The spin and parity of excited states can be determined by measuring the circular polarization from polarized neutron capture reactions. Furthermore, the -ray circular polarization in a neutron capture resonance is crucial for studying the enhancement effect of parity nonconservation in compound nuclei. The -ray circular polarization can be measured using a polarimeter based on magnetic Compton scattering. A polarimeter was constructed, and its performance indicators were evaluated using a circularly polarized -ray beam. Furthermore, as a demonstration, the -ray circular polarization was measured in S(n,)S reactions with polarized neutrons.

Study on eutectic melting behavior of control rod materials in severe accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2022

山野 秀将; 高井 俊秀; 江村 優軌; 福山 博之*; 東 英生*; 西 剛史*; 守田 幸路*; 中村 勤也*; Ahmed, Z.*; Pellegrini, M.*

Proceedings of 14th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation, and Safety (NTHOS-14) (Internet), 12 Pages, 2024/08

本発表はプロジェクト全体概要及び2022年度までの進捗概要について報告する。この論文における具体的成果は、初めての固化試験データを取得したことである。

Benchmark analysis on pipe support structures for establishing inelastic seismic design

中村 いずみ*; 滝藤 聖崇; 嶋津 龍弥*; 奥田 幸彦; 酒井 理哉*; 大谷 章仁*; 渡壁 智祥; 奥田 貴大; 渋谷 忠弘*; 白鳥 正樹*

Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07

A new seismic design procedure which evaluates the inelastic behavior of piping system by detailed finite element method (FEM) analysis has been developed in Japan (the JSME CC); however, the inelastic behavior is only considered for pipe body in the JSME CC, and the evaluation of inelastic behavior of pipe support structure is still not included. To clarify the current analytical accuracy of inelastic analysis of pipe support structures and to develop an analytical guideline to reasonably include the inelastic behavior of pipe support structure in the seismic design of piping system, a series of benchmark analysis on pipe support structures has been launched in 2022. The benchmark analysis of pipe support structures consists of mainly two stages; the first stage is the analysis of pipe support structures themselves, and the second stage is the analysis of piping system with inelastic support structure. As of January 2024, the first stage of benchmark analysis is in progress. It is confirmed that there are some variabilities in modeling of support structures, stress-strain relationship, and boundary conditions. The load-deflection relationships also show variability even when the support structures are in the elastic region. The effect of these variations to the response of piping system model is remained as future tasks.

A Systematic approach for the adequacy analysis of a set of experimental databases; Application in the framework of the ATRIUM activity

Baccou, J.*; Glantz, T.*; Ghione, A.*; Sargentini, L.*; Fillion, P.*; Damblin, G.*; Sueur, R.*; Iooss, B.*; Fang, J.*; Liu, J.*; et al.

Nuclear Engineering and Design, 421, p.113035_1 - 113035_16, 2024/05

https://doi.org/10.1016/j.nucengdes.2024.113035

In the Best-Estimate Plus Uncertainty (BEPU) framework, the use of best-estimate code requires to go through a Verification, Validation and Uncertainty Quantification process (VVUQ). The relevance of the experimental data in relation to the physical phenomena of interest in the VVUQ process is crucial. Adequacy analysis of selected experimental databases addresses this problem. The outcomes of the analysis can be used to select a subset of relevant experimental data, to encourage designing new experiments or to drop some experiments from a database because of their substantial lack of adequacy. The development of a specific transparent and reproducible approach to analyze the relevance of experimental data for VVUQ still remains open and is the topic of this contribution. In this paper, the concept of adequacy initially introduced in the OECD/NEA SAPIUM (Systematic APproach for model Input Uncertainty quantification Methodology) activity is formalized. It is defined through two key properties, called representativeness and completeness, that allows considering the multifactorial dimension of the adequacy problem. A new systematic approach is then proposed to analyze the adequacy of a set of experimental databases. It relies on the introduction of two sets of criteria to characterize representativeness and completeness and on the use of multi-criteria decision analysis method to perform the analysis. Finally, the approach is applied in the framework of the new OECD/NEA ATRIUM activity which includes a set of practical IUQ exercises in thermal-hydraulics to test the SAPIUM guideline in determining input uncertainties and forward propagating them on an application case. It allows evaluating the adequacy of eight experimental databases coming from the Super Moby-dick, Sozzi-Sutherland and Marviken experiments and identifying the most adequate ones.