National Institutes for Quantum and Radiological Science and Technology
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Optical Charge State Manipulation of Lead-Vacancy Centers in Diamond
No full textGroup-IV vacancy centers in diamond exhibit excellent optical and spin coherence properties, making them highly promising and scalable spin qubit candidates. Since only specific charge states are magneto-optically active, control over the charge state is fundamental for quantum applications. Here, we realize the charge state control of lead-vacancy centers (PbV) through multicolor laser irradiation. We achieve tunable population manipulation of the negatively charged state from 0 to 89%, paving the way for spin control of the negatively charged PbV center. Furthermore, through analysis of charge state dynamics, we propose a charge cycle between the neutral and negatively charged states, indicating a possible pathway to the neutral PbV center with a spin-1 system.journal articl
Energy-dispersive X-ray fluorescence analysis of uranium-contaminated stainless-steel surfaces by eliminating the iron sum peak using a titanium filter
No full textDuring energy-dispersive X-ray fluorescence (EDXRF) measurements of stainless steel, sum peaks originating from iron are frequently observed. Among these, the Fe Kα + Kβ sum peak overlaps with the U Lα peak, complicating the analysis of uranium contamination on stainless-steel surfaces. While secondary X-ray filters can mitigate such sum peaks, integrating them into commercially available portable EDXRF analyzers poses technical challenges. This study presents a straightforward method for eliminating iron sum peak interference. A titanium foil, placed over the uranium-contaminated area on a stainless-steel surface, attenuates incident X-rays while allowing significantly higher transmission of U Lα X-rays than Fe K X-rays. EDXRF measurements were conducted on uranium-contaminated stainless-steel models using a portable EDXRF spectrometer equipped with a titanium foil of optimized thickness as a filter. In the resulting EDXRF spectrum, the intensity of the U Lα peak showed a direct correlation with the uranium content, enabling accurate detection of uranium levels as low as 61 ng. The proposed method achieves a uranium detection sensitivity approximately 100 times greater than conventional α-survey meter methods.journal articl
マイクロ波―光量子インターフェースに向けたSiN導波路結合型ダイヤモンドオプトメカニカル結晶デバイスの光学評価
No full text誤り耐性超伝導量子コンピュータの実現に向けて、配線数増大による空間制約と熱流入が課題となっている。この解決策として、マイクロ波配線を光ファイバに置換するための高効率・低ノイズ・超低消費電力量子トランスデューサの開発が求められるが、実用レベルでの実現は開発段階にある。本研究では、ダイヤモンド色中心とオプトメカニカル共振器を用いた超低消費電力量子トランスデューサの開発に向けた成果を報告する。第86回応用物理学会 秋季学術講演会conference presentatio
Developments of a Microwave-to-optical Quantum Transducer Based on a Chip-integrated Diamond Color Center
No full textToward the realization of a large-scale fault-tolerant quantum computer, the development of microwave-to-optical quantum transducers has been actively underway over the past 10 years. Optical connections between refrigerators enable wide-bandwidth, flexible, room-temperature transmission of quantum information, extending the computing capacity of superconducting quantum processors. In this research, we explore the possibility of a diamond color-center-based quantum interface. We report the current status of developments in our fiber-integrated nanophotonic diamond devices.PECS-XIVconference poste
Safety Education and Training for Industrial X-ray Workers
No full textIn May 2021, a big accident occurred in Japan in which radiation workers were exposed to industrial X-ray. IAEA categorized this accident into Level 3 by the International Nuclear and Radiological Event Scale (INES). Considering the latest X-ray device conditions and accident examples, the Japanese authority has started to improve the national radiation control regulation for the use of industrial X-ray instruments. The authors are officially supporting the national movement as an expert team through their research. The authority is targeting the improvement on the structural standards for automatic warning and safety devices of X-ray equipment, the duties of X-ray safety supervisors, education and training for X-ray workers and supervisors, practical identification of controlled areas for X-ray equipment, and support for business operators and industry groups. The authors are especially focusing on safety education and training for X-ray workers and continue to survey the domestic and international status and situation supported by related stakeholders.The main scope of the authors' surveys is to compare the system of safety education and training on industrial X-rays and the way to manage industrial X-ray irradiators for safety in each country with the Japanese ones. The authors identified some countries had unique characteristics and found several differences depending on the country’s safety management history and culture: for example, regulatory system and competent ministries, categorization of equipment, requirements for initial and periodic education for workers, safety management of students, education and training content and time, requirements for safety supervisors, etc.The authors will show the latest results of the survey and Japanese future scope from the viewpoint of an expert team. The authors hope to discuss these topics with international safety experts and stakeholders from various countries at the venue, not only from the radiation field but the others.12th Asian Conference on Safety and Education in Laboratoryconference presentatio
Chemogenetic dissection of primate prefrontal-subcortical circuits in adaptive behavior
No full textAnimals must flexibly adapt to novel environments and optimize their behavior in a dynamically changing world. The prefrontal cortex is known to support such adaptive behavior through, in coordination with subcortical regions such as the striatum and thalamus through direct and indirect connections, i.e., PFC–basal ganglia–thalamus–PFC loop and PFC-thalamus reciprocal projections. However, the specific contribution of these circuits to flexible behavior in primates remains unclear.We have recently demonstrated that neural pathways from the orbitofrontal cortex to these subcortical regions play distinct and essential roles in adapting to changes in reward contingencies by chemogenetic pathway-selective manipulation (Oyama et al., 2024).Building upon these findings, we are currently investigating whether similar principles could be applied across cortico-basal ganglia loops by examining how interactions between other prefrontal regions, such as the dorsolateral prefrontal cortex, and their corresponding subcortical targets contribute to behavioral adaptation. This work combines chemogenetic pathway-selective silencing with large-scale neural recording techniques. In this symposium, we will present our latest results from these ongoing investigations.NEURO2025conference presentatio
INVESTIGATION OF PLASMA PARAMETERS IN SAWTOOTH OSCILLATION BY ABSOLUTE INTENSITY OF SOFT X-RAY EMISSION IN JT-60SA INTEGRATED COMMISSIONING PHASE
No full textJT-60SAの統合試験運転期における主プラズマからの制動放射パワースペクトルから求めた鋸刃状振動中のプラズマパラメータの時間変化について議論する。鋸刃状振動時にプラズマ中心部で制動放射のエネルギー帯によって異なる位相の振動が観測された。制動放射のプラズマパラメータ依存性から、プラズマ中心部では鋸刃状振動の崩壊時に電子温度の減少と、電子密度または実効電荷の上昇が生じたと解釈される。さらに、電子温度の振動の位相が逆転する反転半径の外側では、鋸刃状振動の崩壊時に密度または実効電荷が減少する傾向が見られたことから、鋸刃状振動の崩壊時に反転半径の外側から内側に約3×1018個の粒子が流れ込んでいる可能性が示唆された。QSTフュージョンエネルギーワークショップconference presentatio
難処理廃液中での貴金属イオンの錯形成状態に関するXAFS研究
No full text貴金属リサイクルプロセスでは、金属イオンを安定化させるために添加する強い錯化剤などの 影響により、既存技術では対応が難しい難処理廃液の処理方法が課題となっている。廃液中での 貴金属イオンの錯形成状態は、金属回収効率に影響することがわかっており、貴金属リサイクル を効率的に進める上で必須の情報である。そこで本研究では、実際の貴金属リサイクル工程で扱 われている Au, Ag, Rh, Pd 廃液を模擬した試料の X 線吸収微細構造スペクトルを測定し、標準試料 データと比較することにより、実際の廃液中で貴金属イオンがどのような錯形成状態を保持して いるのか調べたので報告する。journal articl
Combined stimuli of elasticity and microgrooves form aligned myotubes that characterize slow-twitch muscles
No full textSkeletal muscles are classified into slow-twitch muscles composed primarily of type I and IIa fibers with high oxidative metabolism, and fast-twitch muscles composed of type IIx and IIb fibers with high glycolytic metabolism. The shift of fiber types occurs during development and later in life, however, the stimuli that shift these types remain unclear. We analyzed the role of mechanical stimuli in myotube formation and shift to the characteristics of each fiber type using crosslinked gelatin gels with tunable elasticity (10–230 kPa) and microgrooves (3–50 µm). C2C12 myotubes on 10 kPa gel increased the expression of marker genes for type I and IIa fibers (MYH7 and MYH2) and oxidative metabolism (GLUT4 and myoglobin) than those on stiffer gels. Upregulation of PGC-1α on soft gel indicated to induce a shift of myotubes to the genetic characteristics of slow-twitch muscles. Microgrooves (3–10 µm) enhanced myoblast fusion and myotube orientation, without affecting the gene expressions characterizing fiber types. This study demonstrated an approach to create highly oriented slow-twitch muscle models by controlling the elasticity and microgrooves.journal articl
Sensitive detection of trace precious metals in acidic solutions using liquid sheet jet laser-induced breakdown spectroscopy
No full textRapid in-situ analysis of precious metals in liquid has been highly desired for real-time monitoring of recovery processes. We demonstrate that laser-induced breakdown spectroscopy (LIBS) combined with a liquid sheet jet provides a sensitive technique that can directly analyze trace precious metals (Au, Pt, Pd, Ag, Rh, and Ru) in acidic aqueous solutions. A glass slit nozzle resistant to corrosive acids was employed to generate a liquid sheet jet with a thickness of tens of micrometers, which mitigated the liquid splashing inherent in the direct detection of liquid by LIBS, thereby yielding persistent luminous plasma. The optimal thickness of the sheet jet for LIBS measurement was determined as 14 µm. The LIBS spectral profiles for each analyte obtained by 532 nm laser excitation were explored to select the analytical lines for quantitative analysis. The univariate calibration curves of the analyte elements were then constructed to calculate the limit of detection (LODs) as well as other figures of merit. The LODs of Au, Pt, Pd, Ag, Rh, and Ru were estimated respectively to be 0.62, 0.97, 0.09, 0.14, 0.09, and 0.15 mg L–1, achieving detection limits below 1 mg L–1 and being greatly improved from conventional liquid jet LIBS. Thus, liquid sheet jet LIBS would offer a useful tool for real-time monitoring of metal recovery processes.journal articl