Ikuya Sakurai
A5000431875- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Planetary Science and Exploration
- Copper-based nanomaterials and applications
- Astronomical Observations and Instrumentation
- Marine Bivalve and Aquaculture Studies
- Isotope Analysis in Ecology
- Advanced X-ray Imaging Techniques
- CCD and CMOS Imaging Sensors
- Gamma-ray bursts and supernovae
- Calibration and Measurement Techniques
- Nuclear Physics and Applications
- Pulsars and Gravitational Waves Research
- Aquatic Invertebrate Ecology and Behavior
- Astrophysics and Cosmic Phenomena
- Ion-surface interactions and analysis
- Gold and Silver Nanoparticles Synthesis and Applications
- Superconducting Materials and Applications
- Marine and fisheries research
- Solar and Space Plasma Dynamics
- Magnetic confinement fusion research
- ZnO doping and properties
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-Ablation Synthesis of Nanoparticles
Nagoya University
2015-2025
National Institute of Polar Research
2024
Aichi Synchrotron Radiation Center
2020
Japan Synchrotron Radiation Research Institute
2010-2015
Tokai University
2015
RIKEN Advanced Science Institute
2011
SAGA Light Source
2010
SPring-8
2010
Institute for Molecular Science
2010
High Energy Accelerator Research Organization
2010
Abstract Volatile and organic-rich C-type asteroids may have been one of the main sources Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but meteorite record biased: only strongest types survive atmospheric entry are then modified interaction with terrestrial environment. Here we present results a detailed bulk microanalytical study pristine Ryugu particles, brought to Earth Hayabusa2 spacecraft. particles display close...
Abstract The Gas Slit Camera (GSC) is an X-ray instrument on the MAXI (Monitor of All-sky Image) mission aboard International Space Station. It designed to scan entire sky every 92-minute orbital period in 2–30 keV band and achieve highest sensitivity among all-sky monitors ever flown so far. GSC employs large-area position-sensitive proportional counters with a total detector area 5350 cm $^2$. on-board data processor has functions format telemetry as well control high voltage protect them...
Abstract The delivery of water to the inner Solar System, including Earth, is still a debated topic. A preferential role for hydrated asteroids in this process supported by isotopic measurements. Carbonaceous chondrite (CC) meteorites represent our main source information about these volatile-rich asteroids. However, destruction weaker materials during atmospheric entry creates bias CC data. return surface from C-type asteroid 162173 Ryugu Hayabusa2 spacecraft provides unique opportunity...
Abstract Micrometeorites, a possible major source of Earth’s water, are thought to form from explosive dispersal hydrated chondritic materials during impact events on their parental asteroids. However, this provenance and formation mechanism have yet be directly confirmed using asteroid returned samples. Here, we report evidence mild shock metamorphism in the surface particles Ryugu based electron microscopy. All dominated by phyllosilicates but lack dehydration textures, which indicative...
Recently, the demand for high-quality gas-atomized powders has increased. Some particles in contain internal pores, and presence of these pores may result degradation various properties final product manufactured through a specific process. However, mechanism pore formation not yet been elucidated. In this study, alloy were prepared using gas atomization method, their observed synchrotron X-ray CT. The results showed that alloys with wider solid–liquid coexistence temperature range exhibited...
Abstract The potential to fabricate metallic nanoparticles directly on silicon substrates from liquid solutions is ideal for three-dimensional lithography systems, drug delivery materials, and sensing applications. Here, we report the successful synthesis of Au, Cu, Fe corresponding [gold(I) trisodium disulphite, copper(II) sulfate, potassium ferricyanide] by synchrotron (SR) X-ray irradiation. deposition gold in gold(I) disulphite solution was performed monochromatic exposure radiation. use...
Abstract We developed universal sample holders [the Kochi grid, clamp, and Okazaki cell) a transfer vessel (facility-to-facility container (FFTC)] to analyze sensitive fragile samples, such as extremely small extraterrestrial materials. The prevent degradation, contamination due the terrestrial atmosphere (water vapor oxygen gas) particles, well mechanical damage. FFTC can isolate samples from effects of for more than week. grid clamp were made coordinated micro/nano-analysis that utilizes...
Abstract Although CI chondrites are susceptible to terrestrial weathering on Earth, the specific processes unknown. To elucidate mechanism, we conduct a laboratory experiment using pristine particles from asteroid Ryugu. Air‐exposed predominantly develop small‐sized euhedral Ca‐S‐rich grains (0.5–1 μm) particle surface and along open cracks. Both transmission electron microscopy synchrotron‐based computed tomography combined with XRD reveal that hydrous Ca‐sulfate. Notably, this phase does...
The deposition of copper (Cu) and cupric oxide (Cu 4 O 3 , Cu 2 O, CuO) particles in an aqueous sulfate (CuSO ) solution with additive alcohol such as methanol, ethanol, 2-propanol, ethylene glycol has been studied by X-ray exposure from synchrotron radiation. An attenuated radiation time 5 min allows for the synthesis Cu, CuO nano/microscale their aggregation into clusters. morphology composition synthesized Cu/cupric particle clusters were characterized scanning electron microscopy,...
X-ray radiolysis of a Cu(CH3COO)2 solution was observed to produce caltrop-shaped particles cupric oxide (CuO, Cu2O), which were characterized using high-resolution scanning electron microscopy and micro-Raman spectrometry. irradiation from synchrotron source drove the room-temperature synthesis submicrometer- micrometer-scale caltrop an aqueous spiked with ethanol. The size depended on ratio ethanol in stock surface substrate. results indicated that there several synthetic routes obtain...
<title>Abstract</title> Solar system abundances of the elements, which are determined by spectroscopic measurements solar photosphere and laboratory analyses CI (Ivuna-type) carbonaceous chondrites, a cornerstone to understand origin evolution planets other constituents, such as asteroids comets. Mercury (Hg) is one elements whose abundance still poorly constrained due no observable lines for Hg in spectrum large variations chondrites caused mainly terrestrial contamination. Here we...
DIOS (Diffuse Intergalactic Oxygen Surveyor) is a small scientific satellite with main aim for the search of warm-hot intergalactic medium using redshifted OVII and OVIII lines. The instrument will consist 4-stage X-ray telescope an array TES microcalorimeters 256 pixels, cooled mechanical coolers. Hardware development expected results are described. Survey observations over about 5° x area reveal new filamentary structures. be proposed to 3rd mission in JAXA's series 2011, aiming launch...
Synthesis and immobilization of caltrop cupric particles onto a Si substrate using X-ray radiolysis directly from liquid solution Cu(COOCH 3 ) 2 is demonstrated. Caltrop oxide are formed in the aqueous solutions , which also contain methanol, ethanol, 2-propanol or 1-propanol as ^\bulletOH scavenger. The blade lengths dependent on alcohol chain length. In particular, it was found that an alkyl whose length longer than four unable to synthesize any radiolysis. These results attributed...
We are developing Monitor of All Sky X-ray Image (MAXI) which will be mounted on the Japanese Experiment Module International Space Station. MAXI is an all-sky monitor scans sky in every 90 minutes. The sensitivity as high 7 mCrab (5 (sigma) level) one scan and 1 one-week accumulation. GSC (Gas Slit Camera) instrument consists twelve one-dimensional position sensitive proportional counters using Xe++CO2 gas carbon fiber anodes 10micrometers diameter. window size 272 x 190 mm. obtained by...
We have produced various gas electron multiplier foils (GEMs) by using laser etching technique for cosmic X-ray polarimeters. The finest structure GEM we fabricated has 30 μm-diameter holes on a 50 μm-pitch. effective gain of the reaches around 5000 at voltage 570 V between electrodes. is slightly higher than that CERN standard with 70 140 GEMs thickness 100 μm which two times thicker GEM. thick-foil 104 applied 350 per thickness. about orders remarkable characteristic beginning...
Abstract The isolated 4.9 ms pulsar PSR J2124$-$3358 was observed with ASCA on 1998 May 9, and the X-ray spectrum in 0.5–10 keV band obtained. can be fitted a single blackbody model temperature $kT = 0.31^{+0.08}_{-0.06}\,\mathrm{keV}$, although simple power-law relatively large photon index $\Gamma 2.8^{+0.6}_{-0.5}$ cannot rejected.
Spectroscopic diagnostics have been extensively developed for studies of impurity and neutral particle transports at core edge plasmas in LHD. Diagnostics are similar to a tokamak case, i.e., Zeff from visible bremsstrahlung, K-x-ray measurements x-ray spectroscopy using Si(Li) detectors compact crystal spectrometer, high-Z VUV flat-field EUV spectrometer. A combination pellet injection bremsstrahlung is an active tool determination the diffusion coefficient D convective velocity V. Using...
How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question astrophysics. EDGE will trace cosmic history baryons generations massive stars by Gamma-Ray Burst (GRB) explosions, through period galaxy cluster formation, down very low redshift Universe, when between third one half are expected reside in filaments undergoing gravitational collapse dark matter (the so-called warm hot intragalactic medium). In addition EDGE, with its...
Impurity transport was investigated at both edge and core regions in large helical device (LHD) with developed spectroscopic instruments which can measure one- two-dimensional distributions of impurities. The impurity behavior studied recently using four carbon resonant transitions different ionization stages CIII (977Å), CIV (1548Å), CV (40.3Å) CVI (33.7Å). When the line-averaged electron density, ne, is increased from 1 to 6 × 1013 cm−3, ratio (CIII+CIV)/ne increases while (CV+CVI)/ne...