Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Osawa, Takahito; Fukuoka, Takaaki*
Gekkan Chikyu, 40(5), p.302 - 309, 2018/05
Contents of boron, chlorine, hydrogen, and water in volcanic rocks provide important information of magma origin. Here we describe the measurement for boron in volcanic rocks using the automatic prompt -ray analysis system installed in Japan research reactor-3 (JRR-3) at Japan atomic Energy Agency.
Terada, Kentaro*; Sato, Akira*; Ninomiya, Kazuhiko*; Kawashima, Yoshitaka*; Shimomura, Koichiro*; Yoshida, Go*; Kawai, Yosuke*; Osawa, Takahito; Tachibana, Shogo*
Scientific Reports (Internet), 7(1), p.15478_1 - 15478_6, 2017/11
Electron- or X-ray-induced characteristic X-ray analysis has been widely used to determine chemical compositions of materials in vast research fields. In recent years, analysis of characteristic X-rays from muonic atoms, in which a muon is captured, has attracted attention because both a muon beam and a muon-induced characteristic X-ray have high transmission abilities. Here we report the first non-destructive elemental analysis of a carbonaceous chondrite using one of the world-leading intense direct current muon beam source (MuSIC; MUon Science Innovative Channel). We successfully detected characteristic muonic X-rays of Mg, Si, Fe, O, S and C from Jbilet Winselwan CM chondrite, of which carbon content is about 2 wt percent, and the obtained elemental abundance pattern was consistent with that of CM chondrites.
Matsuoka, Moe*; Nakamura, Tomoki*; Osawa, Takahito; Iwata, Takahiro*; Kitazato, Kohei*; Abe, Masanao*; Nakauchi, Yusuke*; Arai, Takehiko*; Komatsu, Mutsumi*; Hiroi, Takahiro*; et al.
Earth, Planets and Space (Internet), 69(1), p.120_1 - 120_12, 2017/09
We have conducted ground-based performance evaluation tests of the Near-Infrared Spectrometer (NIRS3) onboard Hayabusa2 spacecraft and established a method for evaluating its measured reflectance spectra. Reflectance spectra of nine powdered carbonaceous chondrite samples were measured by both NIRS3 and a FT-IR spectrometer. Since raw data obtained by NIRS3 had considerable spectral distortion caused by systematic offsets in sensitivity of individual pixels, we have established two methods for correcting the NIRS3 data by comparing them with the corresponding FT-IR data. In order to characterize the absorption bands in NIRS3 spectra, the depth of each band component D is defined for each wavelength (m). Reflectance spectra of asteroid Ryugu, the target asteroid of Hayabusa2, to be recorded by the NIRS3 are expected to reveal the characteristics of the surface materials by using the evaluation technique.
Iwata, Takahiro*; Kitazato, Kohei*; Abe, Masanao*; Otake, Makiko*; Arai, Takehiko*; Arai, Tomoko*; Hirata, Naru*; Hiroi, Takahiro*; Honda, Chikatoshi*; Imae, Naoya*; et al.
Space Science Reviews, 208(1-4), p.317 - 337, 2017/07
NIRS3: The Near Infrared Spectrometer is installed on the Hayabusa2 spacecraft to observe the target C-type asteroid 162173 Ryugu at near infrared wavelengths of 1.8 to 3.2 micrometer. It aims to obtain reflectance spectra in order to detect absorption bands of hydrated and hydroxide minerals in the 3 micrometer-band. We adopted a linear-image sensor with indium arsenide (InAs) photo diodes and a cooling system with a passive radiator to achieve an optics temperature of 188 K, which enables to retaining sufficient sensitivity and noise level in the 3 micrometer wavelength region. We conducted ground performance tests for the NIRS3 flight model (FM) to confirm its baseline specifications. The results imply that the properties such as the signal-to-noise ratio (SNR) conform to scientific requirements to determine the degree of aqueous alteration, such as CM or CI chondrite, and the stage of thermal metamorphism on the asteroid surface.
Automation and Control Trends, p.149 - 166, 2016/10
The Prompt Gamma-ray activation Analysis system (PGA) installed in the Japan Research Reactor-3 (JRR-3) was automated between 2012 and 2013. This automation is a good example of a large-scale old analytical device automated in a nuclear facility. This automatic system has several useful functions, such as automatic sample exchange and analysis, automatic helium gas flow control and flow channel switching function, automatic neutron recording system, and fail-safe function using Machine Vision, and the Internet. The analysis system was automated using a vertical revolute joint robot, control programs, and data acquisition devices. The main control software named AutoPGA was developed using LabVIEW and the program can control all functions of the automatic system, capable of analysing up to 14 samples automatically. In the automation, the core of the PGA system was not modified and the extremely low background level of rays was maintained well; however, the efficiency of routine measurements dramatically increased.
Fujita, Hiroki; Nojima, Takehiro; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
KEK Proceedings 2016-8, p.168 - 172, 2016/10
An automatic analysis system was developed to analyze Strontium-90 (Sr) radioactivity in environmental sample for 2013-2015. Various kinds of ashed environmental samples were used in performance tests of the automatic system. These tests were successful without any system trouble. However, Sr concentration had not been measured using the samples analyzed by the system. In this research, Sr concentration in seaweed sample was compared by between the system's analysis and worker's one. Moreover, the system was improved in each analysis process.
Nojima, Takehiro; Fujita, Hiroki; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*
KEK Proceedings 2015-4, p.111 - 115, 2015/11
Automatic strontium-90 analysis system was developed for environmental sample in this research. The system was successful to do wet ashing, chemical separation and ion exchange processes using robot, automatic heating system and so on. Hand-made control program can operate the system by itself.
Osawa, Takahito; Ninomiya, Kazuhiko*; Yoshida, Go*; Inagaki, Makoto*; Kubo, Kenya*; Kawamura, Naritoshi*; Miyake, Yasuhiro*
JPS Conference Proceedings (Internet), 8, p.025003_1 - 025003_6, 2015/09
We report a new elemental analysis system that uses an intense negative-muon beam at J-PARC Materials and Life Science Experimental Facility, Muon Science Establishment. This paper presents the preliminary results of measurements for meteorites and standard material. The main system components are a water-cooled electromagnet, an Al flight tube, an Al sample chamber, a lead shielding body, and a Ge detector. Optimum currents for the electromagnet were determined by recording beam profiles with a CCD camera; the muon beam was shaped by collimators. The background and signal-to-noise ratio was significantly better than that obtained in a previous study, and all significant elements in the meteorite and standard samples were detected. Thus, this system can be used for muonic X-ray analysis of extraterrestrial materials.
Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1141 - 1146, 2015/02
An automatic prompt -ray activation analysis system was developed and installed at the Japan Research Reactor No.3 Modified (JRR-3M). This system is mainly composed of two personal computers, four programs, a six-axis vertical revolute joint robot, and a data acquisition device. The main control software, referred to as AutoPGA, was developed using LabVIEW 2011 and the hand-made program can control all functions of the analytical system. The core of the new system is an automatic sample exchanger and measurement system with several additional automatic control functions integrated into the system. Up to fourteen samples can be automatically measured by the system. Therefore, this system can not only dramatically increase the efficiency of routine measurements but also decrease the background level of -rays for the analysis through the use of a sophisticated automatic control system.
Osawa, Takahito; Hatsukawa, Yuichi
Ningen Seikatsu Bunka Kenkyu (Internet), (25), p.221 - 230, 2015/00
Terada, Kentaro*; Ninomiya, Kazuhiko*; Osawa, Takahito; Tachibana, Shogo*; Miyake, Yasuhiro*; Kubo, Kenya*; Kawamura, Naritoshi*; Higemoto, Wataru; Tsuchiyama, Akira*; Ebihara, Mitsuru*; et al.
Scientific Reports (Internet), 4, p.5072_1 - 5072_6, 2014/05
After the discovery of X-ray by Rontgen, mankind got a new eye to see through things. This fluoroscopy, so-called X-ray radiography that gives the density distribution of the inside of an object, has been applied to the vast research field such as natural/material/medical sciences, industry and technology. The recent development on the intense pulsed muon source at J-PARC MUSE (rate of 106 cps for 60 MeV/c) enabled us to pioneer a new frontier of analytical sciences. Here we report on a non-destructive elemental analysis by using muon capture. Controlling muon's momentum from 32.5 to 57.5 MeV/c. we successfully demonstrated a depth-profile analysis of light elements from several mm-thick layered materials, and non-destructive bulk analyses of meteorites containing organics. Now it is a beginning to utilize a new eye, muon radiography.
Osawa, Takahito; Kobayashi, Mikihiko*; Konno, Takeshi*; Egashira, Mitsuru*; Okazaki, Ryuji*; Miura, Yayoi*; Nagao, Keisuke*
Measurement, 50, p.229 - 235, 2014/04
A temperature control system for a laser heating has been developed to extract noble gases from minute material samples recovered from the asteroid Itokawa by the Hayabusa spacecraft. An ultra-fine thermocouple was produced from 3% Re-W and 26% Re-W wires 25 m in diameter, and its electromotive force was calibrated. A temperature control program was originally produced using LabVIEW 2011 in which proportional-integral-derivative (PID) control was not adopted as an algorithm of the program. The program controlled the temperature of the tiny samples appropriately. The average temperature during heating was slightly lower than the setting temperature and the standard deviation and the maximum overshoot were lower than 2.5% and 6.0% of the setting temperature, respectively. The performance of the temperature control system is high enough to conduct the stepwise heating experiment for minute extraterrestrial material samples.
Ningen Seikatsu Bunka Kenkyu (Internet), (22), p.133 - 146, 2013/05
A decrease in the number of measured atoms reveals a serious problem in the concept of isotopic ratio. The first fundamental defect of the isotopic ratio concept is imperfect reversibility of numerator and denominator, leading to two isotopic compositions inconsistent with each other. Secondly, the probability distribution of isotopic ratio is not the same as the binominal distribution, indicating that the mean isotopic ratio is systematically higher than the true isotopic ratio. The potential uncertainty of isotopic ratio and the gap between the obtained isotopic ratio and the true one deriving from the number of sampling atoms and the isotopic ratio are vigorously evaluated here. Isotopic ratio must be below 1, to reduce the effects of distorted probability distribution of isotopic ratio. In the precise measurement of isotopes, the potential error and disagreement with the true value must be tested when the number of sampled atoms is extremely few.
Bajo, Kenichi*; Sumino, Hirochika*; Toyoda, Michisato*; Okazaki, Ryuji*; Osawa, Takahito; Ishihara, Morio*; Katakuse, Itsuo*; Notsu, Kenji*; Igarashi, Joji*; Nagao, Keisuke*
Mass Spectrometry (Internet), 1(2), p.A0009_1 - A0009_10, 2012/11
The construction of a small-size, magnetic sector, single focusing mass spectrometer (He-MS) for the continuous, on-site monitoring of the He isotope ratio (He/He) is described. The instrument is capable of measuring He/Ne ratios dissolved in several different types of natural fluids of geochemical interest, such as groundwater and gas from hot springs, volcanoes and gas well fields. Ion optics of the He-MS was designed by using the ion trajectory simulation program TRIO so as to measure He and He simultaneously with a double collector system under mass resolution power of 500. Presently attained specifications of the He-MS are; (1) mass resolving power of ca. 490, enough to separate He from interfering ions, HD and H, (2) ultra-high vacuum condition, and (3) high sensitivity enough to detect He amount 3000000 atoms).
Onoue, Tetsuji*; Sato, Honami*; Nakamura, Tomoki*; Noguchi, Takaaki*; Hidaka, Yoshihiro*; Shirai, Naoki*; Ebihara, Mitsuru*; Osawa, Takahito; Hatsukawa, Yuichi; Toh, Yosuke; et al.
Proceedings of the National Academy of Sciences of the United States of America, 109(47), p.19134 - 19139, 2012/11
The 34 million year (My) interval of the Late Triassic is marked by the formation of several large impact structures on Earth. As with the Chicxulub impact event at the Cretaceous/Paleogene boudary, the Late Triassic impact events have been considered a factor in biotic extinction events in the Late Triassic (e.g., the Triassic/Jurassic boundary). However, the causal link between these impact events and a mass extinction event in the Late Triassic remains controversial because of a lack of stratigraphic records of their ejecta deposits. Here we report evidence for an impact event (platinum group elements anomaly, nickel-rich magnetite and microspherules) deposited within a Paleo-Pacific basin in the middle Norian (Upper Triassic) deep-sea sediment in Japan. This includes anomalously high abundances of iridium, up to 41.5 parts per billion (ppb), in the ejecta deposit, which suggests that the iridium anomaly may be found on a global scale. The middle Norian age of the ejecta deposit suggests that the impact event that produced the 100-km-wide Manicouagan crater in Canada8 is most likely related to its deposition. Our analysis of siliceous microfossils shows no evidence of a mass extinction event across the impact event horizon, and no contemporaneous faunal turnover is seen in other marine fossils. However, such an event has been reported among terrestrial tetrapods and floras in North America. We therefore hypothesize that the Manicouagan impact caused the catastrophic collapse of terrestrial ecosystems near the impact site, but not within the marine realm.
Nuclear Instruments and Methods in Physics Research B, 274, p.93 - 99, 2012/03
Kr and Xe ion bombardment experiments were conducted on Mo, Hf, Ta, W, Re, Au, and five platinum group elements. The implanted Kr and Xe ions were detected, and their concentrations were determined by X-ray photoelectron spectroscopy (XPS) using synchrotron radiation. In the case of 5d transition metals, the binding energies of Kr 2p, Xe 3d, and Xe 3d in the target metals correlate with the number of d electrons of metals. Furthermore, the Xe concentration in the 5d transition metals correlates with atomic number, but there is no such correlation for Kr. The observed trend for the Xe concentration can approximately be reproduced by a theoretical calculation that takes sputtering yield into consideration. The retentivities of Kr and Xe are defined as the ratio of the experimental and theoretical surface concentrations.
Hatsukawa, Yuichi; Osawa, Takahito; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Koizumi, Mitsuo; Furutaka, Kazuyoshi
Journal of Radioanalytical and Nuclear Chemistry, 291(1), p.143 - 145, 2012/01
The Ir concentrations in some standard rock samples were determined by using the multiple ray detection method. The use of the multiple ray detection method, which was developed for nuclide quantification, yielded better resolution and sensitivity than the ordinary singles ray detection method. Iridium is one of the least abundant elements in Earth's crust, with an average mass fraction of 0.001 ppm in a crust rock. However, iridium is relatively more abundant (concentration: 0.5 ppm or more) in undifferentiated meteorites. Therefore iridium abundance anomalies in geological samples provide important information about meteorite impact. The standard rock samples used in this study were SARM-76, FC-1 and FC-2. The SARM-76 was prepared from a platinum ore, and issued by the South African Bureau of Standards. FC-1 and FC-2 were obtained from fish clay sediment samples from Stevens Klint, Denmark.
Appel, P.*; Na-Oy, L.*; Hatsukawa, Yuichi; Osawa, Takahito; Kystol, J.*; Srensen, L.*
Danmarks og Grnlands Geologiske Undersgelse Rapport, Vol.127, 39 Pages, 2011/12
This report presents the results of experiments involving the revival of an old method for removal of mercury from tailings after gold extraction by small-scale miners. Numerous tailings from small-scale gold mining are found throughout the Philippines. The tailings have proved to contain large amounts of mercury (up to 250 gram per ton). Furthermore, the tailings contain large amounts of gold locked-up in the mercury - up to 16 gram per ton. The mercury occurs as mercury flour (globules less than a millimetre across). Mercury flour is produced through milling of gold ore, when the mercury is added to tailling drums (whole ore amalgamation). The globules "hidden" in the mercury flour cannot be recovered by small-scale gold miners in any environmentally benign ways.