Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2021-2, p.91 - 96, 2021/12
We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.
Sr in cattle bone and tooth samples by inductively coupled plasma mass spectrometryKoarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Terashima, Motoki; Fujiwara, Kenso; Kino, Yasushi*; Oka, Toshitaka; Takahashi, Atsushi*; Suzuki, Toshihiko*; et al.
Journal of Analytical Atomic Spectrometry, 36(8), p.1678 - 1682, 2021/08
Times Cited Count：7 Percentile：53.68(Chemistry, Analytical)Rapid analysis of Sr in bone and tooth samples of cattle were achieved by an inductively coupled plasma mass spectrometry (ICP-MS) coupled with mass shift and solid phase extraction techniques. Limit of detection (LOD) in the ICP-MS measurement of 0.1 g samples was lower than that of the radioactivity measurement. Analytical time of the ICP-MS method was reduced from 20 days to 11 hours, compared with the radiometric method. Therefore, the ICP-MS method can be rapid and useful procedure of Sr in small bone and tooth samples derived from terrestrial animals.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：58 Percentile：96.23(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Mitsuyasu, Yusuke*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; et al.
Radiation Measurements, 134, p.106315_1 - 106315_4, 2020/06
Times Cited Count：9 Percentile：65.08(Nuclear Science & Technology)The relationship between the CO
radical intensity and the absorbed dose (dose response curve) of tooth enamel of Japanese macaque was observed by electron spin resonance and the detection limit of our system was estimated to be 33.5 mGy, which is comparable to the detection limit for human molar teeth. Using the dose response curve, external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined. The results suggest that the external exposure dose for the wild Japanese macaques were ranged between 45 mGy to 300 mGy.
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
Times Cited Count：298 Percentile：99.68(Multidisciplinary Sciences)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.
He Neutron Spin Filter (NSF) in the MLF at J-PARCSakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi*; Kira, Hiroshi*; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Shinohara, Takenao; et al.
JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09
The polarized He filter, which polarizes neutrons due to a large neutron absorption cross section of He with strong spin selectivity, becomes a convenient neutron spin filter (NSF) because it is operated immediately after its installation in beam lines without any neutron beam adjustments. For realizing such the NSF, a nuclear magnetic resonance (NMR) system is indispensable for monitoring He nuclear spin polarization 
of the NSF. We have developed the flexible NMR system based on adiabatic fast passage (AFP) and pulse NMR methods by using their complementary features. In comparing with the values of obtained by neutron transmission measurement at the beam line 10 of the J-PARC, we measured the correlations between the AFP and pulse NMR signals as changing condition of temperature, amplitude and applying period of the radio frequency field for the pulse NMR, and so on. As the results, we confirmed that our system would function enough as the monitor.
Oshima, Takeshi; Onoda, Shinobu; Iwamoto, Naoya; Makino, Takahiro; Arai, Manabu*; Tanaka, Yasunori*
Physics and Technology of Silicon Carbide Devices, p.379 - 402, 2012/10
SiC is regarded as a promising candidate for electronic devices used in harsh radiation environments because of its high radiation tolerance. Radiation effects on SiC devices are reviewed. Firstly, the Total Ionizing Dose (TID) effect in Metal-Oxide-Semiconductor (MOS) Field Effect Transistors (FETs) is introduced. Then, the radiation hardness of SiC based transistors such as MOSFETs, Metal-Semiconductor (MES) FETs, Static Induction Transistors (SITs) is discussed from the point of view of 
-ray irradiation effects. Transient current induced in SiC pn diodes by heavy ions incidence, which is important information on the single event effects (SEEs), is also expressed.
Onoda, Shinobu; Makino, Takahiro; Ono, Shuichi*; Katakami, Shuji*; Arai, Manabu*; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 59(4), p.742 - 748, 2012/08
Times Cited Count：4 Percentile：30.35(Engineering, Electrical & Electronic)no abstracts in English
Oshima, Takeshi; Onoda, Shinobu; Tanaka, Yasunori*; Arai, Manabu*
Isotope News, (686), p.8 - 12, 2011/06
no abstracts in English
Onoda, Shinobu; Iwamoto, Naoya; Ono, Shuichi*; Katakami, Shuji*; Arai, Manabu*; Kawano, Katsuyasu*; Oshima, Takeshi
IEEE Transactions on Nuclear Science, 56(6), p.3218 - 3222, 2009/12
Times Cited Count：18 Percentile：73.31(Engineering, Electrical & Electronic)no abstracts in English
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
The improvement of the ESR dosimetry is required to apply that for the low-dose exposure of wild animals. We will report our progress of the improvement, and compare the external exposure dose estimated by the ESR dosimetry technique and the calculated result based on the external exposure dose rate of the captured point.
Oka, Toshitaka; Takahashi, Atsushi*; Mitsuyasu, Yusuke*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Yamashita, Takuma*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
Electron spin resonance (ESR) dosimetry technique is a powerful tool that has been used in the study of external exposure dose assessment of human by measuring CO radicals of teeth. In this work, we applied this technique for wild monkey and wild racoon captured in Fukushima prefecture, and estimated the external exposure dose.
Takir, D.*; Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; et al.
no journal, ,
JAXA spacecraft and sample return mission Hayabusa2 has arrived at the near-Earth asteroid 162173 Ryugu, which is classified a primitive carbonaceous object. Here we report recent results of near-infrared spectrometer (NIRS3) on the Hayabusa2 spacecraft. The observations provide direct measurements of the surface composition of Ryugu and context for the returned samples. NIRS3 has detected a weak and narrow absorption feature centered at 2.72 micrometer across entire observed surface. This absorption feature is attributed to the presence of OH-bearing minerals. The NIRS3 observations also revealed that Ryugu is the darkest object to be observed up-close by a visiting spacecraft. The intensity of the OH feature and low albedo are consistent with thermally-and/or shock-metamorphosed, and/or carbon-rich space-weathered primitive and hydrated carbonaceous chondrites.
film deposited under 
UV light irradiationSakai, Seiji; Arai, Daijiro; Tanimoto, Hisanori*; Otomo, Manabu; Entani, Shiro; Matsumoto, Yoshihiro
no journal, ,
no abstracts in English
He neutron spin filterOku, Takayuki; Hayashida, Hirotoshi; Sakai, Kenji; Shinohara, Takenao; Nakamura, Mitsutaka; Aizawa, Kazuya; Arai, Masatoshi; Endo, Yasuo; Kakurai, Kazuhisa; Kira, Hiroshi*; et al.
no journal, ,
We have been developing an in-situ SEOP He neutron spin filter to apply it to pulsed neutron experiments at J-PARC/MLF. To introduce the He neutron spin filter into the instruments of the pulsed neutron facility such as J-PARC/MLF, it is important to make the system compact and stable, because the system is located inside thick and bulky radiation shields for high energy ray and neutrons. In this study, we have developed a compact laser optics with a volume holographic grating (VHG) element, and composed an in-situ SEOP He neutron spin filter. We have started to apply the He spin filer as an analyzer to polarized neutron small angle scattering and reflection measurements. A magnetic field imaging are also being tested with the two He neutron spin filter cells which are polarized by the ex-situ SEOP technique. In this paper, we report the design of our SEOP He neutron spin filter system and some results of the related polarized neutron beam experiments.
Koarai, Kazuma; Matsueda, Makoto; Fujiwara, Kenso; Ono, Takumi*; Kino, Yasushi*; Oka, Toshitaka; Okutsu, Kenichi*; Takahashi, Atsushi*; Suzuki, Toshihiko*; Shimizu, Yoshinaka*; et al.
no journal, ,
We have investigated incorporation of Sr and 
Cs in teeth of cattle and otoliths of fish. Specific activity of Sr in the dentin tissue was higher than that in the enamel tissue. The result shows change of Sr incorporation in cattle even within a tooth. Concentrations of stable Sr and Cs were 94 ppm and 3 ppb. Distributions of stable Sr and Cs were uniform in the otolith of fish. If distribution of Sr and Cs in the otolith was measured, change of Sr and Cs incorporation into the fish would be found. These findings suggest that distribution patterns of Sr and Cs in the environment could be estimated from distribution of the radionuclides in the tooth and otolith.
Koarai, Kazuma; Matsueda, Makoto; Aoki, Jo; Yanagisawa, Kayo*; Fujiwara, Kenso; Terashima, Motoki; Kino, Yasushi*; Oka, Toshitaka; Okutsu, Kenichi*; Yamashita, Takuma*; et al.
no journal, ,
We demonstrated a method of Sr measurement in small pieces of hard tissues with radioactivity measurement or ICP-MS measurement. Interference elements of the measurements were removed by chemical separation. We could determine Sr in 0.1 g of hard tissues by radioactivity measurement method and ICP-MS method. Limit of detection of the ICP-MS method was lower than that of the radioactivity measurement. The ICP-MS method is adequate method for distribution analysis of Sr in the hard tissues.
Oyama, Hidenori*; Hayama, Kiyoteru*; Takakura, Kenichiro*; Hirao, Toshio; Onoda, Shinobu; Oshima, Takeshi; Kuboyama, Satoshi*; Arai, Manabu*
no journal, ,
no abstracts in English
He spin filter at J-PARC/MLFSakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi; Kira, Hiroshi*; Okawara, Manabu*; Shinohara, Takenao; Oikawa, Kenichi; Harada, Masahide; Kakurai, Kazuhisa; Aizawa, Kazuya; et al.
no journal, ,
A polarized He spin filter, which polarizes neutrons due to a large neutron absorption cross section of He with strong spin selectivity, works as a simple and convenient neutron spin polarizer. For realizing this filter, a device which monitors a polarization of He spin filter is indispensable. We developed the He polarization monitor based on a nuclear magnetic resonance method by an adiabatic fast passage (AFP NMR) at the MLF of J-PARC. The monitor based on the AFP NMR realizes the polarized He spin flipper functioning as the neutron spin polarizer and flipper. However it has disadvantages on the size of He cell limited by a RF coil and its complicated device structure. So we have developed the monitor based on a pulse NMR which uses only a pick up coil and enables the simple device structure of its own, and realized the more flexible monitor system by utilizing the both of pulse NMR and AFP NMR.
He neutron spin filterOku, Takayuki; Sakai, Kenji; Hiroi, Kosuke; Shinohara, Takenao; Aizawa, Kazuya; Arai, Masatoshi; Kakurai, Kazuhisa; Hayashida, Hirotoshi*; Kira, Hiroshi*; Suzuki, Junichi*; et al.
no journal, ,
no abstracts in English
