Thermally altered subsurface material of asteroid (162173) Ryugu

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

https://doi.org/10.1038/s41550-020-01271-2

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.

A 3 MeV linac for development of accelerator components at J-PARC

Kondo, Yasuhiro; Asano, Hiroyuki*; Chishiro, Etsuji; Hirano, Koichiro; Ishiyama, Tatsuya; Ito, Takashi; Kawane, Yusuke; Kikuzawa, Nobuhiro; Meigo, Shinichiro; Miura, Akihiko; et al.

Proceedings of 28th International Linear Accelerator Conference (LINAC 2016) (Internet), p.298 - 300, 2017/05

https://doi.org/10.18429/JACoW-LINAC2016-MOPLR071

We have constructed a linac for development of various accelerator components at J-PARC. The ion source is same as the J-PARC linac's, and the RFQ is a used one in the J-PARC linac. The beam energy is 3 MeV and nominal beam current is 30 mA. The accelerator has been already commissioned, and the first development program, laser-charge-exchange experiment for the transmutation experimental facility, has been started. In this paper, present status of this 3-MeV linac is presented.

Application of natural linear polysaccharide to green resist polymers for electron beam and extreme-ultraviolet lithography

Takei, Satoshi*; Oshima, Akihiro*; Oyama, Tomoko; Ito, Kenta*; Sugahara, Kigen*; Kashiwakura, Miki*; Kozawa, Takahiro*; Tagawa, Seiichi*; Hanabata, Makoto*

Japanese Journal of Applied Physics, 53(11), p.116505_1 - 116505_7, 2014/11

https://doi.org/10.7567/JJAP.53.116505

The application of natural linear polysaccharide to green resists was demonstrated for electron beam (EB) and extreme-ultraviolet (EUV) lithography. Because of the water solubility of natural polysaccharides, the water spin-coating and water-developable processes realize an environmentally friendly manufacturing process for next-generation electronic devices. The developed green resist with a weight-average molecular weight of 83,000 and 70 mol % hydroxyl groups was found to have acceptable properties such as spin-coat ability on 200 mm wafers, pillar patterns of 100-400 nm with a high EB sensitivity of 10 C/cm, etch selectivity with a silicon-based middle layer in CF plasma treatment, and high prediction sensitivity to EUV region.

Generation and application of ultrahigh monochromatic X-ray using high-quality FeBO single crystal

Mitsui, Takaya; Seto, Makoto; Kikuta, Seishi*; Hirao, Naohisa*; Oishi, Yasuo*; Takei, Fumihiko*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Higashitaniguchi, Satoshi*; Masuda, Ryo*

Japanese Journal of Applied Physics, Part 1, 46(2), p.821 - 825, 2007/02

https://doi.org/10.1143/JJAP.46.821

Ultrahigh monochromatic 14.4 keV X-rays with a narrow bandwidth of 15.4 neV were generated successfully with a high counting rate of 12,000 counts/s at the undulator beamline (BL11XU) of SPring-8. It was achieved by combining an intense X-ray from the third generation synchrotron radiation facility SPring-8 and pure nuclear Bragg scattering of a very highquality FeBO perfect single crystal at the Nel temperature. We describe the detailed study of the beam characteristics and some performance test experiments of energy-domain synchrotron radiation Mssbauer spectroscopy, including a highpressure experiment using a diamond anvil cel.

A computer control system for the PNC high power cw electron linac; Concept and hardware

Emoto, Takashi; Kato, Yuko*; Hirano, Koichiro; Ishikawa, Y.*; Takei, Hayanori; Nomura, Masahiro; Tani, Satoshi

PNC TN9410 98-060, 45 Pages, 1998/06

PNC-TN9410-98-060.pdf:1.17MB

Design and construction of a high power cw (Continuous Wave) electron linac for studying feasibility of nuclear waste transmutation was started in 1989 at PNC. The PNC accelerator (10Mev, 20mA average current, 4 ms pulse width, 50 Hz repetition) is dedicated machine for development of the high current acceleration technology in future need. The computer control system is responsible for accelerator control and supporting the experiment for high power operation. The feature of the system is the measurements of accelerator status simultaneously and modularity of software and hardware for easily implemented for modification or expansion. The high speed network (SCRAMNet15MB/s), Ethernet, and front end processors (Digital Signal Processor) were employed for the high speed data taking and control. The system was designed to be standard modules and software implemented man machine interface. Due to graphical-user-interface and object-oriented-programming, the software development environment is effortless programming and maintenance.

Structure analysis of LBE spallation target for accelerator driven system in JAEA; Effects of pressure waves on the structural integrity of target vessel

Wan, T.; Kogawa, Hiroyuki; Iwamoto, Hiroki; Takei, Hayanori; Obayashi, Hironari; Sasa, Toshinobu; Naoe, Takashi; Futakawa, Masatoshi

no journal, , 

Japan Atomic Energy Agency (JAEA) has proposed an accelerator-driven system (ADS) for nuclear transmutation, which possesses a Lead-Bismuth Eutectic (LBE) target/coolant system with an LBE enclosure vessel. To solve basic technical issues related to the ADS design, the construction of Transmutation Experimental Facility (TEF) including the ADS Target Test Facility (TEF-T) has been proposed within the framework of Japan Proton Accelerator Research Complex (J-PARC) project. In the TEF-T, the LBE spallation target will be installed, and be bombarded by pulsed proton beams (400 MeV, 25 Hz, 0.5 ms in pulse duration). The target vessel suffers the static stress caused by design pressure and thermal stress due to heat deposition owing to the spallation reaction. To assess the structure integrity of target vessel, the pressure waves generated in LBE, which caused by rapid temperature rising due to the bombardment of pulsed proton beam, should be considered. On the basis of the results of neutronic and thermal-hydraulic analyses, the effects of pressure waves on the structural integrity of target vessel were studied through the dynamic analyses in the present study. The structural integrity of the LBE enclosure vessel for the TEF-T target was assessed.

Application of radiochromic dosimeter calibrated for Co-60 ray to 250 keV and 100 keV energy electron beam dosimetry

Takei, Taro*; Ishikawa, Masatoshi*; Seito, Hajime; Hanaya, Hiroaki; Haruyama, Yasuyuki; Kaneko, Hirohisa; Kojima, Takuji

no journal, , 

no abstracts in English

Spectral characteristics of asteroid (162173) Ryugu with Hayabusa2 NIRS3

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.