Space weathering acts strongly on the uppermost surface of Ryugu

Matsuoka, Moe*; Kagawa, Eiichi*; Amano, Kana*; Nakamura, Tomoki*; Tatsumi, Eri*; Osawa, Takahito; 51 of others*

Communications Earth & Environment (Internet), 4, p.335_1 - 335_12, 2023/09

https://doi.org/10.1038/s43247-023-00991-3

Visible and near-infrared (Vis-NIR) spectra of returned samples from Cb-type asteroid (162173) Ryugu exhibit very low reflectance values and absorptions that are generally consistent with observations from the Hayabusa2 ONC-T and NIRS3 instruments. A notable difference is that a metal-OH absorption at 2.72 misrometer is more than twice as deep in laboratory sample spectra compared with those of Ryugu's surface. Based on the laboratory experiments to investigate the range of spectral variation by physical properties and space weathering, we conclude that the spectral differences between returned samples and asteroid surface are best explained by a combination of (1) porosity, (2) particle size, and (3) degree of space weathering effects, with the latter being the most effective. Those effects can explain spectral variations between Cb-type asteroids, suggesting that these asteroids consist of the same CI-chondrite material with different physical properties and weathering degrees. Extremely homogeneous Vis-NIR spectra of the entire Ryugu surface in comparison with the heterogeneous spectra of a near-Earth S-type asteroid (25143) Itokawa indicate that the space weathering has been processing more rapidly on Cb-type asteroids compared with S-type asteroids. Because the major component of Cb-type asteroids are porous hydrous silicates that have lower melting temperature and lower material strength than anhydrous silicates, the surface of Cb-type asteroids are more susceptible to the alteration by impacts of interplanetary dust particles.

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

https://doi.org/10.7566/JPSJ.87.014201

Excitation functions of quasielastic scattering cross sections for the Ca + Pb, Ti + Pb, and Ca + Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Density, porosity and grain size, 2; Irradiated ROX fuels to burn-up of 28%FIMA

Yanagisawa, Kazuaki; Yamashita, Toshiyuki; Kanazawa, Hiroyuki; Amano, Hidetoshi; Muromura, Tadasumi

Journal of Nuclear Science and Technology, 36(12), p.1153 - 1159, 1999/12

https://doi.org/10.3327/jnst.36.1153

no abstracts in English

Present status of PIEs in the department of hot laboratories

Kodaira, Tsuneo; Sukegawa, T.; Amano, Hidetoshi; Kanaitsuka, Fumio;

JAERI-Conf 99-009, p.20 - 31, 1999/09

https://jopss.jaea.go.jp/pdfdata/JAERI-Conf-99-009.pdf

no abstracts in English

Current status of PIE techniques in RFEF

Kodaira, Tsuneo; Yamahara, Takeshi; Sukegawa, T.; Nishino, Yasuharu; Kanazawa, Hiroyuki; Amano, Hidetoshi; Nakata, Masahito

HPR-349, 11 Pages, 1998/00

no abstracts in English

Thermal durability of modified synroc material as reactor fuel matrix

; Kanazawa, Hiroyuki; Togashi, Yoshihiro; ; Nishino, Yasuharu; ; Nakata, Masahito; Amano, Hidetoshi;

JAERI-Research 94-008, 20 Pages, 1994/08

JAERI-Research-94-008.pdf:1.8MB

no abstracts in English

The States of shallow NV centers with surface termination

Kato, Kanami*; Yamano, Hayate*; Kageura, Taisuke*; Seshimo, Yuji*; Inaba, Masafumi*; Higashimata, Itaru*; Koike, Godai*; Tanii, Takashi*; Isoya, Junichi*; Teraji, Tokuyuki*; et al.

no journal, , 

no abstracts in English

Study on reflection of operating experience of Prototype Fast Breeder Reactor Monju fuel handling system to the next generation FBR

Rekimoto, Masafumi; Ando, Masato; Chikazawa, Yoshitaka; Kato, Atsushi; Hamano, Tomoharu; Shiohama, Yasutaka; Miyagawa, Takayuki*; Uzawa, Masayuki*; Hara, Hiroyuki*; Yamauchi, Kanau*; et al.

no journal, , 

no abstracts in English

Development of transient behavior analysis code for metal fuel fast reactor during initiating phase of core disruptive accident, 2; Implementation of advanced analysis models on fuel extrusion and cladding corrosion

Ota, Hirokazu*; Ogata, Takanari*; Kusumi, Koji*; Yamano, Hidemasa; Futagami, Satoshi; Shimada, Sadae*; Yamada, Yumi*

no journal, , 

no abstracts in English

Advancement of detailed core bowing analysis code for fast reactor, 4; Overall plan for thermal bowing experiments of simulated subassemblies

Ota, Hirokazu*; Ogata, Takanari*; Kusumi, Koji*; Ohgama, Kazuya; Yamano, Hidemasa; Futagami, Satoshi; Nakagawa, Naoki*; Kawabata, Ryo*; Gima, Hiromichi*; Matsubara, Shinichiro*

no journal, , 

no abstracts in English

Molecular characterization of reactive deep underground dissolved organic matters for metal ion using high-resolution mass spectrometry

Sato, Hayato*; Toda, Kanako*; Beppu, Hikari*; Amano, Yuki; Miyakawa, Kazuya; Saito, Takumi*

no journal, , 

no abstracts in English