研究者詳細 - 日高　洋

講演・口頭発表等 - 日高　洋

分割表示 43 件中 21 - 40 件目／全件表示 >>

月隕石の宇宙線照射履歴国際共著

日高　洋、西泉邦彦、米田成一

2019年度日本地球化学会第66回年会 2019年9月19日日本地球化学会

Cosmic-ray exposure records of lunar meteorites studied from spallogenic and neutron-captured products 国際共著国際会議

H. Hidaka, K. Nishiizumi, and S. Yoneda

Goldschmidt Conference 2019 2019年8月20日 Geochemical Society

Samarium isotopic compositions of lunar meteorites 国際共著国際会議

H. Hidaka, K. Nishiizumi, M. Caffee, and S. Yoneda

82nd Annual Meteoritical Society Meeting 2019年7月9日 The Meteoritical Society

REE isotopic studies for cosmochemistry: La isotopic variations by spallation reactions 招待有り国際会議

H. Hidaka

Japan India Forum for Advanced Study 2019 2019年3月10日 JSPS, DST

REE isotopic studies for cosmochemistry: Sm, Gd and Er isotopic variations by neutron capture reactions 招待有り国際会議

H. Hidaka

Japan India Forum for Advanced Study 2019 2019年3月14日 JSPS, DST

REE isotopic studies for cosmochemistry: A case study of La and Sm isotopes 国際会議

H. Hidaka

3rd Korea-Japan Joint Workshop on Isotope-Ratio Mass Spectrometry 2018年11月10日 The Mass Spectrometry Society of Japan, The Geological Society of Korea, KIGAM

自然界で生じる核反応がもたらす元素同位体変動に基づく宇宙・地球化学的研究招待有り

日高　洋

2018年度日本地球化学会第65回年会 2018年9月12日日本地球化学会

Neutron energy spectrum at the surface of the moon studied from the REE isotopic compositions 国際会議

H. Hidaka, Y. Mizutani, and S. Yoneda

Goldschmidt Conference 2018 2018年8月16日 Geochemical Society

Isotopic variations of Sm, Gd, Dy, Er and Yb induced from the neutron capture reactions on the Moon 国際会議

H. Hidaka and S. Yoneda

81st Annual Meteoritical Society Meeting 2018年7月26日 The Meteoritical Society

1980年代の地球化学の最前線研究を展開した研究室の一例招待有り

日高　洋

日本地球惑星科学連合2018年大会 2018年5月20日日本地球惑星科学連合

La-Ce chronometry of eucrites and diogenites 国際共著国際会議

H. Hidaka, S. Yoneda, and S.-G. Lee

49th Lunar and Planetary Science Conference 2018 2018年3月19日 Lunar and Planetary Institute, NASA

Cosmic-ray exposure histories of eucrites studied from Sm and Gd isotopic compositions 国際会議

Hiroshi Hidaka, Shigekazu Yoneda

8th Symposium on Polar Science

開催年月日： 2017年12月

記述言語：英語会議種別：口頭発表（一般）

開催地：Tachikawa, Tokyo 国名：日本国

Previous studies of cosmic-ray exposure (CRE) ages for HED meteorites show the existence of two major clusters of the CRE ages around 20-25 Ma and 35-42 Ma and of other three minor clusters around 6-7 Ma, 10-12 Ma, and 14 Ma (Eugster and Michel, 1995; Welten et al., 1997). Our concern is whether the Sm and Gd isotopic shifts of eucrites also show the consistent trend with the CRE age clusters. 149Sm and 157Gd have very large thermal neutron capture cross sections, and change thier isotopic abundances by 149Sm(n,γ)150Sm and 157Gd(n,γ)158Gd reactions, respectively, induced from cosmic-ray irradiation. Providing that the CRE information from the Sm and Gd isotopic shifts are different from the 81Kr-Kr data, there is a possibility that the inconsistency of the CRE information occurred by the pre-irradiation on the eucritic parent body. In this study, eight basaltic eucrites were used.

Isotopic characterization for nuclear reactions in the Oklo natural reactors 国際会議

Hiroshi Hidaka, Salahendric Bentridi, Benoit Gall, N. Amrani

International Conference on Radiations and Applications

開催年月日： 2017年11月

記述言語：英語会議種別：口頭発表（招待・特別）

開催地：Houari Boumediene University of Science and Technology 国名：アルジェリア民主人民共和国

The Oklo uranium ore in the Francevillian basin at the east part of the Republic of Gabon is known as a fossil of natural fission reactors, because large-scaled fission chain reactions spontaneously occurred in the ore two billion years ago. It is of major concern to characterize the properties of nuclear reactors and to investigate the behavior of fission products in and around the Oklo natural reactors. In this review, geological and physico-chemical characteristics of the Oklo natural fission reactor and its implication for radioactive waste disposal are shown.

Redistribution behavior of REE into constituent minerals of eucrites and its implication for the genesis 招待有り国際会議

Hiroshi Hidaka, Tsuyoshi Ohnishi

2nd Korea-Japan Joint SHRIMP Workshop

開催年月日： 2017年10月

記述言語：英語会議種別：口頭発表（招待・特別）

開催地：KBSI Ochang Center 国名：大韓民国

As a simple model, most eucrites are interpreted as primary partial melt products from primitive, metal-free, chondritic material (Stolper, 1977). However, assuming a simple differentiation of two components, eucrite and diogenite, originated from chondritic materials, it is difficult to explain the mass balance of REE among eucrites, diogenites and chondrites, because the chondritic REE pattern cannot be reconstructed only from the mixing of REE components from eucrites and diogenites. As a result of REE measurements of whole rock analysis, most of basaltic eucrites show flatter REE patterns with negative or positive Eu anomaly, and their REE contents are 8-10 times higher than those in chondrites. On the other hand, diogenites generally have significant depletion of lighter REE in the patterns. In this study, REE abundances were measured in single minerals of eucrites in order to study REE distribution behavior in eucritic materials in association with gechemical differentiation from chondritic materials.

REE isotopic study for cosmochemistry: A case study of La and Sm isotopes 招待有り国際会議

Hiroshi Hidaka

5th International Conference on Analytical Science & Technology

開催年月日： 2017年10月

記述言語：英語会議種別：口頭発表（招待・特別）

開催地：KBSI Ochang Center 国名：大韓民国

The data of a series of the elemental abundances of rare earth elements (REE) in planetary materials (REE abundance pattern) have been widely used to understand the geochemical evolution processes of the materials since the pioneering work, because REE have several similarities of physicochemical properties due to their electron configurations of the atomic structures. Furthermore, isotopic compositions of some REE are variable, because they include radiogenic components derived from 138La-138Ce, 146Sm-142Nd, and 147Sm-143Nd decay systems and nucleogenic components like neutron captured products by 149Sm(n,γ)150Sm and 157Gd(n,γ)158Gd due to cosmic-ray irradiation. Here in this talk, I would like to introduce my recent work on La and Sm isotopic study and its application as one of examples for the REE isotopic studies in cosmochemical fields.

太陽宇宙線初期照射説のの同位体化学的検証：Allende隕石のCAI中のLa同位体比測定

日高洋、米田成一

2017年度日本地球化学会第64回年会

開催年月日： 2017年9月

記述言語：日本語会議種別：口頭発表（一般）

開催地：東京工業大学、東京国名：日本国

核破砕反応によって生成される138La を太陽宇宙線初期照射履歴のためのプロキシとする試みがなされているが、その精密同位体測定例は少ない。本研究では、Allende 隕石から採取した2つのCAI粒子を酸分解し、所定のイオン交換法によりLaを化学分離し、表面電離型質量分析計により、その精密同位体測定を行った。

Isotopic evidence for intensive activity of young Sun from REE isotopic compositions in CAIs 国際会議

Hiroshi Hidaka, Shigekazu Yoneda

Goldschidt Conference 2017

開催年月日： 2017年8月

記述言語：英語会議種別：口頭発表（一般）

国名：フランス共和国

Isotopic measurements of excess 10B decayed from 10Be in CAIs and astronomical observations of intensive X-ray emissions from stellar analogues of the young Sun suggest a possibility of intensive irradiation by the young Sun. However, the model for early solar irradiation from young Sun is somehow model-depending and still plausible. For further quantitative discussion about the early solar irradiation models, 138La is one of adequate isotopic tracers as one of refractory and spallogenic products caused by solar irradiation. The presence of excess 138La as a spallogenic product may provide isotopic constraints on the early solar irradiation models. In this study, isotopic analyses mainly of La and other REE like Ce, Nd, and Sm in CAIs collected from the Allende CV3 meteorite were performed to understand the spallogenic reactions in the early solar system.

Systematic REE isotopic studies of eucrites 国際会議

Hiroshi Hidaka, Shigekazu Yoneda

80th Annual Meeting of the Meteoritical Society

開催年月日： 2017年7月

記述言語：英語会議種別：口頭発表（一般）

開催地：Santa Fe, New Mexico 国名：アメリカ合衆国

Most eucrites have basaltic composition and several of them represent lavas or shallow intrusions from a differen-tiated parent body, possibly asteroid 4 Vesta. Many isotopic studies have been conducted using long- and short lived geochronometers to understand accretion, core formation, mantle differentiation, and the formation of prima-ry basalts on the eucritic parent body (EPB). In our previous study, Sr and Ba isotopic analyses were applied mainly for chronometric purposes of eight basaltic eucrites, but Rb-Sr and Cs-Ba decay systems did not provide any chronological information because of the significant contamination of terrestrial Sr and Ba found in five DaG de-sert eucrites. In this study, Ce, Nd, Sm and Gd isotopic compositions of the eight eucrites were further deter-mined for better understanding of differentiation on the parent body.

REE isotopic study for cosmochemistry: A case study of La isotopes 招待有り国際会議

Hiroshi Hidaka

KIGAM seminar

開催年月日： 2017年6月

記述言語：英語会議種別：口頭発表（招待・特別）

開催地：Daejeon, Korea 国名：大韓民国

The data of a series of REE elemental abundances in planetary materials (REE abundance pattern) have been widely used to understand the geochemical evolution processes of the materials since the proposal of pioneering work by Masuda and Matsui (1966), because REE have several similarities of physicochemical properties due to their electron configurations of the atomic structures. Furthermore, isotopic compositions of some REE are variable, because they include radiogenic components derived from 138La-138Ce, 146Sm-142Nd, and 147Sm-143Nd decay systems and nucleogenic components like neutron captured products by 149Sm(n,γ)150Sm and 157Gd(n,γ)158Gd due to cosmic-ray irradiation. In particular, the isotopic variations of REE provide chronological and astrophysical information for cosmochemistry. Here in this talk, I would like to introduce my recent work on La isotopic study and its application as one of examples for the REE isotopic studies in cosmochemical fields.

地球上での汚染が認められる砂漠産ユークライト隕石のRb-Sr壊変系

日高　洋、世羅浩平、米田成一

2016年度日本地球化学会第64回年会 2016年9月15日日本地球化学会

　前のページ - 次のページ　

<日高 洋>

講演・口頭発表等 - 日高 洋

<日高　洋>

講演・口頭発表等 - 日高　洋