日本質量分析学会 第69回質量分析総合討論会会

演題概要

オーラルセッション

第2日 5月20日(木) 11:40~12:00 C会場(Zoom)

超低ブランク希ガス質量分析装置を用いた微量希ガス同位体分析

(1北大院理2九大院理)
o馬上謙一1岡崎隆司2

Noble gas analysis for returned samples by Sample return missions have been investigated to understand formation/metamorphism age, cosmic-ray exposure age, and surface environment of parent bodies. Noble gas initial analysis for Hayabusa mission revealed space weathering process on the Itokawa surface. Returned sample from Hayabusa 2 mission also reveals surface property on the Ryugu, 1999 JU3. Noble gas analysis for returned samples requires high sensitivity and low blank measurement because of their limited materials. We demonstrate ultra-low blank analysis for Ca-Al-rich inclusion (CAI) from Allende meteorite using modified MM-5400 in Kyushu University. The blank level of this measurement was ~2 × 10-13 cm3STP (9 × 10-18 mol). The CAI preserved radiogenic 22Ne from 22Na because we observed clearly excess of 22Ne from the CAI. Sodium-22 would be produced by spallation with solar cosmic-ray and disk gas at the early solar system. The radioactive 22Na and stable 23Na were incorporated into the CAI melilite at the CAI formation.