グリーンランドの氷に含まれるアルミニウム26とベリリウム10
まとめ
宇宙線はベリリウム10とアルミニウム26の同位体を生成し,古代のグリーンランドの氷の中に見つかる. 氷の中の彼らの測定された生産率は,大気中の宇宙線生産と一致しており,最小限の宇宙塵の貢献を示唆しています.
科学分野:
- 地質化学 地質化学
- 宇宙化学 (コスモケミストリー)
- 核物理学 核物理学とは
背景:
- ベリリウム-10 (Be-10) とアルミニウム-26 (Al-26) は宇宙生成の同位体である.
- 氷核は,過去の大気および地球外物質の堆積を研究するための貴重なアーカイブを提供します.
研究 の 目的:
- 古代グリーンランド氷河におけるBe-10とAl-26の濃度を測定し,生産率を計算する.
- これらの速度を,宇宙線からの既知の大気生成速度と比較する.
- これらの同位体の氷の存在に対する地球外塵の貢献を推定する.
主な方法:
- 200年前のグリーンランド氷の溶けたBe-10とAl-26の活動分析.
- 測定された活動と氷の降水率を使用して,同位体生産率の計算.
- 地球外塵の流入に対する上限値の推定.
主要な成果:
- 溶解したBe-10活性:18.4 (+8.4, -4.8) x 10^-6 dpm/L.
- 溶解したAl-26活性:3.2 +/- 0.9 x 10^-7 dpm/L.
- 計算された生産率は,大気中の宇宙線生産と一致しています.
- Al-26による宇宙塵の流入の上限: 3.2 x 10^5トン/年.
結論:
- 宇宙線による大気生成は,研究されたグリーンランド氷のBe-10とAl-26の主な供給源である.
- 地球外塵の寄与は,アル-26. Alの最小限の可能性が高い.
- 微粒子のBe-10とAl-26の上限値は,主な結論を変更しません.
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