Dunham Emilie T, Wadhwa Meenakshi, Desch Steven J, Hervig Richard L
School of Earth and Space Exploration, Arizona State University, 781 Terrace Mall, Tempe, AZ, 85287, USA.
Geostand Geoanal Res. 2020 Dec;44(4):695-710. Epub 2020 Apr 23.
Beryllium-10 ( = 1.4 Ma) is a short-lived radionuclide present in the early Solar System. It is produced solely by irradiation reactions and can provide constraints on the astrophysical environment of the Sun's formation. Calcium- and aluminium-rich inclusions (CAIs), the first solids formed in the Solar System, show clear evidence for live Be at their time of formation, but it is unclear whether they record the same initial Be/Be ratio. In this study, we examine the secondary ion mass spectrometry methods used to determine the initial Be/Be ratio in meteoritic inclusions. Based on analyses of synthesised matrix-matched glass reference materials, we show that the effects of differing major element bulk compositions on the secondary ion yields of Be and B are minor for relevant phases. We demonstrate the importance of using the mean square weighted deviation (MSWD) to interpret the significance of the initial Be/Be value. For thirty-two CAIs, we re-calculated the regressions using literature data, finding that several have unacceptably high MSWD. We calculate the effects of possible sources of isotopic disturbance. Finally, we outline best practices for reporting Be-B data, to enable a more refined determination of the initial Be/Be ratio in the early Solar System.
铍 - 10（半衰期 = 1.4 百万年）是早期太阳系中存在的一种短寿命放射性核素。它仅由辐照反应产生，可对太阳形成时的天体物理环境提供限制。富含钙和铝的包体（CAIs）是太阳系中形成的第一批固体，有明确证据表明它们在形成时存在活铍，但尚不清楚它们是否记录了相同的初始铍/铍比值。在本研究中，我们研究了用于测定陨石包体中初始铍/铍比值的二次离子质谱方法。基于对合成的基体匹配玻璃参考材料的分析，我们表明，对于相关相而言，不同主要元素总体组成对铍和硼二次离子产率的影响较小。我们证明了使用均方加权偏差（MSWD）来解释初始铍/铍值显著性的重要性。对于 32 个 CAIs，我们使用文献数据重新计算了回归，发现其中几个的 MSWD 高得令人无法接受。我们计算了可能的同位素干扰源的影响。最后，我们概述了报告铍 - 硼数据的最佳做法，以便更精确地确定早期太阳系中的初始铍/铍比值。
