Technical note: Accelerator mass spectrometry of 10Be and 26Al at low nuclide concentrations
Technical note: Accelerator mass spectrometry of 10Be and 26Al at low nuclide concentrations
复制标题
技术资料：低核素浓度下 10Be 和 26Al 的加速器质谱分析
DOI：
--
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
K. Simon
中科院分区：
文献类型：
--
作者：
K. Wilcken;A. Codilean;R. Fülöp;Steven Kotevski;A. H. Rood;D. Rood;A. Seal;K. Simon
抽象的。加速器质谱仪(AMS)是目前测量宇宙起源的10Be和26Al浓度的标准技术，但测量低核素浓度的挑战是将高AMS测量效率与低本底相结合。目前的标准测量装置使用Ar剥离气体的3+电荷态，Be为6 mV，Al为4 mV，10Be3+和26Al3+通过加速器的离子传输分别约为35 %和40 %。传统上，26Al的测量不确定度比10Be的测量不确定度大。然而，我们在这里表明，如果测量时间足够长，即使对于26Al / 27Al比率在10−15范围内的样品，26Al也可以测量到与10Be类似的精度。例如，我们可以获得5 %的不确定度，26Al / 27Al比率在1 × 10−14附近，这对于晚全新世的样品或具有长期埋藏史的样品来说是典型的。我们还提供了同位素比率和可实现的测量精度之间的经验函数，使未来的项目具有预测能力，并作为实验室间比较的基准。对于最小的信号，不仅需要了解10Be或26Al背景事件的来源，以选择最合适的空白校正方法，而且数据简化算法对获得的核素浓度的影响也变得明显。在这里，我们讨论背景校正的方法，并推荐指导最合适的背景校正方法的质量保证实践。我们的灵敏度分析表明，对于26Al- -27Al比值低于10- / -14的样品，不同背景校正方法之间的差异为30-−%。最后，我们还表明，当测量信号较小且稀有同位素计数也较少时，如果使用其他数据简化算法，则可以从同一数据中获得不同的26Al或10Be浓度。如果只记录了很少的( 10)计数，得到的同位素浓度的差异可以是50 %或更多，或者如果单次测量小于10 分钟，则大约是30 %。我们的研究提出了一种分析宇宙成因的10Be和26Al样品的综合方法，其分析的同位素浓度为每克样品数千个原子，这为宇宙成因核素分析的新的和更多样化的应用打开了大门。
Abstract. Accelerator Mass Spectrometry (AMS) is currently the standard technique to measure cosmogenic 10Be and 26Al concentrations, but the challenge with measuring low nuclide concentrations is to combine high AMS measurement efficiency with low backgrounds. The current standard measurement setup at ANSTO uses the 3+ charge state with Ar stripper gas at 6 MV for Be and 4 MV for Al, achieving ion transmission through the accelerator for 10Be3+ and 26Al3+ of around 35 % and 40 %, respectively. Traditionally, 26Al measurement uncertainties are larger than those for 10Be. Here, however, we show that 26Al can be measured to similar precision as 10Be even for samples with 26Al / 27Al ratios in the range of 10−15, provided that measurement times are sufficiently long. For example, we can achieve uncertainties of 5 % for 26Al / 27Al ratios around 1 × 10−14, typical for samples of late-Holocene age or samples with long burial histories. We also provide empirical functions between the isotope ratio and achievable measurement precision, which allow predictive capabilities for future projects and serve as a benchmark for inter-laboratory comparisons. For the smallest signals, not only is understanding the source of 10Be or 26Al background events required to select the most appropriate blank correction method but also the impact of the data reduction algorithms on the obtained nuclide concentration becomes pronounced. Here we discuss approaches to background correction and recommend quality assurance practices that guide the most appropriate background correction method. Our sensitivity analysis demonstrates a 30 % difference between different background correction methods for samples with 26Al / 27Al ratios below 10−14. Finally, we show that when the measured signal is small and the number of rare isotope counts is also low, differing 26Al or 10Be concentrations may be obtained from the same data if alternate data reduction algorithms are used. Differences in the resulting isotope concentration can be 50 % or more if only very few ( 10) counts were recorded or about 30 % if single measurement is shorter than 10 min. Our study presents a comprehensive method for analysis of cosmogenic 10Be and 26Al samples down to isotope concentrations of few thousand atoms per gram of sample, which opens the door to new and more varied applications of cosmogenic nuclide analysis.
宇宙成因核素技术
DOI：
10.1038/s43586-022-00096-9
发表时间：
2022
期刊：
Nature reviews methods primers
影响因子：
--
作者：
Schaefer, J.M.;Codilean, A.T.;Willenbring, J.K.;Lu, Z.-T.;Keisling, B.;Fülöp, R.-H.;Val, P.
通讯作者：
Val, P.
影响因子：
4.5
作者：
D. Granger;M. Schaller
通讯作者：
D. Granger;M. Schaller