Technical note: Accelerator mass spectrometry of ¹⁰Be and ²⁶Al at low nuclide concentrations

Abstract 10 Be and 26 Al 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 10 Be3 + 26 Al3 + 26 Al measurement uncertainties are larger than those for 10 Be. Here, however, we show that 26 Al can be measured to similar precision as 10 Be even for samples with 26 Al /27 Al ratios in the range of 10 - 15, provided that measurement times are sufficiently long. For example, we can achieve uncertainties of 5 % for 26 Al /27 Al 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 10 Be or 26 Al 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 26 Al /27 Al 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 26 Al or 10 Be 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 (≲ min. Our study presents a comprehensive method for analysis of cosmogenic 10 Be and 26 Al samples down to isotope concentrations of a few thousand atoms per gram of sample, which opens the door to new and more varied applications of cosmogenic nuclide analysis.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Technical note: Accelerator mass spectrometry of ¹⁰Be and ²⁶Al at low nuclide concentrations ; volume:4 ; number:1 ; year:2022 ; pages:339-352 ; extent:14 ; Geochronology ; 4, Heft 1 (2022), 339-352 (gesamt 14)

Contributors, Places and Time

• Creator: Wilcken, Klaus M. ; Codilean, Alexandru T. ; Fülöp, Réka-H. ; Kotevski, Steven ; Rood, Anna H. ; Rood, Dylan H. ; Seal, Alexander J. ; Simon, Krista

Further information

• DOI: 10.5194/gchron-4-339-2022
• URN: urn:nbn:de:101:1-2022060905144357129587
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 15.08.2025, 7:32 AM CEST