10Be at iThemba LABS using a silicon nitride membrane stack as absorber for isobar suppression

10Be is an important isotope for accelerator mass spectrometry (AMS) because of the demand for cosmogenic radionuclide dating methods in the earth science and paleo-sciences community. At the iThemba Laboratory for Accelerator Based Science (iThemba LABS) we implemented full suppression of the interfering isobar 10B using a silicon nitride foil-stack, utilizing the 2+ charge state for high efficiency. We demonstrate the performance of this newly established AMS system using standards and test samples. We further present the results of an intercomparison between iThemba LABS and the Center for Accelerator Mass Spectrometry/Lawrence Livermore National Laboratory, on AMS samples prepared from purified quartz at the University of Vermont. The results for 10Be from the laboratories are in close agreement, fully consistent with cross-calibration between them. AMS results for 26Al are in similarly good agreement, demonstrating the performance and accuracy of iThemba LABS for the most commonly measured in situ produced cosmogenic nuclides.

Automated summary

This study demonstrates the implementation of full suppression of the interfering isobar 10B using a silicon nitride foil-stack for high efficiency AMS. The performance and accuracy of the AMS system at iThemba LABS are demonstrated through standards and intercomparison with another laboratory. The results show good agreement for 10Be, indicating the reliability of iThemba LABS in measuring cosmogenic nuclides.