Conversion of the LLNL/CAMS 1 MV biomedical AMS system to a semi-automated natural abundance 14C spectrometer: system optimization and performance evaluation

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2021-07, Vol.499 (C), p.124-132
• Main Authors: Broek, Taylor A.B., Ognibene, Ted J., McFarlane, Karis J., Moreland, Kimber C., Brown, Thomas A., Bench, Graham
• Format: Article
• Language: English
• Subjects: Accelerator Mass Spectrometry; Compact AMS; Natural Abundance 14C; Radiocarbon
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2021.01.022

The Lawrence Livermore National Laboratory – Center for Accelerator Mass Spectrometry compact 1 MV biomedical accelerator mass spectrometer was repurposed and optimized for the semi-automated radiocarbon measurement of natural abundance environmental samples. Here we present results from 15 months of routine system operation and evaluate the system performance based on 30 sample wheels measured with consistent operating conditions over 7 months from August 2019 to March 2020. The average measurement precision was 2.7 ± 0.7‰. System accuracy was assessed with measurements of 14C-free materials, standard materials with 14C-content spanning 0.5 to 1.5 F14C, and by comparison to split samples measured with the 10 MV AMS system. Overall, this system can routinely measure samples as small as 300 µgC and less than 33000 years without the need for size-specific correction protocols.