@article {broek_optimization_2022,
	title = {Optimization of the LLNL/CAMS gas-accepting ion source and 1 MV compact AMS for natural abundance radiocarbon analysis of CO2},
	journal = {Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms},
	volume = {530},
	year = {2022},
	month = {11/2022},
	pages = {1{\textendash}7},
	abstract = {The Lawrence Livermore National Laboratory {\textendash} Center for Accelerator Mass Spectrometry (LLNL/CAMS) 1 MV AMS system was converted from a biomedical AMS instrument to a natural abundance 14C spectrometer. The system is equipped with a gas-accepting hybrid ion source capable of measuring both solid (graphite) and gaseous (CO2) samples. Here we describe a series of experiments intended to establish and optimize 14CO2 measurement capabilities at natural abundance levels. A maximum instantaneous ionization efficiency of 8~\% was achieved with 3~\% CO2 in helium at a flow rate of approximately 220~{\textmu}L/min (3.5~{\textmu}g C/min). For modern materials (e.g., OX I) we measured an average of 240~{\textpm}~50 14C counts/{\textmu}g C, equivalent to a total system efficiency of approximately 3~\%. Experimental CO2 samples with F14C values ranging from 0.20 to 1.05 measured as both graphite and directly as CO2 gas produced equivalent values with an average offset of~<~2σ.},
	keywords = {Accelerator mass spectrometry, CO, Gas-accepting ion source, radiocarbon},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2022.08.012},
	url = {https://www.sciencedirect.com/science/article/pii/S0168583X22002178},
	author = {Broek, Taylor A. B. and Moreland, Kimber C. and Ognibene, Ted J. and McFarlane, Karis J. and Brown, Thomas A.}
}
