New results for single stage low energy carbon AMS

A new configuration of the NEC single stage, low energy carbon AMS system (U.S. Patent 6,815,666 B2) has been built and tested. The injector includes two 40-sample ion sources, electrostatic and magnetic analysis, and fast sequential injection. The gas stripper, analyzing magnet, electrostatic analyzer, and detector are on an open air 250 kV deck. Both 12C and 13C currents are measured on the deck after the stripper, and an SSB detector is used for 14C counting. Injected 12C and mass 13 (13C and 12CH) currents are also measured. Automated controls follow a user-specified run list for unattended operation. Initial test results show precision for 14C/12C ratios of better than 5 per mil, and backgrounds for unprocessed graphite of less than 0.005 × modern. We will report final results for precision, background, and throughput and discuss related design features.