Rafter radiocarbon sample preparation and data flow: Accommodating enhanced throughput and precision

Abstract

New Zealand’s National Isotope Centre, including the Rafter Radiocarbon Laboratory, has upgraded its AMS system from a 6 MV EN-Tandem AMS to a new generation 0.5 MV NEC Extended Compact AMS (XCAMS) system. Current precisions represent approximately an order of magnitude improvement during the AMS era – from 1–2% more than 20years ago to ∼0.2% today. The year since 14C operations were shifted from the EN-Tandem to XCAMS has seen a 40% increase in 14C measurements without reaching full capacity of the new AMS system. Increased throughput and precision require improvements to systems used for the preparation of samples and reporting of results. Our approaches to these challenges are outlined here. They include the development of an automated combustion and CO2 collection system, and consideration of sources of error or bias including calibration and background correction. Monitoring for any observable changes in reported values associated with the transfer from the EN-Tandem to XCAMS has also been a high priority, and no issues with the continuity of AMS results have been identified.