Another 6 years of radiocarbon secondary-standard AMS with two spectrometers

The Scottish Universities Environmental Research Centre (SUERC) has analysed >100,000 individual graphite preparations with two accelerator mass spectrometers. Analysis quality is maintained by a programme of secondary-standards measurement, and annual assessment of the resulting large dataset can provide insight into subtle effects. The same analyses that are used to derive external errors within individual batches of samples, or to monitor inter-batch variance, are also employed in aggregate to determine overall instrument and process performance. The recent 2021 findings are consistent with prior years’, including the apparent contradiction that secondary standard analysis can be both consistent and slightly discordant between the two instruments. However, individual sample radiocarbon measurement on both machines remains accurate and typically 3 ‰ precise.