T02_04

GIRI-results from the global intercomparison

Scott M¹,  Naysmith P², Cook G²

¹University Of Glasgow, Glasgow, United Kingdom, ²SUERC, East Kilbride, United Kingdom

GIRI (Glasgow International Radiocarbon Intercomparison) was designed to meet a number of objectives, including the most fundamental one, to provide an independent assessment of the analytical quality of the laboratory/measurement and an opportunity for a laboratory to participate and improve (if needed). The principles that we followed in the design of GIRI were to provide. A) A series of unrelated individual samples, spanning the dating age range, B) Some linked samples to earlier inter-comparisons to allow traceability, C) Some known age samples, to allow independent accuracy checks, D) A small number of duplicates, to allow independent estimation of laboratory uncertainty and E) Two categories of samples - bulk and individual, to support laboratory investigation of variability. All of the GIRI samples are natural (wood, peat and grain), some are known age, and overall their age spans approx. >40,000 years BP to modern.  The complete list of sample materials includes: humic acid, whalebone, grain, a number of single ring dendro-dated samples, a number of dendro-dated wood samples spanning a number of rings (e.g. 10 rings), background and near background samples of bone and wood, as well some samples connect to previous inter-comparisons allowing traceability of results. We present an overview of the results received and preliminary consensus values for the samples supporting a more in-depth evaluation of laboratory performance and variability.