engleski

Rudjer Bošković Institute radiocarbon measurements XV

We present dating of archaeological samples performed in the Radiocarbon Laboratory of the Rudjer Bošković Institute since 1995. Several samples from period before 1995, which were not included in our previous data lists, are given too. Sample preparation, proportional counter technique and processing of data are essentially the same as reported earlier (Srdoč et al. 1971, 1979 ; Obelić 1989). The quality assurance and quality control system according to ISO 17025 has been improved within the IAEA TC Regional Project on Quality Control and Quality Assurance for Nuclear Analytical Techniques. The Laboratory participated in radiocarbon intercomparison studies (Horvatinčić et al. 1990 ; Krajcar Bronić et al. 1995 ; Bryant et al. 2001, Radiocarbon 2001). We use Oxalic Acid I as modern standard, and anthracite and marble as background standards. Age calculations follow the conventional protocol (Mook and van der Plicht 1999) based on Libby half-life of 5570 ? 30 yr and using AD 1950 as the reference year. Ages and standard deviations (1s error) of samples are adjusted for stable isotope fractionation to normalized concentration ratio (d13C = -25?) according to recommendations in Stuiver and Polach (1977) and using the default d13C values. Calibrated ages are calculated from non-rounded 14C conventional ages by using the program OxCal v.3.0 (Bronk Ramsey 1995, 1998) with 1s error (confidence level 68.2%). When several calendar age ranges are obtained, probability for each interval is given. Probabilities less then 5% are omitted. In reports both the conventional 14C ages and the calibrated range intervals are rounded.

14C dating; archaeology; Croatia

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