Radiocarbon Dating

The age of a carbon-containing material can be determined by measuring the C-14 (radiocarbon) activity in a sample relative to a known standard, and calculating the time since it was last living and in equilibrium with its carbon source. The age of a sample of wood, for example, can be determined by using C-14 activity to measure the time since it last acquired carbon dioxide through photosynthesis.

Two methods for radiocarbon dating are available at the CAIS: Low-Level Liquid Scintillation Counting (LSC) and Accelerator Mass Spectrometry (AMS). Using LSC, the age of a sample is determined by measuring the amount of radioactive decay in the sample. Using AMS, the age is determined by directly counting the carbon atoms in the sample. More »

The types of materials that can be age-dated using C-14 include wood, charcoal, bone, leather, shell, seeds, sediments and soils, water, pollen, hair, pottery, blood residues, textiles and fabrics, paper and parchment, antlers or horns, and insect remains.

The C-14 activity in certain sample materials must be corrected for isotopic fractionation, the process by which the isotopes of a given element react at different rates based on variations in size and mass, and over time yield products that are isotopically heavier or lighter than their precursor materials. The result is a sample date that can appear to be older or younger than it actually is, requiring a correction factor. The amount of fractionation can be determined by stable isotope ratio analysis to measure the relative abundance of C-13 and C-12 in the sample.

For further information contact Dr. Doug Dvoracek (706) 542-6136 or
Dr. Alex Cherkinsky (706) 542-6111

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