Carbon dating mathematical modelling

Research has been ongoing since the 1960s to determine what the proportion of in the atmosphere has been over the past fifty thousand years.

The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age.

The older a sample is, the less (the period of time after which half of a given sample will have decayed) is about 5,730 years, the oldest dates that can be reliably measured by this process date to around 50,000 years ago, although special preparation methods occasionally permit accurate analysis of older samples.

The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained.

In 1939, Martin Kamen and Samuel Ruben of the Radiation Laboratory at Berkeley began experiments to determine if any of the elements common in organic matter had isotopes with half-lives long enough to be of value in biomedical research.

For example, two samples taken from the tombs of two Egyptian kings, Zoser and Sneferu, independently dated to 2625 BC plus or minus 75 years, were dated by radiocarbon measurement to an average of 2800 BC plus or minus 250 years. Carbon dioxide produced in this way diffuses in the atmosphere, is dissolved in the ocean, and is taken up by plants via photosynthesis.

Archaeological Research Services Ltd in collaboration with English Heritage have been at the forefront of recent developments including the use of Bayesian probability modelling to date the internationally renowned Mesolithic house site at Howick.

ARS Ltd provides a complete radiocarbon dating service including assistance with sample selection, analysis, calibration and, if appropriate, Bayesian mathematical modelling.

When an organism dies, the amount of 12C present remains unchanged, but the 14C decays at a rate proportional to the amount present with a half-life of approximately 5700 years.

This change in the amount of 14C relative to the amount of 12C makes it possible to estimate the time at which the organism lived.

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