How is a radiocarbon age measured?
Watch a Video: Christine Prior, team leader of the Rafter Radiocarbon Laboratory, explains how radiocarbon dating is carried out.
To determine the radiocarbon age of an organic material it is necessary to measure the proportion of radiocarbon (14C) in the carbon that it contains.
1. Radiometric counting - in which the rate of radioactive decay of the 14C in the material is measured (it is also known as ‘conventional’ radiocarbon dating).
2. Accelerator Mass Spectrometry - in which a particle accelerator is used to directly count the relative numbers of the atoms of the different carbon isotopes present in the material.
Once the 14C content is known, it is compared to that of a standard material. The difference between the sample material and the standard is attributed to the time that has elapsed since the sample was "alive". For example, the radiocarbon age of a piece of wood gives the time since the wood was growing.