Radio carbon dating half life
This does not mean that we have a precise year of 3780BC, it means we then need to calibrate through other methods that will show us how atmospheric concentrations of the C isotope has changed - most typically through the dendrochronology records (tree ring data) (10).
Very old trees such as North American Bristlecone Pine are ideal for constructing long and accurate records of the state of the atmosphere.
This allows researchers to account for variation by comparing the known records of C levels in the tree record, looking for a tree record that has the same proportion of radiocarbon.
The overlapping nature of the tree records means this is the most accurate record we have.
The other two isotopes in comparison are more common than carbon-14 in the atmosphere but increase with the burning of fossil fuels making them less reliable for study (2); carbon-14 also increases, but its relative rarity means its increase is negligible. After this point, other Absolute Dating methods may be used.
Today, the radiocarbon-14 dating method is used extensively in environmental sciences and in human sciences such as archaeology and anthropology.
AMS works slightly differently; it converts the atoms of the sample into fast-moving ions so that they become charged atoms.
By applying magnetic and electrical fields, the mass of these ions is measured and the accelerator is used to remove ions that might contaminate the dating.
If a radioactivity level comes back as half of what would have been expected if the organism had died in 1950, then it is presumed to be 5,730 years before 1950.The sample passes through several accelerators in order to remove as many atoms as possible until the C pass into the detector.These latter atoms are used as part of the calibration process to measure the relative number of isotopes (9).Typically, a Master's Degree in chemistry is required because of the extensive lab work.Increasingly though, students are learning about the principles of radiocarbon dates in archaeology, palaeontology and climate science degrees and can combine cross-disciplinary studies.