Radiocarbon dating may only be used on organic materials.Typically (6): The above list is not exhaustive; most organic material is suitable so long as it is of sufficient age and has not mineralised - dinosaur bones are out as they no longer have any carbon left.AMS works slightly differently; it converts the atoms of the sample into fast-moving ions so that they become charged atoms.
Radiocarbon dating is simply a measure of the level of C isotopes in the atmosphere can vary.
This is why calibration against objects whose age is known is required (14).
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).
It also has some applications in geology; its importance in dating organic materials cannot be underestimated enough.
In 1979, Desmond Clark said of the method “we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation” (3).
It is presumed that the proportion of atmospheric C is the same today as it was in 1950 (10), (11) and that the half-life remains the same.
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.
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.
Archaeologists had used Relative Dating methods to calculate their reigns.