Calibrated dates should also identify any programs, such as OxCal, used to perform the calibration. By knowing how much carbon 14 is left in a sample, the age of the organism when it died can be known. The results from AMS testing are in the form of ratios of 12 C13 Cand 14 Cwhich are used to calculate Fm, the "fraction modern". Discovery of Radiocarbon Dating accessed October 31, More broadly, the success of radiocarbon dating stimulated interest in analytical and statistical approaches to archaeological data.
This provides a value for the background radiation, which must be subtracted from the measured activity of the sample being dated to get the activity attributable solely to that sample's 14 C.
How Does Carbon Dating Work
More recently, accelerator mass spectrometry has become the method of choice; it counts all the 14 C atoms in the sample and not just the few that happen to decay during the measurements; it can therefore be used with much smaller samples as small as individual plant seedsand gives results much more quickly. These measurements are used in the subsequent calculation of the age of the sample. There are two types of testing technology: AMS counts the quantity of 14 C in a sample rather than waiting for the isotope to decay; this also means greater accuracy readings for older dates. The sequence can be compared to the calibration curve and the best match to the sequence established.