Scientific instrument used for carbon dating
The science of dendrochronology is based on the phenomenon that trees usually grow by the addition of rings, hence the name tree-ring dating.Dendrochronologists date events and variations in environments in the past by analyzing and comparing growth ring patterns of trees and aged wood.In later years, the use of accelerator mass spectrometers and the introduction of high-precision carbon dating have also generated calibration curves.A high-precision radiocarbon calibration curve published by a laboratory in Belfast, Northern Ireland, used dendrochronology data based on the Irish oak.Radiocarbon measurements are based on the assumption that atmospheric carbon-14 concentration has remained constant as it was in 1950 and that the half-life of carbon-14 is 5568 years.
Age ranges are calculated either by the intercept method or the probability method, both of which need a calibration curve.Libraries of tree rings of different calendar ages are now available to provide records extending back over the last 11,000 years.The trees often used as references are the bristlecone pine (Pinus aristata) found in the USA and waterlogged Oak (Quercus sp.) in Ireland and Germany.Nowadays, the internationally agreed upon calendar calibration curves reach as far back as about 48000 BC (Reimer et.
al., INTCAL13 and Marine13 radiocarbon age calibration curves 0 – 50000 yrs cal BP, Radiocarbon 55(4), 2013).
It is also called “radiocarbon” because it is unstable and radioactive relative to carbon-12 and carbon-13.