Researchers have studied other radioactive isotopes created by cosmic rays to determine if they could also be used to assist in dating objects of archaeological interest; such isotopes include 3 He10 Be21 Ne26 Aland 36 Cl. The counters work by detecting flashes of light caused by the beta particles emitted by 14 C as they interact with a fluorescing agent added to the benzene. Radiocarbon ages are still calculated using this half-life, and are known as "Conventional Radiocarbon Age". These factors affect all trees in an area, so examining tree-ring sequences from old wood allows the identification of overlapping sequences. A calibration curve is used by taking the radiocarbon date reported by a laboratory, and reading across from that date on the vertical axis of the graph.
This cylinder was inserted into the counter in such a way that the counting wire was inside the sample cylinder, in order that there should be no material between the sample and the wire.
Carbon Dating System
For the same reason, 14 C concentrations in the neighbourhood of large cities are lower than the atmospheric average. Manipulating samples Every time a sample is manipulated, it is absolutely important to keep it from getting contaminated. Memoirs of the Society for American Archaeology 8: Considerations And Conventions". These counters record bursts of ionization caused by the beta particles emitted by the decaying 14 C atoms; the bursts are proportional to the energy of the particle, so other sources of ionization, such as background radiation, can be identified and ignored.