Carbon dating used for
One of the frequent uses of the technique is to date organic remains from archaeological sites.
Plants fix atmospheric carbon during photosynthesis, so the level of C level for the calculation can either be estimated, or else directly compared with known year-by-year data from tree-ring data (dendrochronology) up to 10,000 years ago (using overlapping data from live and dead trees in a given area), or else from cave deposits (speleothems), back to about 45,000 years before the present.
A calculation or (more accurately) a direct comparison of carbon-14 levels in a sample, with tree ring or cave-deposit carbon-14 levels of a known age, then gives the wood or animal sample age-since-formation.
Carbon-14 is produced in the upper layers of the troposphere and the stratosphere by thermal neutrons absorbed by nitrogen atoms.
Such deposits often contain trace amounts of carbon-14.
The gas mixes rapidly and becomes evenly distributed throughout the atmosphere (the mixing timescale in the order of weeks).Atmospheric nuclear weapon tests almost doubled the concentration of The above-ground nuclear tests that occurred in several countries between 19 (see nuclear test list) dramatically increased the amount of carbon-14 in the atmosphere and subsequently in the biosphere; after the tests ended, the atmospheric concentration of the isotope began to decrease.One side-effect of the change in atmospheric carbon-14 is that this has enabled some options (e.g., bomb-pulse dating Carbon-14 is produced in coolant at boiling water reactors (BWRs) and pressurized water reactors (PWRs).When cosmic rays enter the atmosphere, they undergo various transformations, including the production of neutrons.
The resulting neutrons ( but attempts to directly measure the production rate in situ were not very successful.Carbon dating the Dead Sea Scrolls refers to a series of radiocarbon dating tests performed on the Dead Sea Scrolls, first by the AMS (Accelerator Mass Spectrometry) lab of the Zurich Institute of Technology in 1991 and then by the AMS Facility at the University of Arizona in Tucson in 1994-95.