C14 carbon dating process
The method was developed by Willard Libby and his colleagues at the University of Chicago in 1949.
In 1960, he was awarded the Nobel Prize in Chemistry for this work.
However, cosmic radiation constantly collides with atoms in the upper atmosphere.
Part of the result of these collisions is the production of radiocarbon (C, pronounced "c fourteen"), carbon atoms which are chemically the same as stable carbon, but have two extra neutrons.
is a term for radiocarbon dating based on timestamps left by above-ground nuclear explosions, and it is especially useful for putting an absolute age on organisms that lived through those events.
In The Cosmic Story of Carbon-14 Ethan Siegel writes: The only major fluctuation [in carbon-14] we know of occurred when we began detonating nuclear weapons in the open air, back in the mid-20th century.
As we mentioned above, the carbon-14 to carbon-12 ratio in the atmosphere remains nearly constant.
The unstable carbon-14 gradually decays to carbon-12 at a steady rate. Scientists measure the ratio of carbon isotopes to be able to estimate how far back in time a biological sample was active or alive.
This plot shows the level of carbon-14 in the atmosphere as measured in New Zealand (red) and Austria (green), representing the Southern and Northern Hemispheres, respectively.
Radiocarbon is not stable; over time radiocarbon atoms decay into nitrogen atoms.
This tendency to decay, called radioactivity, is what gives radiocarbon the name radiocarbon.