Radio carbon dating techniques

31-Jul-2019 09:46 by 4 Comments

Radio carbon dating techniques

This new method was based on gas and liquid scintillation counting and these methods are still used today, having been demonstrated as more accurate than Libby's original method (3).Willard Libby would receive a Nobel Prize for Chemistry in 1960.

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Bottom line: Radiocarbon dating is a technique used by scientists to learn the ages of biological specimens from the distant past.

It’s not absolutely constant due to several variables that affect the levels of cosmic rays reaching the atmosphere, such as the fluctuating strength of the Earth’s magnetic field, solar cycles that influence the amount of cosmic rays entering the solar system, climatic changes and human activities.

Among the significant events that caused a temporary but significant spike in the atmospheric carbon-14 to carbon-12 ratio were above-ground nuclear test detonations in the two decades following World War II.

The method developed in the 1940's and was a ground-breaking piece of research that would change dating methods forever. Libby calculated the rate of radioactive decay of the C isotope (4) in carbon black powder.

As a test, the team took samples of acacia wood from two Egyptian Pharaohs and dated them; the results came back to within what was then a reasonable range: 2800BC /- 250 years whereas the earlier independent dates (largely the dendrochronology records) were 2625 /- 75 years (3), (5).

If you ever wondered why nuclear tests are now performed underground, this is why.

Most radiocarbon dating today is done using an accelerator mass spectrometer, an instrument that directly counts the numbers of carbon-14 and carbon-12 in a sample.

Here’s an example using the simplest atom, hydrogen. Carbon-14 is an unstable isotope of carbon that will eventually decay at a known rate to become carbon-12.

Radiocarbon dating uses isotopes of the element carbon. Cosmic rays – high-energy particles from beyond the solar system – bombard Earth’s upper atmosphere continually, in the process creating the unstable carbon-14. Because it’s unstable, carbon-14 will eventually decay back to carbon-12 isotopes.

It also has some applications in geology; its importance in dating organic materials cannot be underestimated enough.

In 1979, Desmond Clark said of the method “we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation” (3).

Aboveground nuclear testing almost doubled the amount of carbon-14 in the atmosphere. The black arrow shows when the Partial Test Ban Treaty was enacted that banned aboveground nuclear tests. A special kind of radiocarbon dating: Bomb radiocarbon dating.