Carbon-14 also reveals whether a sample of ivory was removed from an animal before or after the 1989 ban on ivory sales.
“Just the fact that AMS requires only a tiny sample has opened up whole new fields,” says John Southon, co-founder of the AMS facility at the University of California, Irvine.
This isn't a fundamental limit as more accurate measurements could go further back, but at some point you'd simply run out of C-14 atoms.
With our current kit 40-50K years is about the limit.
Step into the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory on any given day, and you may see researchers tracking the dynamics of the Earth’s carbon cycle, searching for signatures of nuclear fuel reprocessing or determining the age of remains from the Chicago Police Department’s cold case files.
These vastly different projects have one thing in common: They all use accelerators to measure levels of carbon-14 and other isotopes.
Radiocarbon dating research has been part of the University of Arizona since 1954.
The AMS Laboratory was founded in 1981 by Professors Douglas J. Damon (Geosciences) with support from the National Science Foundation.
RADIOCARBON dating relies on carbon-14 to decode an object’s age, but the isotope has steadfastly refused to divulge the key to its own unusual longevity.
Samples from the Siloam tunnel, which the books of Kings and Chronicles say was constructed in ancient Jerusalem during the reign of King Hezekiah, have been dated using radiometric techniques by researchers from Israel and the UK.
Amos Frumkin at the Hebrew University of Jerusalem and colleagues at the Geological Survey of Israel and Reading University calculate that the tunnel was built in about 700 BC, and that the biblical text provides an accurate historical record of the tunnel’s construction (A Frumkin et al. To date the tunnel, the researchers measured samples of plants and wood contained within the plaster that lined the tunnel.
But most other atoms that decay in the same way – by converting one of their neutrons into a proton – disappear in less than a day. The nucleus of the carbon-14 isotope has six protons and eight neutrons.
When it decays, one of the neutrons turns into a proton, and also releases an electron and a neutrino.