Radiocarbon dating process
Carbon-13 and carbon-14 are thus isotopes of carbon-12.
Isotopes participate in the same chemical reactions but often at differing rates.
3.5 decays/gram/minute of carbon would be produced by a sample 11,460 years old.
However, atmospheric testing of nuclear weapons in the late 1950's and early 1960's greatly increased the amount of radiocarbon in the atmosphere, so the decay rate of 14 decays per minute more than doubled.
This can be overcome by calibration curves calculated by dating materials of precisely known age.
The best samples are tree rings, but annually laminated sediments have also produced excellent results. Chudy, Eristavi, Pagva, Povinec, Sivo, and Togonidze. Anthropogenic 14C variations in atmospheric CO2 and wines.
The Beta-counting method detects the rate at which purified carbon decays. A rate of 7 decays/gram/minute would indicate an age of one half-life, or 5730 years old.
All carbon atoms have a nucleus containing six protons.
Ninety-nine percent of these also contain six neutrons.
In fact, the natural production of radiocarbon has varied as well.
Before the industrial revolution, from 1800 - 1400 AD, the natural production of radiocarbon was high, so dates are "too young." From 1400 AD to 300 BC they are "too old," and prior to 300 BC , they are too young.