Age dead sea scrolls found carbon dating
We can equally well use a different standard if we know its relation to "modern," or 1950 AD.Radiocarbon ages are then quoted as "years before present" (BP).In 1977, as already mentioned, two papers (Nelson et al., 1977 and Bennett et al., 1977) were published simultaneously in Science, reporting on the development of such a method, which added a particle accelerator into the mass spectrometer to produce an accelerator mass spectrometer.This technique has allowed the measurement of radiocarbon in samples of much less than a milligram, or more than a thousand times less material than is needed for the older counting methods.
It was recognized that direct measurement of the number of C atoms in the sample would greatly enhance the sensitivity, and several unsuccessful attempts were made in this direction using conventional mass spectrometry.
About one carbon nucleus in a trillion contains two extra neutrons, giving a mass of 14.
This carbon-14 is radioactive and decays with a half-life of 5730 years.
C produced in the atmosphere were always the same, then we could calculate a "radiocarbon age" using the equation we have discussed directly as an estimate of sample age. This was recognized soon after Libby published his first Curve of Knowns (Arnold and Libby, 1949).
The cosmic rays striking the upper atmosphere fluctuate in intensity with time by a small amount due to changes in the magnetic fields of the sun and the earth.