Mass spectrometers detect atoms of specific elements according to their atomic weights.
They, however, do not have the sensitivity to distinguish atomic isobars (atoms of different elements that have the same atomic weight, such as in the case of carbon 14 and nitrogen 14—the most common isotope of nitrogen).
Radiometric dating methods detect beta particles from the decay of carbon 14 atoms while accelerator mass spectrometers count the number of carbon 14 atoms present in the sample.
Both carbon dating methods have advantages and disadvantages.
For older items, isotopes of potassium have been used. Some scientists see no need for two different symbols or abbreviations, as something formed 5 million years before the present would indeed be 5 million years old.They are in favor of one system or set of symbols for all sciences, from geology and chemistry to astrophysics and nuclear physics.It is believed by some to have covered Jesus when he was in the tomb.Carbon-14 dating, however, dates the shroud to the 1260 to 1390.