Radiocarbon dating by accelerator mass spectrometry
Sensitivities are achieved which allow detection with high efficiency of trace atoms present in a matrix at about one part in 10.Some details of the operation of the instrument at the AMS laboratory at the University of Arizona will be described.Carbon atoms are incorporated into plant tissue (by photosynthesis) then into animal tissue (by ingestion) in nearly the same ratio as in the atmosphere. The Earth's magnetic field, its history, origin and planetary perspective.
High precision data can be achieved by much longer counting times up to 4 h, often on several targets. Standard materials with known 14C/13C ratios are measured in the same way.
Precisions of better than ±2% in measurement of 14C/13C on a single target, an iron-carbon bead containing about a milligram of carbon can be achieved in about one hour's actual measurement time on the target.
Standard materials with known 14C/13C ratios are measured in the same way.
An accelerator mass spectrometer combines the electric and magnetic analyzing elements of a conventional mass spectrometer with a particle accelerator.
Analyses are performed on ions with energies of the order of 10 million electronvolts (Me V) allowing the use of some techniques of nuclear physics to reduce or eliminate backgrounds from molecules and isobars.