RADIOCARBON ANALYSIS BY ACCELERATOR MASS-SPECTROMETRY

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 (MeV) allowing the use of some techniques of nuclear physics to reduce or eliminate backgrounds from molecules and isobars. Sensitivities are achieved which allow detection with high efficiency of trace atoms present in a matrix at about one part in 10(15). Some details of the operation of the instrument at the AMS laboratory at the University of Arizona will be described. Several applications of the method to detect long-lived cosmogenic isotopes (isotopes produced by interaction of cosmic rays with various materials) will be presented.