Accelerator mass spectrometer dating
Velocity selection is attained by a magnetic field and an electric field that are orthogonal to one another and to the beam direction; they are adjusted so that no deflection takes place for ions of the desired velocity." data-width="600" data-height="300"Be ionized to the 3 charge state.
Measurement of radiocarbon was originally done by beta-counting devices, which counted the amount of beta radiation emitted by decaying atoms in the sample and not just the few that happen to decay during the measurements; it can therefore be used with much smaller samples (as small as individual plant seeds), and gives results much more quickly.
Research has been ongoing since the 1960s to determine what the proportion of in the atmosphere has been over the past fifty thousand years.
The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age.
accelerator mass spectrometer with application to 10Be.
Negative ions of Be O leave the source and are mass analyzed with 10Be O− directed into the accelerator and 9Be O− into a Faraday cup.