A cyclotron is sometimes used for carbon dating
At this stage, other negatively charged atoms are unstable and cannot reach the detector.
When the samples have finally been converted into few milligrams of graphite, they are pressed on to a metal disc.Ions from a cesium gun are then fired at the target wheel, producing negatively ionized carbon atoms.These negatively ionized carbon atoms pass through focusing devices and an injection magnet before reaching the tandem accelerator where they are accelerated to the positive terminal by a voltage difference of two million volts.Accelerator mass spectrometers need only as little as 20 milligrams and as high as 500 milligrams for certain samples whereas conventional methods need at least 10 grams in samples like wood and charcoal and as much as 100 grams in bones and sediments.
Accelerator mass spectrometers typically need sample sizes lesser than conventional methods by a factor of 1,000. Hence, because of its ability to analyze samples even in minute amounts, accelerator mass spectrometry is the method of choice for archaeologists with small artifacts and those who cannot destroy very expensive or rare materials.An accelerator mass spectrometer has a run time of a few hours per sample.