Calculating age using carbon dating
In AMS, the filiamentous carbon or "graphite" derived from a sample is compressed into a small cavity in an aluminum "target" which acts as a cathode in the ion source.
The surface of the graphite is sputtered with heated, ionized cesium and the ions produced are extracted and accelerated in the AMS system.
Organic materials, which require the most processing, are limited to younger ages by their corresponding process blank.
Due to counting and measurement errors for the blanks and samples, statistical errors are higher for very old samples.
Although one can simply measure older samples for longer times, there are practical limits to the minimum sample activity that can be measured.