Pushing the limits of high-precision radiocarbon measurements

Accelerator Mass Spectrometry (AMS) is mostly used for radiocarbon dating, because it allows determining efficiently 14C without isobaric or molecular background. While for many years these measurements were performed on large tandem accelerators (3 - 6 MV), this has changed over the last 10 years and compact AMS systems (<500 kV) are now preferably used. The Mini Carbon Dating Systems (MICADAS) developed at ETH Zurich (200 kV) goes beyond what is generally accepted as high-precision radiocarbon measurements and represents the state of the art. The reason for this originates in the compact design that shows more similarities to a stable isotope mass spectrometer than to an accelerator based AMS system. The perspectives of MICADAS are demonstrated on an example of highest-precision measurements of wood samples for the radiocarbon calibration curve. Inflation in radiocarbon dating is expected, when single compounds isolated by analytical techniques like HPLC or GC can be measured. Unfortunately the isolated material is limited to a few micro-gram. MICADAS is equipped with a gas ion source for the direct measurement of CO2 and allows for the first time precise routine radiocarbon dating of micro-gram samples. The impact of the new-generation compact radiocarbon dating systems is discussed.