The amount of carbon dioxide in the atmosphere today is higher than that at any time in the last 420,000 years (figure 1).
C facility is dedicated to providing radiocarbon measurements on carbon-bearing materials spanning the last 45,000 years.
The facility operates a National Electrostatics Corporation 500k V 1.5SDH-1 Compact Accelerator Mass Spectrometer optimized with a second einzel lens and solid ion source typically generating C beam currents in the range of 120-150 µA.
Thus a 1 mg sample of infinitely old carbon would measure at least 0.1 p MC (percent modern carbon) before background subtraction...
The third contribution, instrument background, has a number of sources.
This is the key to achieving predictive understanding of the carbon cycle.