A research instrument primarily used in physics to accelerate streams of charged subnuclear particles to high velocities in order to sort and analyze them. This technique is now also used to count carbon isotope atoms for radiocarbon dating. The advantage of this technique over the conventional radiocarbon method is that it requires a far smaller sample size and can potentially provide dates going back to around 100,000 B. P. At present, however, AMS dates generally are for events less than 60,000 years old.