LAUSR

With Accelerator Mass Spectrometry (AMS) ultra-low isotopic abundances (10–12 to 10–16) of long-lived radionuclides, both natural and anthropogenic, are being measured by including an accelerator. Direct atom counting results in an enormous gain in detection sensitivity for long-lived radionuclides as compared to their rare decay. For the most-used radionuclide, 14C (half-life = 5,700 yr), this means that instead of grams of carbon required for beta counting one can use milligrams or even micrograms to determine the 14C content. In addition, an AMS measurement takes less than an hour rather than the several days required for beta counting. The gain becomes even larger for longer half-lives in the million-year range and beyond.