Recent Changes

Several ways of reporting 14C activity levels relative to a standard are in use, but no convention has been established for reporting nuclear weapons testing (post-bomb) 14C levels in samples. We advocate the use of fraction modern with a new symbol F14C to prevent confusion with the previously used Fm, which may or may not have been fractionation corrected (Reimer, Brown and Reimer, 2004. "Discussion: Reporting and Calibration of Post-Bomb14C Data", Radiocarbon 46, p 1299-1304)