Evaluation will be based on the scientific significance of the proposed work and on the likelihood that a given project will lead to further, funded research. This policy will be discontinued after a representative sampling of replicates has been obtained. It occurs naturally in the atmosphere at an equilibrium level of 1 in 1,000,000,000,000 relative to the most abundant C-12. C-14 is continually produced in the upper atmosphere by nuclear reaction of nitrogen with cosmic radiation. 30 years, Libby's original value is the conventional basis for radiocarbon date calibration.
Carbon is a part of a wide variety of organic and inorganic chemical compounds.
20 years one needs 160,000 counts, or about 8 days of beta-counting. Please view our General Statement of C-14 Procedures . You'll need Adobe Acrobat Reader.