Radiocarbon dating definition geology
In order to make allowances for background counts and to evaluate the limits of detection, materials which radiocarbon specialists can be fairly sure contain no activity are measured under identical counting conditions as normal samples. Ninety-five percent of the activity of Oxalic Acid from the year 1950 is equal to the measured activity of the absolute radiocarbon standard which is 1890 wood.
Another standard, Oxalic Acid II was prepared when stocks of HOx 1 began to dwindle. The ratio of the activity of Oxalic acid II to 1 is 1.29330.001 (the weighted mean) (Mann, 1983). There are other secondary radiocarbon standards, the most common is ANU (Australian National University) sucrose.
The ratio of the activity of sucrose with 0.95 Ox was first measured by Polach at 1.50070.0052 (Polach, 1976b:122).