46.7 MB (2.1 MB compressed)
4831 x 3378 pixels
40.9 x 28.7 cm ⏐ 16.1 x 11.3 in (300dpi)
JAMES KING-HOLMES / SCIENCE PHOTO LIBRARY JAMES KING-HOLMES / SCIENCE PHOTO LIBRARY
Radiocarbon dating. A mass spectrometer used in radiocarbon dating. This analyses the amount of carbon-12 (12C) in carbon dioxide, produced by the combustion of the sample in oxygen. The carbon-14 (14C) content is assessed using a linear accelerator, as its mass is so close to nitrogen- 14 from the sample. The ratio of radioactive 14C to stable 12C may be related to the time since the death of the animal or plant being investigated. Convention states that 14C has a half-life of 5568 years (+/-30 years), but this is now thought to be too short. Dates from the process are given either as radiocarbon dates, or as solar dates after corrections have been made.
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