RADIOCARBON DATING
Principles of the method, its development in the laboratory, and applications for dating archeologic artefacts are discussed. Theoretical aspects of C/sup 14/ formation from cosmic radiation and calculations demonstrating the validity of using C/sup 14/ content of animal and vegetable matter for age determination are outlined. It is concluded that the agreement between the predicted and observed assays of C/sup 14/ is adequate evidence that the cosmic rays have indeed remained constant in intensity over many thousands of years, and that the mixing time, volume, and composition of the oceans have not changed either. On the assumption that organic matter, while it is alive, is in equilibrium with cosmic radiation; that is, all the C/sup 14/ atoms that disintegrate in human bodies are replaced by the C/sup 14/ contained in food, so that while alive, humans are part of a great pool that contains the cosmic ray- produced C/sup 14/. Cosmic produced C/sup 14/ atoms are assimilated at just the rate that the C/sup 14/ atoms in the body disappear to form N/sup 14/. At the time of death, however, the assimilation process stops abruptly. Development of measurement techniques is discussed, particularly the problems of shielding necessitated by lowactivity samples. The C/sup 14/ counting apparatus is described in detail and illustrated. After developing a technique that could measure natural carbon relatively inexpensively with the requisite accuracy, attempts were made to determine whether the assumption that the variation of radiocarbon production due to the variation of the cosmic rays with latitude, which is very strong, would be wiped out by the movement of the winds and the ocean currents in the 8000 yr lifetime of C/sup 14/. Evidence validating this assumption is discussed. Studies dating various artefacts and comparison with their known ages are extensively reviewed. The problems introduced by the release of fossil CO/sub 2/ into the atmosphere by combustion of coal and oil, resulting in dilution of biospheric C/sup 14/, and by C/sup 14/ formation from neutron capture by N/sup 14/ during nuclear explosions are discussed. Applications of C/sup 14/ dating in geology, oceanography, meteorology, and archeology are reviewed. Construction of a portable radiocarbon dater, that will allow work in the field with the archeologists and geologists in obtaining dates and that is nearly as accurate as those obtained in the laboratory, is discussed. (BBB)
- Research Organization:
- Univ. of California, Los Angeles
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-012369
- OSTI ID:
- 4112665
- Journal Information:
- Annals of Internal Medicine (U.S.), Journal Name: Annals of Internal Medicine (U.S.) Vol. Vol: 59; ISSN AIMEA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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