age determination by radioactivity

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• Environmental radioactivity — is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium 90 (90Sr) and technetium 99 (99Tc), are only found on Earth as a result of human activity, and some, like potassium 40 (40K), are only… …   Wikipedia

• dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …   Universalium

• geochronology — geochronologic /jee oh kron l oj ik/, geochronological, adj. geochronologist, n. /jee oh kreuh nol euh jee/, n. the chronology of the earth, as based on both absolute and relative methods of age determination. [1890 95; GEO + CHRONOLOGY] * * *… …   Universalium

• Willard Frank Libby — (17 décembre 1908, Grand Valley, Colorado, États Unis 8 septembre 1980, Los Angeles) est un physicien et chimiste américain connu pour son rôle dans le développement de la méthode de datation par le carbone 14, qui a révolutionné l archéologie.… …   Wikipédia en Français

• Willard F. Libby — Willard Frank Libby Willard Frank Libby (Grand Valley (Colorado), 17 décembre 1908 Los Angeles, 8 septembre 1980) est un physicien et chimiste américain, célèbre pour son rôle dans le développement de la méthode de datation par le carbone 14, qui …   Wikipédia en Français

• Willard Libby — Willard Frank Libby Willard Frank Libby (Grand Valley (Colorado), 17 décembre 1908 Los Angeles, 8 septembre 1980) est un physicien et chimiste américain, célèbre pour son rôle dans le développement de la méthode de datation par le carbone 14, qui …   Wikipédia en Français

• Radiocarbon dating — (sometimes simply known as carbon dating) is a radiometric dating method that uses the naturally occurring radioisotope carbon 14 (14C) to estimate the age of carbon bearing materials up to about 58,000 to 62,000 years.[1] Raw, i.e. uncalibrated …   Wikipedia

• Radiometric dating — (often called radioactive dating) is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.[1]… …   Wikipedia

• Toy safety — Magnetix, a popular construction toy selling over 3.8 million units, was recalled after injuries and a fatality when magnets came loose. Toy safety is the practice of ensuring that toys, especially those made for children, are safe, usually… …   Wikipedia

• Libby, Willard Frank — ▪ American chemist born Dec. 17, 1908, Grand Valley, Colo., U.S. died Sept. 8, 1980, Los Angeles, Calif.       American chemist whose technique of carbon 14 (or radiocarbon) dating (carbon 14 dating) provided an extremely valuable tool for… …   Universalium

• Dosimeter — Fiber dosimeter (see gallery below for view through dosimeter) Dosimeters measure an individual s or an object s[1] exposure to something in the environment particularly to a hazard inflicting cumulative impact over long periods of time, or over… …   Wikipedia