The prodigious mobilization of science that produced nuclear weapons was so far-reaching that it revolutionized even the study of ancient climates. The radioactive isotope carbon is created in the upper atmosphere when cosmic-ray particles from outer space strike nitrogen atoms and transform them into radioactive carbon.
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- The Remarkable Metrological History of Radiocarbon Dating [II].
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Some of the carbon might find its way into living creatures. After a creature's death the isotope would slowly decay away over millennia at a fixed rate. Thus the less of it that remained in an object, in proportion to normal carbon, the older the object was.
By , Willard Libby and his group at the University of Chicago had worked out ways to measure this proportion precisely. Their exquisitely sensitive instrumentation was originally developed for studies in entirely different fields including nuclear physics, biomedicine, and detecting fallout from bomb tests.
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- Applications of radiocarbon dating.
Much of the initial interest in carbon came from archeology, for the isotope could assign dates to Egyptian mummies and the like. From its origins in Chicago, carbon dating spread rapidly to other centers, for example the grandly named Geochronometric Laboratory at Yale University.
The best way to transfer the exacting techniques was in the heads of the scientists themselves, as they moved to a new job. Tricks also spread through visits between laboratories and at meetings, and sometimes even through publications. Any contamination of a sample by outside carbon even from the researcher's fingerprints had to be fanatically excluded, of course, but that was only the beginning.
Delicate operations were needed to extract a microscopic sample and process it. To get a mass large enough to handle, you needed to embed your sample in another substance, a "carrier.
Frustrating uncertainties prevailed until workers understood that their results had to be adjusted for the room's temperature and even the barometric pressure. This was all the usual sort of laboratory problem-solving, a matter of sorting out difficulties by studying one or another detail systematically for months. More unusual was the need to collaborate with all sorts of people around the world, to gather organic materials for dating.
For example, Hans Suess relied on a variety of helpers to collect fragments of century-old trees from various corners of North America. He was looking for the carbon that human industry had been emitting by burning fossil fuels, in which all the carbon had long since decayed away. Comparing the old wood with modern samples, he showed that the fossil carbon could be detected in the modern atmosphere. Through the s and beyond, carbon workers published detailed tables of dates painstakingly derived from samples of a wondrous variety of materials, including charcoal, peat, clamshells, antlers, pine cones, and the stomach contents of an extinct Moa found buried in New Zealand.
The results were then compared with traditional time sequences derived from glacial deposits, cores of clay from the seabed, and so forth. One application was a timetable of climate changes for tens of thousands of years back. Timothy ; Burr, G. N2 - Radiocarbon dating is an important tool for the determination of the age of many samples and covers the time period of approximately the last 50, years.
The Remarkable Metrological History of Radiocarbon Dating [II]
AB - Radiocarbon dating is an important tool for the determination of the age of many samples and covers the time period of approximately the last 50, years. Some interesting applications of radiocarbon dating to art and archaeology A. Abstract Radiocarbon dating is an important tool for the determination of the age of many samples and covers the time period of approximately the last 50, years.
Keywords Archaeology Art Radiocarbon dating. Archeometriai Muhely , 11 3 , Archeometriai Muhely , Vol.
Timothy AU - Burr, G. PY - Y1 - N2 - Radiocarbon dating is an important tool for the determination of the age of many samples and covers the time period of approximately the last 50, years. Access to Document Link to publication in Scopus.