The Science of Radiocarbon Dating Essay

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The Science of Radiocarbon Dating

When we think of history, we think of important people, places, cultures, events, and much more. The backbone of history rests on its chronology. It gives us the "when" of basic analysis. It gives us a frame of reference, the order of things. Before having an "absolute" way of determining dates, history was based in guesses and assumptions. Many attempts were made to organize the dates of the past. Some of these attempts were made by geologist. Geologist used the idea of "stratigraphic succession" (Renfrew, 1973) which is based on the "principle that when successive layers or strata are observed in position, the underlying ones are the earliest." (Pg. 23 Renfrew, 1973) By setting the layers in
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This changed history forever. While it created controversy, due to some people’s attachments to the old ways of dating and doubts in this revolutionary method, it proved to be the closest method to have an accurate chronology of history. In 1955, to prove the accuracy or radiocarbon, Libby published a graph that showed the comparison of the results of radiocarbon dating of specimens from Egypt. These specimens had already an absolute known date. The graph proved the accuracy of Libby’s radiocarbon dating. Figure 1 (Renfrew, 1973)
Libby developed the method of radiocarbon dating though his observation of how cosmic rays create radiocarbon. From outer space cosmic rays infiltrate earth’s atmosphere. In the upper atmosphere, these rays hit nitrogen and oxygen atoms in the air. (Renfrew, 1973). When the neutrons of these high–energy particles (mostly protons) hit nitrogen atoms, Carbon 14 (C-14) is created. The nitrogen atom (atomic number 7) has an atomic mass of 14 (with 7 protons and 7 neutrons). When the nucleus of the nitrogen is hit by the cosmic ray’s neutrons, the atomic number of the atom decreases by one. The make-up of its atomic mass changes, a proton is emitted and the neutrons are increased by one; therefore, the atomic mass number stays the same. Because the atomic number has changed, a new element, carbon 14, with atomic number 6, has an atomic mass of 14 (with 6 protons and 8 neutrons). (Bowman, 1990) The reaction is 14N + n = 14c + p (where n is a
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