ary 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 Libbys 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 earths atmosphere. In the upper atmosphere, these rays hit nitrogen and oxygen atoms in the air. (Renfrew, 1973). When the neutrons of these highenergy 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 rays 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 neutron and p is a proton). The newly formed carbon 14 combines with the airs oxygen creating carbon dioxide; this is quickly assimilated into the carbon cycle. (Libby, 1955)This C-14 is one of the three isotopes of carbon. The other isotopes are carbons 12 and 13. C-14 is different from the other two isotopes because it is unstable or radioactive, hence the name radiocarbon. is absorbed in a nearly constant ratio in all living organisms. Because C-14 is continually created at a constant rate in the upper atmosphere, and distributed throughout the carbon cycle, the ratio of carbon 14 to carbon 12 is remarkably constant in bo...
