CRIM 356 Lecture Notes - Lecture 8: Nuclear Weapons Testing, Magnetic Moment, Carbon Cycle
17 Nov 2020
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Discovered by willard libby & ernest anderson in 1946. Atmospheric co2 contains about 99% 12c, small amounts of 13c & even smaller amounts of 14c. Only 14c radioactive & has half life of 5730 +/- 40 years. 14c usually produced by interaction b/w thermal neutrons &14n in upper atmosphere. Co2 (& hence radioactive 14c) in atmosphere is taken up by plants through photosynthesis. Since plants are at base of much of food chain, net result - every organism has same radiocarbon to stable carbon ratio as atmosphere. Ratio has & continues to change over time. Once organism dies, 14c no longer updated. Radioactive 14c present in organism decays at given rate according to half life. But any carbon introduced after death will contaminate apparent age. Web - chat will throw up huge number of opinions, some very coherent. Recent work on face area identified blood stain as belonging to blood group ab.
