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Unformatted text preview: are independent of time. You can therefore use the amount of Pb 204 to estimate the amount of nonradiogenic Lead. in the RubidiumStrontium decay the SR 87 is added to nonradiogenic Sr 87 , but we can get this latter from: (Sr 87 /Sr 86 ) nonradiogenic = 0.7 Similarly the Ar 40 in the PotassiumArgon decay will be added to the Ar 40 in the air, but, for the nonradiogenic component: (Ar 36 /Ar 40 ) air = 0.00337 We need also the fact that (K 40 /K total ) = 0.000119 Decay to a single daughter element When a simple onetoone decay takes place we have daughter element D produced to the extent: D = P P eLt = P (eLt1) where D=amount of daughter element, P of parent element and P is the original amount of the parent. L here is lambda, the decay rate. Of course by this definition L = ln2/T 1/2 . if P n (= P now) = P eLt then D = P n (e Lt1) so t = (1/L)[/SUP> 1) so t = (1/L)[ln(1 + D/P n )]...
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 Fall '10
 EmilyHoward
 Astronomy

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