radioactive dating سنیابی ِ پرتو-ژیرا sen yâbi-ye partow-žirâ
*Fr.: datation radioactive*
Determining the age of an object from the → *radioactive decay*
of its constituting material. The technique consists of comparing the
→ *abundance*
ratio of a → *radioactive isotope* to its
→ *decay product*. This will yield the number of
half-lives that have occurred since the
sample was formed. More specifically, if an object is made up of 50 % decay product
then it has gone through 1 → *half-life*.
75% decay product equals 2 half-lives, 87.5% decay product equals 3 half-lives,
93.76% decay product equals 4 half-lives, and so on. For example,
the decay product of → *uranium*-238 (^{238}U) is
→ *lead*-206 (^{206}Pb).
The half-life of ^{238}U is 4.5 billion years. Hence, if the sample has gone
through two half-lives, it is 9 billion years old.
See also: → *radiocarbon dating*. → *radioactive*; → *dating*. |