Radiometric dating
The I – Xe chronometer

I beta-decays to Xe with a half-life of 16.14 ± 0.12 million years. The iodine-xenon chronometer is an isochron technique. Samples are exposed to neutrons in a nuclear reactor. This converts the only stable isotope of iodine (I) into Xe via neutron capture followed by beta decay (of I). After irradiation, samples are heated in a series of steps and the xenon isotopic signature of the gas evolved in each step is analysed. When a consistent Xe / Xe ratio is observed across several consecutive temperature steps, it can be interpreted as corresponding to a time at which the sample stopped losing xenon.
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