The large amount of energy released in the fission process ejects the two nuclear fragments into the surrounding material, causing damage paths called fission tracks. These tracks can be made visible under light microscopy by etching with an acid solution so they can then be counted. The usefulness of this as a dating technique stems from the tendency of some materials to lose their fission-track records when heated, thus producing samples that contain fission-tracks produced since they last cooled down.
The useful age range of this technique is thought to range from years to million years before present BPalthough error estimates are difficult to assess and rarely given. Generally it is thought to be most useful for dating in the window between 30, andyears BP.
A problem with fission-track dating is that the rates of spontaneous fission are very slow, requiring the presence of a significant amount of uranium in a sample to produce useful numbers of tracks over time. Additionally, variations in uranium content within a sample can lead to large variations in fission track counts alabama minor dating laws different sections of the same sample. Because of such potential errors, most forms of fission track dating use a form of calibration or ""comparison of spontaneous and induced fission track density against a standard of known age.
The principle involved is no different from that used in many methods of analytical chemistry, where comparison to a standard eliminates some of the more poorly controlled variables.
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