title: Fossil alpha-particle recoil tracks: a new method of age determination.
abstract: The discovery of a new type of fossil nuclear track in mica is reported. This track is produced by the recoil nucleus accompanying the alpha-particle decay of uranium and thorium impurities. The tracks are very short and can be seen with phase contrast microscopy. Measurement of fossil alpha-recoil track densities, coupled with determinations of the thorium and uranium contents, provides a new dating technique analogous to the previously discovered "fission-track method." The primary advantage of the alpha-recoil method is a several-thousand-fold increase in sensitivity over the fission-track technique. The alpha-recoil method should also prove useful in studying the problem of extinct isotopes in meteorites.
authors.forename: W H
authors.initials: WH
authors.lastname: Huang
authors.forename: R M
authors.initials: RM
authors.lastname: Walker