Fission Track DatingFission Track Dating

Stephanie Owens

July 27, 2006

Nuclear and Radiochemistry Summer School 2006

•Performed on etchable, transparent solids:

Minerals, glass, petrified wood, sediment, meteorites

•Comparable to the K-Ar dating method

•Fission tracks were first observed in mica in 1962

•Provides cooling age of a material NOT absolute age

•Tracks form as a result of spontaneous fission, usually 238U

IntroductionIntroduction

MaterialsMaterials

AssumptionsAssumptions

• Uranium must be homogenous throughout the sample and greater than 0.1 ppm.

• Lattice structure of the solid must be intact excluding track damage.

• Chemical weathering must not cause loss of tracks or uranium.

• Induced fission tracks of 235U must not significantly contribute to total tracks.

• 238U is most significant fission species.

• The decay constant for spontaneous fission of 238U is known.

Track FormationTrack Formation

Calculation of AgeCalculation of Age

Decay constant for spontaneous fission

Density of 238U fission tracks

Density of 235U induced fission tracks

Track densities of the sample Track densities of the standard

Materials and Time RangeMaterials and Time Range

Materials and Time RangeMaterials and Time Range

Materials and Time RangeMaterials and Time Range

Seafloor SpreadingSeafloor Spreading

MeteoritesMeteorites

244244PuPu

Fission Track DatingFission Track Dating

Stephanie Owens

July 27, 2006

Nuclear and Radiochemistry Summer School 2006