usgs logo

U.S. Geological Survey - TRIGA Reactor (GSTR)

Maps, Imagery, and Publications Hazards Newsroom Education Jobs Partnerships Library About USGS Social Media

Fission Track Experiments

This technique measures the spatial distribution of trace amounts of fissile and fissionable materials in a variety of solid materials, at a microscopic scale. Fission of 235U is induced during slow neutron bombardment. Fission fragments emitted from the polished surface of a small sample are recorded as a visible image of fission tracks in a "detector" of mica that is placed over the sample. The density of recorded fission tracks is directly proportional to the uranium concentration in the sample. This low cost spatial–chemical measurement of U can only be duplicated by the most advanced microbeam analytical instruments. Recent applications include screening of suitable samples for dating by U–series or UPb methods, measuring U distribution in small particles of coal fly ash, and determining mineral hosts of U in polished thin sections of natural or contaminated rocks and soils. In some cases the distribution of U can be used as a proxy to suggest the residence of other trace elements of environmental concern such as radium, or arsenic.

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior U.S. Geological Survey
Page Contact Information: Ask USGS
Page Last Modified: Tuesday, 15-Mar-2016 12:01:46 EDT