Tracks to innovation

by R. L. Fleischer

In the early 1960s, it was discovered that when mica is exposed to energetic charged particles (from radioactive decays or cosmic rays, for example), the particles leave latent tracks in the material. Three scientists at General Electric (Buford Price, Robert Walker, and the author) found that chemically etching such an irradiated material reveals the tracks as narrow, deep pits, whose size and shape are determined both by the particle that made the track, by the material in which the track is made, and by the technique used in etching. It soon turned out that glass, plastics, or certain other materials can similarly be used to detect nuclear particles. This discovery paved the way not only for a new and useful method of detecting nuclear radiation, it has also found widespread applications in other fields. Fleischer presents the history of these developments and discusses the applications of the technique in a way that will be of interest to anyone with a minimal knowledge of physics.