Fast ions create linear trails of intense atomic disorder in many solids. The particle tracks are in themselves scientifically interesting because they consist of unique, localized radiation damage. They also are noteworthy for their diverse practical uses, which range from improved high field superconductors to mineral exploration and bird altimetry. The two areas—what tracks are and what they do practically—are the subjects of this introduction and the following three articles. Although the mechanism for producing tracks in insulators is semi-quantitatively well-established, there is a distinct mystery as to the formation mechanism in superconductors, inter-metallics, and metals. This mystery is the subject of the next two articles written by discoverers of tracks in these materials.

We will not discuss in detail the multitude of scientific uses for these tracks as particle-track detectors. Uses range from nuclear, elementary-particle, and cosmic-ray physics to geochronology, geochemistry, and geophysics; chemistry; and radiobiology. The interested reader can learn more on the subject through a book, part of which surveys scientific applications of particle tracks in solids. The key to these uses—and most of the practical uses—is that, in materials where tracks can be observed, either directly or by a widely applicable trick to be described, each detector sample is a nuclear particle-track chamber—the solid-state equivalent of the well-known gaseous and liquid detectors (i.e., cloud chambers and bubble chambers). The major distinction is that tracks in solids are long-lasting rather than transient features.