Solid-state nuclear track detector

A solid-state nuclear track detector or SSNTD (also known as an etched track detector or a dielectric track detector, DTD) is a sample of a solid material (photographic emulsion, crystal, glass or plastic) exposed to nuclear radiation (neutrons or charged particles, occasionally also gamma rays), etched in a corrosive chemical, and examined microscopically.

The size and shape of these tracks yield information about the mass, charge, energy and direction of motion of the particles.

For these reasons, SSNTDs are commonly used to study cosmic rays, long-lived radioactive elements, radon concentration in houses, and the age of geological samples.

Etching, typically for several hours, enlarges the damage to conical pits of micrometer dimensions, that can be observed with a microscope.

Etching to expose radiation damage is typically performed using solutions of caustic alkalis such as sodium hydroxide, often at elevated temperatures for several hours.