Editing Solid-state nuclear track detector

{{Short description|Radiation detection method for analyzing nuclear particles}}
[[File:Tracks in CR-39.jpg|thumb|300px|Microscopic photograph of deuteron tracks in [[CR-39]]]]
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]] ([[neutron]]s or [[charged particle]]s, occasionally also [[gamma ray]]s), [[industrial etching|etched]] in a corrosive chemical, and examined microscopically. When the nuclear particles pass through the material they leave trails of molecular damage, and these damaged regions are etched faster than the bulk material, generating holes called ''[[Ion track|tracks]]''.

The size and shape of these tracks yield information about the mass, charge, energy and direction of motion of the particles. The main advantages over other radiation detectors are the detailed information available on individual particles, the persistence of the tracks allowing measurements to be made over long periods of time, and the simple, cheap and robust construction of the detector. For these reasons, SSNTDs are commonly used to study [[cosmic ray]]s, long-lived [[radioactive element]]s, [[radon]] concentration in houses, and the age of geological samples.

The basis of SSNTDs is that charged particles damage the detector within nanometers along the track in such a way that the track can be etched many times faster than the undamaged material. Etching, typically for several hours, enlarges the damage to conical pits of micrometer dimensions, that can be observed with a microscope. For a given type of particle, the length of the track gives the energy of the particle. The charge can be determined from the etch rate of the track compared to that of the bulk. If the particles enter the surface at normal incidence, the pits are circular; otherwise the [[ellipse|ellipticity]] and orientation of the elliptical pit mouth indicate the direction of incidence.

A material commonly used in SSNTDs is [[polyallyl diglycol carbonate]] (also known as CR-39). It is a clear, colorless, rigid plastic with the chemical formula C<sub>12</sub>H<sub>18</sub>O<sub>7</sub>. Etching to expose radiation damage is typically performed using solutions of caustic alkalis such as [[sodium hydroxide]], often at elevated temperatures for several hours.

==See also==
*nuclear track detectors that are not solid state
**[[cloud chamber]]
**[[bubble chamber]]
*solid-state (semiconductor) nuclear detectors that do not record tracks
**[[silicon detector|surface-barrier detector]]
**[[silicon drift detector]]
**[[lithium-drifted silicon detector]] - Si(Li)
**[[intrinsic detector]]

==External links==
* Gregory Choppin, [[Jan-Olov Liljenzin]], Jan Rydberg '''Radiochemistry and Nuclear Chemistry''', [http://book.nc.chalmers.se/KAPITEL/CH08NY3.PDF Chapter 8, "Detection and Measurement Techniques"]{{dead link|date=May 2018 |bot=InternetArchiveBot |fix-attempted=yes }}

[[Category:Nuclear physics]]
[[Category:Particle detectors]]