SOLID STATE NUCLEAR TRACK DETECTORS AND THEIR APPLICATIONS

摘要

Solid State Nuclear Track Detectors (SSNTDs) [1-2] are insulating solids both naturally occurring and man-made. There are several types of these detectors including inorganic crystals, glasses and plastics. When a heavily ironising charged particle passes through such insulating solids, it leaves a narrow trail of damage about 50 A in diameter along its path. This is called latent Track' as it cannot be seen with the naked eye. It is possible to view this latent track with an electron microscope. The exact nature of the physical and chemical changes occurring at the damage site depends on the charge (Z) and velocity (p = vie, where v is the particle velocity and c is the velocity of light) of the particle, on the chemical structure of the detector material and also on the environmental conditions like temperature and pressure. These latent tracks can be enlarged developed so that they can be viewed under an optical microscope by etching with some chemicals such as sodium hydroxide and hydrofluoric acid. Examples of some commonly used solid state nuclear track detectors are given in Table-1. A list of chemical etchants generally used along with the etching conditions for different detectors, particle sensitivity and the critical angle of etching are also given in Table - -1. General properties of some of the most widely used plastic track detectors are listed in Table - 2.