Positrons as a Probe of the Solid State.

The article focuses on the positron, the antiparticle of the electron which is an instrument of exploring the nature and properties of matter. When positron collides with the electron, they annihilate and their mass is converted into pure energy in the form of gamma rays which yields unique information on the atomic structure of substance. The same process sets when a positron and electron annihilate in condensed matter either in solid and liquid. This positron-electron system illustrates the basic conservation laws found in nature.