The Interaction of Monoenergetic Positrons with Solid Surfaces

Abstract

Abstract Positrons, the antiparticles of electrons, were discovered by Anderson [1] in 1932. Their existence was experimentally established from observations of cloud chamber cosmic ray tracks that showed the presence of a positively charged particle with the same mass and numerical charge as that of the electron. About one year later positron sources became available as a result of the discovery of artificial radioactivity [2]. Positrons from such sources were found to have continuous energy distributions, ranging from hundreds to thousands of keV. No methods were then known for generating usable intensities of positrons with well-defined energies and, partly because of this, applied spectroscopies were limited. A relatively large area of study developed, however, which provided valuable information about the properties of matter through the measurement of positron annihilation characteristics in different media. Positrons may annihilate with electrons from a free state with the production of two coincid...