Monoenergetic positrons beams are applied in a large variety of experiments in solid state physics and material science. Examples are spatially resolved defect maps of plastically deformed or irradiated metals, non-destructive investigation of layered systems, the annealing behavior of defects or the free volume in polymers. At the surface, the annihilation of positrons with core electrons initiates the emission of Auger-electrons that allows the examination of the topmost atomic layer. In addition, the electronic structure such as anisotropies of the Fermi surface can be studied too.
Within this talk the basic properties of positron annihilation studies will be explained. The benefit of positron beam experiments will be elucidated by selected experiments, such as (i) defect sensitive positron lifetime experiments, (ii) elemental selective (coincident) Doppler broadening spectroscopy of the annihilation line, (iii) angular correlation of annihilation radiation experiments, and (iv) time dependent positron annihilation induced Auger-electron spectroscopy. The neutron induced positron source NEPOMUC provides the world's highest intensity of more than 109 moderated positrons per second. An overview of the NEPOMUC beam facility and the positron instrumentation is given and future developments and applications of the high-intensity positron beam will be discussed.
