Division of accelerators, cryogenics and magnetism

Positrons implanted in a solid annihilate within 100 ps-142 ns with an electron of the host material. The lifetime components as well as the momentum distribution of the annihilation radiation carry valuable information on important properties of the sample. Positrons can be used as very sensitive and selective probes of vacancy defects in metals and semiconductors and to study cavities in polymers and properties of porous insulators. After a short review of positron annihilation spectroscopy the potential use of the SELMA/SOPHI intense positron source in materials research will be discussed.