Development of positron annihilation spectroscopy at LEPTA facility

The Low Energy Positron Toroidal Accumulator (LEPTA) at JINR proposed for generation of positronium in flight can be used for Positron Anihilation Spectroscopy (PAS). This is the sensitive method for microstructure studies of solid body. The structural defects such as vacancies, vacancy clusters and nanovoids with the size 0.1–10 nm can be detected. In this paper the progress in the development of PAS at LEPTA facility will be presented. The description of Doppler broadening of annihilation gamma line technique and the examples of results obtained on slow positron beam will be shown.