Development of Positron Annihilation Spectroscopy at Joint Institute for Nuclear Research

The method of Positron Annihilation Spectroscopy (PAS) has been under development and application since 2013 at the Low Energy Particle Toroidal Accumulator (LEPTA) facility in the Dzhelepov Laboratory of Nuclear Problems of JINR. The PAS at the LEPTA is based on the slow positron injector of original design that provides a positron flux of a high monochromaticity. The FWHM of positron energy at the exit of the positron source is of 1.5-3 eV. The positron energy on the target can be varied in the range 50 eV-36 keV (90 keV in the nearest future) with an accuracy of not less than 1%. The first version of a special channel for transportation of the positrons from the source to the target was constructed in 2013. Presently the research is carried out applying the method of the Doppler Broadening of Annihilation Line. In 2018 the channel was developed for application of Positron Annihilation Lifetime Spectroscopy. It will be equipped with instrumentation according to original scheme presented in this article. This article describes three versions of PAS, their peculiarities and specific scheme as well as the parameters of the experimental equipment for PAS used and developed at LEPTA.