Positron Applications Sub-Group

Positron annihilation spectroscopy (PAS) is a well-known technique for investigating the structural properties of materials. Because of the purity of the $2\gamma$ signal produced from the annihilation of positrons with atomic electrons, this technique is a very sensitive probe of material defects and constitutes an accurate method for the measurement of the momentum distribution of electrons. Nevertheless, the globally poor availability of intense positron beams at low energies (1-1000 keV) percludes efficient use of PAS. An MeV electron accelerator production of positrons, like that used in the PEPPo experiment, can easily provide two orders of magnitude greater beam intensities than the most powerful nuclear reactor based facility. Adding controlled and flexible polarization capabilities with the PEPPo technique at accelerator facilities, may constitute a technological breakthrough for PAS and help address the lack of low energy positron research facilities world-wide.