The prediction and discovery of the existence of positron (e+)1-4and positronium atom (Ps)5,6led rapidly to the development of a new spectroscopic technique for the study of the structure and composition of matter. The technique quickly expanded across interdisciplinary from physics to chemistry, metallurgy, biochemistry and recently to superconductors. As an early non-destructive andin situtesting tool, positron annihilation spectroscopy (PAS) has been utilized extensively to measure crystal defects.7-9