Effect of oxygen impurities on positronium formed in voids of vanadium

Abstract
To clarify the effect of oxygen impurity on positronium (Ps) formed in radiation-induced voids, measurements of the angular correlation of annihilation radiation have been made on vanadium samples with controlled oxygen impurity contents up to 1600 at. p.p.m. after irradiation with 1*1020 fast neutrons cm-2 at about 430 degrees C. It has been shown that contamination of voids with oxygen impurities, presumably on the void surface, leads to Ps formation.