SECONDARY REACTION OF PS IN THE POSITRON SPUR

Recently, high-quality positron annihilation lifetime measurements sho wed that four components of lifetime spectra for many liquids could be resolved. The well-known three components (para-Ps (positronium), fre e positron, and ortho-Ps) and a short-lived ortho-Ps component were ob tained in many liquids. This short-lived ortho-Ps is probably caused b y secondary reactions of ortho-Ps and other reactants, such as a posit ive ion, in the positron spur. We report the first results of measurem ents of the yield of this short-lived ortho-Ps component in the system of hexane and the electron scavengers CCl4, CS2, C6F6, and SF6.