Dependence of the yield of the short-lived ortho-Ps state on the concentration of CCl 4 in hexane

Abstract

Recently, high-quality positron annihilation lifetime measurements showed that for many liquids four components of the life- time spectra could be resolved. Apart from the well-known three components caused by para-Ps, free positron, and ortho-Ps annihilations, respectively, a new short-lived ortho-Ps component was obtained in many liquids. It is probably caused by secondary reactions of ortho-Ps with other reactants in the positron spur. The first results on the inhibition of the yield of this short-lived ortho-Ps component are reported. The apparent inhibition of the yield of this component by CCl 4 in hexane is seven times weaker than that of the yield of the long-lived ortho-Ps. Furthermore, new information on the state of the free positron in CCl 4/hexane mixtures is reported.