Positronium Decay in Silica Sol-Gels

Abstract

ABSTRACTPositronium lifetimes inside porous silica are measured and discussed in terms of surface interactions, oxygen and nitrogen induced quenching and pore sizes. Surface interactions are studied for silica gels having surfaces covered solely with hydroxyl or methoxy groups. A rapid decay of positronium inside the pores filled with gaseous or liquid oxygen is reported and explained in terms of quenching mechanisms. An increase in the measured lifetimes for pores filled with nitrogen is attributed to the change in the pore distribution function.