Influence of 3γ-annihilation events on o-Ps lifetime and intensities in mesoporous materials

摘要

Influence of the differences in the detection efficiencies of 2γ and 3γ events on the positron annihilation parameters have been evaluated in XAD resin samples, where a significant fraction of o-Ps decays via 3γ-annihilation. The contribution of 3γ-annihilation events in the data has been changed by widening the energy window of the stop detector. The intensity of the longest lived component in these samples is foundrnto increase with the increase in the detection window of 3γ events. Small but significant increase in life-time with increase in the detection window of 3γ-annihilation events is also observed. This is attributed to the inherent pore size distribution in the samples. A correlation between the increase in the lifetime and pore size distribution is established.