The effect of γ-irradiation on positronium formation in polyethylene

Abstract

The effect of γ-irradiation on positronium (Ps) formation, especially the decrement of Ps formation at room temperature, was studied in linear poly(ethylene). We found that chemical changes, such as oxidation, cross-linking, or radicals created by γ-irradiation of ∼50 kGy do not affect Ps formation very much. The decrement of Ps formation was probably caused by a temporary change of physical structure by irradiation that disappears by anneals in the temperature range from room temperature to 120°C, gradually.