The Effect of Visible Light Irradiation on Positronium Formation in Polyethylene at Low Temperature

The effect of visible light exposing on the ortho-positronium formation in polyethylene was studied. Lifetime spectra of positrons in polyethylene were measured in the temperature range between 50 K and 370 K. It was observed that the visible light quenches the enhancement of ortho-positronium intensity (I$\text{}_{3}$) at lower temperature than ca. 250 K - the glass transition temperature of polyethylene. On the other hand, the lifetime of ortho-positronium component (τ$\text{}_{3}$) was not affected by the presence of the visible light.