Comments on the effect of gamma-irradiation on positronium formation in polymers at low temperatures

Quantitative description of the effect of gamma -irradiation of PE and PMMA on positronium formation on the trapped electrons at low temperatures is s uggested. The consideration shows that, at least in these substances, the n umber of the trapping centers is probably enough to localize all ortho-posi tronium, and therefore the intensity of the long-lived positronium componen t is dependent mostly on the probability of Ps formation but not on the num ber of the trapping centers.