Binary potassium-silicate glass irradiated with electrons

Binary potassium-silicate glass of composition 15 mol% K2O + 85 mol% SiO2 was irradiated with 2.5 MeV. The thickness of glass was chosen so as electrons stopped near the back surface. After the high-energy irradiation both, back and top surfaces, were depleted from potassium; the back surface was depleted more than the top one. The decay curves were recorded on pristine glass, and on top and back surfaces of the glass pre-irradiated with high-energy electrons. The incubation times of the top surface increased while the incubation time of the back one decreased in comparison with the pristine glass. Observation of the volume changes induced by the following impaction of 50 keV revealed the top surface is closer to the pristine glass than the back one.