Irradiation Effect of Glass Containing Cerium

Abstract

The electrical breakdown of shielding window glass is induced indispensably by irradiation, with ⁶⁰Co-gamma-rays. In order to elucidate the mechanism of the breakdown, electrical conductivity and thermally released current in various glasses irradiated as a function of temperatureunder the condition of temperature-gradient have been studied. The electrical conductivity curve of the irradiated cerium glass shows a positive maximum or a negative minimum at 55°C, according as directions of electric field and irradiation are same or reverse. If the directions of tempera ture-gradient and irradiation are same, the thermally released current shows a positive maximum at 55°C and a negative minimum at 75°C, but if reverse, it shows a negative minimum at 55°C and a positive maximum at 75°C. When the samples are irradiated under the rotation, no maxima and minima are observed. It is suggested that the maxima and minima at 55°C are based on the thermal release of trapped electrons which are entered from atmosphere into sample by Compton recoils. The maxima and minima at 75°C imply the thermal release of trapped electrons which are generated within the sample by Compton recoils. The maxima and minima are also observed in the samples containing titanium or vanadium substituting cerium.