γ線照射による遮蔽窓ガラスの着色と電気的性質の変化について

抄録

Coloration of shielding window glass of various kinds by γ-ray irradiation is studied. With Co⁶⁰-1 KC as radiation source, 23°±3°C as irradiation temperature, 10⁵ r/h as irradiation dose rate and 10⁵-10⁷r as total dose, the coloration increases gradually.
Volume resistivity of glass and its change by gamma-ray irradiation are measured. D. C. 100V is applied to a sheet of glass sandwitched between two electrodes to measure the time change of its electric resistance. Quantity of induced space charge by radiation is calculated by time integra-tion of the current which is obtained from reciprocal of the resistance. Resistance of high density glass is found to become minimum - hence the current becomes maximum - at the dose of 10⁶ r and increases as the dose increases, but resistance of medium density glass decreases gradually. Change of the resistance is exponential and the charge is always positive at any dose. This testifies that glass is electretized by radiation. On the other hand, linearity is established between the quantity of space charge and the dose in a range of 10⁵-4×10⁶ r. This suggests the possibility of the electretization to be utilized for dosimetry.
The above not only demonstrates the physical properties of shielding window glass and the effect of radiation on it but seems to help finding the means of preventing glass from breakdown by radiation.