F-Centres in Metaphosphate Glass
A NUMBER of investigators1 have shown that glass on exposure to radioactive and X-radiation becomes coloured. Sheline, Sharp and Arner2 suggested that this may be due to F-centres similar to those produced in alkali halides when bombarded by X-rays and cathode rays. Yokota3 found that F-centres could be created in fused silica and α-quartz by X-irradiation. He further showed that alkali silicate and borate glasses become coloured on X-irradiation due to formation of F-centres4. Przibram5 showed that F-centres could also be created in borate glass by β- and γ-irradiation from radium.
Dosimetry of X‐Rays and Gamma‐Rays by Radiophotoluminescence
The effects of high energy radiation on the luminescence properties of solids are surveyed. Of the four effects considered—radiophotoluminescence, radiophotostimulation, radiothermoluminescence, and the ``killing'' of luminescence by x‐rays or gamma‐rays—the first effect is shown to have advantages in principle over the others as a basis for dosimetry.The absorption, excitation, emission, sensitivity, energy dependence, and stability characteristics of a radiophotoluminescent Ag‐activated phosphate glass are described. It is shown that dosage measurements can be made with this material, employing a simple fluorophotometer, from 10 roentgens to a few thousand roentgens of gamma‐rays. By proper shielding, such a dosimeter element can be made reasonably independent of energy. The dosage indication obtained is quite stable with time and is not seriously affected by exposure of the glass to visible or ultraviolet light or to temperatures in the range of −70° to +100°C. Because of its sensitivity range and its ...
Distribution of Fluorescence Excitation of Bivalent Europium in Calcium Fluoride and of Bivalent Samarium in Calcium Sulphate
IN the course of the investigation of the fluorescence of fluorite conducted in the Institut fur Radiumforschung, Vienna1, it seemed desirable to determine the distribution of excitation in fluorite for the blue Eu + + band.