Effect of fission fragments on the electric properties of phosphate glasses and their application in personal neutron dosemetry

Abstract

This work represents a development in fast neutron dosemetry using phosphate glass in which radiation damage was registered. The damaging effects of fission fragments and fast neutrons on the dielectric constant and loss and d.c. electrical resistivity of zinc and iron phosphate glasses were measured. The results indicated the increase of both dielectric loss (ϵ″) and electric resistivity (ρ d.c. ) of the zinc phosphate specimens after being irradiated with fission fragments. An increase of 300% in ρ d.c. and 195% in ϵ″ were induced in the samples after exposure to a neutron fluence of 2.1×10 7 n cm -2 . However, iron phosphate glasses did not show significant changes after irradiation with fission fragments. Irradiation with gamma-doses up to 5 kGy did not cause measurable changes in both glass specimens properties. Electrical properties measurements and X-ray diffraction studies proved that the most predominant bulk effects of fission fragments on phosphate glasses is the decrease of the crystalline sites in the zinc phosphate samples and increase in the crystallinity of the amorphous sites in the iron phosphate glasses. Storage of the irradiated samples at 45°C for periods of up to 2 weeks did not cause measurable fade in the induced changes in both sets of glasses. This technique enables measurements of neutron fluences, in mixed fields, without interference of the associated gamma-component in the range from 10 5 up to 10 10 n cm -2 .