Exciton-phonon mechanism of the dose rate effect in dielectrics with soft optical phonons

Radiation defect formation in dielectrics has been described theoretically using the model of dispersed admixed centres placed in a crystalline matrix with active phonon mode and strong exciton-phonon interaction. A radiation defect is, in our conception, an anomalously charged admixed centre formed by the decay of exciton in its field. It was shown that the number of such centres at a constant absorbed radiation dose is higher, the lower the dose rate. The parameter of the 'dose rate effect' has been obtained analytically using microscopic parameters of the model. These results are adequate to the experimental data. (author)