NONLINEAR X-RAY-PRODUCTION OF DEFECT SPINS IN VITREOUS SIO2 - THE ROLES OF CREATION AND ACTIVATION

The dependence of spin concentration on X-ray dose is shown to be nonlinear in distinctive ways for the three most common defect structures in vitreous SiO2. We fit the data with a model invoking two concurrent simple processes: creation of new defects and activation of preexisting ones. The resultant fit parameters show dependencies on hydroxyl concentration and fictive temperature that shed new light on the processes, the defects, their origins and the radiation hardness of upsilon-SiO2.