DOSE-RATE DEPENDENCE IN THE PRODUCTION OF POINT-DEFECTS IN QUARTZ

A model has been developed which generates the complex shapes of the experimentally observed production curves for aluminum-associated trapped hole centers in hydrogen-swept quartz. All of the aluminum ions are initially charge-compensated by an adjacent hydrogen ion (in the form of an OH-molecule). Radiation dissociates the hydrogen from the aluminum and forms two separate defects, a trapped hole center and an interstitial hydrogen atom. The hydrogen atom rapidly migrates along a c-axis channel and either (1) becomes trapped or (2) recombines with a hole center to restore the original lattice. Hydrogen atoms become trapped as di-interstitials (i.e., as H-2 molecules) in our model. Rate equations have been developed for this sequence of events, and computer-generated solutions are compared with experimental ESR data. A variation of this model in which the hydrogen atoms are assumed to be singly trapped did not agree with experiment.