Point defects and the blue emission in fired quartz at high doses: a comparative luminescence and EPR study.

The dose response of the 375 degrees C. 470 nm TL peak in fired quartz is studied by using thermoluminescence emission spectra and monochromatic glow curves. The blue emission displays a significant sensitivity increase for doses in excess of 1000 Gy, subsequent saturation at 16 kGy and a pre-dose effect over the entire dose range. Comparison with the growth of the known electron paramagnetic resonance (EPR) centres and radioluminescence emission spectra indicates that the [AlO4] centre is the recombination site for the blue emission, whereas the electron trap remains unknown. The sensitivity change seems to be linked to the dose-induced reduction of the [GeO4/Li] centre. Possible mechanisms for the observed dose response are discussed.