Studies of radiation damage in crystals using nuclear-track and thermoluminescence methods

Abstract

The radiation damage in three types of U-rich crystals, viz. zircons, sphenes and apatites, has been studied using nuclear-track and TL methods. Fossil fission tracks have been used as a convenient means of gauging the degree of natural radiation damage, and the TL signal as the indicator of the resulting impairment of the crystal lattice. A clear inverse relation is found between the natural TL (as well as the TL sensitivity) and the fission track density. Artificial damage, produced by 40 MeV α's and 8 MeV/nucleon U ions, also adversely and progressively affects the TL sensitivity. Annealing out of the radiation damage, whether natural or artificial, restores the TL sensitivity progressively as the preannealing temperature is increased. In the case of apatites, however (but not zircons or sphenes), annealing beyond ∼ 800 °C (for 1 h) causes the TL sensitivity to start declining from its maximum value.