Radiation F-center production in LiF at and above room temperature

Abstract

Radiation defect production in LiF has been measured at and above room temperature as a function of dose, dose rate, temperature, impurity content and pre-irradiation sample deformation. Emphasis has been placed on the growth rate of the 250 nm F band and the ratio α₄₄₅/αF² where α₄₄₅is the absorption coefficient at the peak of the 445 nm F-aggregate band. Comparison of the behavior of LiF with that of KCl indicates that the dose rate and temperature dependences of LiF can be accounted for in terms of the mobility of the F⁺ center (negative ion vacancy containing no electron) in the same way as they are for KCl and other alkali halides. On the other hand, the effect of trace impurities on the defect production rate appears to be different in LiF than in KCl. For example, among several impurities only Mg produces a significant increase in the F-center production efficiency. Also, no rapidly saturating early stage coloration can be observed for any impurity.