Thermoluminescence dosimetric properties of beryllium oxide

Abstract

Beryllium oxide (BeO) displays strong thermoluminescence (TL) together with tissue - equivalent properties which underline its application as a TL dosimeter. In the dosimetry of X- and γ-rays some of the advantages of BeO over other TL materials are its commercial availability, low cost, chemical inertness, non-toxicity (as a ceramic), high sensitivity to ionizing radiations, good reproducibility of response, low fading, absence of low-temperature peaks and moderate energy dependence. Various authors have reported glow curves of BeO TL phosphor, whose dominant dosimetric peak lies between about 160 and 200 °C. The position of this peak, however, depends upon the type of the radiation used for exciting the phosphor. Although fading of TL is nominal when kept in the dark, the γ-exposed BeO phosphors fade faster when exposed to ambient light. When exposed to γ-radiation, these phosphors exhibit linearity from a minimum of about 1 mrad (1 rad =10-2 gray) up to approximately 10 rad, above which there is supralinear behaviour, and the concentration of impurity ions in BeO is reported to expand the linearity region. Ceramic samples have been reported to exhibit a roughly flat response when exposed to X-rays of 30–115 keV and γ-rays of 60Co. Because their response to thermal neutrons is negligible compared to the γ-response, the use of BeO has been suggested to measure the γ-component in the (n, γ) mixed fields.