Effect of Particle Size on the Thermoluminescence of Lithium Fluoride

Abstract

THERMOLUMINESCENCE induced by radiation was one of the earliest ways of detecting ionizing radiation¹ and has now become widely used as a dosimeter in personal monitoring, radiotherapy and specialized investigations. Because of its high sensitivity, wide dynamic range, lack of fading and relative independence of photon energy², lithium fluoride is one of the materials most frequently used for thermoluminescence dosimetry. Recently Zanelli³ has reported that the luminescence efficiency of lithium fluoride varies with the particle size, suggesting that one possible cause of this phenomenon could be the presence of an “inactive” surface layer. This article reports further measurements on the variation in the efficiency of luminescence for small particles with photon energy, and discusses another factor which, in some circumstances, can lead to a decrease in response for small particle sizes. This latter effect and its relevance will be discussed first.