18 - Thermoluminescent study of borates for dosimetric applications

Abstract

A variety of thermoluminescent materials are being developed for their use in radiation dosimetry where a phosphor material is exposed to some ionizing radiation and the thermoluminescence signal obtained gives the measure of the radiation dose. Nowadays, need of charged particle beams for dosimetric use is on rise because of their use in diagnostic and therapeutic purposes. There is wide range of commercial thermoluminescence dosimeters (TLD) available which have been used in research but new materials are being searched and explored with improved thermoluminescence (TL) characteristics. Borates are the topic of interest in TL dosimetry purposes because of their chemical stability and they show remarkable TL properties when doped with rare-earth activators, copper, manganese ions, etc. Borates are synthesized using different techniques, viz. conventional solid-state reaction method, coprecipitation method, melt quenching technique, etc. and have profound applications in dosimetry. Alkali and Alkaline earth metal borates having close tissue equivalence (Zeff=7.3) are highly sensitive phosphors and find significant use in (TL) dosimeter. Since calcium-based TLDs are highly sensitive so they are used for environmental radiation monitoring. Lithium borate TLDs are can detect very high dose so they are used in high dosimetry. Due to low-temperature synthesis, excellent chemical, physical, and environmental stability, some alkaline earth haloborates having general formula M2B5O9Cl:R (M=Ca, Sr, Ba and R=Cl, Br) are found to have effective luminescent hosts. High sensitivity and linearity in a wide range of absorbed dose, low fading, high resistance against environmental factors like temperature, humidity, light are the characteristics exhibited by borate nanomaterials. So, they find remarkable and potential applications in dosimetry of ionizing radiations for the measurement of heavy dosage using TL phenomena.