Environmental radioactivity and thermoluminescence: A review

Abstract

A close link exists between environmental radioactivity and thermoluminescence (TL) and this connection can be gainfully employed in (i) environmental radiation surveillance, (ii) radioactive prospecting and (iii) dating. The science of thermoluminescence dosimetry (TLD) is very well established for use in routine radiation monitoring. With the increased public awareness of health effects due to radioactivity releases from nuclear operations. TLDs have become indispensible ‘watchdogs’ in environmental surveillance; in high natural background areas such as the monazite regions, TLDs have yielded invaluable dosimetric data. Over large areas where the cosmic background can be assumed constant, the TLD-recorded radiation profiles can reflected the terrestrial gamma radioactivity distribution pattern and even seasonal variations in the radiation levels above ground may be delineated. A variety of natural materials like minerals, rocks, soils, sands, sediments, fossils, etc., as well as ancient artefacts like potteries and ceramic wares, yield TL even without any irradiation in the laboratory: the natural radioactivity in these materials, together with the radiation incident on them from the environment, causes a TL build-up during antiquity. It is possible to measure this natural TL and relate it to the natural radioactivity of the sample and hence to its age. In contrast, observations of a kind of anticorrelation between TL and a sample's radioactivity have also been made in recent times and the effect is mostly ascribable to alpha-radioactivity-induced damage effects. Typical results from recent investigations of the various aspects mentioned above are presented in this review, with particular emphasis on applications in India.