Studying of Common Factors Affecting Reading of Lithium Fluoride Thermo-Luminescence Dosimeter Crystal

Abstract

The aim of this study was to study the technical factors affecting the reading of TLD (LiF:Mg:Ti) for radiation dosimetry. The method adapted was an exposure of LiF:Mg:Ti crystal with γ-ray with the following filters (Hp 0.07 and Hp 10), before and after usage of filter Hp (0.07), annealing, cooling by nitrogen flux and crystal morphology by scanning electron microscope. The collected data analyzed by EXCELL software showed that: TLD average count/second (C/s) with filter Hp (10) was greater than that obtained with filter Hp (0.07) with an amount of 1191 c/s (19%). Also the analysis showed that: the average C/s without filter Hp (0.07) was greater than that with filter by an amount of 994.5 C/s (16.4%), and there was proportional linear relationship; as the applied dose increased the TLD C/s increased significantly (R2 = 0.9) based on the equations: y = 885.1x ? 286.5 and y = 860.5x + 856.8 for filtered and without filtered beam respectively, where x refers to applied dose in mGy and y refers to C/s. Also the average C/s without nitrogen flux (cooling) was greater than with nitrogen count with an amount of 52.4 C/s (11%). The annealing (without filter) causes a reduction in dose by 82.2 μGy (19.2%), and in case of annealing with filter, the dose reduced by 66.7 μGy (21.9%) relative to annealing without filter. The morphology of TLD crystal shown by scanning electron microscope SEM was a darkening surface after irradiation.