ABSTRACT
For routine dosimetry, several TLD materials have been used, each having its
own definite properties. In this paper, the physical TL properties of the three used
commercial thermoluminescent (TL) materials, [ LiF (TLD-100), CaF2:Dy (TLD-200)
and CaSO4:Dy (TLD-900) ], have been studied in order to identify the efficiency of the
optimum material for gamma radiation measurements. The main investigated
dosimetric properties are glow curve structure, sensitivity, dose response, fading,
memory effects and sensitization.
The experimental results show that the glow curve structure of the , TLD-100
includes 4 glow peaks at 135, 182, 210 & 230 oC , TLD-200 includes 2 peaks at 179
& 240 oC and TLD-900 includes 3 peaks at 123, 220 & 338 oC. The sensitivity of
TLD-200 was found to be 9-20 times greater than the standard one (TLD-100), but
for TLD-900, it was found 8-13 times greater than the standard one. It was found that
the TL response of the three phosphors fit to a straight line in the logarithmic scale
from, 50 μGy – 5 Gy , 50 μGy – 10 Gy and 5 μGy – 10 Gy, respectively. The fading
values were found to be ≈ 7.5 & 20.1 %, 14 & 32% and 10.4 & 12 % for the three
phosphors, respectively, after the storage for 3 months at 25 & 50 oC, respectively.
From the results which previously mentioned, calcium Sulphate doped by dysprosium
has been selected for local preparation.