Dosimetric properties of a home-Made Calcium Sulfates: Dy TL and environmental measurements

Calcium Sulfates: Dy thermoluminescence dosimeters could be useful for measurements when the dose levels are relatively low. The used material is a home-made Calcium Sulfates: Dy prepared under controlled laboratory conditions with certain activator concentration to optimize its sensitivity and to improve stability of dosimetric traps. The experimental result indicated that the response of the prepared Calcium Sulfates: Dy phosphor to gamma-rays is linear over the range from 0.01 mGy up to 0.57 mGy which is the useful range for environmental application. It was also found that, the energy response is not tissue-equivalent, but this disadvantage could be overcomed by using 0.3 mm lead as a compensation shield. Long term TL storage was investigated and improved by proper choosing of the initial reading temperature. After correction against the recorded fading, the home-made Calcium Sulfates: Dy TL dosimeter could be considered as a suitable technique for application in environmental dosimetry. The results of measurements in 6 locations in Nasr-City, Cairo indicated an average annual background dose of 704+ 40 Gy/y.5 fig.,1 tab